will a 2.9 trans work on a 4.0? | Ford Explorer Forums - Serious Explorations

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will a 2.9 trans work on a 4.0?

dangeranger93

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December 17, 2010
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City, State
lawrenceburg IN
Year, Model & Trim Level
91 Ranger
ok i have a 91 ranger 4.0 auto, and ive been looking for a 5 speed for the swap and it seems all i can find are 2.9 trucks, im pretty sure i read that the 2.9 and 4.0 transmissions were interchangeable.

so my question is can i use the 2.9 transmission on my 4.0? whats the difference between the 2? what else should i get off the 90 b2 donor, and what will i need to get from somewhere else?

anything else you want to say to help with the swap is apreciated also
 



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As far as I know, it should be fine. The only thing I'd suggest is to make sure you get an M5OD. The older Mitsubishi and TK transmissions aren't usually considered as good as the M5OD. I just think that if I was doing this swap, I'd try to get the best transmission I could get.
 






im pretty sure with it being a 90 it should have the m5od in it, my 89 ranger had one. is the one for a 2.9 weaker or anything? not like i go hardcore 4 wheelin or anything so its probably not the biggest deal
 






Wish you were closer. I have some 4.0 m5od id trade for a 2.9 m5od.

2.9 will bolt right up. Its what I have in mine. 1-3 gear ratios are a little lower then a 4.0 trans but other then that there the same.
 






The issue doesn't come from wheeling, it's while trying to pull a grade while on the highway (or while towing anything). The Mitsubishi transmissions are known for poor oiling of the 5th/rev gear cavity, and the input shaft ball bearing is known to fail often too (though I had an output shaft ball bearing fail on mine... :confused: ).

4WD 2.9L M5ODs are out there, but they are quite rare (the 2WD version was more common). I think only a very select few 1990 models got them, the majority of them will be FM146 transmissions.
Being you said the donor's a '90, I think there's a chance it'll have one.

Something to note, the 2.9L transmissions have lower 1st, 2nd & 3rd gears than their 4.0L counterparts. Might come in handy for towing or rockcrawling, but can be a bit "short" geared for a 4.0L in everyday use. (edit: too slow lol)
 












how can i tell if its an m5 or mitsubishi? i know what my 2wd m5 looks like but never really messed with 4x4, also does anyone know if i will need any crossmembers off the donor, or if my driveshaft will work?
 






If it has a pan on the bottom with 12 bolts it's an FM.
 

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thats easy enough, i assume the m5 will look like a 2wd with a different tail section?
 






One other thing to know. The early BII and Ranger TK trans had an external slave cylinder. If one is used you need the smaller 2.8 clutch and flywheel. And you would use the 4.0 auto starter. The TK, FM and M5 with the internal slave will use the 4.0 larger clutch and need the std. starter.
 






Thanks guys, im actually getting answers to questions ive asked other places and gotten nothing, im sure ill be back with more
 






well it a FM but he only wants 125 for it so if a cant find an m5 i might go for it, with the FM what clutch and flywheel and starter do i need? will the 2.9 stuff work
 






All the clutch stuff fits the same M5OD/FM146 (at least when I swapped from my FM146 to a M5OD, I reused everything being that I had already done a 4.0L clutch upgrade).

Do not use the smaller 2.9L clutch behind a 4.0L though, you'll likely smoke it 1st time you step on it lol (the 2.9L clutch barely even holds the torque of a 2.9L).
 






well i actually just came across an m5 so i might try to get it, will the master cylinder from a 95 2wd ranger work? he doesnt have the truck just the motor and transmission but i have a 95 master cylinder and pedals, also can i get the line from the master and the reservior from a different ranger, the 4x4 5 speeds dont exist in the junk yard
 






would a 2.9 auto transmission fit a 4.0 auto?
 






would a 2.9 auto transmission fit a 4.0 auto?
As far as bolting in, yes, it should bolt in fine. The earliest 2.9 A4LD's ('85-'87) only had one solenoid in the valve body, so there are some electrical issues if you get an old A4LD. The most important difference, though, between the 2.9 A4LD and the 4.0 A4LD is that the 4.0 A4LDs were built with stronger internals. A 2.9 A4LD can be rebuilt to 4.0 specs, but people asking this question are usually trying to avoid the cost of a rebuild. So, like a lot of economic type questions, it really comes down to balancing how much the 2.9 transmission is going to cost vs. the cost of rebuilding your existing transmission vs. the time it might take to continue shopping for a used 4.0 transmission vs. how hard you drive the truck vs. how important longevity and reliability are vs. how lucky you feel.
 






yea like i will just but using the the truck to get my family back and forth to work i will do the swap to the 2.9 since its cheaper for me right now and then i will just rebuild the 4.0 on my free time do you think the swap woud be worth it for every day driving im in raleigh NC where the roads are posted at like 35-45mph do you think i should be ok?
 






yea like i will just but using the the truck to get my family back and forth to work i will do the swap to the 2.9 since its cheaper for me right now and then i will just rebuild the 4.0 on my free time do you think the swap woud be worth it for every day driving im in raleigh NC where the roads are posted at like 35-45mph do you think i should be ok?
 






yea like i will just but using the the truck to get my family back and forth to work i will do the swap to the 2.9 since its cheaper for me right now and then i will just rebuild the 4.0 on my free time do you think the swap woud be worth it for every day driving im in raleigh NC where the roads are posted at like 35-45mph do you think i should be ok?
So how did the swap go as far as bolting right on?
Was there any modifications and how is it running?
I am curious because I am ready to buy a 2.9L automatic transmission and place into my 4.0L engine
 



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