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General Forums => The Mess Hall => Topic started by: D42 on September 14, 2008, 09:16:28 AM

Title: Need some advice
Post by: D42 on September 14, 2008, 09:16:28 AM

I need some advice, I have a 94 YJ with 2.5 engine, And a 3-speed auto transmission. What if any problems would there be in installing a 1991 4.0 that had a 5 speed transmission behind it. I know that I will need new motor mounts. Comes with the ecm and part of the wireing harness. ??

Thank you.

Title: Re: Need some advice
Post by: D42 on September 14, 2008, 09:24:36 AM

Would it bolt up, would the transmission input shaft fit the crank shaft. What would I need to do??

Title: Re: Need some advice
Post by: Jeffy on September 14, 2008, 01:19:19 PM

The engine tabs on the frame will need to be cut off and replaced with new ones.  The tabs on the frames are different as well as the mounts.  If you get an engine that's from the same year it's easier then trying to match up changed stuff like connectors and fittings.

You will need to replace the transmission and the input shaft on the transfer case.  You'll probably want to replace the radiator to a 3 core as well.  You will also need to get the pedal's from the manual, cut a hole in the floor, get the shifter boot and the shifter cover plate.  Grab the tach/speedo as well.  Then you'll need the engine harness and PCM. 

Title: Re: Need some advice
Post by: CountryRunner on September 14, 2008, 05:20:55 PM

I think he wants to keep his auto if he can.

Title: Re: Need some advice
Post by: aw12345 on September 14, 2008, 06:16:17 PM

In that case flexplate and make sure the Torque converter has a slip fit in the cranck for centering or you will need to find or fabricate a bushing for that. other than that motormount brackets and radiator and rob the harness and ecm of the 6 cyl engine and mate it to yours

Title: Re: Need some advice
Post by: dudley on September 14, 2008, 07:08:17 PM

Quote from: aw12345 on September 14, 2008, 06:16:17 PM

In that case flexplate and make sure the Torque converter has a slip fit in the cranck for centering or you will need to find or fabricate a bushing for that. other than that motormount brackets and radiator and rob the harness and ecm of the 6 cyl engine and mate it to yours

Wouldn't the auto from behind a 2.5 be way too weak for a 4.0?

Title: Re: Need some advice
Post by: Jeffy on September 15, 2008, 12:06:10 AM

Quote from: CountryRunner on September 14, 2008, 05:20:55 PM

I think he wants to keep his auto if he can.

Not gonna happen then.  The 3-speed for the 2.5L's was a TF904/30RH.  The bell housing is a part of the transmission and is the bell housing pattern uses a GM 60* bolt pattern.  The transmission for the 4.0L's was a TF999/32RH which with has a AMC bolt pattern.

Title: Re: Need some advice
Post by: D42 on September 15, 2008, 05:49:13 AM

Thank you all for the replay's,  And for all the info.   :beers:

Title: Re: Need some advice
Post by: D42 on September 17, 2008, 02:38:17 PM

This Look's good:http: //4bangerjp.com/forums/index.php?topic=3560.0   :thumb: