Home » Public Forums » GMCnet » [GMCnet] fan clutches / Nylon fan
| [GMCnet] fan clutches / Nylon fan [message #292780] |
Wed, 23 December 2015 04:32  |
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mark grady
Messages: 70
Registered: November 2015
Location: northern Indiana
Karma: 0
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Jim -
I almost ordered one, and thought that the new clutch - which did set coil
side down for two days before install - would be good. But it was not.
I saw an earlier thread with the debate on larger/heavier/OEM versus more
blades/lighter/less power/more air/not OEM, and seemed to recall that the
severe duty clutch was the 'best' combo for the nylon fan.
Can I assume you've had good reports from the field on these?
I've changed several clutches on our '77, and this is the first out of box
clutch failure. Our fleet mechanic said they often fail if changed in
colder weather. He recommended baking them in the oven for an hour at 200
face down before installing. I can't imagine that the rich creamy silicone
center wouldn't warm up in 3 hours of driving.
The rubber flaps in front of the condenser are good on one side, but the
whole metal filler and flap is missing on the passenger side. So I have
some fabrication and work to do.
I'll get back to this after the holiday...
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'77 + 78 Kingsley
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| Re: [GMCnet] fan clutches / Nylon fan [message #292781 is a reply to message #292780] |
Wed, 23 December 2015 06:52  |
rcjordan
Messages: 1913
Registered: October 2012
Location: Elizabeth City, North Car...
Karma: 1
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>Can I assume you've had good reports from the field on these?
I've put approx 1500 miles on my Royale with John Biwersi's nylon fan. So far, results are very good.
SOLD 77 Royale Coachmen Side Dry Bath
76 Birchaven Coachmen Side Wet Bath
76 Eleganza
Elizabeth City, NC
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| Re: [GMCnet] fan clutches / Nylon fan [message #292798 is a reply to message #292780] |
Wed, 23 December 2015 11:20 |
Chris Tyler
Messages: 458
Registered: September 2013
Location: Odessa FL
Karma: 7
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Senior Member |
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I would think that the nylon fan, having less mass, would use a lighter clutch. But maybe that is offset by the higher air resistance afforded by the extra blades.
On my Tacoma 4.0, the clutch seems pretty light
I heard somewhere that these fans are atually toyota parts, maybe from a different app as I thing the direction of rotation is different
76 Glenbrook
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| Re: [GMCnet] fan clutches / Nylon fan [message #292803 is a reply to message #292780] |
Wed, 23 December 2015 11:55 |
rcjordan
Messages: 1913
Registered: October 2012
Location: Elizabeth City, North Car...
Karma: 1
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Senior Member |
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There is another post here saying that solid hub nylon fans restrict air flow and retard the clutch action. John Biwersi's nylon fan has a solid hub. During the above 1500 miles, I was thinking that the clutch didn't engage very often but wrote that off to the high temp only being around 90f and I was almost always at highway speed.
SOLD 77 Royale Coachmen Side Dry Bath
76 Birchaven Coachmen Side Wet Bath
76 Eleganza
Elizabeth City, NC
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| Re: [GMCnet] fan clutches / Nylon fan [message #292828 is a reply to message #292809] |
Wed, 23 December 2015 18:52 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Has anyone run the new fans with auxilery holes in the steel plate area?
John B and I are trying to find out.
I know it will make a difference, but we would like to hear from people
that has done that.
Gordon S has sent me data to show that it has worked on Ford diesel units.
On Wed, Dec 23, 2015 at 10:40 AM, John Wright wrote:
> Having run John Biwersi Nylon fan for over a year (since Oct 2014,
> purchased at Chippewa Falls GMCMI rally) and about 12K miles, have
> probably run it longer than most. I discovered what I think you need to
> make it work. The fan is 10 blade 2 1/2 pitch unit compared to the 7 blade
> 2 1/2 pitch of the stock fan. It actually takes more torque to spin the
> fan (10 blades VS 7 blades) to move the air but you actually do it at a
> lower RPM, it moves more air, so you barely hear in run. You need to use a
> severe duty fan clutch to spin the fan. A 2747 or similar rated clutch
> will not spin the nylon fan as the fan clutches in this rating only spin at
> 70 to 90% of engine RPM mostly at the bottom end and the additional
> required torque to spin the fan it overpowers the clutch. The 2797 or
> other similar rated fan clutches spins at better than 80 to 90% of engine
> RPM and that it why you hear them when they engage with the 7 blade stock
> fan. The 2947 and 2797 rated clutches are rated for 2 1/2 pitch blades.
> depending on the number of blades per fan.
>
> “STORY TIME” - Actual Experience
> I installed John B's 10 blade fan (Oct 2014) using the 2747 fan clutch
> that I had used with the original 7 blade fan and it was fairly new, less
> 4k Miles. Left Michigan in early January heading to Tucson AZ to spend the
> winter. The weather all the way out to Tucson was cold 60 deg F. I said, “ Boy this is working great, almost never hear the fan
> clutch engage”! In Mid April on the way home we decided to go up to Page,
> AZ on AZ 89 to see Antelope Canyon and then on to 4 corners and then on
> home on I-40. The outside temp was mid 80’s to 90 deg’s F and there were a
> number of medium climbs to get up to Page. North of Flagstaff, on very
> good divided hwy I noticed that the temp gauge was creeping up to about 205
> to 210 and the coach always ran locked in at (195 Robertshaw Thermostat)
> 195 or slightly less with the stock fan. Thinking that we had a failure of
> the fan clutch, we pulled into a rest area that just happened to pop up and
> we changed the fan clutch out with a new 2747 unit. I alway carry a spare
> fan clutch making sure that it is stored in the correct position, with the
> mounting flange up and the clutch assembly down and NOT on its side or
> flange side down. They are not that expensive and I may never need to
> change it one the road. Within 20 miles the temp was climbing again back
> up in the 205+ deg F range. Luck intervened again as a auto parts store
> appeared in the next small town that was on the road. Stopped and bought a
> 2797 fan clutch, they had one on the shelf and the dust was on the top of
> the box so it had been stored correctly on the shelf. Installed the new
> unit and the temp dropped back to the +/- 195 deg F range where it is
> suppose to run at and I could hear the clutch engage and disengage quietly
> never aggressively as it would would the 7 blade fan. Still running that
> unit today.
