I just got thru helping a friend rebuild a 5spd with 285k on it (worn out synchros) that had almost no bearing wear. The tranny had been rebuilt at about 13k miles, and the owner had used nothing but dexron (NOTE - not gear lube) in it since. Bearings were all suprisingly tight. Thrust plate was ok (and was the upgrade part) but was slightly worn. This is the second time I've seen dexron used or recommended by a tranny tech for the KM145, and I'm beginning to be a believer. Lower friction losses from lower viscosity lube, and may be a better gear lubricant...

hi kev,

i'm in virginia, the raider is in california. if it were closer i would look into it further. thanks for the tips.

I remember you mentioning this before Eddy. You have me starting to wonder too. The company that rebuilt my transmission recommended using 10W30. I've been running Mobil1 in it since then. This tranny has lasted much longer that the previous rebuilt which I used gear lube in.

Mitsu made a change to the box in mid- 86 for the '87 model year. They beefed up the countershaft bearings to a tapered roller, but didn't do anything to RETAIN the bearing better- which was, in a word, stupid, since tapered rollers produce significant side load when unevenly loaded. Like in a transmission.
There's an uprated part to use when the transmission's rebuilt (it has more metal and is machined rather than stamped) that retains the main and countershaft bearing. Sadly, I can't find part #'s now...

Also, be really careful about your choice of rebuilders- this thing went through a dozen minor changes and upgrades in 86-87, and the manuals aren't really clear about it. Heck, I don't think MITSUBISHI really remembers what was done!
Mine had been built (before I bought it) by a local shop, and they removed a spacer that the manual says was removed in July (my car has an Oct build date) and the transmission promptly ate the 3-4 shift fork. I rebuilt it, asked 2 or 3 people, didn't replace the spacer- and the tranny ate another fork! Ya, the 3rd time, it got the spacer!

My 2c would be to hit the yards- get an '88 4- cyl transmission, pop the bottom cover and make sure the countershaft doesn't have much end- to- end play, and drop it in.

If you run with it grinding, it eats the end off the 5th gear hub, as the end of the synchronizer hub runs into its driving gear. So I'd fix it as soon as you can. And use 4th a lot in the meantime- it bypasses the countergear, so you don't do more damage.

hth,
Toby
have done the transmission thing too many times...

That thrust plate is mentioned in a TSB, my 88 transmission had a problem with it as well. It was way too soft and when it pounded out it not only let the main shaft move back an forth it allowed the counter shaft to loosen.

That change was made in the Starion... Probably back in 84 or so. The needle bearing counter shafts failed very easily. Once you fix the plate problem you have a pretty strong transmission.

Definatly worth getting the better part from the dealer. Also shimming the counter shaft to zero clearance seems to help.

I machined up a spacer for the main shaft that also engauges the snap ring for even more support.

Kevin

I have also had the rear thrust plate failure where the rear main shaft bearing started to ream out the thrust plate. The first sign of the failure was a fore and aft movement of the shift lever on acceleration/deaccelation. The next result was slipping out of gear. If someone else has worked on the transmission, it is wise to check the three 1-2 and 3-4 shift rods detent ball/spring/plug preload. It is not mentioned in some editions of the FSM. The correct depth from the top of the plug to the case is .22-.24 in. The small end of the spring goes next to the ball and sealer is applied over each plug. This does not apply to the neutral detent.

Nice Tranny6 Knowledge Breakdown!!! If I were To just drop an Auto Tranny in my rig would the wiring have to be yanked from an auto also????????