What do I need now !! [Archive]

SteveT

11-25-2007, 07:25 AM

Hey everyone,
Here is what I am working with. An 88 YJ with a 4.2 carbed motor and a peugot trans. I have now completed my 98 4.0 F.I motor(on a stand in my garage) that came out of a wrecked Grand cherokee with an auto trans. I no longer have the auto trans. I have all of the wiring harness and computers. I can swap the motor but what will I need to complete the drivetrain with a standard transmission? I assume I will need an AX15 trans with bell housing and a clutch assembly. Will I be able to use my old transfer case (NP231 I think?) or What would you suggest? I will need to buy these parts and probably need some help with hooking up the wiring harness. You guys have been a great help in the past and look forward to your input.
Thanks,
Steve T.

Gasman

11-25-2007, 08:44 AM

You will need either an AX-15 or NV3550 (2000 and later TJ) out of a 4.0 equipped vehicle. I would go with an NV3550. Swapped one into my XJ in place of the BA10 several years ago. Lower 1st gear and a bit beefier than the AX. If you go for the AX, get one with an external slave cylinder (I think they became external around 94'). Much easier to service than the internal slave design. You can use your existing clutch master cylinder. Advance Adapters makes a nice braided steel line kit to mate the master to the AX/NV slave cylinder. Much better than the stock plastic line junk. For the T-case, the AX and NV trannys use a 23 spline output and your BA10 has a 21 spline so it won't bolt right up. You either will have to swap input gears in the t-case to a 23 spline input, get a whole tcase with 23 spline input, or find a 23 spline front case half and swap the "guts" from your tcase in to it. Many people have 23 spline front case halves laying around from Tera Low conversions and you can probably pick one up for free. If you swap input gears, be aware that the pitch on the planetary gears changed around 95' and the input gears are not swappable between pre and post pitch change. To fire the 4.0, you will need a Crank Position Sensor that your 4.2 does not have. You have a couple of options here. You can use an aftermarket CPS kit that mounts on the hamonic balancer (HESCO makes one) or use the factory set up in the bellhousing. If you use the aftermarket kit, you can keep your 4.2 flywheel and get a clutch from a mid 90's YJ AX-15 application (even if you use the later NV3550, use the mid 90's AX clutch). If you go the stock route, you will need to get a flywheel and CPS from the same year 4.0 as your motor. The flywheel triggers the CPS in stock form and there were some variations over the years. Might be easier to go with the aftermarket kit.

Hope this helps!