>
> IMHPO Section:
> Fan Clutches today are a crap shoot when it comes to buying one that will
> work out of the box, work a long time or just work for a short time. Most
> today are made offshore including Napa, Imperial, Torqflow, Murray and
> questionably Hayden in the past. I have primarily used the Torqflow from
> AutoZone over the year and sometimes Hayden. I had 3 each of the 2747 and
> 2797 units in my shop early in the year as I was doing testing for the old
> and new fans. The Torqflo units were 2 made in USA and 1 China and the
> Hayden were unmarked. The Torqflo were stamped on face of the clutch and
> other than that they looked the same. Were they stored correctly? Is the
> ACDelco any better? IMHPO NO as I had one fail out of the box when
> testing. Some have had a catastrophic failure of various brands, but in
> the world of the number of fans in service out there it is a very small
> percentage. I don’t see anyone make better than another!
>
> Our first coach purchased in 1998 came with a 2797 as that was the flavor
> of the day and I ran the 2797 for years. I have had 3 failures in the 17
> years, one locked up after a number of years in service, one would not spin
> the fan after several years in service and one failed right out of the box
> in testing. In my testing I found that the 2747 fan worked well for me in
> our 2 coach that we have used it in with the stock fan. The 1997 Eleganza
> II 403 had a 185 thermostat and it would run all day locked in at 185
> degs. The stretch runs a 195 stat as it has MPFI and it ran all day at
> 195. The 2747 units did not fail with the nylon fan, they couldn’t spin
> the fan.
>
> I have only seen the solid center nylon fan and are unaware of one with
> holes, need to have John B. comment here.
>
> This is my person experiences over the last 17, yours may vary.
>
> Regards,
>
> J.R. Wright
> GMC GreatLaker Member Since 1998
> GMC Tech Editor
> GMC Eastern States Charter Member
> GMCMI Member since 1998
> 78 Buskirk 30' Stretch
> 1975 Avion (Under Reconstruction)
> On location in Tucson
>
>
>> On Dec 23, 2015, at 5:52 AM, RC Jordan wrote:
>>
>>> Can I assume you've had good reports from the field on these?
>>
>> I've put approx 1500 miles on my Royale with John Biwersi's nylon fan.
> So far, results are very good.
>> --
>> 77 Royale Coachmen Side Dry Bath
>> 76 Birchaven Coachmen Side Wet Bath
>> Elizabeth City, NC
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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>
> _______________________________________________
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] fan clutches / Nylon fan [message #292833 is a reply to message #292828] |
Wed, 23 December 2015 19:48 |
powwerjon
Messages: 849
Registered: March 2013
Karma: -2
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Senior Member |
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Jim,
I don’t see how putting holes in the center support plate would increase air flow unless the holes had some sort of an inducer that would guide or grab air and bring it thru the hole.
J.R. Wright
30' Buskirk Stretch
Michigan
On Location in Tucson
> On Dec 23, 2015, at 5:52 PM, Jim Kanomata wrote:
>
> Has anyone run the new fans with auxilery holes in the steel plate area?
> John B and I are trying to find out.
> I know it will make a difference, but we would like to hear from people
> that has done that.
> Gordon S has sent me data to show that it has worked on Ford diesel units.
>
> On Wed, Dec 23, 2015 at 10:40 AM, John Wright wrote:
>
>> Having run John Biwersi Nylon fan for over a year (since Oct 2014,
>> purchased at Chippewa Falls GMCMI rally) and about 12K miles, have
>> probably run it longer than most. I discovered what I think you need to
>> make it work. The fan is 10 blade 2 1/2 pitch unit compared to the 7 blade
>> 2 1/2 pitch of the stock fan. It actually takes more torque to spin the
>> fan (10 blades VS 7 blades) to move the air but you actually do it at a
>> lower RPM, it moves more air, so you barely hear in run. You need to use a
>> severe duty fan clutch to spin the fan. A 2747 or similar rated clutch
>> will not spin the nylon fan as the fan clutches in this rating only spin at
>> 70 to 90% of engine RPM mostly at the bottom end and the additional
>> required torque to spin the fan it overpowers the clutch. The 2797 or
>> other similar rated fan clutches spins at better than 80 to 90% of engine
>> RPM and that it why you hear them when they engage with the 7 blade stock
>> fan. The 2947 and 2797 rated clutches are rated for 2 1/2 pitch blades.
>> depending on the number of blades per fan.
>>
>> “STORY TIME” - Actual Experience
>> I installed John B's 10 blade fan (Oct 2014) using the 2747 fan clutch
>> that I had used with the original 7 blade fan and it was fairly new, less
>> 4k Miles. Left Michigan in early January heading to Tucson AZ to spend the
>> winter. The weather all the way out to Tucson was cold > 60 deg F. I said, “ Boy this is working great, almost never hear the fan
>> clutch engage”! In Mid April on the way home we decided to go up to Page,
>> AZ on AZ 89 to see Antelope Canyon and then on to 4 corners and then on
>> home on I-40. The outside temp was mid 80’s to 90 deg’s F and there were a
>> number of medium climbs to get up to Page. North of Flagstaff, on very
>> good divided hwy I noticed that the temp gauge was creeping up to about 205
>> to 210 and the coach always ran locked in at (195 Robertshaw Thermostat)
>> 195 or slightly less with the stock fan. Thinking that we had a failure of
>> the fan clutch, we pulled into a rest area that just happened to pop up and
>> we changed the fan clutch out with a new 2747 unit. I alway carry a spare
>> fan clutch making sure that it is stored in the correct position, with the
>> mounting flange up and the clutch assembly down and NOT on its side or
>> flange side down. They are not that expensive and I may never need to
>> change it one the road. Within 20 miles the temp was climbing again back
>> up in the 205+ deg F range. Luck intervened again as a auto parts store
>> appeared in the next small town that was on the road. Stopped and bought a
>> 2797 fan clutch, they had one on the shelf and the dust was on the top of
>> the box so it had been stored correctly on the shelf. Installed the new
>> unit and the temp dropped back to the +/- 195 deg F range where it is
>> suppose to run at and I could hear the clutch engage and disengage quietly
>> never aggressively as it would would the 7 blade fan. Still running that
>> unit today.
