Not Sure What Step To Take First


ImJace

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Alright, guys....
I've got an '87 Bronco II that was completely rebuilt 5 years ago. Engine, transmission, interior, t-case, paint, all of it. The truck still remains stock with a 2.9L v6 and a fm145 transmission. The transmission gave out on me one day on the freeway as it got stuck in 4th gear. The shifter would move freely through all the gears, but the transmission wouldn't actually change gears. After reading how unreliable the fm145 transmission is typically... I wanted to put a better one in. Hopefully this will save myself from rebuilding the same thing every 3000 miles. On top of this, my 4WD doesn't fully engage because my transfer case isn't aligned correctly. Ideally I'd like to get a transmission that is an upgrade to my current one (I've been looking at the M5OD R1) but also allows me the option to upgrade my engine to a 4.0L with an eventual supercharger option. I am most definitely going to swap my transmission. Just not sure which one to get the ideal fit for what I'm looking for. Also since this would be my first time doing a swap like this, was curious if there are any problems or complications I can be on the lookout for. I want to be prepared before I purchase this thing. Thanks for reading this if you took the time. Will be looking forward to hearing from you fellas
 


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adsm08

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The M5OD from an Explorer will fit your bill of needs. The 2.9 and 4.0 share a bell pattern and you can put a 4.0 trans on a 2.9.

Complications, as it were, will be as follows.

1) for a manual transfer case you need to find a matched set. Your existing case will cause issues. This will also mean you need the correct front drive shaft. That's gonna need replaced anyway because trans length dictates front drive-shaft length, and the M5OD is about 2 inches longer than the FM145.

2) The M5OD is 2 inches longer than the FM145. Your transmission cross member needs to move back accordingly. Lucky for you the A4LD is the same length as the M5OD. What this means for you is the holes you need are already in your frame. You just need to grind out the rivets on the mounting ears and move them to the rear set of holes.

3) Despite all that the shifter on the M5OD sits slights forward of any of the FM series transmissions. This will require a slight modification of the floor pan.

4) Drive shafts are all the wrong length now. Look for an 88-90 B2. Those shafts will be the correct length. Front one needs to match the transfer case used.

5) Hydraulic hook up to the slave cylinder will be wrong. The FM145 uses a zerk-like fitting and a butterfly pin near 11:00. The M5OD uses a quick-connect fitting at 9:00. You will need the correct slave and line, at a minimum. Personally I'd get a master/line/slave set.

6) Speedo cable is wrong now. It's too short, and will need replaced. One for an 88 Ranger/B2 will work, or an 85-87 with automatic trans.

I think that's everything.
 

ImJace

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Thanks a lot this was incredibly helpful! Looking forward to getting this started with a little stimulus bill!
 

PetroleumJunkie412

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The fm146 is also a major upgrade to the fm145. May be worth looking into as they can be had on the cheap, and a rebuild kit can be had for around 150. If you talk to the folks on here, you'll usually be told that if you run the right fluids and change when needed, they're solid units. What the right fluids are, however... ☠
 

PetroleumJunkie412

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Also, 4.0 swaps are for chevy owners and men that drive autos instead of getting erections from the pain of shifting.

I sh*t bald eagles. Fight me.






Get a copy of the pruett book, and read. There's a free one out there on pdf. Most of the cologne guys have it as well.

The 2.9 has serious potential. I'm building the proof of concept engine as I type this.

DSC_0134.JPG


Old valves to protect the seats while working.

I won't put the 4.0 down too badly, but look at it this way. My 2.9 is getting the porting work while my 1994 4.0 is hanging on the engine stand
 

franklin2

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Get a copy of the pruett book, and read. There's a free one out there on pdf. Most of the cologne guys have it as well.
I found that pdf a couple of years ago and was a little disappointed in it. It would be ok if you never rebuilt a engine before, but I was looking for hints and procedures special to these engines. That book is full of conventional generic engine rebuilding guidance, and has about 5 pages worth of info peculiar to the cologne engine.
 

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The fm146 is also a major upgrade to the fm145.
Very minor.

The FM145 had an issue with cracking the 5th speed gear. The FM146 fixed THAT issue and little to nothing else. They share the same inherent weakness, which is that the FM series of transmissions all used ball bearings on the main shaft. Ball bearings give a very small portion of their overall surface to actual contact with the races, and so under the side-loading force of being the main bearings of a manual transmission will flat-spot over time, and can fracture the balls.

The M5OD uses coned rollers on all major bearings, and long caged needles or Torrington bearings anywhere else.

The work to do the FM146 swap is 100% identical to the M5OD as the 146 is the same length and uses the same slave cylinder, and length and hydraulic connection differences are responsible for nearly 100% of the modifications needed to do the M5OD swap.

