4 " lift

I'm getting a 4' lift kit from a friend for my XJ. I have an aisin 4 speed automatic and he says I will not need my driveshafts lengthened or a transfer case lowering kit. Is this true? or will I experience problems?

You MAY need to use t-case lowering kit or even a longer driveshaft but it depends too much on your particular Jeep. I am waiting for a SYE and driveshaft to ship for mine because even with a t-case drop I've got vibes between 25-35mph

You'll find out, either you'll have vibes or your drive shaft will fall out. You may not have to get it lengthened, but you should get an extended slipyoke. This reduces the binding on the u-joint off the tcase.

Considering you have an '89, you might be ok. I ran 5" on my '87 with a few vibes and no 'pull out' problems although it didn't flex worth a *****.

An extended slip yoke will help the 'pull out' problem but will do nothing to solve vibe problems if you end up with them.

Use this drawing for reference to set your driveshaft angles correctly.

Courtesy Tom Woods website

I beg to differ, I remember hearing my rear u-joint popping before I put on the ext. slip yoke, that's when I was only at 3" of lift. the extended length is in the yoke not the female shaft. This allows more movement in the u-joint.

Now I have +6", ext slipyoke, and tcase drop, and ext rear shacles. I have vibes between 45-55 MPH then they go away, and the vibes are only noticable in the rear view mirror.

Most likely you will not be able to eliminate all your vibes. Just plan for and SYE, I have mine, but need to get off my lazy A$$ and put it in.

If you have the np242 tcase you should be fine.. it has a longer fantail and should support it ok.. push come to shove.. drop that tcase 1/2" and say to hell with it.....

But like stated many times before (in other threads) every jeep is diff... im at 6" lift with about a 1.5" tcase drop.. no vibes at all...

XJCHUCK72 said:

I beg to differ, I remember hearing my rear u-joint popping before I put on the ext. slip yoke, that's when I was only at 3" of lift. the extended length is in the yoke not the female shaft. This allows more movement in the u-joint.

Click to expand...

I thought you were talking about the long travel yoke that Rusty sells or a YJ yoke which have longer splined area. I didn't realize there was a slip yoke out there that had higher working angles.