Hi all, I've got an 86 BII with the Mitsu FM145 tranny. Having difficulty finding another Mitsu for a decent price, especially compared to the plethora of M5s floating around off of Rangers, Explorers, etc. I know that the M5 is a little longer overall than the 145, so I'll need to shorten/replace the driveshaft, and I believe I'll also have to move the crossmember as well. I also know that I need a 4x4 unit off of a 2.8 or 4.0 V6, IIRC, for the bellhousing patterns to match up. Is there anything else I'll need to worry about for this swap? Such as the pilot bearing?

I actually won an ebay auction for a fresh rebuilt 145 about six weeks ago. Seller hasn't shipped it, won't answer my emails, so I'm working on extracting my $$$ back from him. Once I do that, there's a u-pull-it yard near me that just opened up- going to go hunting there, and I'd like to know that I've got more options available- and I might even be able to get a usable and BETTER driveshaft as well.

Thanks!

 

I'm fairly certain the input shaft spline and pilot bearing size is the same. As you know 2.8l/2.9l/4.0l all use the same bellhousing pattern, no problem there. I'm unsure about the spedo gear. Also, I believe you'll need the master-to-slave hydraulic line for the clutch, IIRC they couple differently at the slave. Be sure to get the shift lever and boot with the M5! You'll want the front driveshaft, preferably off of a truck equipped with the same front axle (D28/D35) as I think the driveshaft coupling is different between the two. If you can find a truck with the same wheelbase, get the rear DS as well, it'll save you machine shop charges. Your TCase should work, as long as you get a 4x4 equipped M5 (duh). All in all it's doable, out of curiosity, have you looked into rebuilding the 145?

 

I've not yet priced out a rebuild for my tranny- I fear that as bad as the thing sounds, it'd cost me as much as a reman, but I'm still going to look into it. All this is pretty academic until I get my $$$ back from eBay ripoff guy. I had looked into doing the M5 swap because I understand that it's a heavier-duty unit than the Mitsus, which have a bad habit of bearing failure. I also know about the shift plug issues w/ the M5- but if I go that route, I can easily take care of the plug issue before I install the tranny.

I had forgot about the driveshaft issues. From looking at info at RangerStation, looks the only vehicle that would be suitable for a DS theft would be another M5-equipped BII. Closest thing to having a wheelbase as short as the BII is an early 2D Explorer,and it's still 7" longer. I'd be more likely to just pony up for a new rear DS rather than get the crappy factory CV shaft shortened- but then that adds some more expenditure to just getting my daily driver back on the road.

Speedo gear shouldn't be a problem, as it's located in the t-case.

If I can find a BII donor w/ an M5 in good condition, at a decent price, I think that's the route I'll go if the rebuild isn't insanely cheap or something. At least I've had the tranny out of this thing once already for a clutch swap, so it'll be somewhat familiar and therefore faster.

 

That is correct about the same bell housing so you will not need to change the transfer case. This is info. from a response I got on an older thread I started.

As far as rebuilding goes, it'll cost an arm and a leg to rebuild it. The FM146 in my '89 B2 is in the middle of taking a dump (202K miles). A common response to a rebuild was around $1500 due to the difficulty in disassembling and re-assembling the 145's and 146's. When those transmissions go, you're better off finding a decent used one or switch to the M5OD. I do not have any idea what the difference is in gearing between the 145/146 and M5OD but I do understand they are not identical and will throw off the speedometer reading. At that point you would need to find the correct speedo gear to get it back on track.

One more thing is that the M5OD is approximately 2 in. longer than the FM145 because I believe the M5 is the same length as the FM146 which is 2 in. longer than the 145 (someone please correct me if I am wrong).

 

The speedo reading won't change because the tranny gearings are the same, since the gear is taken from the output of the tranny (2WD) or transfer case (4WD). As long as the rear diff gears and tires remain the same, the value will be constant no matter the transmission installed.

The speed is a factor of the tire size and speed, which is directly proportional to the driveshaft speed, which leads to the rear of the tranny or transfer case, where the speedo gear is.

EDIT: And for comparison purposes, the M5OD's gears are:
3.40, 2.20, 1.50, 1.00, 0.79 Reverse is somewhere similar to first.

 

Thanks for the correction. I was under the impression there would be a difference. I stand corrected.

What about the clutch assembly? Is the M5OD's the same as the FM145/146?

 

i my self have own 4 BII from 84-89 and if i remember right the transmission xmember is in the same location from 86-90. the 84,85 models have a diffent style xmember all to gether. and in my 84 i changed out the 2.8 for the 2.9 and the toyo-koygo 5 speed for the mit. 146 (its what i had available at the time) and i had to move the x member in the 84. though getting new drive shafts made would not be a bad idea, the cvc style ds are junk. i broke 3 of them b4 i found a universal style ds at the local bone yard from a 90 BII.