My 1987 Montero 5 speed tranny is howling and whining in 1st, 2nd, 3rd and 5th gear. Surprisingly, 4th gear is quiet. The tranny is popping out of 1st gear once and awhile if I go down a hill. It also grinds slightly in 4th unless you let the RPMS die down before you shift. The grinding in 4th can't be heard, but only felt in the shifter slightly. The higher the RPM the more grind and resistance going into 4th. Any ideas what I'm looking at here. I haven't checked the oil level yet, but I'm thinking it is OK because 4th gear is quiet. I'm telling you, she's howling pretty good but runs great. She's got 189,000 miles to her credit.

Sounds like the counter shaft bearings are bad. Also the bearing thrust plate that keeps them preloaded may have pounded out.

The synchros will need to be checked and probably replaced. Though they may be shifting poorly from the bad bearings that could cause a lot of extra friction.

Kevin C

My '92 5-spd with 152k was making the same kind of noise, and only quiet in 4th...I didn't have any of the popping out of gear problems though. I took mine in to get fixed, and it was the main bearing at the head of the tranny...sorry I can't be more specific...the guy showed it to me and that's what he called it. I had it in to have the top end redone, and to have a new clutch put in, so it was all apart anyway.

As stony man noted....the main bearing on the input shaft will cause similar problems.

Kevin

Standard tranny's are weak. Put in an automatic. I'll sell you mine cheap. I can't give you the shift lever and linkage. I modified them to fit the TH700R4.
superchief87@adelphia.net

PFfffffttttthhhttt...I got over 152 out of mine, and while noisy, it was still workin' fine...I don't think that qualifies it as weak..although perhaps I was just very lucky...or is it the GenI standard tranny you were talking about? I don't have any experience with those <img src="/forums/images/graemlins/pfft.gif" alt="" />

A decent 2.6 manual tranny can hold up quite well. There are a few things that can go wrong but if you address those you should have a very tough unit.

First off any manual transmission has an inherent weakness. The gears produce metal and the ball bearings get damaged from running through it. On a bearing that is highly laoded this can greatly shorten it life.

I have gotten front bearings that were sealed to prevent this from happening. The input shaft bearing seems to be the most sensitive. A rebuilt unit produces less metal so is should last longer (the gears have been run in).

The 2.6 transmissions can pound out the thrust plate for the main-shaft and the counter shaft. The metal used was soft and allows too much endplay over time. This makes for a noisy counter shaft and when the main shaft moves it causes the tranny to pop out of gear when you let off the gas and also puts a lot of metal into the oil since the shifter forks are rubbing a lot. There is a TSB on this plate / problem (I think there is a better part available).

On some transmissions the retaining nut on the main-shaft works loose. This appears to happen from the parts that are clamped taking a bit of a set, reducing the clamping. That gets parts pounding and lets the nut back off. Never ever try and tack weld the nut to the shaftà The shaft will break.

Use a new nut when you put the unit back together and use loctite on the nut and the bearings. Make sure you pean the locking tabs.

Use a die grinder to take the old nut off, just grind away the area around the tabs.

The last issue is the OD gear. The hub and the gear are welded together (most transmissions do this thatÆs how you can cut gear teeth very close to the synchro hub). Some of those parts are defective from the factory and break from stress points created from the weld. If you have a good gear that lasted that long it should keep on working. New OD gear sets has been known to just blow up. The new part is a new design that must be changed as a set. Perhaps this is a good candidate for cryogenic treatment?

I have used the manual tranny with a turbo motor and it never broke, that was at 250 ft lbs of torque. A better description would be it wore outà

Most of these problems happen over a very long time and most units last at least 125,000 miles. Personaly I like the standard trannyà The performance is good as is the fuel economy. The auto is slower and you lose 2 mpg. Adding a lockup converter auto fixes most of those problems but that is a big conversion.

I would stick with what you got (pun intended) and see if you can find a shop that can go through the unit or score a good used one.

Kevin

One last note... Bob is right in that the auto tranny is just about unbreakable.

Kevin

I have almost 190k on my five speed and to my knowledge, it has never been touched. I am just now having problems with it and am going to get it rebuilt. but i agree that I would keep the manual if it were my truck.

Look on E bay.... There is a 87 Raider with a bad motor and a new transmission.

Kevin