2.9 flywheel, starter and clutch on a 4.0

[DL BOGART]

I understand it may not be an advisable move, but since it is possible to bolt in a set of these from a 4.0 onto a 2.9, is it possible to go the other way and use my 2.9 components when swapping in a 4.0? The smaller clutch may have a shorter life span than the larger one, but it may also reduce the load on my weeker '87 trans if the clutch can't hold it. (Up until the clutch goes up in smoke...)The donor truck doesn't have the trans or the starter, or the disc/pressure plate. It also has the electric transfer case which I really don't want to mess with...

 

[mp3deviant721]

You can put a 4.0 clutch on your 2.9. It's in the Tech Library. When you do swap in the 4.0 however, use the 4.0 parts. The 2.9 clutch is smaller and probably will not be able to handle the 4.0's power.

 

[gribly]

FYI - I had a fresh stock clutch behind my fairly stout 2.9 that wasn't much slower than a 4.0. It did not have the low-end of the 4.0, but it had strong mid-range, and the stock clutch was fine, and I did 4wd clutch drops on a regular basis. It probably would work fine, and the clutch would be like a fuse for the tranny in that case.

 

[99RangerKrazy]

You can put a 2.9L clutch assembly/flywheel on a 4.0L. I bought a 92 Ranger with a 4.0L and the kid said it had a new clutch. It had a really bad stuttering problem (warped flywheel) and I discovered it had a 2.9L clutch...Idiot.

I wouldn't advise it. I'd put a 4.0L clutch on a 4.0L as that is what it was designed for. Plus, even if your weaker tranny takes a dump (my FM145 lasted a long time behind a 4.0L - it's still working) you'll already have the 4.0L clutch when you replace it with a M5OD. You won't have to mess with it for a while.

 

[country0001]

The starter will not work. Its not wired the same. Already tried it.

 

[heptofite]

the automatic 4.0 starter will start up a 4.0 with a 2.9 clutch.

the 2.9 manual flywheel is the same size as the automatic 4.0 flywheel (since the 2.9 and the 4.0 use the same auto flywheel.

and the automatic and manual 2.9s had the same flywheel diameter between manual and auto, they only had one starter option.

 

[feellnfroggy]

NO matter how weak your tranny may be its all mechanical and will hold up fine for regular driving with the proper clutch, the only thing I would worry about is hammering on it offroad. But im pretty sure it'll be just fine.

 

[03ranger4x4]

If you do decide to steer away from doing a 4.o clutch, i highly suggest getting a NEW 2.9l flywheel. I made the mistake of getting mine resurfaced when i did a clutch on my old bronco. The clutch held up just fine, and didnt slip. But it was obvious the clutch wasnt getting its full grip. The friction point was very high the pedal and if you poped the clutch out the engine would slowly rev down as the trans speed matched the flywheel. I like a nice stiff clutch that you can chirp gears with, and i think most agree with me on that. If i could go back, i would have done it right with the 4.0 clutch with new everything.

 

[adsm08]

It doesn't matter if you use a 2.9 clutch or a 4.0 clutch. Your 4.0 WILL toast your FM transmission. It is not a question of if, it's a question of when, and I highly suspect that a smaller clutch won't lengthen the life of your FM trans by much, if any.

The smaller clutch won't transfer any less torque, it will start to transfer it more abruptly off the bigger engine since the smaller clutch doesn't allow for the same slowness in release and grab as the larger one does. It will slip more at the start, but my experience is that it also grabs on suddenly at the top, likely delivering more of a shock to your admittedly weak transmission.