Options for Tranny Replacement?

[TonkaSTX]

First of all, Hey, my name's Rob, I'm new to the forum!
I have an '88 2.9L 4X4 with the Mitsubishi FM146 5-speed. The tranny for some reason is in 2nd gear when its in the NEUTRAL postition. Every other gear just stalls out. This is my mud truck so its not something I want to spend a load of $$$ on. But I was curious to see what my options are. I heard the Mazda tranny is better (though more expensive) but it takes a little bit of modification to fit the 2.9? Any help here would be greatly appreciated. I wanna get her back out there

 

[fastpakr]

Actually, on an '88 I think the Mazda is a direct swap (provided you get one from behind a 2.9 or 4.0).

 

[TonkaSTX]

Sweet... can anyone confirm this?

 

[drmazda94]

the 4.0 has higher gears on 1-3 the 2.9 would be better for you. also the mazda is longer witch means you will need to change the drive line langths
ps you said you dont what to spend much money it sounds like your tranny is stuck in 2nd and when you put it in gear its now in 2 gears and the that dont work try taking the shifter out and making shure to get all you shift forks lined up and if your tranny is not to bad it should fix it. I had a truck that was a mudder and it would do about the same thing just about every time out just brought tools to fix it on the trail. hope this helps

 

[fastpakr]

the 4.0 has higher gears on 1-3 the 2.9 would be better for you. also the mazda is longer witch means you will need to change the drive line langths
ps you said you dont what to spend much money it sounds like your tranny is stuck in 2nd and when you put it in gear its now in 2 gears and the that dont work try taking the shifter out and making shure to get all you shift forks lined up and if your tranny is not to bad it should fix it. I had a truck that was a mudder and it would do about the same thing just about every time out just brought tools to fix it on the trail. hope this helps

His 88 has an FM146 which is the same length as the Mazda. There are differences in gearing between the 4.0 and 2.9 transmissions, but they aren't that critical. I've had a 2.9 trans behind my 4.0 for several years now. For a few days it seemed a little strange, but after that you just adjust your driving style and move on.

 

[mjonesjr]

The Mazada M50D transmission is the same length as your FM-146. The Mazada M50D is a bolt in swap. I would recommend swapping in a 10" 4.0 clutch, flywheel, and starter.

I like the gearing in my Bronco II with the 2.9 and 4.0 M50D transmission. The RPM's is much lower at highway speeds than my buddies '90 Bronco II with the FM-146. I can run 65-70 mph at about 2500 RPM's where he is running about 3200 RPM's.

 

[fastpakr]

I like the gearing in my Bronco II with the 2.9 and 4.0 M50D transmission. The RPM's is much lower at highway speeds than my buddies '90 Bronco II with the FM-146. I can run 65-70 mph at about 2500 RPM's where he is running about 3200 RPM's.

Something else is going on there - the O/D gearing is almost the same between the two transmissions - if he's at 3200RPM, you'd still be over 3100 with the Mazda. Tire size or diff gearing has to be different to account for the difference you're seeing.

 

[mjonesjr]

Something else is going on there - the O/D gearing is almost the same between the two transmissions - if he's at 3200RPM, you'd still be over 3100 with the Mazda. Tire size or diff gearing has to be different to account for the difference you're seeing.

Could be since I do have 4.56 gears and 31's compared to his 4.10 gears and 30's.

 

[fastpakr]

That would send you the other direction though, pushing your engine speed higher than his.

 

[mjonesjr]

I don't know then.

 

[fastpakr]

Honestly, it sounds like one of your tachs is reading wrong.

 

[mjonesjr]

Could be his. A couple gauges on his cluster do not work at all.

 

[LittleHorse]

The tranny for some reason is in 2nd gear when its in the NEUTRAL postition. Every other gear just stalls out.

you may be able to do some minor disassembly and fix it. If the transmission is in more than one gear at a time it will just lock tighter than a nuns you know what, which would explain the stalling. I would pull out the shifter and check out the shift rails, synchro collars, etc. You might be able to just get it out of second, put it back together with some new shifter bushings and be good to go.

Unless your secong gear bearing experienced a meltdown and locked up solid in which case you'd need a rebuild.

Just saying - you might take it out and look into it before you buy another tranny, just in case it's a cheap fix.

 

[fastpakr]

+1 on that - this does sound like an issue of being locked up in two gears at once.

 

[drmazda94]

His 88 has an FM146 which is the same length as the Mazda. There are differences in gearing between the 4.0 and 2.9 transmissions, but they aren't that critical. I've had a 2.9 trans behind my 4.0 for several years now. For a few days it seemed a little strange, but after that you just adjust your driving style and move on.

yes going with the lower geared tranny with the higher hp engine is good but not the other way