Thank you to my Old Friend Kevin Kleinweber at Hughes for taking the time to write this information up and shoot some photos for our members. Kevin wanted this placed on the "poweglide just quit thread" but I thought more people would see it in a separate post.

We both hope this helps you guys understand a little more about what is going on inside a glide.

Thank you Kevin! ... SL


The P/G input shaft spline length has changed over the years by different manufacturers, and even today there is no set length or standard length in the industry. For example, below is a picture of (2) Powerglide 17-spline input shafts; the short set of splines are from a factory 1960’s untouched Powerglide, and the longer set of splines are from a current manufacturer. As you can see there is a significant difference in length:




This holds true today with the Turbo splines as well. Back in the mid-to-late 80’s, the Powerglide splines evolved into the Turbo spline/30 spline input shafts.



When this transition took place a bushing had to be installed into the end of the stator support tube to support the input shaft, which also centered the turbine in the converter. When the bushing was installed, converter exhaust holes had to be machined in the input shaft on each side of the bushing surface area to allow the proper exhaust of fluid out of the converter. Due to this design characteristic, the input shaft splines were kept short to allow for the exhaust holes and shoulder on the input shaft for the bushing in the stator tube to keep the input shaft and turbine centered. The shorter splines kept the input shaft from sliding through the turbine splines and preventing the shaft to sliding out of the planetary input gear. Over time, torque converter manufactures started installing a bushing in the converter to center the turbine and input shaft which allowed them to eliminate the holes in the input shaft and the raised bushing surface on the input shaft. With the elimination of the holes and bushing surface, the length of the splines were not limited, thus longer splines now allowed the shaft to float further forward, which, in some circumstances, would allow the input shaft to pull out of the planetary input gear. The picture below illustrates what I am trying to explain:



See how the shaft can pass through the splines further?

Due to the many different spline lengths, we have changed our turbine spline heights to accommodate the various lengths. The pictures below show the difference:


Early Style



Later Style

Notice how the picture on the top has a pocket and the picture on the right has the raised set of splines?

All of our torque converters now have the raised set of splines. Older units with the recessed splines can be updated as well. Welding a button in the bottom of the converter is a band aid and not recommended as that can create metal fragments from rubbing on the input shaft.

This evolution in Powerglide input shaft spline length that resulted in increasingly longer splines from a variety of manufacturers across the industry has resulted in a variety of torque converter manufacturers not only limited to Hughes Performance experience a problem with excess input shaft travel within the torque converter, resulting in spline disengagement within the planetary as noted earlier. Fortunately, only our GM95 and GM96 torque converters are affected by this evolution of input shaft design. Hughes Performance has made every effort possible to stay current with the industry, and update our torque converter turbine splines accordingly as input shafts have changed over the years. However, because Hughes Performance has so many GM95 and GM96 torque converters in circulation, there are many customers running older design torque converters with newer design input shafts, and that’s where the spline engagement issue can potentially become a problem in a Powerglide transmission.
If you encounter this problem with your combination, or would like to have your older GM95/GM96 torque converter updated, please send your converter to our facility ASAP. We will be happy to update your converter accordingly!

If you have any questions feel free to email myself at kevin_k@hughesperformance.com or call me at 602-424-9892.

Kevin Kleineweber
Hughes Performance

thanks to both for the info

Thanks to Kevin and the DRR folks for getting this out there.

Some really good info there! Thanks Kevin for the explanation and thanks Scott for posting it where it will be seen!

Sound information Kevin and I'm sure this will help a lot of racers effected by this issue. Great write up.

Kevin and Scott,

I dont want to high jack this post as it is very informative but I think we should add another issue I have seen. We have addressed the same issue and found another one that by moving the splines wont fix. we have actually shortened the pocket depth in the pilot below the turbine so the input cant pass thru as some of the input shafts by other manufactures are made like the black one in the pic and will pass all the way thru because there is no stop at the back of the spline.

-Greg

Great idea Greg. We opted to not use the pilot as a stop because front cover spinning faster then the input shaft could cause potential metal fragments. We would rather have them run the correct input shaft. As you know Greg, there are many different ways to correct the problem. On a different note, when we going deer hunting?

One thing I forgot to mention is the over all lengths of the input shafts. Originally on the OEM power glide transmissions, there were 2 different length input shafts. 12 5/8" for the 1.82 planetary and 12 7/8" on the 1.76 planetary. That is a 1/4" difference in lengths. If put a 1.82 input shaft in a 1.76 planetary, the shaft will disengage from the splines, this holds true on OEM p/g converters. Most of the after market gearsets are based on the 1.76 planetary, (1.80, 1.68, 1.58) etc.. which takes the 12 7/8" input shaft. There are aftermarket companies building the "combo" shaft", us included, and they measure 12 3/4". This shaft was made to work in both 1.82 and 1.76 housing planetaries.


Hopefully this gives racers enough info to help them identify a potential problem.


Hey Greg, feel free to chime in at any time, I'm just trying to educate our customers.


Kevin Kleineweber

Hughes Performance

Thanks guys for all the info and help with my “powerglide that just quit” issue. I have two glides that have two different input shafts that look exactly like the picture above that Greg posted. The dark colored shaft is like the one that caused the problem. I used the light gray colored shaft for 4 years with same converter and never had an issue. If you look closely, the dark shaft’s diameter is smaller after the splines and the gray shaft diameter is the same as the spline O.D. This is why one shaft migrated forward and the other did not.
My converters are at Hughes being modified so that should solve my issue.

The transmission is from BTE. When I contacted them they immediately put me in touch with a local vendor of theirs to resolve the issue.

The converter involved is from Hughes Performance. I contacted them to see if they had heard of the issue I had and they did not hesitate to try and get to the bottom of this.

Lastly I posted the scenario here on DRR where Rusty and Greg from FTI gave me direction on where to look for evidence of the problem. They were dead one with there diagnosis. I also own 2 converters from FTI.

All 3 of these companies jumped in with both feet to help. Not one of them tried to place blame on anyone else’s product, on me, or on anything. They all just wanted to get it fixed. It’s good to see customer service like this still exist!

Again, I appreciate all of your help.

David Bills

Kevin. I agree 100% that if we could get a standard on input shafts it would make things much better for the industry and stop all of the finger pointing! I always try to help everyone. I try not to use any the inputs that can go all the way thru but sometimes the customer doesnt want to change. double edged sword for sure!!

Kevin, as far as hunting we are 58 days out!!

But you could come over and I will take ya fishing!!

Greg