2.9 to 4.0

charles3805 · May 4, 2008

I have a 1987 ford Bronco II 4x4 with 2.9 and five speed transmission fm 145
I also have a 1991 ford ranger 2wd with a 4.0 engine. I want to swap the 4.0 for the 2.9 and the rear ends. But I want to keep the transmissions in the respective vehicles. anyone know of any problems I am goin to encounter?

swamprat · May 10, 2008

The 145 is a week trany. these dont satnd up well behind a 2.9 much less a 4.0. Get a m5od, much better. You said that you are going to swap rear ends. 7.5 to 8.8. That will work if the have the same gear ratio.

charles3805 · May 11, 2008

thanks! looked for a m50d but couldnt find one. I will keep looking.

golosov · May 12, 2008

I really don't have experience with the 145 but i ran a Fm146 behind 280hp for 160,000 miles with no trouble. you might want to check to make sure your ranger axle has an abs sensor not all 2wd did but most BRII's did.

rickcdewitt · May 12, 2008

just get the m5od,the whole fm series is weak

BlackBII · May 12, 2008

The FM series is weak, and I have blown a few myslef...

But, I had one behind a 4.0 for almost a year of beating the shiite out of it and it held strong with 33's, it depends on what condition it is in now. I suggest doing the swap if the tranny isn't making any noise, then continue to look for a M5OD, you can always bolt a new tranny in there, they aren't hard to do...

mhughes165 · May 12, 2008

charles3805 · May 12, 2008

Thanks for the input. I have started the disassembly process on the bronco II. what problems am I going to have with the 4.0 being auto switching to manual? do I need another eec??

Randy M. · May 13, 2008

You don't HAVE to have another ecm, but you will be doing some extra wiring. You'll have to make sure you trace out the wiring for the clutch switch.

charles3805 · May 17, 2008

Well got the engine trans and transfer case out in one day by myself. now I'm gonna start cleanin up the engine bay.

charles3805 · May 25, 2008

I have put the 4.0 in the bronco and started the process of re connecting everything and have run into a couple of snags.
1. transmission is couple inches longer and will have to move transmission mount and replace drive shafts.
2. fuel lines are completly different.
3. the wiring harness doesnt look like it is gonna be an easy swap especially goin from auto to manual.

AllanD · May 26, 2008

There should be an exsisting set of holes in the frame rails to reposition the brackets that mount the transmission crossmember.

However I'll recommend that if you remove the brackets for the early crossmember that you can install the explorer crossmember by drilling ONE carefully positioned 1/2" hole in the bottom flange of the drivers side frame rail.

BTW, that MAY interfere with the frame rail mounted fuel pump, but to connect the 4.0 to the fuel system is basically going to require going to an '89-90 junkyard donor
and getting the fuel tank unit and the fuel lines from the tank unit all the way to the frame rail just behind the power steering box.

the 4.0 uses different style connections and trust me you'll be far better off
with relocating your fuel filter to the position now occupied by your frame rail
mounted pump as the '89-90 fuel lines will do...

if nothing else it makes the fuel filter FAR easier to change.

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