Transmission / Overdrive: Top shifter stuck

[ncalder]

I have a T 86 E1A gearbox with overdrive (not the correct transmission for my 55 224 truck). It was working fine and shifting well. I took the top cover off to remove the transmission (I replaced the old engine and dialed in the bellhousing). All I did to the gearbox is change the oil and replace the rear seal. The oil I have in now is non detergent motor oil while I wait for my gallon of GL1 to arrive. I had problems getting the clutch to disengage do to linkage issues - now mostly resolved. The shifting was really bad - noisy, I drove it about a mile, found all the gears and finally jammed the gear stick. This looks like it was originally a column shifter that someone adapted to a top shifter. Any ideas on how to fix it? thanks -- Nick

[gordr]

Take the top cover off and have a look. Sounds like something inside broke or got bent enough to allow the shoe on the bottom of the shift lever to get between the sockets on the shift rails. Or maybe one of the shift fork was not properly engaged with its gear down below.

[ncalder]

Thanks Gord, I'll take a look - unfortunately I don't understand gearboxes the way I do engines.

[JoeHall]

Thanks Gord, I'll take a look - unfortunately I don't understand gearboxes the way I do engines.

Compared to engines, trannys are a piece of cake, and you seem perfectly capable of understanding them. If you have to take that bad boy out again anyway, pop the top off and take a couple of hours to play with it. You ain't gonna break it, but will likely see just how simple it is. Spin it back and forth and use a screwdriver or something to move the gears around to see it "go through" all the gears. Maybe pop the rear end off it and explore the OD gears a bit. Once basically familiar, you will not feel so inadequate when it is not performing correctly.
A common problem on T86 is the bronze synchronizer gears. If they are worn, it will never shift easily, or without grinding. You can inspect them easily enough by looking at the visible edge; the cogs should have a sharp "doghouse" shape. If the peak of the "roof is rounded, they must be replaced.
Another common problem with T86 is the clustergear & bearings; look for chipped teeth, and feel for smoothness of operation.
Another common problem is input shaft bearing failure, which stems from misaligned engine & tranny. That bearing's failure leads to other problems with 2nd & 3rd, i.e. difficult shifting.

I once tried to use a T86, for maybe 60,000 miles. Back then, when I was intimidated by them, I sent that tranny off to an "expert" in Oklahoma for rebuild. After a few thousand miles, I banged 1st & 2nd a couple of times (honestly only a couple) and chipped a tooth in the clustergear. That time I repaired it myself. A few thousand miles later, I had to replace synchronizer gears. A few thousand miles later, the input shaft bearing was going out. That was the third and final time I removed that T86; I replaced it with a T85 and that was the end of that; waay over 100,000 miles now on this T85 and it has been trouble free.

If you get sick and tired of working on, and spending money on that T86, try a T85. You'll never regret it.

[tbirdtbird]

"I had problems getting the clutch to disengage do to linkage issues - now mostly resolved."

The clutch must fully release or you will have a world of problems....hard shifting, rapid wear on synchros

The only time I have seen a shift lever lock up was when the top cover was installed in such a way that the tranny was in 2 gears at once at certain times. Seems imposssible to do, but it can happen

[JoeHall]

"I had problems getting the clutch to disengage do to linkage issues - now mostly resolved."

The clutch must fully release or you will have a world of problems....hard shifting, rapid wear on synchros

The only time I have seen a shift lever lock up was when the top cover was installed in such a way that the tranny was in 2 gears at once at certain times. Seems imposssible to do, but it can happen

I agree wholeheartedly on the clutch. Sticking in two gears at same time is another common problem with T86. Most of the time, no amount of yanking & cursing from topside will fix it. A quick crawl under the car with a screwdriver and it is usually remedied, a few skinned knuckles later.

All the above are common problems with T86; talk to anyone who has had one and actually used a lot can identify. Its the nature of the beast, and a case of marginal engineering, at best.

[Alan]

Nick, I see possibly 2 things here. One is the motor oil in the tranny. Second is did you refill the OD unit before you drove it. If you filled the trans but not the OD thinking that it would overflow into the OD, you fried the OD.

[ncalder]

Thanks for all the help - it was the clutch adjustment. I have it over tightened right now with no free play and everything is super smooth (after I unstuck the top shifter). I will need to find a way to get a little more efficiency out of the linkage. The gearbox hasn't felt this good before - even the overdrive kicked in!

[ncalder]

If I did go to a T85 would the same overdrive fit behind it or is it a whole new set up from bell housing back

[ncalder]

Thanks for the encouragement Joe - I imagine down the road I'll be pulling that box apart - but for now as long as I can get some free play in that linkage it's all good!