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Power Drive [message #327191] Sat, 16 December 2017 22:20 Go to next message
NextGenGMC is currently offline  NextGenGMC   United States
Messages: 146
Registered: December 2017
Location: Washington State
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Senior Member
Hello Everyone,
I'm a new member here on the forum, looking for some information. I'm a relatively recent owner of a beautiful 26' 1976 GMC Glenbrook. It is still pretty new to us and we are in the process of learning all its little quirks and peculiarities.

The coach has a 455 Olds and transmission with the PowerDrive unit. When I first learned about the PowerDrive, I thought it was a modification of some planetary gears in the transmission to modify output ratio and thus reduce stress on the internal transmission components. However, reading more about the TH425 transmission, I discovered that the PowerDrive is the modification to the chain drive part of the tranny (the power that goes TO the planetary gears). As I see it, the PD makes the engine rotate more revolutions in order to make the same number of revolution on the shaft going to the planetary gears. What is the exact benefit of this? Having PD and the 3.21 final drive ratio makes the engine run at much higher RMPs than I'm comfortable with - 2,700 RPM at 60MPH. Seems pretty excessive for the giant engine like 455. All my other cars (granted they are all newer) run at slightly above 1,500-1,700 RPM at the same speed.

When I try to visualize the power transfer in the transmission, it seems that the amount of torque transmitted through the internal components is actually higher with the Power drive than without PD. This is because engine makes more revolutions per same distance of travel (per same number of rotations in the transmission). To me that means that internal components (after the chain drive) will receive higher level of stress. Am I wrong about this? Was PD developed for the 403 engines? To help them with transmitting more power to the ground? Is this setup really beneficial on the coaches with 455? From reading info on various forums, nearly everyone recommends to have PD if you are towing a toad (which we do).

I would really appreciate your input and advice on this topic. Looking forward to learning form the combined wisdom of all. Please educate me Smile


Vadim Jitkov '76 Glenbrook 26' Pullman, WA
Re: Power Drive [message #327192 is a reply to message #327191] Sat, 16 December 2017 22:52 Go to previous messageGo to next message
bwevers is currently offline  bwevers   United States
Messages: 597
Registered: October 2010
Location: San Jose
Karma: 5
Senior Member
Sounds like you have a good set-up.
Most people prefer final drive ratios between 3.50 and 3.70.
The power drive is equivalent to having 3.50.
The 3.21 will bump it up to 3.66 equivalent.

With the 3.07 gears, the carburetor power enrichment circuit
kicks in a lot because of the low manifold vacuum.




Bill Wevers GMC49ers, GMC Western States 1975 Glenbrook - Manny Powerdrive, OneTon 455 F Block, G heads San Jose
Re: [GMCnet] Power Drive [message #327193 is a reply to message #327192] Sat, 16 December 2017 23:26 Go to previous messageGo to next message
James Hupy is currently offline  James Hupy   United States
Messages: 6806
Registered: May 2010
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Senior Member
The TM 425 was originally designed to move a 4000 pound car. We are asking
it to move a 12,000 pound motor home. The same old formula, F x D = Torque
applies in both situations. The motor home is at a three to one
disadvantage weight wise to the cars. Thus, the power drive and different
gearing in the final drives. Manny T sells the power drive and builds
transmissions too. Good guy, knows his stuff. Good friend to the whole GMC
community. The power drive is hell for strong, like the rest of the TM-425.
I wouldn't worry about it.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

On Dec 16, 2017 8:53 PM, "Bill Wevers" wrote:

> Sounds like you have a good set-up.
> Most people prefer final drive ratios between 3.50 and 3.70.
> The power drive is equivalent to having 3.50.
> The 3.21 will bump it up to 3.66 equivalent.
>
> With the 3.07 gears, the carburetor power enrichment circuit
> kicks in a lot because of the low manifold vacuum.
>
>
>
> --
> Bill Wevers GMC49ers, GMC Western States
> 1975 Glenbrook - Manny Powerdrive, OneTon
> 455 F Block, G heads
> San Jose
>
> _______________________________________________
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>
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Re: [GMCnet] Power Drive [message #327194 is a reply to message #327193] Sun, 17 December 2017 00:05 Go to previous messageGo to next message
jimk is currently offline  jimk   United States
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
Senior Member
On Sat, Dec 16, 2017 at 9:27 PM James Hupy wrote:

