T90 Transmission removal

4x4M38 · Post by **4x4M38** » Sun Mar 05, 2017 4:57 pm

Thanks Wes. Perfectly explained as usual.

John looking at his pics looks like he has a separate solenoid and no
foot switch.

jsnwalker · Post by **jsnwalker** » Sun Mar 05, 2017 7:19 pm

The jep did have quite a bit of grinding when starting but she would start up eventually. The couple of times I did drive her, she shifted great but it would slip out of second gear almost every time unless you held the shift lever in place. That is the main reason I am taking apart the tranny, that and to stop the flood of fluid coming out of it.

As confirmed earlier, it does not have the foot operated pedal.

After looking at all the pictures and more detailed info, I'm still feeling confident that everything is disassembled/removed that needs to be. Just need to stop being a baby about it and yank that sucker outta there. I'll work on getting those guide rods made while I'm 'working' tomorrow.

Really appreciate all the help guys.

jsnwalker · Post by **jsnwalker** » Thu Mar 09, 2017 10:25 pm

Well, I finally got the bell housing/tranny/transfer out of the jeep today with the help of a can of PB blaster, 2 ratchet straps and a 25lb sledge hammer. It seems that the input shaft had some rust built up at the end that was binding up when trying to slide it apart. I sprayed a can of PB blaster into the bell housing, let it sit overnight, then the ratchet straps to the sides and used the sledge to hammer the cross member backwards as I tightened the straps. After a few minutes, the shaft popped out and it was smooth sailing from then on. Got the bell housing, tranny and transfer disassembled and am letting them all drain tonight.

Despite everything being coated in oil, I believe I saw some pitting in some of the gears were they were rusting. Whats the consensus on using rusted/pitted gears if the teeth look fine? I called the guys at Novak today and they said I could use a wire brush to clean them all and reuse as long as teeth are fine. I'll post some photos of the gears tomorrow when the oil has been cleaned off.

Post by **wesk** » Thu Mar 09, 2017 11:10 pm

Looks like you should replace the pilot bushing in the flywheel. With a rusty input shaft and popping out of 2 & 3 I would.

Pitting all the way around a set of gears is indicative of very long non-use periods with little or no oil. Speck pitting is not a big issue. Larger measurable pot holes in the hard surface are a gamble to reuse. Any chipping of gear teeth you must replace.

Don't be satisfied to blame the synchro's for the jumping out of gear. Bad bearings can cause it as well. So can excessive end play in the gear sets. So can a worn pilot bushing and so can worn shift forks and rails.

Do your self a favor and inspect as you tear down / Not after you tear down! Take photos showing relationship of all parts. Take notes on all out of limit findings during teardown and during the after teardown inspections.

If you have a copy of TM 9-8012, TM 9-1804A, TM9-1804B, SM-1005 and all of Rick stiver's Videos on the work bench you will have no insurmountable problems.

jsnwalker · Post by **jsnwalker** » Fri Mar 10, 2017 11:00 pm

Alright, managed to tear down the tranny completely today. While my shopping list is a bit bigger than I was hoping, I believe I have confirmed what is causing most of my problems (at least one of the main factors). Most of the gears and bearings have some rust but only a few are bad enough to replace I believe. A few of the gears have what look like some bad wearing. There are two rings, I believe they are the blocking rings, that at first glance seems had some wear but its really uniform so maybe it is meant to be shaped as they are? I'm going to thrown up some photos of the stuff I need/might need to replace to see if anything else stands out to you guys.

I'm curious as to what causes this type of damage inside the transmission. My guess is that the gaskets start to fail allowing moisture to get inside. Gears and bearings start to rust allowing for premature wearing allowing more moisture and gears to start grinding away at others. But things like the rear bearing having quite a bit of rust while the front main drive gear bearing has none seems a bit odd. Maybe the jep sat for a while on a slope or do you think something else could be wrong that I am not thinking of?

Shopping list:

Reverse Idler Gear

Rear Bearing Adapter

Rear Bearing

Counter Shaft Gear Set

Sliding Gear

Clutch Sleeve

Clutch Hub

Second Speed Gear

Oil Collector

All gaskets, needle bearings, snap rings, washers, spacers, etc.

Post by **wesk** » Fri Mar 10, 2017 11:29 pm

The corrosion usually enters thru the vent. It also involves simple condensation over and over again. When the oil is full the gear are not completely covered. Moisture always gets in but routine use cooks the moisture out. It's when they sit still for months and years that they are ravaged by moisture and corrosion.

Here's photos of new ones:

Here's a comparison of old vs new:

oilleaker1 · Post by **oilleaker1** » Sat Mar 11, 2017 5:59 am

If your Jeep had a missing M38 style shift boot rubber and sat outside uncovered, the shifter cane acts like a funnel and wicks water into the transmission. Or as Wes said through the vent from driving in deep streams etc. Check the inside of the cluster gear and main drive gear where all the needles run for ridges caused by wear or rust damage. Check the shafts for ridges. Measure the mainshaft where the needles up front are and where second gear bushing runs to see if it's in spec. See if the rear gear on the mainshaft has hammered the splines out. Your gears shown don't look bad at all. I'd look very hard at the drive dogs on 2nd gear, and the inside of the shift collar. If the pyramids show taper on one side, chipping, or rounding off of the tip, replace all. I'd also replace the brass blocking rings, bearings, small parts, and check the fit of the bushing inside 2nd gear on the mainshaft. You don't want it to wobble. Take a look at the case where the cluster gear thrusts fit against it. Hopefully they never spun and damaged the case. Leave nothing to doubt about 2nd gear or it will bite you. You know how much fun it is to pull the transmission so why do it again?

John

4x4M38 · Post by **4x4M38** » Sat Mar 11, 2017 8:34 am

As reccomended to me. I would replace the entire synchronizer assembly
including blocking rings. All of those teeth get worn, not just the brass
rings but the teeth inside the clutch hub. One and probably a couple
more of the vendors sell the entire synchro assembly all together.

It's not that much more for that versus just a few of the parts plus you know
the heart of your tranny is all new. If you do that replace second gear as well.
You don't want worn teeth on the gear working on all new teeth in the synchro.

Just my opinion.

As John says, now that you know what it takes to pull the thing you want
to fix anything suspect, one time.

Except of course for Bretto that somehow figured out a quick release and removal kit for his jeep!