• Registered: 2009-07-19
  • Posts: 1,585

Topic: THM 350 output shaft play question

Output shaft on a THM 350, how bad is this? There's a bushing in the tailshaft housing that I can press out and press in a new one so the driveshaft doesn't flop around, but it seems to wear out quickly, like after 3-4 races. Do I need to put some new bearings in the transmission or just replace the bushing again? If this was a Honda, then it would be very bad, but Hondas don't have that replaceable bushing and I'm learning that things in Buick-land are generally a lot looser than they were in Honda-land:

https://youtu.be/GWY8iC0QiSM

Everybody grab your brooms, it's shenanigans!

2 Reply by Team Infinniti (edited by Team Infinniti 2019-08-11 06:10 PM)

  • From: WPB Fl.
  • Registered: 2010-10-27
  • Posts: 1,571

Re: THM 350 output shaft play question

Have handled chevy stuff for 40 years, seems a bit excessive, what is going on with the drum inside?... saying that, the driveshaft yolk/bushing should be keeping it straight.

Stock driveshaft?

Homestead Chump 5th-Sebring 6th-PBIR Lemons 9th - Charlotte Chump  CrashnBurn 9th
Sebring 6th again -NOLA Chump 1st -PBIR Chump Trans Fail 16th
Daytona 11th - Sebring 6th - Atlanta Motor Speedway 2nd - Road Atlanta Trans Fail 61st-Road Atlanta 5th
Daytona 13th - Charlotte 9th - Sebring 2nd-Charlotte 25th broken brakes - Road Atlanta 14 10th-Daytona 14  58th- Humid TT 19th Judges' Choice!
  • Registered: 2009-05-27
  • Posts: 361

Re: THM 350 output shaft play question

GM transmission repair guy here. that play is normal.
the bushing in the output housing is the only thing that keeps it in place for  lateral and radial play.
unless it moves side to side with the driveshaft yoke in place you are fine.
Manny

  • Registered: 2009-07-19
  • Posts: 1,585

Re: THM 350 output shaft play question

Thanks, the bushing was worn when I got the car, so I put a new bushing in it.

The new bushing worked well for three races, and then this:

https://youtu.be/N0_f8cUzlTw

I can put another bushing in it, that's easy enough, but I'm thinking something else is wrong if it's done after three races.

Everybody grab your brooms, it's shenanigans!
  • Registered: 2009-05-27
  • Posts: 361

Re: THM 350 output shaft play question

THAT is a problem!
drive shaft balance comes to mind.....
worn end yoke. rough surface?
incorrect shaft length.(too short can cause a wobble.)
Manny

  • Registered: 2009-07-19
  • Posts: 1,585

Re: THM 350 output shaft play question

Thanks again, looking at the yoke, there is an oval patch on one side where it is worn. Picture is attached. I called the local Fleet Pride shop and they can check and balance the driveshaft for $80, so I'll have them check that. Rock Auto has new yokes in stock, so I'll get a new one, put a new bushing/seal in the tailshaft housing, and give it another go.

It is a '73 Triumph Stag driveshaft with a '77 Buick Skylark yoke on the front.

http://www.carolinahondas.com/members/roger-albums-pj-picture6827-yoke1.jpg

Everybody grab your brooms, it's shenanigans!
  • Registered: 2009-07-19
  • Posts: 1,585

Re: THM 350 output shaft play question

Thanks for the info. Neither yoke was welded to the driveshaft straight and it beat up the tailshaft housing bushing until is spun and moved back up the output shaft. Driveshaft has been professionally re-welded and balanced. New slip yoke end and tailshaft housing have been ordered.

Everybody grab your brooms, it's shenanigans!
  • chaase
  • Lemons Staff Stalker
  • Offline
  • From: East Meadow, NY
  • Registered: 2009-08-06
  • Posts: 1,560

Re: THM 350 output shaft play question

rmcdaniels wrote:

Thanks for the info. Neither yoke was welded to the driveshaft straight and it beat up the tailshaft housing bushing until is spun and moved back up the output shaft. Driveshaft has been professionally re-welded and balanced. New slip yoke end and tailshaft housing have been ordered.

That'll do it. Glad to hear it was sorted out.

1992 Saturn SL2 (retired) - Elmo's Revenge -  Class B winner, Heroic Fix winner x2
1969 Rover P6B 3500S(sold) - Super G-Rover - I.O.E Winner, Class C Winner
1996 Saturn SW2 - Elmo's Revenge (reborn!), Saturn SL1  Dazzleshipm Class C x2 and IOE winner
1974 AMC Javelin - Oscar's Trash heap - IOE,”Organizer's Choice" and "I got Screwed" award winner