Drive line experts, please!

[Firemanray]

I consider myself a pretty good trouble shooter on anything mechanical but now I'm stumped.

My Xj had a bad driveline vibe in it when I bought it. the front shaft was shot so I removed it. Vibe gone. I replaced it with a brand new Wood's shaft. I noticed the vibe was back but not that bad.

This week I took a road trip for the first time and the vibe seemed to be worse. I removed the shaft before returning home and had ZERO vibes. The u-joint and CV joint are good and tight and there is no play in the slip joint. I can't seem to find any thing that would cause the vibes I'm getting. Anyone have any experience with this problem??

[msmoorenburg]

Any play in your pinion bearing?

[Mudderoy]

Any play in your pinion bearing?

Yeah time to suspect the front diff.

[Firemanray]

I'll have a close look. I was in the hotel parking lot when I took the shaft out this time.

[msmoorenburg]

Are you gonna be in the cleveland area next weekend? We can put it on the lift and give it a go :thumbsup:

[4.3LXJ]

Ray

You have a 98, which means low pinion. These are more difficult to lift because the castor angle is hard to maintain and not have driveline vibes. You play a balancing game between castor angle and pinion u joint angle. You are supposed to have a fairly straight shot on that with the CV on the other end.

http://i649.photobucket.com/albums/uu215/warriorsuspension/cv_angle.gif

Here is the geometry you are supposed to have. If that pinion angle gets too great, it will vibrate no matter whose shaft it is. You will have to tip the axle forward a little.

[Firemanray]

Ray

You have a 98, which means low pinion. These are more difficult to lift because the castor angle is hard to maintain and not have driveline vibes. You play a balancing game between castor angle and pinion u joint angle. You are supposed to have a fairly straight shot on that with the CV on the other end.

http://i649.photobucket.com/albums/uu215/warriorsuspension/cv_angle.gif

Here is the geometry you are supposed to have. If that pinion angle gets too great, it will vibrate no matter whose shaft it is. You will have to tip the axle forward a little.

The front drive line is exactly as your picture shows (it is a high pinion), my rear drive line is in question, 4.5" lift w/ stock drive line (no vibes there). This is why I was so puzzled since it was coming from the front.

[XJ Rat]

98 and 99 have high pinion. Low pinion Dana 30 did not start being used until the end of 2000 and all the 2001 models.

Like 4.3LXJ stated, first check your angles on the driveshaft. If the angles check out, have the driveshaft inspected. Tom Woods does make excellent stuff, but there is a chance something is not right. Those two are the easiest. Before you take out the driveshaft, grab it at the diff end and try to move up and down. There should be no play. Then do the same at the TC end. There should also be no play. Any play at either end, that is where to look first.

[OrangeXJ]

I had vib issues with mine when I first got it. Replaced the rear u joints and broken trans mount. Got better but still vibrated. Took the front drive shaft out to replace the u joints. Vibration went a way with the shaft out. Put shaft back in with new u joints it was better but still vibrated. The only u joints left to replace in the drive train were the axle u joints. Replaced them and vibration went away.

[Firemanray]

I had vib issues with mine when I first got it. Replaced the rear u joints and broken trans mount. Got better but still vibrated. Took the front drive shaft out to replace the u joints. Vibration went a way with the shaft out. Put shaft back in with new u joints it was better but still vibrated. The only u joints left to replace in the drive train were the axle u joints. Replaced them and vibration went away.

I've replaced the right side recently. I need to do the left wheel bearing so I'll replace u-joints at that time. Maybe that will help.

[Firemanray]

Are you gonna be in the cleveland area next weekend? We can put it on the lift and give it a go :thumbsup:

I might could make it down there next Sat. 1-1-11 in the afternoon. If that works for you I'll see what I can do. Maybe James and Rene could pop in and we could have another "shop" day since I missed the last one.

[msmoorenburg]

I might could make it down there next Sat. 1-1-11 in the afternoon. If that works for you I'll see what I can do. Maybe James and Rene could pop in and we could have another "shop" day since I missed the last one.

that will work :thumbsup: how bad is the old front shaft?

[Firemanray]

that will work :thumbsup: how bad is the old front shaft?

125,000+ miles on it. the slip joint has side to side slop, that's the main reason I changed it. I'm thinking of having it re-built and using it when I do SYE.