T18a Input Shaft Leaks. Cant Get It To Stop.

As if I didn't have enough issues with my own t18..

A old friend seeing I was working on my cj6 project has brought his cj7 out of mothballs and wants help with a ongoing issue.

First the trans is a t18a and was purchased used 30 years ago when we were a lot younger.. . It was setup for a sbc. But we found a bell housing and got a stock bearing retainer and input shaft from Novak for it and essentially converted it back to stock specs.

It has always had a leak from the Input shaft tube. I donno how many times we had this pig out cleaning or changing out clutches. We replaced the Novak retainer with a factory CJ7 retainer but it didn't help.

The pilot bushing is correct. Didn't the T98 have a issue like this? I thought they had found a sealed bearing to replace the pass thru bearing on those?

Anyone know if they did and if the bearing is the same part that I could use in his jeep? He's 60 and I'm 40.....I don't want to tear into this thing again unless I can try and figure out how to correct it.

Ideas?

 

The T-18 bearing retainer has a neoprene seal in it, between the input shaft and the retainer. The retainer is sealed to the case with a paper gasket. So, unless the seal or gasket fails, or the sealing surface is chewed up, oil can't come out. Some of the earlier transmissions have a felt seal or a slinger that's supposed to direct the oil back to the case. AFAIK the T-18 has always had a postive-sealing neoprene seal on the input, like the T-14 and T-15. The T-90 often gets a sealed bearing because it has the ineffective felt and/or slinger, and no provision for a neoprene seal. Maybe the T-98 has that problem too.

 

Yeah it does have the seal on the inside end but it's getting past it somehow. The seals been replaced twice with the Novak bearing retainer and then again with the used factory part.

The shaft mics out just a few thousand smaller than my input shaft seal face. And it's pretty free of any burrs or scratches.

It's crazy.

 

is seal installed backwards . to what you would normally see . large side in - open side to transmission

 

Nope. It's in the correct way.

 

Jeep T98 had no actual seal.
Just a spiral cut into the ID of the front bearing retainer.

Is your T18 equipped wioth a 1-1/16" diameter main shaft and your using the seal for a 1-1/8"" main shaft ?

 

Do You have the part number of the bearing that's in the transmission ?

It's possible there is A doubled sealed bearing to take its place.

 

This is in my friends t18a is from a 1978 so I assume it has the 1 1/16 shaft.

All the input shaft seals fit snugly like they should.

I'm almost thinking the input shaft on his has run out on the seal surface. It isn't damaged though.. Next week I'll tear it all out and put it up between centers and see it if isn't machined right.

 

Check the breather to be sure it's open?

 

Yeah..... well it sure seems like a strange mystery at this point.
Let us know what you find out.

 

It has extended breathers on the trans and tcase. By nature of the design the t18 isnt really sealed anyway. The shifter does a lot of the venting by itself.

But last time we yanked it we made sure the vent was unobstructed by blowing through it.
I plan on taking the bellhousing into work next week and checking it against a NOS one I have on a CMM. A Friend has offered to metalize the seal surface and regrind it if that is the issue. I haven't looked to see if they make a replacement input shaft yet. If they do that may be his easiest route to go.

Looks like I get to spend some quality time with t18 pigs in the next couple of weeks. Mine is getting a clutch kit put in and then I have to deal with my friends mystery leak. My backs already starting to hurt and I haven't even done anything yet..

 

Update. Sealing surface diameter is running out .020". Probably enough to cause the seal to weep over time. I guess we will try to find a new input shaft for it.

 

Yeah that's a rarity and yes .020 sounds like a lot for the maindrive.

 

I don't know. Everything else runs out perfect. Even the tips of the gears are all right on. But the seal diameter is running out. This was brand new when we put it in years ago. I assume since it has seeped forever it must have been machined like that. Must have got bumped during the process when they manufactured it.

 

Check with the different Bearing Companies and see if they have A seal that will fit the shaft

and the housing bore. Or even an auto parts store should be able to help.

 

The shaft would have to be turned down in between center's and have a underside id seal installed. Maybe it could be turned down and metalized but that's pretty costly unless a friend in the industry could do it. Turning it undersized and using a spedi sleeve may work as well but I haven't looked into it..

Also just of note this is out of the trans and in between center's and showing the run out.

 

If it's the short Ford input shaft, Parts Mike has those - T18-16LX T18 -17 Tooth Short Input Gear - for $100 it's probably your cheapest fix.

 

It's whatever is in the factory 76 + Cj's with the low first gear