Pilot Bearing

I know a lot of T86s were converted to the stronger T90 gears. Did this include changing the input shaft? If so, is the pilot tip on the input shaft the same size?

 

I measured the T86 shaft tip with a dial caliper, not a micrometer so I will double check that measurement. I also appreciate the part numbers. The T14 bushing sounds like the best option, as expressed by others too.

 

You are so right! The journals are shared on the '77 crankshaft in my 225. Duh. I apologize for being a rookie with this drivetrain, but I hope you can see that I am trying hard to learn so I can figure it out! I also should have searched the fora for pilot bearing threads before posting, so thanks for those links. I am also repairing the heater, bought new lights, steps, tie rod ends, electrical and a host of other parts, so I am taking up the whole garage/shop AND... my wife wants to park her car inside. Some small parts I can get in my small town, but most of the time I am waiting for parts from Kaiser Willys or others. I live in the mountains and there is a foot of ice on the ground at the moment. I need to slow down to make sure I am doing this right and not let the pressure push me too fast to get it done. Jeep should be a zen thing for a retired guy like me. Ohmmmmm.

All of you folks have been very helpful with your knowledge and suggestions. Thanks!

 

Yep, that's what I am going to go with. Tip 'o my hat sir.

 

My T90 and T14 pilot diameters may be off.
Sometimes I can’t decipher my own notes.
According to the parts catalogs the GM part #3752487 is correct and I measured a NOS bushing at .590.ID.

 

I do not know the answer to that question, since I am brand new to this drivetrain. The transmission in my CJ appears "new". That is to say that the gears aren't worn at all and the case is freshly painted. There's wear on the synchro clutch clips but not bad enough to replace them. My semi-informed guess based on that info was that someone installed a rebuilt T86. I wish I had the "venerable" T90 instead for strength, but I am not going to the Rubicon with this jeep; it's just for going up to my mining claims and to explore for new ground. I won't be abusing the drivetrain, I just want to enjoy the Jeep CJ5 experience.

 

AFAIK the only differences between the T-90 and T-86 are
1) the T-86 case has a bigger front bolt pattern than the T-90, same as a T-14 or T-15.
2) the splines on the main shaft of the T-86 have a slight spiral, while the T-90 splines are straight.
3) the 1st and reverse gears of a T-90 are straight cut, while these gears are helical in a T-86.
You can take all the gears from a T-90 and install them into a T-86 case. This is the usual way you repair a T-86 with broken gears, since the T-90 gears are available both from core transmissions and new on the aftermarket. To repair a broken T-86 gear, you'd have to find a NOS replacement on eBay, or scavenge it from a junk T-86 transmission.

The only difference in strength is the straight-cut gears are somewhat stronger. The same otherwise.

Now, this suggests that the T-90J input gear (the long one used with the V6 conversion) is the same as the T-86 input gear. Maybe. I have a T-90J input gear in my basement, and its pilot tip measures 0.6275" in diameter. (I always mess up "its" possessive.).

 

T90J maindrive gear = 641460
T86AA maindrive gear = 946111

 

No worries about being a rookie. That's what the forum is for. Also no worries about searching for the old pilot bearing threads. The search tools on the forum don't work great. I found those links through clever google searches the most recent time this came up. At the time, I knew I had read the threads but had a heck of a time finding them again.

As for the Jeep being Zen I agree. My '69 is a mostly original Jeep except a '77 231 swapped into it years ago and some period stuff like a roll bar and tire rack. It's in very solid shape but over the last several years I've gone through tons of stuff to get it to the point where everything works as as it should. I slowly grind to a halt on full restos, so it's been one project at a time over several years and I've been able to enjoy driving the Jeep while doing so. Some of the things that have gotten fixed while keeping it's worn-in character:

• Brakes
• Hubs
• Wheel breaings
• Every piece of the steering
• Turn signals
• Motor mounts
• Parking brake
• Cleaning up all the electrical
• New seats
• Fuel sender

You can see the build thread here if you're interested: Old Red Maintenance Thread It's some of the same stuff you're doing and you might find some useful information there. I couldn't have done it all without this forum.

 

That Old Red thread is the gravy! Thanks!

 

timgr: I believe that the possessive is "its", and that the contraction is "it's" (it is), i.e. It's a beautiful day in the Jeeper-hood!

 

Indeed. It was wrong previously. It's right now!

 

One last thing to mention in this thread. When I bolted the transmission to the adapter (on the engine), the transmission would still not go all the way in. But, I was able to get it close enough to get the 4 bolts started and pulled it in by tightening the bolts. I think this suggests that my pilot bearing was not installed all the way into the crankshaft as it should be, and that by tightening the bolts, the pilot tip pushed the bearing in far enough. I remember asking myself when I put the pilot bearing in, "How far in should I push the pilot bearing in?" I looked in the books I have and in the service manual but I couldn't find it. I think the transmission bearing tip made the decision for me.

Now I am wondering what will keep the bearing from spinning inside the crankshaft and welding itself to the crank, but there is a small ridge inside the crankshaft pilot hole that keeps the bearing from spinning. I hope I am right about this because I won't know until I start the engine and engage the clutch a few times.

*eyes tilted up toward the heavens*