The FM146 to M5OD swap however is almost bolt in. When I did my B2 I had the new trans setup on a jack at work before I left Friday, drove in Saturday and did the whole job in 4 hours.
 
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ImJace

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The M5OD from an Explorer will fit your bill of needs. The 2.9 and 4.0 share a bell pattern and you can put a 4.0 trans on a 2.9.

Complications, as it were, will be as follows.

1) for a manual transfer case you need to find a matched set. Your existing case will cause issues. This will also mean you need the correct front drive shaft. That's gonna need replaced anyway because trans length dictates front drive-shaft length, and the M5OD is about 2 inches longer than the FM145.

2) The M5OD is 2 inches longer than the FM145. Your transmission cross member needs to move back accordingly. Lucky for you the A4LD is the same length as the M5OD. What this means for you is the holes you need are already in your frame. You just need to grind out the rivets on the mounting ears and move them to the rear set of holes.

3) Despite all that the shifter on the M5OD sits slights forward of any of the FM series transmissions. This will require a slight modification of the floor pan.

4) Drive shafts are all the wrong length now. Look for an 88-90 B2. Those shafts will be the correct length. Front one needs to match the transfer case used.

5) Hydraulic hook up to the slave cylinder will be wrong. The FM145 uses a zerk-like fitting and a butterfly pin near 11:00. The M5OD uses a quick-connect fitting at 9:00. You will need the correct slave and line, at a minimum. Personally I'd get a master/line/slave set.

6) Speedo cable is wrong now. It's too short, and will need replaced. One for an 88 Ranger/B2 will work, or an 85-87 with automatic trans.

I think that's everything.
Referring to your 4th point. If I get a man refurbished bw1350 transfer case (the same one that is already in there). Couldn't I just take my front driveshaft to my local driveline shop and have them shorten it? In my head this should work because the splines aren't going to need to change. Seems that there is practically zero B2's in my area with these parts available. I am attempting to avoid spending over $600 on the driveshafts alone.
 

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I swapped my fm146 and 1350 with a m5od and 1354.

I used the 1354 front driveshaft and original rear driveshaft. I have a d28 front end, 1988 extended cab, 1990 short cab long bed donor. You'll need the starter plate and floor plate as well. Slave cylinders, clutch, and other crap all interchange.
 

adsm08

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Referring to your 4th point. If I get a man refurbished bw1350 transfer case (the same one that is already in there). Couldn't I just take my front driveshaft to my local driveline shop and have them shorten it? In my head this should work because the splines aren't going to need to change. Seems that there is practically zero B2's in my area with these parts available. I am attempting to avoid spending over $600 on the driveshafts alone.
Two issues to this idea.

The 1350 was never mated to the M5OD. The bolt pattern is correct, but the shifters on the transfer cases and case bosses on the transmissions are in slightly different spots. This makes the linkages not line up correctly.

The front driveshaft needs to be longer, not shorter. As the trans gets longer the front shaft needs to grow too because the front of the t-case is now farther from the front diff. The rear shaft shrinks because the rear of the t-case is now closer to the rear diff. Shortening a drive shaft is cheap and easy. Making one longer is basically the same price as getting one built from scratch.

Keep in mind though, the only part of this project that requires parts unique to a Bronco II is the rear drive shaft. Literally every other part in question is best scavenged from a 1st gen Explorer. And even the rear drive shaft can be gotten from a 1st gen Explorer, if you are handy enough. A front shaft from that application can be modified to be used at a rear shaft in a B2.

I swapped my fm146 and 1350 with a m5od and 1354.

I used the 1354 front driveshaft and original rear driveshaft. I have a d28 front end, 1988 extended cab, 1990 short cab long bed donor. You'll need the starter plate and floor plate as well. Slave cylinders, clutch, and other crap all interchange.
The starter plate is only needed if he goes with the 4.0 clutch at this time. Since it sounds like the 2.9 is sticking around the 2.9 plate would be used with the 2.9 clutch/flywheel. If he goes with the 4.0 clutch then he needs the starter plate and the 4.0 starter as well. I'd grab that plate either way.

The floor plate from the donor can be used, or the existing one can be fixed with a Dremel.
 

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I looked up a 1995 explorer on autozone. They have two different front driveshafts they sell one is 28 1/4 inches long and the other is 29 7/16 inches long. They say these measurements are taken with the shaft compressed all the way, and from bearing cap centerline to bearing cap centerline. One of them is $309.99 and the other is $425.99.
 

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Everything adsm08 has been correct, but you can use the one aftermarket made for BII rear driveshaft that is with a sliding shaft made for the stock fm145 but it can slide to the length with the M50D1-mine did and has under severe load with no problems. Get the 93-94 slave cylinder/clutch kit when you do the 4.0 swap-it is an upgrade and will work even though the books do not say it is a swap. Use Luk pro gold- definitely a better product.
 


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