Powerglide F-up, how screwed am I?

June 02, 2026, 11:39 PM

truckman

quote:

Powerglide input shafts vary by gear ratio: 12.625 inches for 1.82 planetary and 12.875 inches for 1.76 planetary units, with aftermarket “combo” shafts around 12.75 inches to fit both.
OEM Shaft Lengths
Original Powerglide transmissions have two primary input shaft lengths depending on the planetary gear ratio:

1.82 planetary gearset: 12.625 inches (12 5/8")
1.76 planetary gearset: 12.875 inches (12 7/8")
Using a shaft with the wrong length for a given planetary can cause disengagement from the splines or improper seating in the torque converter, potentially leading to transmission damage

Stock case.
The only history I have on this is that it was allegedly a never used spare. Don't know any specifics as the builder has had a stroke and can't be contacted.
Am picking up the converter from my friend in the AM and will see if it solves the issue.

June 03, 2026, 12:20 AM

rusty

my WAG at this point is that it has a 1.82 in it and the wrong shaft

June 03, 2026, 10:10 AM

Eman

Put a caliper/micrometer on the output shaft and check the diameter of it. The 1.76 should measure about 1.170 and a 1.82 should be about 1.145. Some aftermarket input shafts are made to work with either.

June 03, 2026, 12:29 PM

Eman

I just measure 2 PG's I have in the shop from the stator to the end of the input shaft one meaesure 1.70 and the other is 1.825. I know they both have 1.82n gear sets and after market input shafts and they have different brand input shafts in each one and both are stock cases.

June 03, 2026, 12:53 PM

rusty

i think i have a better understanding after reading again the PILOT extension you installed is sometime used to set converter depth into the pump, if the converter is completely in the pump and it moves out approximately .150 and you still have a gap between the pad and flex plate ,fill the gap with washer. Getting the converter in the is sometimes a challenge. You should feel 2 bumps when going in pump.one other thing ,the pilot bushing must be short enough to allow the converter to moe out of the pump near .150

June 03, 2026, 05:19 PM

truckman

So here is the update.
Got the TH350 converter from my friend. With both converters sitting on the bench with inputs in them, pointing up, the TH input is about 1/2" shorter. Both input shafts are the same length, so I don't know why the TH one is shorter overall unless it has something to do with the snout of the converters. There is no foreign object in the 'glide converter.
As for the pilot extension, it is to center the converter in the end of the crank, as a non-lock up converter is too short to reach.
Anyways, the trans is bolted in, I need to measure the clearance to the flexplate but I estimate 1/4" - 3/8", will verify. Now I need to finish hooking it up, drop the pan, clean, re-install and refill with fluid.
Then, say my prayers and fire it up!

Thank you all for your assistance!

June 03, 2026, 09:01 PM

rusty

quote:
posted June 03, 2026 05:19 PM Hide Post
So here is the update.
Got the TH350 converter from my friend. With both converters sitting on the bench with inputs in them, pointing up, the TH input is about 1/2" shorter. Both input shafts are the same length, so I don't know why the TH one is shorter overall unless it has something to do with the snout of the converters. There is no foreign object in the 'glide converter.
As for the pilot extension, it is to center the converter in the end of the crank, as a non-lock up converter is too short to reach.
Anyways, the trans is bolted in, I need to measure the clearance to the flexplate but I estimate 1/4" - 3/8", will verify. Now I need to finish hooking it up, drop the pan, clean, re-install and refill with fluid.
Then, say my prayers and fire it up!

Thank you all for your assistance!

before you crank it be sure the converter moves out of the pump near .150 then shim with washers