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Fm-146 reliability


MEWolf

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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.
 


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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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."
 

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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.
 
Last edited:

bobbywalter

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Reliable.....IS NOT A WORD FOR THIS USE.
 

4x4junkie

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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.
 

19Walt93

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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.
I'm working on an 86 4x4 for a friend, it has a noisy Fm145 trans and I was considering swapping in an M50D. What has to be changed to swap it in? I assume it will bolt up to the transfercase, will the clutch slave cylinder hose connect? Any advice is appreciated.
 

Shran

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I'm working on an 86 4x4 for a friend, it has a noisy Fm145 trans and I was considering swapping in an M50D. What has to be changed to swap it in? I assume it will bolt up to the transfercase, will the clutch slave cylinder hose connect? Any advice is appreciated.
Both driveshafts, clutch hose, floor plate, engine block plate (I think) slave cylinder itself, shifter boot, possibly the t-case shifter as well, trans cross-member will need to move backwards. If it's electric shift 4x4 you may run into clearance issues with the gas tank and t-case shift motor on a short box single cab truck.

Unless you have access to a significant stockpile of donor parts, it may be easier and a lot cheaper to rebuild the FM145.
 

19Walt93

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My credo
If you don't have time to do it right will you have time to do it over?
Both driveshafts, clutch hose, floor plate, engine block plate (I think) slave cylinder itself, shifter boot, possibly the t-case shifter as well, trans cross-member will need to move backwards. If it's electric shift 4x4 you may run into clearance issues with the gas tank and t-case shift motor on a short box single cab truck.

Unless you have access to a significant stockpile of donor parts, it may be easier and a lot cheaper to rebuild the FM145.
Thanks, I'll rebuild it. As many years as I've worked on Fords I should have known it wouldn't be a straight swap.
 

Shran

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The driveshafts are really the biggest issue - if you can find a 1st gen truck with an A4LD, 4x4 and the same wheelbase as yours, you'll have what you need. Everything else isn't too bad, the t-case shifter can be hard to find plus the potential gas tank thing.

I will probably leave the FM145 in my '87 just because I don't feel like rounding up a ton of parts. It whines quite a bit but it may last another 20 years for as much as my fiance drives it.
 

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