Osmosisfrank
NAXJA Forum User
- Location
- Salt Lake City, UT
I bought a '99 XJ about two months ago, and have been working to get it ready for Moab. It has a 6.5" Rock Krawler 3-link front suspension on the Dana 30 HP and 2" Teraflex spring pucks. The rear is a Teraflex "Grand-up" coil spring conversion, 8.5" lift on the 8.25" unit. ARB's front and rear, 35"x13.5" Toyo's, SYE on the rear with a new driveshaft and double-cardan yoke, 4.56:1 gearing. The thing does great out at 5-Mile Pass here in Utah. But getting there is a real treat...enough vibration to shake the fillings out of your teeth.
On the highway, it feels okay up to about 50 MPH, then the vibes become noticeable. At 70+, there's a deafening low-freq vibration. Today I pulled the front driveshaft out, and the low-freq went away, but there is still a vibration under throttle load coming from the rear. When I back off of the throttle, it goes away. I originally thought it might be a bent axle, but now I don't think so. I'm thinking pinion angle or caster is contributing to the front vibe.
I had the alignment done a couple weeks ago at Empire Tire in SLC, and the caster up front is 5.1* and 5.3* left and right. The measurements I just took on the rear: Driveshaft is at 21*, rear pinion is at 12*, so a difference of 9*. I know that you want the angle to be close to 0* or 1* as possible. Would 9 degrees difference make the vibration under acceleration occur at higher speeds?
Also, when slowing down to a stop, I can hear a lot of gear noise from the front end. I thought it was the unit bearings with a flat spot, so I replaced them. Now it almost sounds like a spider gear, but I'm leaning toward improper pinion depth/backlash. The axle seals were recently done at a local shop, and since then I can really hear that gear clicking sound.
Any help or advice on what to do nect would be greatly appreciated.
On the highway, it feels okay up to about 50 MPH, then the vibes become noticeable. At 70+, there's a deafening low-freq vibration. Today I pulled the front driveshaft out, and the low-freq went away, but there is still a vibration under throttle load coming from the rear. When I back off of the throttle, it goes away. I originally thought it might be a bent axle, but now I don't think so. I'm thinking pinion angle or caster is contributing to the front vibe.
I had the alignment done a couple weeks ago at Empire Tire in SLC, and the caster up front is 5.1* and 5.3* left and right. The measurements I just took on the rear: Driveshaft is at 21*, rear pinion is at 12*, so a difference of 9*. I know that you want the angle to be close to 0* or 1* as possible. Would 9 degrees difference make the vibration under acceleration occur at higher speeds?
Also, when slowing down to a stop, I can hear a lot of gear noise from the front end. I thought it was the unit bearings with a flat spot, so I replaced them. Now it almost sounds like a spider gear, but I'm leaning toward improper pinion depth/backlash. The axle seals were recently done at a local shop, and since then I can really hear that gear clicking sound.
Any help or advice on what to do nect would be greatly appreciated.