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| Transmission [message #350534] |
Fri, 06 December 2019 15:43  |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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Senior Member |
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Had seen a chain about getting a 3:55 or higher transmission to get best bang for buck on performance. I have a 3:42 ratio and wonder if that would work well enough? My gmc is a 76 Eleganza 2 with a 455 w/ quad.
Thanks,
Tom
Tom Geiger
76 Eleganza II
KCMO
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| Re: [GMCnet] Transmission [message #350540 is a reply to message #350537] |
Fri, 06 December 2019 17:40  |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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If you already have a 3.50 chain drive or a 3.42, I would not waste your
money on a lower gear unless your a 55 mph driver.
Lower gear works well if you drive slow as the rpm need to be around
2900-3100 rpm to take advantage of the torque curve.
Even my Cad 540 does well with the 3.70 and I drive it 70-75 mph most of
the time.
All our engines can run all day at 4,000 rpm stock.
Only an uninformed person will tell you that 3,500 is too high an rpm.
Several of us have been running the 4.10 gears and like it at speed around
60-65 mph.
I drive the 4.10 with the 403 engine at 75-80 on the open road.
On Fri, Dec 6, 2019 at 2:57 PM Mike Kelley via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Hi Tom G.:
> I have always heard that a 3:70 was the best final drive for our rigs.
> That said - I must tell you I have a 76 Eleganza II 26’ w/ a 3:21 and a 76
> Glenbrook 28’ stretch w/ a 3:21 and they both perform fine (much better
> than the original 3:07’s).
> Soo - I would think a 3:42 would work well and the only way I would change
> that would be if I traveled in the mountains all the time!
> Of course I am not a mechanic or an expert - just a guy who regularly
> puts about 12,000 miles per year on my coach (which ever one I am
> driving). Many trips from Tx. to IL. and back - but not to many through
> the mountains.
> Mike/The Corvair a holic
> P S You might consult w/ Jim K. on this subject - just call him by phone.
>
> Sent from my iPhone
>
>> On Dec 6, 2019, at 3:43 PM, tom geiger via Gmclist gmclist@list.gmcnet.org> wrote:
>>
>> Had seen a chain about getting a 3:55 or higher transmission to get best
> bang for buck on performance. I have a 3:42 ratio and wonder if that would
>> work well enough? My gmc is a 76 Eleganza 2 with a 455 w/ quad.
>>
>> Thanks,
>> Tom
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
> _______________________________________________
> GMCnet mailing list
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>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmcrvparts.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Transmission [message #350541 is a reply to message #350540] |
Fri, 06 December 2019 18:53 |
Mike Kelley
Messages: 467
Registered: February 2017
Karma: -2
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Senior Member |
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Thanks Jim K. for the clarification - always good to hear from the Expert!
Mike/The Corvair a holic
Sent from my iPhone
> On Dec 6, 2019, at 5:40 PM, Jim Kanomata via Gmclist wrote:
>
> If you already have a 3.50 chain drive or a 3.42, I would not waste your
> money on a lower gear unless your a 55 mph driver.
> Lower gear works well if you drive slow as the rpm need to be around
> 2900-3100 rpm to take advantage of the torque curve.
> Even my Cad 540 does well with the 3.70 and I drive it 70-75 mph most of
> the time.
> All our engines can run all day at 4,000 rpm stock.
> Only an uninformed person will tell you that 3,500 is too high an rpm.
> Several of us have been running the 4.10 gears and like it at speed around
> 60-65 mph.
> I drive the 4.10 with the 403 engine at 75-80 on the open road.
>
> On Fri, Dec 6, 2019 at 2:57 PM Mike Kelley via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> Hi Tom G.:
>> I have always heard that a 3:70 was the best final drive for our rigs.
>> That said - I must tell you I have a 76 Eleganza II 26’ w/ a 3:21 and a 76
>> Glenbrook 28’ stretch w/ a 3:21 and they both perform fine (much better
>> than the original 3:07’s).
>> Soo - I would think a 3:42 would work well and the only way I would change
>> that would be if I traveled in the mountains all the time!
>> Of course I am not a mechanic or an expert - just a guy who regularly
>> puts about 12,000 miles per year on my coach (which ever one I am
>> driving). Many trips from Tx. to IL. and back - but not to many through
>> the mountains.
>> Mike/The Corvair a holic
>> P S You might consult w/ Jim K. on this subject - just call him by phone.
