sorry this thing is so damn long.

This is the second time its happend. heres the story last august (of this year) i took out the 1-2 syncro and the 3-4 syncro and it got stuck in 4th gear. out at the track. so i had to drive it home in 4th gear all the way from the track. took out the tranny the next day and had a friend of mines buddy rebuild it it cost me 900 bucks. we got the tranny back in about a week and put it back in and everything seemed fine. we did 4 races on it just 4. we werentr even hot rodding it we were just driving normal and it popped out of third. i puit it back in and drove for about antother 10 min. and poppd out for no reason. then this time when i tried to put it back in it went in fine. then when i tried to pull it out it got stuck in between 3rd and neutral. when i tried to pull it out it would make a bubble popping sound (with the clutch in) and when i tried to put it in gear it would grind. so i had to get under 35 and rev it a little and then it would pop right out so a buddy of mine here locally has a repair shop and he drove it and said 3rd gear syncro is out. what would cause this to go out so quick. (in 2 months) and get this the guy told us to put havoline motor oil in it instead of ATF.
again im sorry its so long. help me out here guys i dont want this to happen again is there any thing i can do any help appreciated
Thanks Jason

 

I am not a trans expert, but I have rebuilt a 5-speed by my self and I have read some on the T56 and I have owned a 95 6spd for the past 10 years.

The motor oil idea is a bad one and if you ran it like that it may explain the early synchro failure. The trans is built for the type of oil that it is supposed to use. The syncro must cut through the oil film and create friction to work. If you use a thicker oil, that creates a thicker film and more pressure is required to cut through it. This is not what you would expect since in most gear situations a heavier oil is better. But in this case the machined gaps are set for ATF and heavier oils can cause problems.

A distant possibliity is the rubber shift boot, it can bind and pull on the shifter and was a problem in some early cars and caused them to pop out of reverse.

I have not had this problem yet but many people have to replace the 3-4 shift fork with an updated steel version. If the heavier oil is causing the problem then you might have bent the shift fork trying to change gears.

What to do, if you still have motor oil in the trans, drain it and refill with ATF. See if this helps, if not then things get expensive.

If I was rebuilding the trans I would try to find out about the upgraded 3-4 shift fork and I think there are Corvette syncros that are two or three stage units.

If you do a search under T56 you migh find some p/N's and more suggestions.

 

well can i just drain the oil and then put atf in it or do i have to put atf in it and then drain it again to get the rest of the oil film out or should i just fill it with atf and see if it works? whats the deal with the shifter boot? any help appreciated
Thanks Jason

 

I would just drain the oil and put ATF in it. If it is going to help, that should be enough oil to thin everything out nicely. If you don't se an imediate improvement, then I don't think more ATF will help.

The boot should not be tightly stretched when the car is in gear, or it could act like a big rubber band. I would just pull the upper console plate and get the leather boot out of the way and then you should see the rubber boot. Go through the gears sitting still and see if it get real tight in any position or appears to be installed badly.

The boot is a long shot and I would do the oil first.

Best of luck.

 

hey thanks for your help bud ill keep you up to date on what happens
Thanks Jason
any other help appreciated