Powerglide Transmissions

offroadaction

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I am in the process of gathering information and parts for my new short course truck. I have picked up a tube chassis that was originally going to be a rock crawler but the guy ran out of funds. Being that the courses up here do not have many long straight stretches, the guys do not get into 3rd gear very often. So I am considering using a powerglide transmission. Anybody have an experience with them? I assume they are strong because you see them on lots of drag cars. Would I be better going to a TH400? What are the CORR guys using?

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V8Ranger

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I assume your talking about the racing powerglides and not the General Motor's two speed "power failures?"
 

Klaus

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From what i heard in Pro2 and Pro4 they use one or two speeds only, so a PG might work for you. Isn't it lighter then a TH400 ?
 

offroadaction

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V8- Yes, I am thinking of a pro built Powerglide. There is a transmission shop up here that does a lot of work with the drag and circle track guys that can pretty much build whatever I want. (in terms of ratios, etc.)

Klaus-From my understanding, it is lighter. I figured the CORR guys used two speeds, but was not sure. I want something that is light, strong enough to hold up to 630hp/525lb as well as the abuse of off road racing and is simple to work with.

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AllwaysRcn

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The Ex-Riviera Racing 4wd car that Nick Baldwin drove has a PowerSlide in it! That motor WAS a high horsepower unit - until it let go out at the Fud race last weekend. It seemed like he was tapping out first gear way to high (to keep from bogging in drive). it sounded like some valve train decided to do some mingling with some of the other parts- and they all jumped ship...lol
 

BradM

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That is one issue with powerglides. The split between first and second is fairly large. They can be built to hold the power but you have to be able to get the power to the ground. There are a lot of aftermarket parts available for them, call Mikes Transmission in Lancaster, CA. They build glides for many drag racers.
 

Dave_G

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Re: Would I be better going to a TH400?

With the kind of horse power you want to run I'm not sure the powerglide will be up to it. The Turbo 400 can be beefed up in a lot of ways and I think it will be stronger although slightly heavier. I make quite a few beefed up components for the 400 in the Herbst Truggy. As I recall, I don't think they've had a trans failure in it for numerous years now.

Are you going to run 2WD or 4WD in this car?

Dave

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offroadaction

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I have used the TH400 in the past and have been happy with it. If I run it only in 1st and 2nd 90% of the time, will that be ok? I am not going to damage anything by running in 2 out of the 3 gears most of the time right? Especially if it is built properly? Most of my experience has been with distance racing, where the 3rd gear was nesc. The short course stuff that we did, I think we were always in 1-2. I believe you can get different ratios for the glide to help with the difference between gears.

The p/glide was a consideration, but I am sort of leaning towards a TH400. The vehicle will be 4wd, but I can use a 4wd trans or a 2wd trans as I am not 100% sure on what t/case I will be running. That sort of depends on the transmission I will be using. One of the considerations is a modified chain drive t/case that will allow me to swap gear ratios, depending on the track. I have a retired machinist as a neighbour who's shop is better equiped than most modern shops and is looking for new projects. :)

I am building the vehicle to be light, but it is not my biggest concern. I want it to be strong. I do not think that the weight difference between the PG and the 400 would be worth it if the PG will not hold up or work properly.

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ntsqd

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I think a PG built by someone who knows them and is at least a little familiar with your intended use will stand up to the abuse. I've seen PG's at the drags run in the lo 8's to hi 7's for a whole season w/o more than regular maintenence. Years ago Frank & Lena Williams took a Top Gas car into the 7's with one, that took way more than ~650 HP.
Why carry the extra gear if you won't ever use it ?
The only PG optional first ratios I'm familiar with are lower than stock, widening the split.

TS

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Flea

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couldn't you use a three speed and gear your rear end kinda low so it will use third gear all the time? that way you have three close ratio gears instead of two very wide gears. But I think I read that with extreme low ratio rear end gears your pinion ends up getting so small that it makes the gears weaker. well maybe i just answered my own question... :)
 

Kritter

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Above a 6.0:1 and you will have problems eating gears. Run a splitter and some normal gears and it will rock all 3 gears.

Kris

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Dave_G

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RE: . I've seen PG's at the drags run in the lo 8's to hi 7's for a whole season w/o more than regular maintenence

Big, big, difference here when it comes to drive train abuse. Off road vehicles load and unload the drive train more violently and at higher loads more often than a dragster. Hell, I make maraging drive axles for the K&N GT car that runs 700hp on the asphalt and the axle diameter is only .980 Try running an axle that size on a 7S car. It would be broke in the first 100 feet of a race. When it comes to off road cars they are the most abusive on drive components as compared to an asphalt car.

Dave

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ntsqd

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I wasn't saying it would go a whole season w/o anything more than normal maintenence. I was saying that it is possible to build one to take some pretty serious loads. In racing everything is a consumable part. You know that better than most of us. It comes down to who can afford to replace the light parts often and who has to run the heavier parts so they stay in the operating budget.
If you've never seen a trans brake in operation, those loads have got to be far higher than anything off road can generate. Same or more HP, far better traction, nearly instant application of said HP. Granted they don't happen with the regularity of an off road loading, but I think the guy who came up with them was probably a hard parts supplier in need of cash flow.

TS

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offroadaction

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All good points guys. I now have some different opinions to consider. I am personally leaning towards a TH400...It may be heavier, but it is proven. I have used them in the past and have been really happy. Weight is not a huge concern as I am running a tube chassis with aluminum side panels and FG front clip (it will resemble a long Willys Jeep when finished) and the guys up here are all running 4000-5000lb trucks. The powerglide was an idea, and is something I still may investigate more in the future.

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