Hot Rods Powerglide Transmission Flexplate/Converter Questions

I'm building a RushNoMore 32 Ford Fibergl*** 3 window coupe. I have a crate 350 and a Powerglide transmission for the car, and need a flex plate and torque converter. I ***ume that I need an internally balanced flex plate (guessing the crate motor is internally balanced), and the PG transmission is an older sealed Transmission Specialties unit with a trans brake which the previous owner says the complete unit has never been used.

I realize it's probably more transmission than I need for a street rod, but it's what I have and I'd like to get the parts I need and install it. I've found a lot of used parts, but no one seems to know for sure their flex plate and torque converter will work. Part numbers would help. Good used parts would work too. IDEAS?

 

Does the transmission have a co**** or fine spline input shaft? Powerglides all had co**** splines, but you can get a fine spline that will fit the TH350-400 converters.

You need to figure out how much stall speed you want. The transmission is probably set up to shift hard, and if you have a stock converter that matches the engine, you'll feel the shifts a lot more than if you had a higher stall converter. Tough dilemma.

Once you figure out what converter you need, you then have to get a flex plate that has the same bolt pattern as the converter, and a starter that matches. There are two sizes of flex plates, 153 and 168 tooth, many 168 tooth flex plates have dual bolt patterns that will fit most converters.

If the 350 engine is the earlier 2 piece rear seal design, then you need a neutral flex plate. If it's one piece seal with the small crank flange you need a weighted flex plate.

Good luck...

 

I suspect that you will come to regret the effort that you put into getting this into the car.

Given that it has a transbrake, it is likely also a full manual valve body.

Only a handful of folks will tell you that's just fine on the street.

All the rest will tell you otherwise. There is a very solid reason for this skewed ratio.

 

yup, the reason is that I'm an idiot...I have 30k miles on my full manual shift TH400. I don't know what the big deal is, doesn't need the use of a clutch pedal, and only half the number of shifts that my wife has to do in her modern sporty car with three pedals

But a trans brake powerglide, I don't know about that, especially if it's reverse pattern.

 

The only you, is you.

Everyone else is someone else.

 

I agree that the full manual shift transbrake powerglide is a PITA; I have one in my Nova.
I was going to change the Nova over to a stock valve body and remove the transbrake, but
didn't --- a friend told me it makes a good theft deterrent as most thieves wouldn't know how to put it in reverse!! It's such a pain to pull out the trans on the ch***is car, I just didn't do it. (Don't drive it much anyway).
I may change the 32 over to a stock valve body as the transmission hasn't been installed yet.

 

Jim, it appears to me that it has the fine spline input shaft. I have a racing Powerglide in my Nova, but have never had it out of the car to look at the input shaft, so I don't really know the difference. The splines on this transmission look close together to me. That could've been done by Transmission Specialties.
I also don't know if the 350 has the small crank flange -- how can I tell? Thanks, Jim C.

 

The older two piece seal has a large crank flange, the newer one piece has no flange past the seal-- you can see the seal, which is enclosed in an aluminum housing.

internet pic: (of course they don't show the crank, to confuse you)

Two piece on left, one piece on right.



And the crankshafts, left and right same as above



It makes sense that since they can't put the extra weight on the flange itself with the one piece seal, they have to put it on the flexplate.

 

Thank you! I don't know much about 350's, am still learning. Looks like I have a 2 piece crank. But, I'm not sure that the Powerglide input shaft is fine as I thought. In looking at internet photos it may be co****. Jim C.

 

see if you can count 17 or 30 splines.

Or post a picture.

 

Just curious: why would that be? Just because people are coming from an automatic-transmission mindset which results in automatic-transmission expectations, or is there something else?

 

That’s 30 spline, and make sure you wire the trans brake to an arming switch.

 

The driver has to make every single shift.

With the exception of a special few, this is not well-tolerated by most drivers.

It defeats the purpose of having an automatic. It is just a clutchless manual.