> The TM 425 was originally designed to move a 4000 pound car. We are asking
> it to move a 12,000 pound motor home. The same old formula, F x D = Torque
> applies in both situations. The motor home is at a three to one
> disadvantage weight wise to the cars. Thus, the power drive and different
> gearing in the final drives. Manny T sells the power drive and builds
> transmissions too. Good guy, knows his stuff. Good friend to the whole GMC
> community. The power drive is hell for strong, like the rest of the TM-425.
> I wouldn't worry about it.
> Jim Hupy
> Salem, Or
> 78 GMC ROYALE 403
>
> On Dec 16, 2017 8:53 PM, "Bill Wevers" wrote:
>
>> Sounds like you have a good set-up.
>> Most people prefer final drive ratios between 3.50 and 3.70.
>> The power drive is equivalent to having 3.50.
>> The 3.21 will bump it up to 3.66 equivalent.
>>
>> With the 3.07 gears, the carburetor power enrichment circuit
>> kicks in a lot because of the low manifold vacuum.
>>
>>
>>
>> --
>> Bill Wevers GMC49ers, GMC Western States
>> 1975 Glenbrook - Manny Powerdrive, OneTon
>> 455 F Block, G heads
>> San Jose
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>> why don't you go back to 3.07 then tell me your experience.

some have done that but too proud to admit the mistake.
All the RV units that use chassis from suppliers run 4.11 /4.55 using the
same wheel and tire.GM , Ford and Chrysler know more than us

>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
http://list.gmcnet.org/mailman/listinfo/
> B

--
Jim Kanomata
Applied/GMC, Newark,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
Re: Power Drive [message #327195 is a reply to message #327192] Sun, 17 December 2017 00:55 Go to previous messageGo to next message
NextGenGMC is currently offline  NextGenGMC   United States
Messages: 146
Registered: December 2017
Location: Washington State
Karma: -1
Senior Member
bwevers wrote on Sat, 16 December 2017 20:52
Sounds like you have a good set-up.
Most people prefer final drive ratios between 3.50 and 3.70.
The power drive is equivalent to having 3.50.
The 3.21 will bump it up to 3.66 equivalent.

With the 3.07 gears, the carburetor power enrichment circuit
kicks in a lot because of the low manifold vacuum.




I must admit that carburetors are a mystery to me... I feel much easier with computers and fuel injection (conversion project is going to happen some day). Would it be beneficial to change a final drive ratio to bring it closer to a 3.55 combined number?


Vadim Jitkov '76 Glenbrook 26' Pullman, WA
Re: [GMCnet] Power Drive [message #327196 is a reply to message #327194] Sun, 17 December 2017 01:02 Go to previous messageGo to next message
NextGenGMC is currently offline  NextGenGMC   United States
Messages: 146
Registered: December 2017
Location: Washington State
Karma: -1
Senior Member
[quote

some have done that but too proud to admit the mistake.
All the RV units that use chassis from suppliers run 4.11 /4.55 using the
same wheel and tire.GM , Ford and Chrysler know more than us

[/quote]

Are you referring to making a mistake of lowering final drive ratio on the GMC?
As far as box RVs - yes, they run a much higher final drive ratios, but that it because output shaft on transmission comes out at a very different speed from what we have going on in our GMCs