>>
>> IMHPO Section:
>> Fan Clutches today are a crap shoot when it comes to buying one that will
>> work out of the box, work a long time or just work for a short time. Most
>> today are made offshore including Napa, Imperial, Torqflow, Murray and
>> questionably Hayden in the past. I have primarily used the Torqflow from
>> AutoZone over the year and sometimes Hayden. I had 3 each of the 2747 and
>> 2797 units in my shop early in the year as I was doing testing for the old
>> and new fans. The Torqflo units were 2 made in USA and 1 China and the
>> Hayden were unmarked. The Torqflo were stamped on face of the clutch and
>> other than that they looked the same. Were they stored correctly? Is the
>> ACDelco any better? IMHPO NO as I had one fail out of the box when
>> testing. Some have had a catastrophic failure of various brands, but in
>> the world of the number of fans in service out there it is a very small
>> percentage. I don’t see anyone make better than another!
>>
>> Our first coach purchased in 1998 came with a 2797 as that was the flavor
>> of the day and I ran the 2797 for years. I have had 3 failures in the 17
>> years, one locked up after a number of years in service, one would not spin
>> the fan after several years in service and one failed right out of the box
>> in testing. In my testing I found that the 2747 fan worked well for me in
>> our 2 coach that we have used it in with the stock fan. The 1997 Eleganza
>> II 403 had a 185 thermostat and it would run all day locked in at 185
>> degs. The stretch runs a 195 stat as it has MPFI and it ran all day at
>> 195. The 2747 units did not fail with the nylon fan, they couldn’t spin
>> the fan.
>>
>> I have only seen the solid center nylon fan and are unaware of one with
>> holes, need to have John B. comment here.
>>
>> This is my person experiences over the last 17, yours may vary.
>>
>> Regards,
>>
>> J.R. Wright
>> GMC GreatLaker Member Since 1998
>> GMC Tech Editor
>> GMC Eastern States Charter Member
>> GMCMI Member since 1998
>> 78 Buskirk 30' Stretch
>> 1975 Avion (Under Reconstruction)
>> On location in Tucson
>>
>>
>>> On Dec 23, 2015, at 5:52 AM, RC Jordan wrote:
>>>
>>>> Can I assume you've had good reports from the field on these?
>>>
>>> I've put approx 1500 miles on my Royale with John Biwersi's nylon fan.
>> So far, results are very good.
>>> --
>>> 77 Royale Coachmen Side Dry Bath
>>> 76 Birchaven Coachmen Side Wet Bath
>>> Elizabeth City, NC
>>>
>>>
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
>
> --
> Jim Kanomata
> Applied/GMC, Fremont,CA
> jimk@appliedairfilters.com
> http://www.appliedgmc.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: [GMCnet] fan clutches / Nylon fan [message #292836 is a reply to message #292828] |
Wed, 23 December 2015 19:53 |
powwerjon
Messages: 849
Registered: March 2013
Karma: -2
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Senior Member |
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That area where the holes would be are blocked by the back side of the clutch housing and the fins on the clutch housing would direct the air flow away from the centerline of the fan clutch shaft. I don’t see how the air would go thru any holes.
J.R. Wright
30' Buskirk Stretch
Michigan
On Location in Tucson
> On Dec 23, 2015, at 5:52 PM, Jim Kanomata wrote:
>
> Has anyone run the new fans with auxilery holes in the steel plate area?
> John B and I are trying to find out.
> I know it will make a difference, but we would like to hear from people
> that has done that.
> Gordon S has sent me data to show that it has worked on Ford diesel units.
>
> On Wed, Dec 23, 2015 at 10:40 AM, John Wright wrote:
>
>> Having run John Biwersi Nylon fan for over a year (since Oct 2014,
>> purchased at Chippewa Falls GMCMI rally) and about 12K miles, have
>> probably run it longer than most. I discovered what I think you need to
>> make it work. The fan is 10 blade 2 1/2 pitch unit compared to the 7 blade
>> 2 1/2 pitch of the stock fan. It actually takes more torque to spin the
>> fan (10 blades VS 7 blades) to move the air but you actually do it at a
>> lower RPM, it moves more air, so you barely hear in run. You need to use a
>> severe duty fan clutch to spin the fan. A 2747 or similar rated clutch
>> will not spin the nylon fan as the fan clutches in this rating only spin at
>> 70 to 90% of engine RPM mostly at the bottom end and the additional
>> required torque to spin the fan it overpowers the clutch. The 2797 or
>> other similar rated fan clutches spins at better than 80 to 90% of engine
>> RPM and that it why you hear them when they engage with the 7 blade stock
>> fan. The 2947 and 2797 rated clutches are rated for 2 1/2 pitch blades.
>> depending on the number of blades per fan.
>>
>> “STORY TIME” - Actual Experience
>> I installed John B's 10 blade fan (Oct 2014) using the 2747 fan clutch
>> that I had used with the original 7 blade fan and it was fairly new, less
>> 4k Miles. Left Michigan in early January heading to Tucson AZ to spend the
>> winter. The weather all the way out to Tucson was cold > 60 deg F. I said, “ Boy this is working great, almost never hear the fan
>> clutch engage”! In Mid April on the way home we decided to go up to Page,
>> AZ on AZ 89 to see Antelope Canyon and then on to 4 corners and then on
>> home on I-40. The outside temp was mid 80’s to 90 deg’s F and there were a
>> number of medium climbs to get up to Page. North of Flagstaff, on very
>> good divided hwy I noticed that the temp gauge was creeping up to about 205
>> to 210 and the coach always ran locked in at (195 Robertshaw Thermostat)
>> 195 or slightly less with the stock fan. Thinking that we had a failure of
>> the fan clutch, we pulled into a rest area that just happened to pop up and
>> we changed the fan clutch out with a new 2747 unit. I alway carry a spare
>> fan clutch making sure that it is stored in the correct position, with the
>> mounting flange up and the clutch assembly down and NOT on its side or
>> flange side down. They are not that expensive and I may never need to
>> change it one the road. Within 20 miles the temp was climbing again back
>> up in the 205+ deg F range. Luck intervened again as a auto parts store
>> appeared in the next small town that was on the road. Stopped and bought a
>> 2797 fan clutch, they had one on the shelf and the dust was on the top of
>> the box so it had been stored correctly on the shelf. Installed the new
>> unit and the temp dropped back to the +/- 195 deg F range where it is
>> suppose to run at and I could hear the clutch engage and disengage quietly
>> never aggressively as it would would the 7 blade fan. Still running that
>> unit today.
