Technical Manual transmission replaced with Powerglide

This is a question related to the Whatever project. First a picture.


If you have read the posts in the Whatever project, you probably know that I tend to overthink things. And make some mistakes. And over complicate stuff. Here’s an example.

That picture is of the firewall structure that I made that does a couple of things. 1-rear engine support. 2-body support. 3-way overbuilt firewall! It’s shown here without the body, which would be sandwiched between the two aluminum plates. The bellhousing is also sandwiched between the two plates. Fortunately both the body and the bellhousing flange are 1/4 inch thick. Using a manual transmission, I’ll use an extended pilot bearing to support the nose of the transmission, and the splines are long enough that the clutch plate will still be fully supported on the input shaft. That is not the problem.

What is the problem is if I replace the standard transmission with a Powerglide, and it is placed on the back side of the front engine plate/firewall support, how do I accommodate that 1/4 inch with regard to the torque converter? The torque converter needs to be inserted in the transmission to fully engage the pump, and the splines of the transmission. Further, the torque converter needs to be supported by the recess on the crankshaft.

So, what do I need? Or do I need to redesign the motor plate so that the
Powerglide is on the front side of the forward plate? Suggestions?

 

Could you add spacers between the flex plate and the torque converter to make up for plate thickness. I don’t know if this I good idea or not. That might add shear stress because of the longer bolts required. Or maybe weld thicker threaded pads onto the TC. A torque converter manufacturer should know what to do.
Dan

 

Contact the guys that make blow proof bellhousings for powerglides.
Sure looks thick!
https://racewithjw.com/product/ultra-bell-powerglide-to-gm/

It's not cheap as some washers, but if it's like a lot of race stuff, it may age out and have to be replaced/inspected?

 

It's pretty well standard procedure to use a spacer ring on the torque converter snout and on the torque converter/flexplate bolts when using one of those plates. My searching ability went to hell in a handbasket on this one though.

 

No different than using a motor plate in a race car. Have the converter built for whatever the thickness of your mid plate is.

 

Can you have something similar to this made? https://snapklik.com/bdfhyk-flexpla...h-th350-th400-transmission/pr2/08HP4P472I9P5/ Or have the torque converter made with a extra long locator on the front?

 

This is a Standard in house modification for converter builders. Just tell them the plate thickness when having it built and it will come ready to install. Of course, you still need to check your Thrust clearance. This has been standard mod forever. No big deal.

 

Or you could ditch the engine plate and build a crossmember to support the rear of the transmission like it was in a car with a rubber mount.

 

I see another potential issue were it me that I would double check. The travel arc of your pedals. Depending on the travel amount and if your shoe size is 9 or more, looks like your heal will hit the pedal arm before you get full throw of the Clutch pedal. That of course depends on how low in the chassis you're sitting. The foot pad looks to be forward of the pivot shaft. That's not good. In most locations the pedal swings 50% fore and aft of the shaft. Maybe it's just camera angle but for sure something I would want to make sure is correct.

 

And you just discovered one of my issues! Give PnB a cookie! My feet are size 9. 8E width! Try getting shoes that fit on feet like a duck! Seriously, I have the parts and a design concept for hanging pedals if I stay with the standard transmission, and a single pedal, which is a piece of cake, for going automatic.

These answers are what I needed to find out, that converter manufacturers have seen this before and can compensate for the engine plate. Next question, what company(s) would you recommend? And which company would you recommend for a built Powerglide for say 500 hp max?

 

I don't know if I'd do a total change over. It looks like that piece of 3/4" X 3' rectangle tube is stopping the pedals from getting more return. I'd probably start by relocating that. I always work with total Clutch pedal travel needed. Whatever that number is I split 50-50 from vertical. That's usually more than what's needed for brakes. Once you do that Math you may be able to just move the mount tabs forward if you need to use the travel space between pedal and firewall at full forward travel.
Ther's a lot of shops out there that can build performance transmissions. Probably someone in your back yard if you nose around. For us with a bit more H.P. than our average H.A.M.B. friendly race car we used Hughes Performance or Mikes Transmissions. These guys build what you need for the total package of the car. We often got a total season without failures. That says a lot when you're pushing 1200 HP and the largest slicks the car needs to launch. You may not need that much gearbox.
I haven't read anything else you have posted up but sounds like you have the desire but little hands on building a race chassis. My advice is don't try to engineer things that have already been done and proven. You can find plenty of how To's online. You just need to be able to weed out the Junk work from the Good. When in doubt go to the N.H.R.A. rule book (it's online now) and look at the photos and descriptions of basic rules. Nothing is more Depressing than doing a lot of hard work and spending a lot of $$$$ only to not pass tec inspection and be sent home. The photo looks to me like you are using C.M. tube. It also looks like Mig Welds and some Mild Steel mixed in. Pending on where you're planning on going you may or may not meet spec. Gathering correct information while in the build stage is Priceless.

 

I welded on three spacers of the required thickness.
I have had good luck with Coan converters over the years (Kokomo IN). They are top notch units.
I get my 'glides done locally.

 

Coan worked very well until we stepped past 800 H.P. There prices were good, so we bought 2 for back-up. Seemed there was always 1 in transit and soon we didn't care about the cost, and it became about time. Hughes to the rescue.

 

@Dave G in Gansevoort
Since you are in Ny
I would NOT recommend
ATI in Md , seems to be different service, Care & builder For customer's they Sponsor
Then Ones Purchase transmission & parts here & there ,
In my case ,Price was what 100 gal of
Nitro

 

No only dom. I pm you a few minutes ago for more details. Thanks. Yeah I’ve been reading the rules and given what I want to do, I’ll be using dom. The only moly chassis I was ever involved with was a sprinter that my good friend Jim built, for a hill climb. He was a fabricator and did all of the welding. I was the engine guy for it. Fun car, nothing I ever wanted to drive

 

So you guys have now steered me to the internet AGAIN! I spend way too much time on it, instead of getting into the garage… thanks for the advice though, even if I have to surf the internet some more