Vadim Jitkov '76 Glenbrook 26' Pullman, WA
Re: [GMCnet] Power Drive [message #327199 is a reply to message #327196] Sun, 17 December 2017 03:29 Go to previous messageGo to next message
johnd01 is currently offline  johnd01   United States
Messages: 354
Registered: July 2017
Location: Sacrameot
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Senior Member
[quote title=NextGenGMC wrote on Sun, 17 December 2017 01:02][quote

some have done that but too proud to admit the mistake.
All the RV units that use chassis from suppliers run 4.11 /4.55 using the
same wheel and tire.GM, Ford, and Chrysler know more than us

[/quote]

Are you referring to making a mistake of lowering final drive ratio on the GMC?
As far as box RVs - yes, they run a much higher final drive ratios, but that it because output shaft on transmission comes out at a very different speed from what we have going on in our GMCs[/quote]

Are you saying that both transmissions do not have a 1 to 1 ratio in high gear?


Johnd01 John Phillips Avion A2600 TZE064V101164 Rancho Cordova, CA (Sacramento)
Re: [GMCnet] Power Drive [message #327204 is a reply to message #327191] Sun, 17 December 2017 09:52 Go to previous messageGo to next message
Ken Henderson is currently offline  Ken Henderson   United States
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
Senior Member
Vadim,

After having a GMC for 19 years, variously equipped with standard, Power
Drive, and higher ratio final drives; and having talked to and listened
here to literally hundreds of other GMCers, including every expert in the
community, I have an opinion. That opinion is that the Power Drive+3.21 is
as close to the ideal drive train as one can get for the GMC. Yes, the
Power Drive DOES increase the torque load on the TH-425, which can easily
withstand the increase; I'd have no qualms about using it with my Cad500.

Keep it as it is unless you just want to experiment with others -- but
don't let go of the pieces, 'cause you'll probably want to go back.

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
www.gmcwipersetc.com

On Sat, Dec 16, 2017 at 11:21 PM, Vadim Jitkov
wrote:

> Hello Everyone,
> I'm a new member here on the forum, looking for some information. I'm a
> relatively recent owner of a beautiful 26' 1976 GMC Glenbrook. It is still
> pretty new to us and we are in the process of learning all its little
> quirks and peculiarities.
>
> The coach has a 455 Olds and transmission with the PowerDrive unit. When I
> first learned about the PowerDrive, I thought it was a modification of some
> ​...
>
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
Re: Power Drive [message #327205 is a reply to message #327191] Sun, 17 December 2017 10:02 Go to previous messageGo to next message
Matt Colie is currently online  Matt Colie   United States
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
Senior Member
NGG,

Welcome to the group, family, cult, asylum....

Education of new owners is something we make a serious issue of here. All of us here have been witness to enough mistakes to make for a massive experience base.

You are largely correct about the powerdrive being a less than optimum solution, and if the TH425 were a weaker beast, it would be. It was a much better solution than GM came up with 3 years too late. The stock 3.07 was chosen because it was all that GM had. It was actually for the towing package for the Oldsmobile Toronado. It is not that bad if you have a light 23' and cruise at 70+. That was the plan in 1973 and that died fast with the first Arab Oil Embargo (that really made only political complications) and the 55MPH national speed limit. The fact is that the only torque that can be transmitted through the transmission is what it takes to accelerate and move the vehicle. So, the powerdrive cannot vastly effect that transmitted torque.

How tough is a TH425? Lots of owners have put Cadillac 500s on them and have no more trouble than the rest of us. Then there is Jim Kanomata (Applied GMC => put them in your speed dial) that has a twin turbo 540 and the only thing that he does not break all the time is the transmission. So, don't sweat that one.

GMs recommended solution was the 3.41. That is just enough to keep the carburetor out of power enrichment is most cases. But for my money (I am only a couple of kinds of engineer and worked in as with automotive for decades) the 3.55 is a better choice. I know you are looking at 2700 at 60, but do not try to relate this to a modern much lighter vehicle. That is just wrong in so many ways. Our coach with a 3.07 is running a 19~2100 at ~60MPH, and the intake depression (vacuum) is disturbingly low and this is with a 9600# coach.

