How my trans survives with a 17 to 24, 000 lbs GVW all the time. A simple rule.

B

Bob Dunahugh

New member
Sep 17, 2012
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I rebuilt my trans myself. 17 years ago. I have a very simple rule. That I fallow religiously. Never use more than half throttle on any climb. PIRIOD. EVER. It comes down to BTU input by way of the throttle position. I'm an active down shifter. Have a 3:70. Sometimes I'll have the engine over well over 4,000 RPM's. I up shift, or down shift manually on climbs. And always let off the throttle during shifts. I change my trans fluid every year.
Sometimes I have a contest with myself. As to how many cars can I get to pass me each mile. ( I'm so easy to keep entertained on the road.) GRIN.
Bob Dunahugh
 
Hi Bob,
If you monitored all the temps would you use more throttle while they were
low? We have a relatively large engine that can produce a lot of power but
if the cooling systems seem to be under configured. Pound for pound we have
as much power as a big 400 HP diesel pusher. Is all your concern thermal
limited or are you also concerned about mechanically overloading the
transmission and final drive?

John Phillips
1975 Avion VIN A26000
Citrus Heights CA. 95610

On Sat, Jul 11, 2020 at 11:13 PM Bob Dunahugh via Gmclist <

> I rebuilt my trans myself. 17 years ago. I have a very simple rule. That I
> fallow religiously. Never use more than half throttle on any climb.
> PIRIOD. EVER. It comes down to BTU input by way of the throttle position.
> I'm an active down shifter. Have a 3:70. Sometimes I'll have the engine
> over well over 4,000 RPM's. I up shift, or down shift manually on climbs.
> And always let off the throttle during shifts. I change my trans fluid
> every year.
> Sometimes I have a contest with myself. As to how many cars can I get to
> pass me each mile. ( I'm so easy to keep entertained on the road.) GRIN.
> Bob Dunahugh
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--

*John Phillips*
 
John Phillips. I have a Digi Panel. My trans temp stays about the same. Mtn's, or the flats of the Midwest. If you want to get more life from your trans. Be nice to it as to driving habits. Put a large aux trans cooler in CORRECTLY. Most that I've seen are installed incorrectly. Get a 3:70, or 4:10 FD. To reduce a lot of load on that 425 trans. And improve your MPGs. I'd never install a 3:21 FD. As it's such a tiny improvement. Towing or not. My Trans has put up with all this loading for over 100,000 miles. With standard ATF. Has stood up by what I do to it. Or I'm just dam lucky. ( GRIN )
Bob Dunahugh

________________________________
From: Bob Dunahugh
Sent: Sunday, July 12, 2020 1:13 AM
To: gmclist
Subject: How my trans survives with a 17 to 24,000 lbs GVW all the time. A simple rule.

I rebuilt my trans myself. 17 years ago. I have a very simple rule. That I fallow religiously. Never use more than half throttle on any climb. PIRIOD. EVER. It comes down to BTU input by way of the throttle position. I'm an active down shifter. Have a 3:70. Sometimes I'll have the engine over well over 4,000 RPM's. I up shift, or down shift manually on climbs. And always let off the throttle during shifts. I change my trans fluid every year.
Sometimes I have a contest with myself. As to how many cars can I get to pass me each mile. ( I'm so easy to keep entertained on the road.) GRIN.
Bob Dunahugh
 
sounds like good advice Bob,
So what makes a CORRECT trans cooler install?
________________________________
From: Gmclist on behalf of Bob Dunahugh via Gmclist
Sent: Monday, July 13, 2020 12:35 AM
To: gmclist
Cc: Bob Dunahugh
Subject: [GMCnet] Fw: How my trans survives with a 17 to 24, 000 lbs GVW all the time. A simple rule.

John Phillips. I have a Digi Panel. My trans temp stays about the same. Mtn's, or the flats of the Midwest. If you want to get more life from your trans. Be nice to it as to driving habits. Put a large aux trans cooler in CORRECTLY. Most that I've seen are installed incorrectly. Get a 3:70, or 4:10 FD. To reduce a lot of load on that 425 trans. And improve your MPGs. I'd never install a 3:21 FD. As it's such a tiny improvement. Towing or not. My Trans has put up with all this loading for over 100,000 miles. With standard ATF. Has stood up by what I do to it. Or I'm just dam lucky. ( GRIN )
Bob Dunahugh

________________________________
From: Bob Dunahugh
Sent: Sunday, July 12, 2020 1:13 AM
To: gmclist
Subject: How my trans survives with a 17 to 24,000 lbs GVW all the time. A simple rule.