>>
>> Sent from my iPhone
>>
>>> On Dec 6, 2019, at 3:43 PM, tom geiger via Gmclist > gmclist@list.gmcnet.org> wrote:
>>>
>>> Had seen a chain about getting a 3:55 or higher transmission to get best
>> bang for buck on performance. I have a 3:42 ratio and wonder if that would
>>> work well enough? My gmc is a 76 Eleganza 2 with a 455 w/ quad.
>>>
>>> Thanks,
>>> Tom
>>>
>>> _______________________________________________
>>> 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, Newark,CA
> jimk@appliedairfilters.com
> http://www.appliedgmcrvparts.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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Unsubscribe or Change List Options:
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| Re: [GMCnet] Transmission [message #350542 is a reply to message #350541] |
Fri, 06 December 2019 19:38 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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I always run my 403 @ 3200 or so. If I am in a hurry, I will notch it up to
3600. With 3:70 gearing the mph is 65 or 75+ mph. It is a happy camper at
those rpm's. Vacuum on flat and level is 12 to 15 inches of vacuum.
Mileage? I don't ever check it. I run 4 or 5 hours and refuel. Usually
takes 25 gal. or sometimes more if I am in the mountains.
Jim Hupy
Salem, Oregon
On Fri, Dec 6, 2019, 4:53 PM Mike Kelley via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Thanks Jim K. for the clarification - always good to hear from the Expert!
> Mike/The Corvair a holic
>
> Sent from my iPhone
>
>> On Dec 6, 2019, at 5:40 PM, Jim Kanomata via Gmclist gmclist@list.gmcnet.org> wrote:
>>
>> If you already have a 3.50 chain drive or a 3.42, I would not waste your
>> money on a lower gear unless your a 55 mph driver.
>> Lower gear works well if you drive slow as the rpm need to be around
>> 2900-3100 rpm to take advantage of the torque curve.
>> Even my Cad 540 does well with the 3.70 and I drive it 70-75 mph most of
>> the time.
>> All our engines can run all day at 4,000 rpm stock.
>> Only an uninformed person will tell you that 3,500 is too high an rpm.
>> Several of us have been running the 4.10 gears and like it at speed
> around
>> 60-65 mph.
>> I drive the 4.10 with the 403 engine at 75-80 on the open road.
>>
>> On Fri, Dec 6, 2019 at 2:57 PM Mike Kelley via Gmclist > gmclist@list.gmcnet.org> wrote:
>>
>>> Hi Tom G.:
>>> I have always heard that a 3:70 was the best final drive for our rigs.
>>> That said - I must tell you I have a 76 Eleganza II 26’ w/ a 3:21 and a
> 76
>>> Glenbrook 28’ stretch w/ a 3:21 and they both perform fine (much better
>>> than the original 3:07’s).
>>> Soo - I would think a 3:42 would work well and the only way I would
> change
>>> that would be if I traveled in the mountains all the time!
>>> Of course I am not a mechanic or an expert - just a guy who
> regularly
>>> puts about 12,000 miles per year on my coach (which ever one I am
>>> driving). Many trips from Tx. to IL. and back - but not to many through
>>> the mountains.
>>> Mike/The Corvair a holic
>>> P S You might consult w/ Jim K. on this subject - just call him by
> phone.
>>>
>>> Sent from my iPhone
>>>
>>>> On Dec 6, 2019, at 3:43 PM, tom geiger via Gmclist >> gmclist@list.gmcnet.org> wrote:
>>>>
>>>> Had seen a chain about getting a 3:55 or higher transmission to get
> best
>>> bang for buck on performance. I have a 3:42 ratio and wonder if that
> would
>>>> work well enough? My gmc is a 76 Eleganza 2 with a 455 w/ quad.
