Jackman5003

anyone know how i can cheak to see if my input shaft is bent? a guy at my local speed shop said look on mrgasket.com but i couldn't find anything. just want to make sure its not bent and thats why i just went through my 2nd throwout bearing.

i'm guesing sticking a guage againt it attached to the bellhouseing and spinning the driveshaft or maybe even starting the engine and seeing is the guage fluctuates. if it does, how muc is allowable?

1981LT1

iTrader: (1)

use a magnetic base with a dial indicator and check the runout by placing the car on jackstands and have someone turn the engine by hand slowly. I have no clue what the acceptable tolerances would be though. I would ASSUME no more than 10 thousandths.

Ricktpi

I am not real sure a bent input shaft would cause a TO bearing failure. The TO bearing rides on the front bearing retainer, not the input shaft. A bent input would cause pilot bearing or the hub of the clutch disc to fail, but not the TO bearing. The most common cause of TO bearing failure is misajusted linkage.

Jackman5003

i was thinking it was mis-adjusted linkage too. but more like, i have the wrong clutch fork. haha. when i bought the bellhouseing the guy gave me the fork with it and said it was the right one. but it doesn't look it because the slave cylinder rod is cocked towrds the bellhouseing so much that its hitting the houseing of the slave and even wore a grove in the rod. so i MUST have the wrong fork, a shorter one. it looks like forks i've seen on ebay when i was looking for pictures but it just seems too short. JEGs sells a "hevy duty" clutch fork but its only for GM applications. are all GM forks the same? i wouldn't think so right? so do you guys think i have the wrong fork?

when i took that boot off the bellhouseing to look in, the TO bearing was right up against the pressure plate fingers. i'm thinking thats why it blew(it was constantly on those fingers) but the bearing was cocked on the fork because it JAMMED itself into the fork this time, so maybe thats why it was rideing on the fingers?

Petes 84Z28

There are different styles and sizes of forks. The hydraulic ones for the 84-92 thirdgens have their pivot point about halfway between the slave cylinder rod and the fingers that contact the TO bearing. The earlier mechanical style have the pivot point more towards the fingers. The V6 and V8 forks differ in their length as well.
The TO bearing itself should sit very close, if not in contact with, the fingers of the pressure plate. The face of it rides on bearings to spin with the PP, so it's not a big deal.

Although if the wrong fork is being used, it will push the bearing ****-eyed and cause premature wear and failure.

It kind of sounds like you have hydraulic V6 fork, as the mechanical kind are just too different to work at all.

Jackman5003

i was told that the TO bearing shouldn't be constantly riding the clutch fingers?

Petes 84Z28

Actually, it will ride on them with a hydraulic system, as they are self adjusting to take out any slack in the linkage.

Jackman5003

hmmm....alright well, i have this "high performance" TO bearing now, getting a new fork straight from GM and replaced the pilot bushing...see what happens now...

what i don't get now is, the front of the bearing was all discolored like it got realllllly hot???the pressure plate fingers are fine, a little bit of wear from the grinding of the bearing when it blew up but aren't discolored.

and the "front bearing retainer" has a couple groves in it from when my first bearing blew up. the bearing covers them up no problem with even space to ride on smooth metal and i rounded the grooves off and all but you think that might make this new bearing go and could be part of the cause the last one went? sounds stupid and jerry-rigging but what if i filled it in with cold weld or something and then filed/sanded it all down perfectly smooth? i mean there not deep at all.