Home » Public Forums » GMCnet » [GMCnet] 3.21 final drive, any opinions
| [GMCnet] 3.21 final drive, any opinions [message #304844] |
Wed, 03 August 2016 15:50  |
glwgmc
Messages: 1014
Registered: June 2004
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With two coaches (a 77 Clasco and a 78 Royale, both 455) and lots of driving all over north America every year I really like the 3.67 ratio from a 3.5 chain in the transmission plus a 3.21 planetary gear final drive. You can achieve the same outcome with a 3.7 final drive alone. I rarely shift into second gear going up hill with either coach, drive about 65 on average and get right around 8.5 on regular crap gas in both coaches. I do regularly add an ethanol conditioner to the “fuel” to try to mitigate some of the ill effects from 10% alcohol. My mileage went up a bit when I changed from the 3.07 to the 3.67 in both coaches. Both coaches drive far more like cars with this gearing than either did with the 3.07. Quick merging into traffic, easy overtake on the freeway - just generally a lot peppier feeling. I don't tow anything.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
glwork@mac.com
http://jerrywork.com
=================
Message: 7
Date: Wed, 03 Aug 2016 11:16:12 -0600
From: Todd Perkins
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] 3.21 final drive, any opinions
Message-ID:
Content-Type: text/plain; charset="utf-8"
great questions. I drive in the 70s pull 3,000 to 5,000 loads also.
Another question is what kind of mileage before and after would be interesting. I'm getting around 7 MPG. Too many WOT runs up the hills I guess. I
assume i would get a little better buy staying out of the secondary throttles :)
please share what you find.
Todd
--
Todd
Owner of a 1976 Eleganza II 26?
other toys:
93 Vette
84 Goldwing
and gone but not forgotten
72 CB750 Chopper
96 Caprice Classic
34 Ford roadster
94 Fleetwood
==================
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Jerry & Sharon Work
78 Royale
Kerby, OR
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| Re: [GMCnet] 3.21 final drive, any opinions [message #304848 is a reply to message #304844] |
Wed, 03 August 2016 16:25  |
sgltrac
Messages: 2797
Registered: April 2011
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What Jerry said. Jerry has the 321 and chains out of the 77 that the
Kanomata 355 replaced. I live on a very strep hill and traction was very
important. I thought the lim slip would hook up better than the 321
planetary but they seemed pretty equivalent.
Sully
77 eleganza 2
Seattle
On Wednesday, August 3, 2016, Gerald Work wrote:
> With two coaches (a 77 Clasco and a 78 Royale, both 455) and lots of
> driving all over north America every year I really like the 3.67 ratio from
> a 3.5 chain in the transmission plus a 3.21 planetary gear final drive.
> You can achieve the same outcome with a 3.7 final drive alone. I rarely
> shift into second gear going up hill with either coach, drive about 65 on
> average and get right around 8.5 on regular crap gas in both coaches. I do
> regularly add an ethanol conditioner to the “fuel” to try to mitigate some
> of the ill effects from 10% alcohol. My mileage went up a bit when I
> changed from the 3.07 to the 3.67 in both coaches. Both coaches drive far
> more like cars with this gearing than either did with the 3.07. Quick
> merging into traffic, easy overtake on the freeway - just generally a lot
> peppier feeling. I don't tow anything.
>
> Jerry
> Jerry Work
> The Dovetail Joint
> Fine furniture designed and hand crafted in the 1907 former Masonic Temple
> building in historic Kerby, OR
>
> glwork@mac.com
> http://jerrywork.com
> =================
> Message: 7
> Date: Wed, 03 Aug 2016 11:16:12 -0600
> From: Todd Perkins
> To: gmclist@list.gmcnet.org
> Subject: Re: [GMCnet] 3.21 final drive, any opinions
> Message-ID:
> Content-Type: text/plain; charset="utf-8"
>
> great questions. I drive in the 70s pull 3,000 to 5,000 loads also.
>
> Another question is what kind of mileage before and after would be
> interesting. I'm getting around 7 MPG. Too many WOT runs up the hills I
> guess. I
> assume i would get a little better buy staying out of the secondary
> throttles :)
>
>
> please share what you find.
>
>
> Todd
> --
> Todd
>
> Owner of a 1976 Eleganza II 26?
> other toys:
> 93 Vette
> 84 Goldwing
>
> and gone but not forgotten
> 72 CB750 Chopper
> 96 Caprice Classic
> 34 Ford roadster
> 94 Fleetwood
> ==================
>
>
>
>
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| Re: [GMCnet] 3.21 final drive, any opinions [message #304860 is a reply to message #304844] |
Wed, 03 August 2016 19:31 |
Scott Nutter
Messages: 782
Registered: January 2015
Location: Houston/San Diego
Karma: 4
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Thanks to both you guys for the info. I've been drooling over that setup for a while. And it might happen..it might be close to time to rebuild the tranny anyway.. Scott
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, Dave Lenzi super duty mid axle disc brakes, tankless water heater, everything Lenzi. Alex Ferrera installed MSD Atomic EFI
Houston, Texas
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| Re: [GMCnet] 3.21 final drive, any opinions [message #304864 is a reply to message #304862] |
Wed, 03 August 2016 20:30 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Bruce,
You are correct vis-à-vis the added stress on the trans, however, the real question is - does it matter?
I will be spending several days at Manny's the week after next to do the oil filter mount bypass valve testing and I'll discuss this
with him.