>>
>> IMHPO Section:
>> Fan Clutches today are a crap shoot when it comes to buying one that will
>> work out of the box, work a long time or just work for a short time. Most
>> today are made offshore including Napa, Imperial, Torqflow, Murray and
>> questionably Hayden in the past. I have primarily used the Torqflow from
>> AutoZone over the year and sometimes Hayden. I had 3 each of the 2747 and
>> 2797 units in my shop early in the year as I was doing testing for the old
>> and new fans. The Torqflo units were 2 made in USA and 1 China and the
>> Hayden were unmarked. The Torqflo were stamped on face of the clutch and
>> other than that they looked the same. Were they stored correctly? Is the
>> ACDelco any better? IMHPO NO as I had one fail out of the box when
>> testing. Some have had a catastrophic failure of various brands, but in
>> the world of the number of fans in service out there it is a very small
>> percentage. I don’t see anyone make better than another!
>>
>> Our first coach purchased in 1998 came with a 2797 as that was the flavor
>> of the day and I ran the 2797 for years. I have had 3 failures in the 17
>> years, one locked up after a number of years in service, one would not spin
>> the fan after several years in service and one failed right out of the box
>> in testing. In my testing I found that the 2747 fan worked well for me in
>> our 2 coach that we have used it in with the stock fan. The 1997 Eleganza
>> II 403 had a 185 thermostat and it would run all day locked in at 185
>> degs. The stretch runs a 195 stat as it has MPFI and it ran all day at
>> 195. The 2747 units did not fail with the nylon fan, they couldn’t spin
>> the fan.
>>
>> I have only seen the solid center nylon fan and are unaware of one with
>> holes, need to have John B. comment here.
>>
>> This is my person experiences over the last 17, yours may vary.
>>
>> Regards,
>>
>> J.R. Wright
>> GMC GreatLaker Member Since 1998
>> GMC Tech Editor
>> GMC Eastern States Charter Member
>> GMCMI Member since 1998
>> 78 Buskirk 30' Stretch
>> 1975 Avion (Under Reconstruction)
>> On location in Tucson
>>
>>
>>> On Dec 23, 2015, at 5:52 AM, RC Jordan wrote:
>>>
>>>> Can I assume you've had good reports from the field on these?
>>>
>>> I've put approx 1500 miles on my Royale with John Biwersi's nylon fan.
>> So far, results are very good.
>>> --
>>> 77 Royale Coachmen Side Dry Bath
>>> 76 Birchaven Coachmen Side Wet Bath
>>> Elizabeth City, NC
>>>
>>>
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
>
> --
> Jim Kanomata
> Applied/GMC, Fremont,CA
> jimk@appliedairfilters.com
> http://www.appliedgmc.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
_______________________________________________
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| Re: [GMCnet] fan clutches / Nylon fan [message #292837 is a reply to message #292833] |
Wed, 23 December 2015 20:16 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
|
Senior Member |
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John
I agree with you on this. The holes will be spinning and I doubt much air would go through
Emery Stora
> On Dec 23, 2015, at 6:48 PM, John Wright wrote:
>
> Jim,
> I don’t see how putting holes in the center support plate would increase air flow unless the holes had some sort of an inducer that would guide or grab air and bring it thru the hole.
> J.R. Wright
> 30' Buskirk Stretch
> Michigan
> On Location in Tucson
>
>> On Dec 23, 2015, at 5:52 PM, Jim Kanomata wrote:
>>
>> Has anyone run the new fans with auxilery holes in the steel plate area?
>> John B and I are trying to find out.
>> I know it will make a difference, but we would like to hear from people
>> that has done that.
>> Gordon S has sent me data to show that it has worked on Ford diesel units.
>>
>>> On Wed, Dec 23, 2015 at 10:40 AM, John Wright wrote:
>>>
>>> Having run John Biwersi Nylon fan for over a year (since Oct 2014,
>>> purchased at Chippewa Falls GMCMI rally) and about 12K miles, have
>>> probably run it longer than most. I discovered what I think you need to
>>> make it work. The fan is 10 blade 2 1/2 pitch unit compared to the 7 blade
>>> 2 1/2 pitch of the stock fan. It actually takes more torque to spin the
>>> fan (10 blades VS 7 blades) to move the air but you actually do it at a
>>> lower RPM, it moves more air, so you barely hear in run. You need to use a
>>> severe duty fan clutch to spin the fan. A 2747 or similar rated clutch
>>> will not spin the nylon fan as the fan clutches in this rating only spin at
>>> 70 to 90% of engine RPM mostly at the bottom end and the additional
>>> required torque to spin the fan it overpowers the clutch. The 2797 or
>>> other similar rated fan clutches spins at better than 80 to 90% of engine
>>> RPM and that it why you hear them when they engage with the 7 blade stock
>>> fan. The 2947 and 2797 rated clutches are rated for 2 1/2 pitch blades.
>>> depending on the number of blades per fan.
>>>
>>> “STORY TIME” - Actual Experience
>>> I installed John B's 10 blade fan (Oct 2014) using the 2747 fan clutch
>>> that I had used with the original 7 blade fan and it was fairly new, less
>>> 4k Miles. Left Michigan in early January heading to Tucson AZ to spend the
>>> winter. The weather all the way out to Tucson was cold >> 60 deg F. I said, “ Boy this is working great, almost never hear the fan
>>> clutch engage”! In Mid April on the way home we decided to go up to Page,
>>> AZ on AZ 89 to see Antelope Canyon and then on to 4 corners and then on
>>> home on I-40. The outside temp was mid 80’s to 90 deg’s F and there were a
>>> number of medium climbs to get up to Page. North of Flagstaff, on very
>>> good divided hwy I noticed that the temp gauge was creeping up to about 205
>>> to 210 and the coach always ran locked in at (195 Robertshaw Thermostat)
>>> 195 or slightly less with the stock fan. Thinking that we had a failure of
>>> the fan clutch, we pulled into a rest area that just happened to pop up and
>>> we changed the fan clutch out with a new 2747 unit. I alway carry a spare
>>> fan clutch making sure that it is stored in the correct position, with the
>>> mounting flange up and the clutch assembly down and NOT on its side or
>>> flange side down. They are not that expensive and I may never need to
>>> change it one the road. Within 20 miles the temp was climbing again back
>>> up in the 205+ deg F range. Luck intervened again as a auto parts store
>>> appeared in the next small town that was on the road. Stopped and bought a
>>> 2797 fan clutch, they had one on the shelf and the dust was on the top of
>>> the box so it had been stored correctly on the shelf. Installed the new
>>> unit and the temp dropped back to the +/- 195 deg F range where it is
>>> suppose to run at and I could hear the clutch engage and disengage quietly
>>> never aggressively as it would would the 7 blade fan. Still running that
>>> unit today.
