4.0 to 2.9 flywheel starter

[wolfman]

I swapped a 1990 4.0 into my 1988 bronco 2.For the time being I am using the 2.9 flywheel and clutch.I tried a 4.0 manual trans starter,but it just freewheels.I read on another forum to use a 4.0 auto starter as the 4.0 auto flexplate has the same number of teeth with the same thickness as a 2.9 flywheel.I just need to drive it for awhile,so I can pull the bigger flywheel,clutch,8.8"diffs,ect. from my 1991 explorer and then it will get all the big stuff.Anyone done a 4.0 swap using a 2.9 flywheel?

 

[silverslug]

Which transmission are you using now? Did you try the 2.9 starter?

 

[adsm08]

The 2.9 starter WON'T WORK! It isn't strong enough to turn the 4.0. Why didn't you just put a 4.0 clutch and flywheel on the 4.0 !?!? The 4.0 flywheel is 10". The 4.0 flexplate and the 2.9 flywheel are 8 2/3". WHY did you put a 2.9 flywheel and clutch on a 4.0!?!?!? The 4.0 auto starter should work for now. WHY didn't you just put a 4.0 clutch and flywheel on the 4.0!?!?!?!?

 

[Clem]

2.9 &4.0 flywheels are all 132 tooth. The difference is the distance from the end of the crank to the flywheel starter ring. the flywheel from a 4.0 SOHC will not work on a 4.0 OHV, the OHV has 6 bolt holes, the SOHC has 8. The 2.9 starter will fit, but as stated before, it lacks the power to turn the 4.0 over. There is also a wiring difference.
The 4.0 auto starter will start a 4.0 manual, but it won't disengage. And a 4.0 manual won't engage the teeth on the automatic flywheel all the way.
You are going to have to use the 4.0 manual starter to make it work no matter what manual transmission you use.
The 10" 4.0 flywheel will rub on the stiffener of some of the early transmissions, but you can grind them back a little for clearance and run it that way. Don't expect the Mitsi. transmission to last very long if you are using it off road or getting on the throttle much, the 4.0 torque is a real drive train killer, that is why they changed to the D35 and 8.8.

Ray

 

[adsm08]

+1.

Also, why did you put a 2.9 clutch of a 4.0?

 

[twoll86]

to run it with the 2.9 clutch u need a 4.0 auto starter but i am curious why you used the 2.9 clutch money? time? or both?

 

[BONES]

Ok so I did the 4.0L swap in my 86 BII, I kept the fm145 bII manual trans, the 4.0L came with a dead a4ld and I was broke so I used the 2.9L flywheel with the spacer behind the flywheel, I now use an auto 4.0L starter on my fm145 manual trans. Yes you read it right, I use an auto trans starter on my manual trans rig. On my 4.0L the 2.9L starter wouldn't bolt up because of oil pan interference.

Biggest problem with using the 2.9L flywheel and clutch is it doesn't have enough pressure to prevent slipping in extreme situations. I have ran it this way for 4 years now on 35's with 3.73 gears and for the last year on 38's with 3.50 gears, it slips only when I try and slip the clutch when climbing something very difficult because of my lack of gearing, the rest of the time it's fine.

It has worked for me for 4 years now and I have beat the piss out of this thing time and time again, but we don't have rocks here so it may be a whole different story if your climbing difficult rocky terrain all the time.

 

[adsm08]

5.13 gears

 

[BONES]

5.13 gears

Yeah I'm saving for 5.38/5.42 combo