I rebuilt my trans myself. 17 years ago. I have a very simple rule. That I fallow religiously. Never use more than half throttle on any climb. PIRIOD. EVER. It comes down to BTU input by way of the throttle position. I'm an active down shifter. Have a 3:70. Sometimes I'll have the engine over well over 4,000 RPM's. I up shift, or down shift manually on climbs. And always let off the throttle during shifts. I change my trans fluid every year.
Sometimes I have a contest with myself. As to how many cars can I get to pass me each mile. ( I'm so easy to keep entertained on the road.) GRIN.
Bob Dunahugh
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Bob, as I read that you are more concerned about overloading the 425 trans
and the lower FD gives reduces the torque on the transmission. You do
not use the power the 455 has available. What is the stock FD? How do
people connect a cooler incorrectly? I have not checked but I think my
coach has a stock FD and cooler. I do have an aluminium radiator.

*J**ohn Phillips*
*1975 Avion VIN A26000 *
*Citrus Heights (Sacramento) CA 95610*

On Sun, Jul 12, 2020 at 10:36 PM Bob Dunahugh via Gmclist <

> John Phillips. I have a Digi Panel. My trans temp stays about the same.
> Mtn's, or the flats of the Midwest. If you want to get more life from your
> trans. Be nice to it as to driving habits. Put a large aux trans cooler in
> CORRECTLY. Most that I've seen are installed incorrectly. Get a 3:70, or
> 4:10 FD. To reduce a lot of load on that 425 trans. And improve your MPGs.
> I'd never install a 3:21 FD. As it's such a tiny improvement. Towing or
> not. My Trans has put up with all this loading for over 100,000 miles. With
> standard ATF. Has stood up by what I do to it. Or I'm just dam lucky. (
> GRIN )
> Bob Dunahugh
>
> ________________________________
> From: Bob Dunahugh
> Sent: Sunday, July 12, 2020 1:13 AM
> To: gmclist
> Subject: How my trans survives with a 17 to 24,000 lbs GVW all the time. A
> simple rule.
>
> I rebuilt my trans myself. 17 years ago. I have a very simple rule. That I
> fallow religiously. Never use more than half throttle on any climb.
> PIRIOD. EVER. It comes down to BTU input by way of the throttle position.
> I'm an active down shifter. Have a 3:70. Sometimes I'll have the engine
> over well over 4,000 RPM's. I up shift, or down shift manually on climbs.
> And always let off the throttle during shifts. I change my trans fluid
> every year.
> Sometimes I have a contest with myself. As to how many cars can I get to
> pass me each mile. ( I'm so easy to keep entertained on the road.) GRIN.
> Bob Dunahugh
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--

*John Phillips*
 
Trans fluid has an additive package that is exhausted by heat.
I try to change it every 10,000 miles as I tend to drive hard and tackle
mountains.
Since we travel accross the country , I drop the pan and visually check for
metel paticals.
If it looks good, we install the pan W/O new filter.
Synthetic fluid has lot of great advantages.

On Mon, Jul 13, 2020 at 7:04 AM Keith V via Gmclist
wrote:

> sounds like good advice Bob,
> So what makes a CORRECT trans cooler install?
> ________________________________
> From: Gmclist on behalf of Bob Dunahugh
> via Gmclist
> Sent: Monday, July 13, 2020 12:35 AM
> To: gmclist
> Cc: Bob Dunahugh
> Subject: [GMCnet] Fw: How my trans survives with a 17 to 24, 000 lbs GVW
> all the time. A simple rule.
>
> John Phillips. I have a Digi Panel. My trans temp stays about the same.
> Mtn's, or the flats of the Midwest. If you want to get more life from your
> trans. Be nice to it as to driving habits. Put a large aux trans cooler in
> CORRECTLY. Most that I've seen are installed incorrectly. Get a 3:70, or
> 4:10 FD. To reduce a lot of load on that 425 trans. And improve your MPGs.
> I'd never install a 3:21 FD. As it's such a tiny improvement. Towing or
> not. My Trans has put up with all this loading for over 100,000 miles. With
> standard ATF. Has stood up by what I do to it. Or I'm just dam lucky. (
> GRIN )
> Bob Dunahugh
>
> ________________________________
> From: Bob Dunahugh
> Sent: Sunday, July 12, 2020 1:13 AM
> To: gmclist
> Subject: How my trans survives with a 17 to 24,000 lbs GVW all the time. A
> simple rule.
>
> I rebuilt my trans myself. 17 years ago. I have a very simple rule. That I
> fallow religiously. Never use more than half throttle on any climb.
> PIRIOD. EVER. It comes down to BTU input by way of the throttle position.
> I'm an active down shifter. Have a 3:70. Sometimes I'll have the engine
> over well over 4,000 RPM's. I up shift, or down shift manually on climbs.
> And always let off the throttle during shifts. I change my trans fluid
> every year.
> Sometimes I have a contest with myself. As to how many cars can I get to
> pass me each mile. ( I'm so easy to keep entertained on the road.) GRIN.
> Bob Dunahugh
> _______________________________________________
> 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
http://www.gmcrvparts.com
1-800-752-7502
 
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