>>>
>>> IMHPO Section:
>>> Fan Clutches today are a crap shoot when it comes to buying one that will
>>> work out of the box, work a long time or just work for a short time. Most
>>> today are made offshore including Napa, Imperial, Torqflow, Murray and
>>> questionably Hayden in the past. I have primarily used the Torqflow from
>>> AutoZone over the year and sometimes Hayden. I had 3 each of the 2747 and
>>> 2797 units in my shop early in the year as I was doing testing for the old
>>> and new fans. The Torqflo units were 2 made in USA and 1 China and the
>>> Hayden were unmarked. The Torqflo were stamped on face of the clutch and
>>> other than that they looked the same. Were they stored correctly? Is the
>>> ACDelco any better? IMHPO NO as I had one fail out of the box when
>>> testing. Some have had a catastrophic failure of various brands, but in
>>> the world of the number of fans in service out there it is a very small
>>> percentage. I don’t see anyone make better than another!
>>>
>>> Our first coach purchased in 1998 came with a 2797 as that was the flavor
>>> of the day and I ran the 2797 for years. I have had 3 failures in the 17
>>> years, one locked up after a number of years in service, one would not spin
>>> the fan after several years in service and one failed right out of the box
>>> in testing. In my testing I found that the 2747 fan worked well for me in
>>> our 2 coach that we have used it in with the stock fan. The 1997 Eleganza
>>> II 403 had a 185 thermostat and it would run all day locked in at 185
>>> degs. The stretch runs a 195 stat as it has MPFI and it ran all day at
>>> 195. The 2747 units did not fail with the nylon fan, they couldn’t spin
>>> the fan.
>>>
>>> I have only seen the solid center nylon fan and are unaware of one with
>>> holes, need to have John B. comment here.
>>>
>>> This is my person experiences over the last 17, yours may vary.
>>>
>>> Regards,
>>>
>>> J.R. Wright
>>> GMC GreatLaker Member Since 1998
>>> GMC Tech Editor
>>> GMC Eastern States Charter Member
>>> GMCMI Member since 1998
>>> 78 Buskirk 30' Stretch
>>> 1975 Avion (Under Reconstruction)
>>> On location in Tucson
>>>
>>>
>>>> > On Dec 23, 2015, at 5:52 AM, RC Jordan wrote:
>>>> >
>>>> > Can I assume you've had good reports from the field on these?
>>>>
>>>> I've put approx 1500 miles on my Royale with John Biwersi's nylon fan.
>>> So far, results are very good.
>>>> --
>>>> 77 Royale Coachmen Side Dry Bath
>>>> 76 Birchaven Coachmen Side Wet Bath
>>>> Elizabeth City, NC
>>>>
>>>>
>>>> _______________________________________________
>>>> GMCnet mailing list
>>>> Unsubscribe or Change List Options:
>>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>>
>>>
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>>
>>
>>
>>
>> --
>> Jim Kanomata
>> Applied/GMC, Fremont,CA
>> jimk@appliedairfilters.com
>> http://www.appliedgmc.com
>> 1-800-752-7502
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
_______________________________________________
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| Re: [GMCnet] fan clutches / Nylon fan [message #292839 is a reply to message #292828] |
Wed, 23 December 2015 20:22 |
Kosier
Messages: 834
Registered: February 2008
Karma: 1
|
Senior Member |
|
|
Whoa...... What am I missing here? I thought the nylon fan mounted to the
back side of the fan clutch just like the stocker. How is it blocking the
air
from the thermostatic spring on the front of the clutch?
Gary Kosier
77PB w/500Cad
Newark, Ohio
--------------------------------------------------
From: "Jim Kanomata"
Sent: Wednesday, December 23, 2015 7:52 PM
To:
Subject: Re: [GMCnet] fan clutches / Nylon fan
> Has anyone run the new fans with auxilery holes in the steel plate area?
> John B and I are trying to find out.
> I know it will make a difference, but we would like to hear from people
> that has done that.
> Gordon S has sent me data to show that it has worked on Ford diesel units.
>
> On Wed, Dec 23, 2015 at 10:40 AM, John Wright wrote:
>
>> Having run John Biwersi Nylon fan for over a year (since Oct 2014,
>> purchased at Chippewa Falls GMCMI rally) and about 12K miles, have
>> probably run it longer than most. I discovered what I think you need to
>> make it work. The fan is 10 blade 2 1/2 pitch unit compared to the 7
>> blade
>> 2 1/2 pitch of the stock fan. It actually takes more torque to spin the
>> fan (10 blades VS 7 blades) to move the air but you actually do it at a
>> lower RPM, it moves more air, so you barely hear in run. You need to use
>> a
>> severe duty fan clutch to spin the fan. A 2747 or similar rated clutch
>> will not spin the nylon fan as the fan clutches in this rating only spin
>> at
>> 70 to 90% of engine RPM mostly at the bottom end and the additional
>> required torque to spin the fan it overpowers the clutch. The 2797 or
>> other similar rated fan clutches spins at better than 80 to 90% of engine
>> RPM and that it why you hear them when they engage with the 7 blade stock
>> fan. The 2947 and 2797 rated clutches are rated for 2 1/2 pitch blades.
>> depending on the number of blades per fan.
>>
>> “STORY TIME” - Actual Experience
>> I installed John B's 10 blade fan (Oct 2014) using the 2747 fan clutch
>> that I had used with the original 7 blade fan and it was fairly new, less
>> 4k Miles. Left Michigan in early January heading to Tucson AZ to spend
>> the
>> winter. The weather all the way out to Tucson was cold > 60 deg F. I said, “ Boy this is working great, almost never hear the fan
>> clutch engage”! In Mid April on the way home we decided to go up to
>> Page,
>> AZ on AZ 89 to see Antelope Canyon and then on to 4 corners and then on
>> home on I-40. The outside temp was mid 80’s to 90 deg’s F and there were
>> a
>> number of medium climbs to get up to Page. North of Flagstaff, on very
>> good divided hwy I noticed that the temp gauge was creeping up to about
>> 205
>> to 210 and the coach always ran locked in at (195 Robertshaw Thermostat)
>> 195 or slightly less with the stock fan. Thinking that we had a failure
>> of
>> the fan clutch, we pulled into a rest area that just happened to pop up
>> and
>> we changed the fan clutch out with a new 2747 unit. I alway carry a
>> spare
>> fan clutch making sure that it is stored in the correct position, with
>> the
>> mounting flange up and the clutch assembly down and NOT on its side or
>> flange side down. They are not that expensive and I may never need to
>> change it one the road. Within 20 miles the temp was climbing again back
>> up in the 205+ deg F range. Luck intervened again as a auto parts store
>> appeared in the next small town that was on the road. Stopped and bought
>> a
>> 2797 fan clutch, they had one on the shelf and the dust was on the top of
>> the box so it had been stored correctly on the shelf. Installed the new
>> unit and the temp dropped back to the +/- 195 deg F range where it is
>> suppose to run at and I could hear the clutch engage and disengage
>> quietly
>> never aggressively as it would would the 7 blade fan. Still running that
>> unit today.