 

You need a turbo 350 or 400 type converter and flex plate from about any early 1970's chevy V8 thats not a 400 SB. For that input shaft .


On a light car I'd suggest something with a bit higher stall speed than stock . Your rear gear and cam will also play a part in that decision.


Read up and know how to use the trans brake and reverse .
It may be a reverse shift pattern also.

Nothing that bad about a manual valve body on hot rod lets you keep the car in low untill you want to shift and let's you down shift when you choose to. It's simple and works especially on a PG.

With a glide you got two gears to choose its not that complicated.

Being a race trans it's likely going to shift very hard that may not be what you want .

A glide is a cheap trans to rebuild and modify and in a light car with lots of HP they work great.

I'm putting a manual shift glide in my 27 roadster build with about a advertised 2200 stall . If I can't remember to shift at about 30 mph I should not be driving.
At about 450 HP a 1900 pound car it will not really need a extra gear.
OD would be nice with the low gears however for the interstate .

 

Thank everyone, that's what I needed to know.

Jim

 

I’d use it full manual. No biggie with a powerglide. Probably need to hold the brake ****on to back it up but again, no biggie. You will find out real quick if it’s forward or reverse pattern.

 

Now that we've got you sorted out on the converter and flexplate you need....off to the side discussion...

I guess that depends on what you think the purpose of having an automatic transmission is. Maybe there's more to it than the shifting part? How about the advantages of having a torque converter, and planetary ge****ts? And how much power you can put through something you can buy cheap, and that was available in the era that the HAMB caters to?

 

Clutch Turbo with manual valve body on street

 

TH400.

 

yup, manual shift TH400. It's great!

 

I just got done putting a TH350 with a manual valve body in a friend's ride, and I must admit I liked a lot more than I thought I would. It took him a while to grasp the concept ("It doesn't shift into Low gear!!!") but once he realized HE was in charge of which gear it was in, he liked it too. For most people, a good shifter is a must have, thank goodness my friend has one. I would get the fine spline input shaft, then you can use the convertor on a TH350, the short tailshaft version of which is a fairly straightforward swap for a late Powerglide, even the driveshaft will work.

 

I come from a manual-transmission mindset, so I expect to make every single shift anyway. I think I'd find a really tough (though not very efficient) effective CVT below first gear really useful, and not having the 2-3 shift as an awkward dogleg would be good. And the parts are all available and understood, and it can all be done without digital electronics, and clutch plates become less of a short-life consumable, etc. etc. etc.

 

If your thinking of using the trans brake you really should have a safety shield in place.
I have seen a few come apart .

 

Hold up a second.......A trans brake as theft deterrent ? I hope you know what a brake does, and how it's activated....
So, just leave it there......it's not going to hurt a damn thing........You use it when you want if you feel froggy......
Just my suggestion, like many you might get, find a few more knowledgeable friends to seek advice from............

 

The theft deterrent statement was made by a friend of mine -- his point was most car thieves wouldn't know to hold the ****on down to reverse the car.

 

if you are going to play like that, buy a sfi flywheel. they are built for abuse.
btw, the hi power feds usually only use 2nd to launch. my low power buick we use 1 & 2.
fwiw, my son has a 67 buick 350 4 spd. wanted a blower on it. i did it, but blowers aren't
really for 4 spds. lol

 

Thanks guys, now I have another question. The speedometer bullet and I also suspect that the tooth driven and drive gear are missing. What I need to know is if a 21 tooth driven and a 8T drive gear would work. I plan on using an Auto meter manual speedometer. If not, what do I need to use?

 

I have truly been considering changing the valve body back to a stock pattern operating one -- even though it's never been used - this transmission has been sitting in storage for a few years, and I'm going to have the transmission shop look it over really well and replace the seals and anything else needed -- may have it changed back to more like stock then. My 32 is only about 400 HP, and I don't need all that race function.

 

Yr drive & driven gears for speedo reflects what rear gear & tire size is
( tall) to read correct