So, for the near term, leave it alone. Learn to drive and maintain her and enjoy what she brings you. If you are going to make the change to EFI, you are in the right place. There are many here with very successful installations. This forum can be searched and so can both GMCMI and GMCWS for more information. When you have learned enough to frame a question, come back here for the right answer. We have people writing here with literally millions of miles and many decades of experience. Me? Yeah, I'm a ship's engineer by training and other things, but I have only had a GMC for 12 years and 70K, that makes me young in this group. Yes, I write long answers, but they are simply because most serious questions cannot be covered with a simple answer. I don't mind as I am trying real hard to pass along what many very patient people have taken the time to teach me.

There are other GMC Motorhome places on the web. There are multiple on FaceBook, but technical answers there should be checked as I have seen several occasions of wrong and dangerous answers. That does not mean stay away. It a great social forum. There is also a group at RVillage.com. I know, I started it and so far it has little value.

Before too long, do us all a favor. You are running the forum, so, go to <Control Panel/Account Settings> and scroll down to the place that you can fill in a sigfile. Please put in a real name (so when other GMCers meet you, they will know who you are), Short about the coach (you did say 76 Glenbrook in the first, but some E-mail readers only see one post at a time) and a geographic reference (the header the e-mail readers never see does say Washington) but try to be a little specific and I will tell you why later. This will be a help to both you and us, and again there is a reason. Remember to scroll down to <Update> when you are done.

You bought a coach and found your way here, that is good, but what you may not realize is that the coach is more than just a new big toy because it connects you to this community. You are now part of a community like very few others. It is filled with helping and supportive people that really do want you to enjoy both the coach and what she can bring to you. To this end, they can do just amazing things. If you hang around here, you will get to read some incredible but very real stories. The only other community like this that I know of is that of the watermen that are my world. For that reason, I have taken to welcoming new owners here much as any new owner or vessel would be welcomed there. So,

May the Good Lord bless this coach and all those that set forth within her.

Welcome Vadim

Matt



Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
Re: Power Drive [message #327229 is a reply to message #327191] Sun, 17 December 2017 20:44 Go to previous messageGo to next message
NextGenGMC is currently offline  NextGenGMC   United States
Messages: 146
Registered: December 2017
Location: Washington State
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Senior Member
Thank you everyone for the warm welcome and for your replies. This is exactly the information I was looking for. I'm just trying to better understand the purpose of some of the modifications that are on this unit. That way i will know better what its doing and why when we are on the road...
The answer I hear from the members - leave it as is, slow down to 55 (maybe 60) MPH, chill out and enjoy the scenery Smile I plan on doing exactly that.


Vadim Jitkov '76 Glenbrook 26' Pullman, WA
Re: [GMCnet] Power Drive [message #327231 is a reply to message #327229] Sun, 17 December 2017 20:48 Go to previous messageGo to next message
James Hupy is currently offline  James Hupy   United States
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Registered: May 2010
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Senior Member
You won't hurt that 455 if you keep the rpm's under 4200 or so.
Jim Hupy
Salem, Or
78 GMC Royale 403

On Dec 17, 2017 6:44 PM, "Vadim Jitkov" wrote:

> Thank you everyone for the warm welcome and for your replies. This is
> exactly the information I was looking for. I'm just trying to better
> understand
> the purpose of some of the modifications that are on this unit. That way i
> will know better what its doing and why when we are on the road...
> The answer I hear from the members - leave it as is, slow down to 55
> (maybe 60) MPH, chill out and enjoy the scenery :) I plan on doing exactly
> that.
>
> --
> Vadim Jitkov
> '76 Glenbrook 26'
> Pullman, WA
>
> _______________________________________________
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> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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Re: [GMCnet] Power Drive [message #327233 is a reply to message #327229] Sun, 17 December 2017 20:56 Go to previous messageGo to next message
Ken Henderson is currently offline  Ken Henderson   United States
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Registered: March 2004
Location: Americus, GA
Karma: 9
Senior Member
Or, if you HAVE to get on a freeway, and it makes you more comfortable,
stay with the traffic. The GMC should still be comfortable at 75-80. :-}

​Just what I do -- but, then, there are some who advise against caravaning
with me. :-{​

Ken H.