>>
>> IMHPO Section:
>> Fan Clutches today are a crap shoot when it comes to buying one that will
>> work out of the box, work a long time or just work for a short time.
>> Most
>> today are made offshore including Napa, Imperial, Torqflow, Murray and
>> questionably Hayden in the past. I have primarily used the Torqflow from
>> AutoZone over the year and sometimes Hayden. I had 3 each of the 2747
>> and
>> 2797 units in my shop early in the year as I was doing testing for the
>> old
>> and new fans. The Torqflo units were 2 made in USA and 1 China and the
>> Hayden were unmarked. The Torqflo were stamped on face of the clutch and
>> other than that they looked the same. Were they stored correctly? Is
>> the
>> ACDelco any better? IMHPO NO as I had one fail out of the box when
>> testing. Some have had a catastrophic failure of various brands, but in
>> the world of the number of fans in service out there it is a very small
>> percentage. I don’t see anyone make better than another!
>>
>> Our first coach purchased in 1998 came with a 2797 as that was the flavor
>> of the day and I ran the 2797 for years. I have had 3 failures in the 17
>> years, one locked up after a number of years in service, one would not
>> spin
>> the fan after several years in service and one failed right out of the
>> box
>> in testing. In my testing I found that the 2747 fan worked well for me
>> in
>> our 2 coach that we have used it in with the stock fan. The 1997
>> Eleganza
>> II 403 had a 185 thermostat and it would run all day locked in at 185
>> degs. The stretch runs a 195 stat as it has MPFI and it ran all day at
>> 195. The 2747 units did not fail with the nylon fan, they couldn’t spin
>> the fan.
>>
>> I have only seen the solid center nylon fan and are unaware of one with
>> holes, need to have John B. comment here.
>>
>> This is my person experiences over the last 17, yours may vary.
>>
>> Regards,
>>
>> J.R. Wright
>> GMC GreatLaker Member Since 1998
>> GMC Tech Editor
>> GMC Eastern States Charter Member
>> GMCMI Member since 1998
>> 78 Buskirk 30' Stretch
>> 1975 Avion (Under Reconstruction)
>> On location in Tucson
>>
>>
>>> On Dec 23, 2015, at 5:52 AM, RC Jordan wrote:
>>>
>>>> Can I assume you've had good reports from the field on these?
>>>
>>> I've put approx 1500 miles on my Royale with John Biwersi's nylon fan.
>> So far, results are very good.
>>> --
>>> 77 Royale Coachmen Side Dry Bath
>>> 76 Birchaven Coachmen Side Wet Bath
>>> Elizabeth City, NC
>>>
>>>
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
>
> --
> Jim Kanomata
> Applied/GMC, Fremont,CA
> jimk@appliedairfilters.com
> http://www.appliedgmc.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
|
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| Re: [GMCnet] fan clutches / Nylon fan [message #292842 is a reply to message #292833] |
Wed, 23 December 2015 20:03 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
|
Senior Member |
|
|
J.R. I mean no disparagement on the 10 blade nylon fan. It just did NOT
WORK for me. When you look at it, it is easy to see that the solid hub
obscures the thermostatic coil spring on the fan clutch. I agree that the
quality of just about any make of fan clutches is poor. I replaced three of
them on my coach in one trip from Salem, Or to Palm Desert, Ca. Jim K.
replaced ALL of them with NO Hassle. Must be really frustrating for him
too.
Jim Hupy
Salem, Or
On Dec 23, 2015 5:49 PM, "John Wright" wrote:
> Jim,
> I don’t see how putting holes in the center support plate would increase
> air flow unless the holes had some sort of an inducer that would guide or
> grab air and bring it thru the hole.
> J.R. Wright
> 30' Buskirk Stretch
> Michigan
> On Location in Tucson
>
>> On Dec 23, 2015, at 5:52 PM, Jim Kanomata wrote:
>>
>> Has anyone run the new fans with auxilery holes in the steel plate area?
>> John B and I are trying to find out.
>> I know it will make a difference, but we would like to hear from people
>> that has done that.
>> Gordon S has sent me data to show that it has worked on Ford diesel
> units.
>>
>> On Wed, Dec 23, 2015 at 10:40 AM, John Wright
> wrote:
>>
>>> Having run John Biwersi Nylon fan for over a year (since Oct 2014,
>>> purchased at Chippewa Falls GMCMI rally) and about 12K miles, have
>>> probably run it longer than most. I discovered what I think you need to
>>> make it work. The fan is 10 blade 2 1/2 pitch unit compared to the 7
> blade
>>> 2 1/2 pitch of the stock fan. It actually takes more torque to spin the
>>> fan (10 blades VS 7 blades) to move the air but you actually do it at a
>>> lower RPM, it moves more air, so you barely hear in run. You need to
> use a
>>> severe duty fan clutch to spin the fan. A 2747 or similar rated clutch
>>> will not spin the nylon fan as the fan clutches in this rating only
> spin at
>>> 70 to 90% of engine RPM mostly at the bottom end and the additional
>>> required torque to spin the fan it overpowers the clutch. The 2797 or
>>> other similar rated fan clutches spins at better than 80 to 90% of
> engine
>>> RPM and that it why you hear them when they engage with the 7 blade
> stock
>>> fan. The 2947 and 2797 rated clutches are rated for 2 1/2 pitch blades.
>>> depending on the number of blades per fan.
