I own a '95 Wrangler and am about to have a Rough Country 4-inch lift installed. I plan to buy some new wheels and tires, but before I do, I want the right size. I will be buying 33x12.50-15 tires, so do I need 15x8- or 15x10-inch wheels? I drive my Jeep every day and will do limited off-roading.
C.L. Long
Teague, Texas
I ran 33x12.50-15s on my '95 YJ on 15x8s with a 4-inch lift. I had a little rubbing of the front tires on the springs at full turn, and I needed to nip just a tiny bit of plastic from the rear of the back fender flares. Otherwise, they were a good fit. I think you'll have more clearance issues than this with the wider 15x10s. My advice would be go for the 15x8s.
I believe the time has come to rebuild my NP231. I have a '95 ZJ with a 4-inch Rock Krawler lift and a 1-inch T-case drop kit that I swapped the NP231 into. I've been experiencing some bad vibrations, especially at highway speeds, and I have deduced that it's the T-case causing the problem
I removed the front driveshaft the other day to see if that was the issue, and it seemed to be. I took my ZJ on the highway all the way up to 85 mph and didn't feel a single vibration. I thought it was the driveshaft's balance. I took it to a very reputable shop that built it for me, and the guy there said it was probably out of balance due to the rub mark on the tubing (from my crossmember when I didn't have the T-case drop kit installed). He put it on the machine and informed me that it was, indeed, out of balance. He balanced it, and I reinstalled it under my ZJ. The vibration was still as bad as it was before. This tells me that it's not the tires being out of balance nor is it anything in my frontend, and it ultimately was not the driveshaft.
I put it up on an alignment rack at work and jacked it up by the axles. I put it in 4-High, so the front driveshaft would be spinning as if I were going down the road and accelerated to about 70 mph. A few technicians said my T-case was pretty noisy and felt like it was shuddering a bit.
Now, a few questions for you:
1) What does this sound like to you?
2) Should I go ahead and get a complete rebuild kit for it?
3) Since I'm already going to be tearing into it with the rebuild kit, should I upgrade components like the kits offered by Tri-County Gear?
4) Should I just go ahead and do a slip-yoke eliminator and get a CV rear shaft because the only way to upgrade components in that way is with a short-shaft conversion through Tri-County Gear?
5) If I get the slip-yoke eliminator and take the T-case drop kit out, how do I keep the front driveshaft from rubbing the crossmember when the axle is at full droop?
Mike Kline
Charleston, South Carolina
From what you're saying, it sounds like the vibration came on at the same time you installed the T-case drop. I'm thinking your vibration is caused by less than ideal front driveshaft angles and not by any problem with your T-case.
When you lower the rear yoke of the T-case for a better rear driveshaft angle, you raise the front yoke, which worsens the angle. Since your ZJ has no front hubs, your front driveshaft angle affects vibration just as much as the rear because it's always spinning. A 4-inch lift on these trucks is a lot and is just marginal for the front driveshaft angle. Dropping the case or adding 1-inch lift motor mounts could be just the thing that would push the front driveshaft angle over the top and make it start buzzing.
First, you can add locking hubs to your front Dana 30 with a kit from Warn. Sorry, I know it's pricey, but that's pretty much the only way you're going to keep that front driveshaft from spinning in 2WD.
Second, you can install adjustable control arms or cam bushings on the lower control-arm mounts at the axle to rotate the front pinion up to alleviate the driveline vibration. However, this will reduce caster and can lead to some wandering.