>>>>
>>>> Thanks,
>>>> Tom
>>>>
>>>> _______________________________________________
>>>> 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, Newark,CA
>> jimk@appliedairfilters.com
>> http://www.appliedgmcrvparts.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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| Re: Transmission [message #350549 is a reply to message #350534] |
Sat, 07 December 2019 11:35 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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I'm "happy" with my 3.42 from Cinnabar. Happy in quotes as all ratios are a compromise. The root problem is that 3 gears in the TH425 are outdated by today's standards. Perfectly fine on flat ground, but too wide a ratio change when pulling over 6% grades. You wind out say in first then shift to second and are at or bellow the power curve bottom RPM. Then you have to struggle back into the middle of the 2nd gear power band. Same true at higher speeds between 2nd and 3rd. But I see no THM 9 speed in our future, hence the compromise. I don't like, on paper, the idea of changing chain ratios BEFORE the transmission gears and clutches, increasing torque loading, but the fact most have success is a testament to the durability of the TH425. I love the switch pitch as designed in big passenger car application as a quick getaway and passing gear kickdown even with high 2 series axle gears, but I think using switch pitch on long grades in a vehicle with 2X GVW is a misapplication of the original design which was for short term use not 15 Mins of continuous mountain grade climb. So for now staying with 3.42, no chain mod, especially with high speed limits in many states and fast moving 18 wheelers.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Transmission [message #350552 is a reply to message #350534] |
Sat, 07 December 2019 13:30 |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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Senior Member |
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Good news fellas. I was not planning on running thru the Rockies a whole bunch but certainly possible once in a awhile. Thanks for the input!
TG
Tom Geiger
76 Eleganza II
KCMO
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| Re: Transmission [message #350553 is a reply to message #350549] |
Sat, 07 December 2019 13:35 |
Hal StClair
Messages: 971
Registered: March 2013
Location: Rio Rancho NM
Karma: -12
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Senior Member |
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I'm happy with my 2.82 final ratio. Without a toad long 5% grades don't pull it down to direct, 6% can though on longer grades during the cooler seasons. With A/C and fan clutch engaged things change a bit.  Was happy how it performed last week on our trip to Grand Canyon. Would out pull a 26' Jayco V10 Ford powered mini motor home on the hills my son-in-law drove. (almost twice the MPG also).
Still lovin' the Diesel. Hal
"I enjoy talking to you. Your mind appeals to me. It resembles my own mind, except you happen to be insane."
1977 Royale 101348,
1977 Royale 101586, Diesel powered,
1974 Eagle Bus 45',w/slideout,
Rio Rancho, NM
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| Re: [GMCnet] Transmission [message #350564 is a reply to message #350553] |
Sat, 07 December 2019 22:14 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Hal,
Your running a Diesel??
On Sat, Dec 7, 2019 at 11:48 AM Hal StClair via Gmclist <
gmclist@list.gmcnet.org> wrote:
> I'm happy with my 2.82 final ratio. Without a toad long 5% grades don't
> pull it down to direct, 6% can though on longer grades during the cooler
> seasons. With A/C and fan clutch engaged things change a bit. :? Was happy
> how it performed last week on our trip to Grand Canyon. Would out pull a
> 26' Jayco V10 Ford powered mini motor home on the hills my son-in-law
> drove. (almost twice the MPG also).
> Still lovin' the Diesel. Hal
> --
> 1977 Royale 101348,
>
> 1977 Royale 101586, Diesel powered,
>
> 1975 Eleganza II, 101230,
>
> 1974 Eagle Bus 45',w/slideout,
>
> Rio Rancho, NM
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmcrvparts.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] Transmission [message #350572 is a reply to message #350564] |
Sun, 08 December 2019 16:25 |
Hal StClair
Messages: 971
Registered: March 2013
Location: Rio Rancho NM
Karma: -12
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Senior Member |
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Hal
jimk wrote on Sat, 07 December 2019 21:14Hal,
Your running a Diesel??
On Sat, Dec 7, 2019 at 11:48 AM Hal StClair via Gmclist <
gmclist@list.gmcnet.org> wrote:
> I'm happy with my 2.82 final ratio. Without a toad long 5% grades don't
> pull it down to direct, 6% can though on longer grades during the cooler
> seasons. With A/C and fan clutch engaged things change a bit. Was happy
> how it performed last week on our trip to Grand Canyon. Would out pull a
> 26' Jayco V10 Ford powered mini motor home on the hills my son-in-law
> drove. (almost twice the MPG also).
> Still lovin' the Diesel. Hal
> --
> 1977 Royale 101348,
>
> 1977 Royale 101586, Diesel powered,
>
> 1975 Eleganza II, 101230,
>
> 1974 Eagle Bus 45',w/slideout,
>
> Rio Rancho, NM
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmcrvparts.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
"I enjoy talking to you. Your mind appeals to me. It resembles my own mind, except you happen to be insane."
1977 Royale 101348,
1977 Royale 101586, Diesel powered,
1974 Eagle Bus 45',w/slideout,
Rio Rancho, NM
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