>>>
>>> “STORY TIME” - Actual Experience
>>> I installed John B's 10 blade fan (Oct 2014) using the 2747 fan clutch
>>> that I had used with the original 7 blade fan and it was fairly new,
> less
>>> 4k Miles. Left Michigan in early January heading to Tucson AZ to spend
> the
>>> winter. The weather all the way out to Tucson was cold mid
>>> 60 deg F. I said, “ Boy this is working great, almost never hear the
> fan
>>> clutch engage”! In Mid April on the way home we decided to go up to
> Page,
>>> AZ on AZ 89 to see Antelope Canyon and then on to 4 corners and then on
>>> home on I-40. The outside temp was mid 80’s to 90 deg’s F and there
> were a
>>> number of medium climbs to get up to Page. North of Flagstaff, on very
>>> good divided hwy I noticed that the temp gauge was creeping up to about
> 205
>>> to 210 and the coach always ran locked in at (195 Robertshaw Thermostat)
>>> 195 or slightly less with the stock fan. Thinking that we had a
> failure of
>>> the fan clutch, we pulled into a rest area that just happened to pop up
> and
>>> we changed the fan clutch out with a new 2747 unit. I alway carry a
> spare
>>> fan clutch making sure that it is stored in the correct position, with
> the
>>> mounting flange up and the clutch assembly down and NOT on its side or
>>> flange side down. They are not that expensive and I may never need to
>>> change it one the road. Within 20 miles the temp was climbing again
> back
>>> up in the 205+ deg F range. Luck intervened again as a auto parts store
>>> appeared in the next small town that was on the road. Stopped and
> bought a
>>> 2797 fan clutch, they had one on the shelf and the dust was on the top
> of
>>> the box so it had been stored correctly on the shelf. Installed the new
>>> unit and the temp dropped back to the +/- 195 deg F range where it is
>>> suppose to run at and I could hear the clutch engage and disengage
> quietly
>>> never aggressively as it would would the 7 blade fan. Still running
> that
>>> unit today.
>>>
>>> IMHPO Section:
>>> Fan Clutches today are a crap shoot when it comes to buying one that
> will
>>> work out of the box, work a long time or just work for a short time.
> Most
>>> today are made offshore including Napa, Imperial, Torqflow, Murray and
>>> questionably Hayden in the past. I have primarily used the Torqflow
> from
>>> AutoZone over the year and sometimes Hayden. I had 3 each of the 2747
> and
>>> 2797 units in my shop early in the year as I was doing testing for the
> old
>>> and new fans. The Torqflo units were 2 made in USA and 1 China and the
>>> Hayden were unmarked. The Torqflo were stamped on face of the clutch
> and
>>> other than that they looked the same. Were they stored correctly? Is
> the
>>> ACDelco any better? IMHPO NO as I had one fail out of the box when
>>> testing. Some have had a catastrophic failure of various brands, but in
>>> the world of the number of fans in service out there it is a very small
>>> percentage. I don’t see anyone make better than another!
>>>
>>> Our first coach purchased in 1998 came with a 2797 as that was the
> flavor
>>> of the day and I ran the 2797 for years. I have had 3 failures in the
> 17
>>> years, one locked up after a number of years in service, one would not
> spin
>>> the fan after several years in service and one failed right out of the
> box
>>> in testing. In my testing I found that the 2747 fan worked well for me
> in
>>> our 2 coach that we have used it in with the stock fan. The 1997
> Eleganza
>>> II 403 had a 185 thermostat and it would run all day locked in at 185
>>> degs. The stretch runs a 195 stat as it has MPFI and it ran all day at
>>> 195. The 2747 units did not fail with the nylon fan, they couldn’t spin
>>> the fan.
>>>
>>> I have only seen the solid center nylon fan and are unaware of one with
>>> holes, need to have John B. comment here.
>>>
>>> This is my person experiences over the last 17, yours may vary.
>>>
>>> Regards,
>>>
>>> J.R. Wright
>>> GMC GreatLaker Member Since 1998
>>> GMC Tech Editor
>>> GMC Eastern States Charter Member
>>> GMCMI Member since 1998
>>> 78 Buskirk 30' Stretch
>>> 1975 Avion (Under Reconstruction)
>>> On location in Tucson
>>>
>>>
>>>> On Dec 23, 2015, at 5:52 AM, RC Jordan wrote:
>>>>
>>>> > Can I assume you've had good reports from the field on these?
>>>>
>>>> I've put approx 1500 miles on my Royale with John Biwersi's nylon fan.
>>> So far, results are very good.
>>>> --
>>>> 77 Royale Coachmen Side Dry Bath
>>>> 76 Birchaven Coachmen Side Wet Bath
>>>> Elizabeth City, NC
>>>>
>>>>
>>>> _______________________________________________
>>>> GMCnet mailing list
>>>> Unsubscribe or Change List Options:
>>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>>
>>>
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>>
>>
>>
>>
>> --
>> Jim Kanomata
>> Applied/GMC, Fremont,CA
>> jimk@appliedairfilters.com
>> http://www.appliedgmc.com
>> 1-800-752-7502
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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|
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| Re: [GMCnet] fan clutches / Nylon fan [message #292854 is a reply to message #292780] |
Thu, 24 December 2015 08:30 |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
|
Senior Member |
|
|
I chose to go with a STOCK DELCO clutch with John's Nylon fan. LOVE it. MUCH quieter. MUCH! The clutch engages at startup and goes off a few minutes later. It's come on a couple times but with my aluminum radiator and the nylon fan, the temp gauge never waivers.
We can actually converse while driving now.
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
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| Re: [GMCnet] fan clutches / Nylon fan [message #292886 is a reply to message #292879] |
Thu, 24 December 2015 16:23 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
|
Senior Member |
|
|
John W,
Look at the picture again, it is the same as ours.
I'm sure as the lowest part of the fan cups the air, the air moves up
towards the tip of the fan and the additional air is pulled from the hub
area.
It might be minimal amount of air, but enough to pull some air that is
stagnating at the front of the clutch where the coil is nested and
stimulates the air movement close enough to have the coil sense the air
from radiator.
Like Gordon says, those holes were not put there for structural purpose.
I know from my course in aerodynamics and model airplane, that there is
value there.
How much is questionable, but the people that did the Ford fan must have
spent some time on it with people that understood behaviour of air in that
region to warrant placing those holes.
On Thu, Dec 24, 2015 at 1:14 PM, John Wright wrote:
> In our case the fan clutch is in front of the fan assembly in the air
> flow. In this application the clutch appears to be behind the fan assembly.
