Fm-146 reliability


MEWolf

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Prescott Valley, AZ
Vehicle Year
1990
Make / Model
FORD Ranger SC
Engine Type
4.0 V6
Engine Size
4.0L
Transmission
Manual
2WD / 4WD
4WD
Total Lift
4"
Tire Size
285X75X16
I have been looking for a 5 speed manual trans for my project 90 Supercab Ranger and may have found an FM-146 with a transfer case. My project came with a 93 4.0L engine and M5OD-R1 2WD trans, which is not much use. How reliable is the Fm-146 in a 4WD application with a stock 4.0L engine, 4.56 gears and 285/16 tires? I am not a racer, so just want the truck to go hunting and maybe some trail running.
 


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Shran

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Check it for input bearing wear by seeing if the input shaft will move in any direction other than rotational like it should... if it moves up, down, sideways, don't use it. A tiny, tiny bit of movement is probably OK but a lot of them develop quite a bit of slop and need a rebuild...the input bearing is the main point of failure in these, and if you're gonna pay for a rebuild, you're better off spending the money on a 4x4 M5OD instead.

If it appears to be in good shape, I'd probably use it but I'd baby it too. Make sure you get the shifter, floor plate, boot, etc with it if at all possible.
 

SenorNoob

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I haven't had any problems with mine. (Supposedly rebuilt just before I got the truck.) However, I do still have the 2.9 clutch which slips pretty easy.
 

MEWolf

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1990
Make / Model
FORD Ranger SC
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4.0 V6
Engine Size
4.0L
Transmission
Manual
2WD / 4WD
4WD
Total Lift
4"
Tire Size
285X75X16
Thanks, guys!! Still in search for a trans...good or otherwise.
 

gearfather

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Thanks, guys!! Still in search for a trans...good or otherwise.
biggest issue with the fm145 and fm146 was cracking the 5th gear on the mainshaft due to driving to slow in 5th gear.. don't lug it down in 5th gear and do not run 80-90 lube and they hold up pretty good "for the application."
 

PetroleumJunkie412

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2WD / 4WD
4WD
I've had two. One at 266k was noisy AF in every gear but fourth, other is a bit smoother than my m5od, but I think my synchros are singing a swan song.

Either way, I've had good luck with them. The 2.9 clutch is a weakness in the system. Guys here watched my dead cam 2.9 smoke one out before it moved the wheels in reverse on sand. They're far too small. Looking forward to the difference of swapping to a 4.0 clutch after I finish rebuild.
 
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bobbywalter

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4WD
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sawzall?
Tire Size
33-44
My credo
it is easier to fix and understand than "her"
Reliable.....IS NOT A WORD FOR THIS USE.
 

4x4junkie

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1990
Make / Model
Bronco II
Engine Type
2.9 V6
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2.9L V6
Transmission
Manual
2WD / 4WD
4WD
Tire Size
35x12.50R15
Oil starvation seems to be an issue with the bearings in the FM-series transmissions (plus the fact it uses ball bearings rather than tapered roller bearings). If you overfill the trans by about a half-quart, helps it live a little bit easier.

Ultimately I had the output shaft bearing go out on mine (this was with the 2.9L, I wouldn't trust it at all behind a 4.0L). So in went the M5OD from a '90 2.9L 4x4 Supercab truck. No issues since.
 


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