As far as I'm concerned he's the only person in our group with enough experience to provide a credible response
Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of Bruce Hislop
Sent: Thursday, August 04, 2016 11:04 AM
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] 3.21 final drive, any opinions
Just my farmboy mechanic thoughts here... would it not be better for the transmission to put less torque through it by increasing
the ratio only at the final drive?
Increasing the torque through the transmission by using the chain drive would put more strain on the clutch packs etc..
I was sweating the 15% grades around the Finger Lakes a couple weeks ago and I just open the throttle enough to get into Power
Enrichment on the EBL
Am I missing something?
--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
Hubler 1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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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] 3.21 final drive, any opinions [message #304865 is a reply to message #304864] |
Wed, 03 August 2016 21:01 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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I would consult with Wes Coughlin of Cinnabar Engineering.
He is a degreed mechanical engineer PE, I'm sure he will explain and then
you can bank on it.
On Thu, Aug 4, 2016 at 3:26 AM, Rob Mueller wrote:
> Bruce,
>
> You are correct vis-à-vis the added stress on the trans, however, the real
> question is - does it matter?
>
> I will be spending several days at Manny's the week after next to do the
> oil filter mount bypass valve testing and I'll discuss this
> with him.
>
> As far as I'm concerned he's the only person in our group with enough
> experience to provide a credible response
>
> Regards,
> Rob M.
> USAussie - Downunder
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
>
>
> -----Original Message-----
> From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of Bruce
> Hislop
> Sent: Thursday, August 04, 2016 11:04 AM
> To: gmclist@list.gmcnet.org
> Subject: Re: [GMCnet] 3.21 final drive, any opinions
>
> Just my farmboy mechanic thoughts here... would it not be better for the
> transmission to put less torque through it by increasing
> the ratio only at the final drive?
>
> Increasing the torque through the transmission by using the chain drive
> would put more strain on the clutch packs etc..
>
> I was sweating the 15% grades around the Finger Lakes a couple weeks ago
> and I just open the throttle enough to get into Power
> Enrichment on the EBL
>
> Am I missing something?
> --
> Bruce Hislop
> ON Canada
> 77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
> Hubler 1 ton front end
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
> My Staff says I never listen to them, or something like that
>
> _______________________________________________
> 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
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] 3.21 final drive, any opinions [message #304869 is a reply to message #304867] |
Wed, 03 August 2016 23:42 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Rob,
He will explain to you why under engineering standards it is PREFERED,not
best.
Another way I look at it , the most important thing is to get the ratio in
the 3.67-3.70 for overall performance.The wind drag on our coaches are
great, so by gearing to get optimum torque from the engine is a good
thing.Using one form or other.No one has said one is less dependable.
I'm sure you will sort of agree to that.
On Thu, Aug 4, 2016 at 5:23 AM, Rob Mueller wrote:
> Jim,
>
> If you are suggesting I contact Wes I'll pass because I already know what
> his response will be; the 3.42 to 1 final drive unit that
> they sell is the only way to go.
>
> You and I both KNOW that's BULLSHIT! ;-)
>
> Regards,
> Rob M.
> USAussie - Downunder
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
>
> -----Original Message-----
> From: Jim Kanomata
>
> I would consult with Wes Coughlin of Cinnabar Engineering.
> He is a degreed mechanical engineer PE, I'm sure he will explain and then
> you can bank on it.
>
> Jim
>
>
> _______________________________________________
> 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
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] 3.21 final drive, any opinions [message #304878 is a reply to message #304869] |
Thu, 04 August 2016 09:40 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Jim,
I think I'll wait until I've had the opportunity to discuss this with Manny before commenting further.
Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: Jim Kanomata
Rob,
He will explain to you why under engineering standards it is PREFERED, not best.
Another way I look at it , the most important thing is to get the ratio in
the 3.67-3.70 for overall performance.The wind drag on our coaches are
great, so by gearing to get optimum torque from the engine is a good
thing.Using one form or other.No one has said one is less dependable.
I'm sure you will sort of agree to that.
Jim
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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] 3.21 final drive, any opinions [message #304880 is a reply to message #304878] |
Thu, 04 August 2016 10:03 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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ok
On Thu, Aug 4, 2016 at 4:35 PM, Rob Mueller wrote:
> Jim,
>
> I think I'll wait until I've had the opportunity to discuss this with
> Manny before commenting further.
>
> Regards,
> Rob M.
> USAussie - Downunder
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
>
>
> -----Original Message-----
> From: Jim Kanomata
>
> Rob,
> He will explain to you why under engineering standards it is PREFERED, not
> best.
> Another way I look at it , the most important thing is to get the ratio in
> the 3.67-3.70 for overall performance.The wind drag on our coaches are
> great, so by gearing to get optimum torque from the engine is a good
> thing.Using one form or other.No one has said one is less dependable.
> I'm sure you will sort of agree to that.
>
> Jim
>
>
> _______________________________________________
> 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
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| Re: [GMCnet] 3.21 final drive, any opinions [message #304926 is a reply to message #304911] |
Fri, 05 August 2016 00:00 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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John,
I have two 3.21 to 1 drives and as you know have taken one partially apart to replace the pinion seal(s). For the life of me I can't
figger out why they act like a limited slip function.
Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of John Biwersi
Sent: Friday, August 05, 2016 10:48 AM
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] 3.21 final drive, any opinions
Interesting comment how the traction performance of the 3.21 planetary final drive was similar to a limited slip spider gear final
drive. A member of the Greater Midwest Classics was in a difficult situation and had to maneuver his coach quickly which he did by
smoking both front tires. He has a stock 403, power drive chain, and a 3.21 final drive.
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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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