>
> J.R. Wright
> 30' Buskirk Stretch
> Michigan
> On Location in Tucson
>
>> On Dec 24, 2015, at 2:08 PM, Robert Mueller
> wrote:
>>
>> G'day,
>>
>> I received the following from Gordon Seykora:
>>
>>
> http://www.gmcmhphotos.com/photos/aa-miscellaneous-photos/p59754-diesel-fan.html
>>
>> Regards,
>> Rob M.
>> The Pedantic Mechanic
>>
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
|
|
|
|
| Re: [GMCnet] fan clutches / Nylon fan [message #292893 is a reply to message #292886] |
Thu, 24 December 2015 18:17 |
 |
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
|
Senior Member |
|
|
Jim,
Sorry to disagree but it is NOT the same as the fan on a GMC, the fan clutch on the 455 Olds is in front of the fan and heated air
from the radiator hits it (and the bimetallic strip) directly.
I don't think boring holes in the back side would make any difference as they would be covered by the fan clutch.
http://www.gmcmhphotos.com/photos/stuff/p58522-fan-blade.html
Note the decal on the one blade, I don't know where Carl got it but it's COOL as far as I'm concerned!
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: Jim Kanomata
John W,
Look at the picture again, it is the same as ours.
I'm sure as the lowest part of the fan cups the air, the air moves up
towards the tip of the fan and the additional air is pulled from the hub
area.
It might be minimal amount of air, but enough to pull some air that is
stagnating at the front of the clutch where the coil is nested and
stimulates the air movement close enough to have the coil sense the air
from radiator.
Like Gordon says, those holes were not put there for structural purpose.
I know from my course in aerodynamics and model airplane, that there is
value there.
How much is questionable, but the people that did the Ford fan must have
spent some time on it with people that understood behaviour of air in that
region to warrant placing those holes.
Jim
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
|
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| Re: [GMCnet] fan clutches / Nylon fan [message #292898 is a reply to message #292893] |
Thu, 24 December 2015 19:48 |
powwerjon
Messages: 849
Registered: March 2013
Karma: -2
|
Senior Member |
|
|
If it was the same then the flange to the water pump would be visible.
J.R. Wright
GMC GreatLaker
Newsletter Editor/Publisher
78 Buskirk 30' Stretch
75 Avion Under Reconstruction
Michigan
> On Dec 24, 2015, at 5:17 PM, Robert Mueller wrote:
>
> Jim,
>
> Sorry to disagree but it is NOT the same as the fan on a GMC, the fan clutch on the 455 Olds is in front of the fan and heated air
> from the radiator hits it (and the bimetallic strip) directly.
>
> I don't think boring holes in the back side would make any difference as they would be covered by the fan clutch.
>
> http://www.gmcmhphotos.com/photos/stuff/p58522-fan-blade.html
>
> Note the decal on the one blade, I don't know where Carl got it but it's COOL as far as I'm concerned!
>
> Regards,
> Rob M.
> The Pedantic Mechanic
>
>
> -----Original Message-----
> From: Jim Kanomata
>
> John W,
> Look at the picture again, it is the same as ours.
> I'm sure as the lowest part of the fan cups the air, the air moves up
> towards the tip of the fan and the additional air is pulled from the hub
> area.
> It might be minimal amount of air, but enough to pull some air that is
> stagnating at the front of the clutch where the coil is nested and
> stimulates the air movement close enough to have the coil sense the air
> from radiator.
> Like Gordon says, those holes were not put there for structural purpose.
> I know from my course in aerodynamics and model airplane, that there is
> value there.
> How much is questionable, but the people that did the Ford fan must have
> spent some time on it with people that understood behaviour of air in that
> region to warrant placing those holes.
>
> Jim
>
>
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| Re: [GMCnet] fan clutches / Nylon fan [message #292934 is a reply to message #292780] |
Sat, 26 December 2015 12:39 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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Senior Member |
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ROB and JR.
The photo you are showing is the rear side of the fan Gordon Sekora cut off the mounting flange to the water pump in this photo. We are looking at the waterpump side. (The clutch is on the Rad side just as you would expect) He uploaded it as part of another of his regular Negative and disparaging Rant on his (and another owner) facebook Group
Gordon Sekora is one of the moderators to the GMC Motorhome Parts Facebook page hiding behind the fictitious name of Gordon Reid Nicol who is regularly writing rants and negative comments about others in the the GMC supplier community the purpose of that page is not necessary to help find sources of parts but to find non traditional sources. There is a definite "Negative agenda"
For what its worth to this discussion, the fins on the outside of the clutch are to cool the silicone fluid in the clutch from the heat generated by the constant slipping. Air is "pumped " in a radial fashion from the center of the clutch fins to the outside of the clutch (like the holes drilled radially through a disk brake rotor) air will travel through the holes in the hub because those holes are on the high pressure side of the fan and the radial pressure of the clutch and fan rotation,and the lower air pressure on the front of the fan will have a tendency to pull the air in to help cool the clutch fluid..
Those holes will do nothing to the engage temperatures of the clutch because that is controlled by the thermostatic spring controlled valve on front of the clutch.
The clutch actually creates its own heat during times the spring controlled valve is allowing fluid between the plates and the clutch is transfering as much torque to the fan as it can. The slippage (at high percentage of RPM Transfer such as 80% or 90%) is a real heat producer. When the clutch is not engaged and the thermostatic spring is cool, the silicone is not allowed between the plates and way less friction is produced and not as much heat is produced (hense low torque transfer). Under higher heat conditions when the clutch is engaged for longer periods of time (or whenever a less extreme duty clutch is used causing more slippage) cooling of the silicone becomes more important.
I have no opinion whether the holes are need or not, but I suspect that ensuring air circulation on both the front side and the rear side of the clutch would improve the cooling. However That being said, less extreme duty clutches do not have significant cooling fins on the back of the clutch and are different shaped. Like many discussions here, the real question is What's sufficient for the application and whats "mo better"and What's over kill? One thing we know is that most Extreme Duty and HD Trucks with Diesel engines have way more HD cooling systems and technology implimented than our GMCs so is it all necessary to our application? Even in Gordons Rant he states that he had to change over to less HD equipment in his trucks. "(NOT ALL Extreme duty or HD is appropriate in ALL. Applications.
FULL DISCLOSURE: I do not have a plastic fan and I dont think I need one so I have no experience to say how this application of parts measures up.
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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