[jpcounty69]

I have a 86 mj and would like to have taller gearing for the occasional highway drive. How dififcult is it to convert the 4spd to a 5spd and what donor parts or vehicle do I need to find? Also the 2.5 mj has 150k, is this the end of the typical life of this motor? Any insight and information is appreciated. Really like this small longbed 4wd truck and would like to know if its worth investing in.

[karik]

5 speed transmission out of a cherokee or comanche of similar year is your best bet. did the swap myself when i lost 2nd on my 86 mj. try and find one from a 2.5 to make things even simpler, but pretty positive that 4.0 and 2.5 have exactly the same bolt pattern. most transfer cases should interchange between jeep transmissions.

best get the transmission, clutch assembly, flywheel and and brakets / mounts you can get off the donor to make the job easier.

has well over 250k on the engine when i sold the truck and still se it on the road delivering parts, so 150k is just broken in properly.

[Pete M]

the 2.5L and 4.0L do NOT share engine-to-bellhousing bolt patterns. You'll need a 5-speed from a 2.5 or 2.8L Jeep. The 4spd AX-4 and 5spd AX-5 are identical except for the 5 has a 5th gear inside. some of the middle years used an internal slave bellhousing. just reuse your current bellhousing and bolt up the gearbox.

2.5 and 4.0 engines can easily see 250k if properly maintained.

[jpcounty69]

Thanks for the quick info. Any chance that my 86 4cyl 4sp might be a BW and not AX4? Will it make a difference in upgrading to a 5spd if it is? Is there an easy way to identify from looking underneath? Thanks!

[Pete M]

there is a very small chance that it is the BW. But if it is the case, you'll need pretty much everything that goes with the AX-5 (bellhousing and guts inside the bellhousing).

the older T-5s don't quite look like the new one in the photo, but the huge top plate is unmistakable.

The Borg-Warner T4 & T5 Jeep Transmissions - Novak Conversions
The Jeep AX5 Transmission - Novak Conversions