On Sun, Dec 17, 2017 at 9:44 PM, Vadim Jitkov
wrote:

> Thank you everyone for the warm welcome and for your replies. This is
> exactly the information I was looking for. I'm just trying to better
> understand
> the purpose of some of the modifications that are on this unit. That way i
> will know better what its doing and why when we are on the road...
> The answer I hear from the members - leave it as is, slow down to 55
> (maybe 60) MPH, chill out and enjoy the scenery :) I plan on doing exactly
> that.
>
> --
> Vadim Jitkov
> '76 Glenbrook 26'
> Pullman, WA
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
Re: [GMCnet] Power Drive [message #327239 is a reply to message #327233] Sun, 17 December 2017 22:24 Go to previous messageGo to next message
Richard Denney is currently offline  Richard Denney   United States
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Registered: April 2010
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Senior Member
Only the Redhead, when punching a hole through Atlanta traffic at 70 mph on
a congested freeway, but I actually think it was Manny the Maniac that was
driving your coach.

Rick "who needed that big margarita after that one" Denney

On Sun, Dec 17, 2017 at 9:57 PM Ken Henderson
wrote:

> Or, if you HAVE to get on a freeway, and it makes you more comfortable,
> stay with the traffic. The GMC should still be comfortable at 75-80. :-}
>
> ​Just what I do -- but, then, there are some who advise against caravaning
> with me. :-{​
>
> Ken H.

--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com
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Re: [GMCnet] Power Drive [message #327240 is a reply to message #327239] Sun, 17 December 2017 23:14 Go to previous messageGo to next message
Kingsley Coach is currently offline  Kingsley Coach   United States
Messages: 2691
Registered: March 2009
Location: Nova Scotia Canada
Karma: -34
Senior Member
Ken

I've followed Kerry Tandy through El Paso in the outside lane at 4:30 doing
75 + ...Clearly a student of your driving school !

Mike in Las Cruces


Virus-free.
www.avast.com



On Mon, Dec 18, 2017 at 12:24 AM, Richard Denney wrote:

> Only the Redhead, when punching a hole through Atlanta traffic at 70 mph on
> a congested freeway, but I actually think it was Manny the Maniac that was
> driving your coach.
>
> Rick "who needed that big margarita after that one" Denney
>
> On Sun, Dec 17, 2017 at 9:57 PM Ken Henderson
> wrote:
>
>> Or, if you HAVE to get on a freeway, and it makes you more comfortable,
>> stay with the traffic. The GMC should still be comfortable at 75-80.
> :-}
>>
>> ​Just what I do -- but, then, there are some who advise against
> caravaning
>> with me. :-{​
>>
>> Ken H.
>
> --
> Rick Denney
> 73 x-Glacier 230 "Jaws"
> Off-list email to rick at rickdenney dot com
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>



--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS

Life is too short to hold a grudge; slash some tires and call it even !
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Re: [GMCnet] Power Drive [message #327241 is a reply to message #327240] Sun, 17 December 2017 23:22 Go to previous messageGo to next message
James Hupy is currently offline  James Hupy   United States
Messages: 6806
Registered: May 2010
Karma: -62
Senior Member
Jim K. has that 540 cubic inch dual turbocharged, intercooled, for a
purpose, and he only drives 55 on his way to 80. I have followed him a
couple of times to and from rallies. You need to be on your "A" game to
keep him in view. The 403 is really happy above 3000 rpms. Don't ask me how
I know.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

On Dec 17, 2017 9:15 PM, "Kingsley Coach" wrote:

> Ken
>
> I've followed Kerry Tandy through El Paso in the outside lane at 4:30 doing
> 75 + ...Clearly a student of your driving school !
>
> Mike in Las Cruces
>
> source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon>
> Virus-free.
> www.avast.com
> source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link>
>
>
> On Mon, Dec 18, 2017 at 12:24 AM, Richard Denney
> wrote:
>
>> Only the Redhead, when punching a hole through Atlanta traffic at 70 mph
> on
>> a congested freeway, but I actually think it was Manny the Maniac that
> was
>> driving your coach.
>>
>> Rick "who needed that big margarita after that one" Denney
>>
>> On Sun, Dec 17, 2017 at 9:57 PM Ken Henderson
>> wrote:
>>
>>> Or, if you HAVE to get on a freeway, and it makes you more comfortable,
>>> stay with the traffic. The GMC should still be comfortable at 75-80.
>> :-}
>>>
>>> ​Just what I do -- but, then, there are some who advise against
>> caravaning
>>> with me. :-{​
>>>
>>> Ken H.
>>
>> --
>> Rick Denney
>> 73 x-Glacier 230 "Jaws"
>> Off-list email to rick at rickdenney dot com
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
>
> --
> Michael Beaton
> 1977 Kingsley 26-11
> 1977 Eleganza II 26-3
> Antigonish, NS
>
> Life is too short to hold a grudge; slash some tires and call it even !
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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Re: [GMCnet] Power Drive [message #327242 is a reply to message #327240] Sun, 17 December 2017 23:19 Go to previous messageGo to next message
Kingsley Coach is currently offline  Kingsley Coach   United States
Messages: 2691
Registered: March 2009
Location: Nova Scotia Canada
Karma: -34
Senior Member
Vadim

When you get a chance, could you connect with John Shotwell and record your
TZE number so we know where these machines are living :)
And there is also the Black List for you to get on...help for the GMC owner
when on the road. If you need more info on finding these, let us know.
Thanks for the sig addition to your posting....

Mike in NM

On Mon, Dec 18, 2017 at 1:14 AM, Kingsley Coach
wrote:

> Ken
>
> I've followed Kerry Tandy through El Paso in the outside lane at 4:30
> doing 75 + ...Clearly a student of your driving school !
>
> Mike in Las Cruces
>
>
> Virus-free.
> www.avast.com
>
>
>
> On Mon, Dec 18, 2017 at 12:24 AM, Richard Denney
> wrote:
>
>> Only the Redhead, when punching a hole through Atlanta traffic at 70 mph
>> on
>> a congested freeway, but I actually think it was Manny the Maniac that was
>> driving your coach.
>>
>> Rick "who needed that big margarita after that one" Denney
>>
>> On Sun, Dec 17, 2017 at 9:57 PM Ken Henderson
>> wrote:
>>
>>> Or, if you HAVE to get on a freeway, and it makes you more comfortable,
>>> stay with the traffic. The GMC should still be comfortable at 75-80.
>> :-}
>>>
>>> ​Just what I do -- but, then, there are some who advise against
>> caravaning
>>> with me. :-{​
>>>
>>> Ken H.
>>
>> --
>> Rick Denney
>> 73 x-Glacier 230 "Jaws"
>> Off-list email to rick at rickdenney dot com
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
>
> --
> Michael Beaton
> 1977 Kingsley 26-11
> 1977 Eleganza II 26-3
> Antigonish, NS
>
> Life is too short to hold a grudge; slash some tires and call it even !
>
>
>


--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS

Life is too short to hold a grudge; slash some tires and call it even !
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Re: [GMCnet] Power Drive [message #327243 is a reply to message #327229] Sun, 17 December 2017 23:30 Go to previous messageGo to next message
USAussie is currently offline  USAussie   United States
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
Senior Member
Vadim,

Double Trouble has a 3.21 to 1 planetary gear final drive. They were OEM equipment in the 1966 & 67 Olds Toronado; GMC "folklore"
notes that they are "bulletproof."

Based on what I've read on the GMC net and my personal experience it's not high speed that will alter the life of a TH425
negatively; it is constantly putting a heavy load on them when you accelerate from a stop.

I do my best to accelerate slowly from a stop up to the speed limit.

I drive whatever the speed limit is; be it 55, 60, 65, 70, or 75.

As noted the Toronado weighed around 4000 lb and the GMC weighs THREE times that much. Once you have the mass in motion the stress
on the transmission drops. Of course it takes more power to move the GMC down the road because of the weight AND the drag.

IIRC I've noted that the RPM's of the 455 with the 3.21 to 1 final drive runs around 2400 at 65 and it loves it! It will cruise at
that rpm range all day long without a hiccup.

Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808


-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of Vadim Jitkov
Sent: Monday, December 18, 2017 1:44 PM
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Power Drive

Thank you everyone for the warm welcome and for your replies. This is exactly the information I was looking for. I'm just trying to
better understand the purpose of some of the modifications that are on this unit. That way i will know better what its doing and why
when we are on the road...
The answer I hear from the members - leave it as is, slow down to 55 (maybe 60) MPH, chill out and enjoy the scenery :) I plan on
doing exactly that.

--
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA

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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
Re: [GMCnet] Power Drive [message #327257 is a reply to message #327242] Mon, 18 December 2017 12:01 Go to previous messageGo to next message
NextGenGMC is currently offline  NextGenGMC   United States
Messages: 146
Registered: December 2017
Location: Washington State
Karma: -1
Senior Member
Already done so for both list Smile
The support network I've seen while researching the GMCs as well as the knowledge sharing among the owners was one of the factors that lessened my anxiety over purchasing a 40+ year old coach.

Kingsley Coach wrote on Sun, 17 December 2017 21:19
Vadim

When you get a chance, could you connect with John Shotwell and record your
TZE number so we know where these machines are living Smile
And there is also the Black List for you to get on...help for the GMC owner
when on the road. If you need more info on finding these, let us know.
Thanks for the sig addition to your posting....

Mike in NM

On Mon, Dec 18, 2017 at 1:14 AM, Kingsley Coach
wrote:

> Ken
>
> I've followed Kerry Tandy through El Paso in the outside lane at 4:30
> doing 75 + ...Clearly a student of your driving school !
>
> Mike in Las Cruces
>
>
> Virus-free.
> www.avast.com
>
>
>
> On Mon, Dec 18, 2017 at 12:24 AM, Richard Denney
> wrote:
>
>> Only the Redhead, when punching a hole through Atlanta traffic at 70 mph
>> on
>> a congested freeway, but I actually think it was Manny the Maniac that was
>> driving your coach.
>>
>> Rick "who needed that big margarita after that one" Denney
>>
>> On Sun, Dec 17, 2017 at 9:57 PM Ken Henderson
>> wrote:
>>
>>> Or, if you HAVE to get on a freeway, and it makes you more comfortable,
>>> stay with the traffic. The GMC should still be comfortable at 75-80.
>> :-}
>>>
>>> ​Just what I do -- but, then, there are some who advise against
>> caravaning
>>> with me. :-{​
>>>
>>> Ken H.
>>
>> --
>> Rick Denney
>> 73 x-Glacier 230 "Jaws"
>> Off-list email to rick at rickdenney dot com
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
>
> --
> Michael Beaton
> 1977 Kingsley 26-11
> 1977 Eleganza II 26-3
> Antigonish, NS
>
> Life is too short to hold a grudge; slash some tires and call it even !
>
>
>


--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS

Life is too short to hold a grudge; slash some tires and call it even !
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Vadim Jitkov '76 Glenbrook 26' Pullman, WA
Re: [GMCnet] Power Drive [message #327268 is a reply to message #327257] Mon, 18 December 2017 15:26 Go to previous messageGo to next message
Kingsley Coach is currently offline  Kingsley Coach   United States
Messages: 2691
Registered: March 2009
Location: Nova Scotia Canada
Karma: -34
Senior Member
You're on top of things, young fellow !
Thanks

