T90 case replacement required?

CapnDan · Post by **CapnDan** » Tue Mar 12, 2024 7:16 pm

Howdy Jeepers: Lots of information on here about transmission leaks. I cannot seem to find what the hole size in the case should be for a tight and leak free counter shaft install. I rebuilt mine in 2009 and it leaked bad from counter shaft hole, sealed between case and bell housing with permatex in lieu of gasket that was not in my gasket set. Now it is leaking again. I have pulled tranny and transfer with bell housing to rebuild transfer case. Plan on putting a gasket in there this time and using a sealant for gear oil. How big can the hole in case before you just scrap it and get another case?

Post by **wesk** » Wed Mar 13, 2024 2:20 pm

Which hole?

If a bearing race or housing fits in it the required normal fit is an interference fit.

CapnDan · Post by **CapnDan** » Wed Mar 13, 2024 3:06 pm

Hello Wes:
The hole at the 6 o'clock position as seen in the left view in the figure you attached, it's the hole in the front of the case that the counter shaft goes into, nothing in the repair limits in the tech manual.

CapnDan · Post by **CapnDan** » Wed Mar 13, 2024 3:47 pm

I am also working on my transfer case. Got it all torn down and I need to replace the pilot bushing in the rear output shaft that the front output gear shaft fits in. Any tricks to pulling this pilot bushing out of the end of shaft?

Mike_B · Post by **Mike_B** » Wed Mar 13, 2024 7:13 pm

Check out Rick Stivers on You Tube, he has a bunch of really good trans and transfer rebuilds that are easy to follow.

https://www.youtube.com/watch?v=-m_LGKv ... stZbqQPZJ0

Mike B

Post by **wesk** » Wed Mar 13, 2024 9:27 pm

On the counter shaft opening in the case the only official limit announced in the jeep manuals is no out of roundness is allowed.

It helps to get very familiar with Novak's and Rick Stiver's T90 guides! I try to emphasize this to all folks asking how questions on T90 overhauls.

Here's a quoted paragraph from Rick Stiver's T90 guide about the fit of the countershaft to the tranny case hole:

I-15. The Countershaft should fit very tightly into the case. It should also have no perceptible grooves or ridges worn into the bearing surface. These shafts are cheap so do yourself a favor and replace it.

Here are the links to these guides:

chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www.novak-adapt.com/files/5014/ ... ebuild.pdf

https://cj3b.info/Tech/T90.html

https://www.cj3apage.com/index/Tech_Tip ... ebuild.htm

chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www.thecj2apage.com/pdf/t-90-rebuild-guide.pdf

chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www.thecj2apage.com/pdf/the-dan ... ansfer.pdf

CapnDan · Post by **CapnDan** » Thu Mar 14, 2024 5:48 am

I have been using Rick Stiver's guide and TM 9015-2 Chapter 5 and 6. I sent Rick and email and this is his reply:

"Danny, as for removing the bushing, I used a sharp chisel and cut the bushing down both sides to split it in half. Then the halves came out easily.

The counter shaft normally won’t leak at the back as long as you install the gasket. At the front though is another story. I finally got to where I installed the shaft most of the way. Then I packed the hole with Permatex #2 and then drove the shaft the rest of the way in. Then I made sure to seal around it the best I could. Success rate was about 50% of the time. As long as the hole fits snug on the counter shaft it should be fine."

Rick

4x4M38 · Post by **4x4M38** » Sat Mar 16, 2024 7:55 am

Yes, I think that is in Rick’s directions for reassembly.

CapnDan · Post by **CapnDan** » Thu Mar 21, 2024 5:24 pm

The other thing on the T90 transmission I don't seem to find in any of the guides or tech manuals is if there is any requirement for checking input shaft end play. The Supply Manual Ord 9 SNL G-758 pages 190-191 lists 5 different thickness retaining rings. No mention in the manuals of using different thickness retaining rings to allow the input shaft and bearing to be moved farther into case when the front bearing retainer is installed.

TM9-8015-2 chapter 5 paragraph 99b reads: Install bearing snap ring. Lock ball bearing to input shaft with the 0.086 thick bearing snap ring. If new ball bearing is being installed, install 0.0625 thick bearing snap ring in groove of bearing outer race.

I get about .030 end play, I checked it by pulling out (forward) and pushing in (aft) on shaft, measured movement from end of shaft relative to front of bearing retainer. Is that an acceptable amount of end play?

Post by **wesk** » Fri Mar 22, 2024 2:51 am

I reviewed your manual references and looked up the CJ5 civvy manual tranny rebuild data and it seems both resolve the input shaft end play by using one of two different thickness snap rings. But they do not publish what the acceptable end play is.

However the counter shaft gear end play is controlled by a fixed thickness thrust washer and a second thrust washer that is offered in two thicknesses. But here there is a specified end play limit for the main shaft gears of 0.012-0.018.

We can only assume that the manufacturer saw no need for a test end play figure for the input shaft alone.

Pierre · Post by **Pierre** » Fri Mar 22, 2024 2:24 pm

Sal at Vintagejeeper.com has T-90 transmission shaft shims in different thicknesses for this issue. He specializes in T-90 rebuilds...

Keep end play at minimum to help prevent popping out of second gear.

With today's supply of shitty repro parts, you really need to measure every thing to make sure everything is withen specs...

When possible go NOS