Mike in NM

On Mon, Dec 18, 2017 at 2:01 PM, Vadim Jitkov
wrote:

> Already done so for both list :)
> The support network I've seen while researching the GMCs as well as the
> knowledge sharing among the owners was one of the factors that lessened my
> anxiety over purchasing a 40+ year old coach.
>
> Kingsley Coach wrote on Sun, 17 December 2017 21:19
>> Vadim
>>
>> When you get a chance, could you connect with John Shotwell and record
> your
>> TZE number so we know where these machines are living :)
>> And there is also the Black List for you to get on...help for the GMC
> owner
>> when on the road. If you need more info on finding these, let us know.
>> Thanks for the sig addition to your posting....
>>
>> Mike in NM
>>
>> On Mon, Dec 18, 2017 at 1:14 AM, Kingsley Coach
>> wrote:
>>
>>> Ken
>>>
>>> I've followed Kerry Tandy through El Paso in the outside lane at 4:30
>>> doing 75 + ...Clearly a student of your driving school !
>>>
>>> Mike in Las Cruces
>>>
>>>
>>> Virus-free.
>>> www.avast.com
>>>
>>>
>>>
>>> On Mon, Dec 18, 2017 at 12:24 AM, Richard Denney
>>> wrote:
>>>
>>>> Only the Redhead, when punching a hole through Atlanta traffic at 70
> mph
>>>> on
>>>> a congested freeway, but I actually think it was Manny the Maniac
> that was
>>>> driving your coach.
>>>>
>>>> Rick "who needed that big margarita after that one" Denney
>>>>
>>>> On Sun, Dec 17, 2017 at 9:57 PM Ken Henderson
>>>> wrote:
>>>>
>>>> > Or, if you HAVE to get on a freeway, and it makes you more
> comfortable,
>>>> > stay with the traffic. The GMC should still be comfortable at
> 75-80.
>>>> :-}
>>>> >
>>>> > ​Just what I do -- but, then, there are some who advise against
>>>> caravaning
>>>> > with me. :-{​
>>>> >
>>>> > Ken H.
>>>>
>>>> --
>>>> Rick Denney
>>>> 73 x-Glacier 230 "Jaws"
>>>> Off-list email to rick at rickdenney dot com
>>>> _______________________________________________
>>>> GMCnet mailing list
>>>> Unsubscribe or Change List Options:
>>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>>>
>>>
>>>
>>>
>>> --
>>> Michael Beaton
>>> 1977 Kingsley 26-11
>>> 1977 Eleganza II 26-3
>>> Antigonish, NS
>>>
>>> Life is too short to hold a grudge; slash some tires and call it even
> !
>>>
>>>
>>>
>>
>>
>> --
>> Michael Beaton
>> 1977 Kingsley 26-11
>> 1977 Eleganza II 26-3
>> Antigonish, NS
>>
>> Life is too short to hold a grudge; slash some tires and call it even !
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> --
> Vadim Jitkov
> '76 Glenbrook 26'
> Pullman, WA
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>



--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS

Life is too short to hold a grudge; slash some tires and call it even !
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Re: [GMCnet] Power Drive [message #327269 is a reply to message #327243] Mon, 18 December 2017 19:38 Go to previous messageGo to previous message
Carl S. is currently offline  Carl S.   United States
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
Senior Member

Vadim,

I have a 3.70 final drive in my '75 26 footer and I normally drive between 62 and 65 MPH with no problems. Most 3/4 ton pickups of the same era had 4.10 rear end gears and most 1-Ton pickups were equipped with 4.56 gears, with essentially the same size tires as our GMCs.

The main difference between then and now is the overdrive transmissions on the newer cars. Prior to that, trucks, motorhomes, etc ran at higher RPMs than they do now. Of course, we were lucky to get much more than 100,000 miles out of those older vehicles, but that is only one of the reasons the newer ones last longer.


Carl Stouffer '75 ex Palm Beach Tucson, AZ. Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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