Vibes at 110kmh

[Steve F]

I've recently fitted a SYE to my XJ (4" lift) and I still have some vibes. I've tried 2 degree shim, 4 degree shim and 6 degree shim, the 2 and 4 dont seem any different but the 6 induces obvious vibes under acceleration. I've also dropped the front driveshaft to see if this is causing it but the vibes are still there. Up until about 100 it's so smooth, much much better than without the SYE.

Any suggestions on where to look next as it's really beginning to bug me and eat into my spare time with trial and error fixes.

Cheers
Steve

[94limitedxj]

Don`t really know if this will help but have u looked at the tracbar. With your lift have you relocated the tracbar?

[Hic]

Steve:

Talk to your supplier, XJ's have all sorts of drivetrain vibration issues that need to be assesed prior to SYE fit. Have you regeared ?

[Steve F]

Haven't relocated the tracbar yet, Im planning on an adjustable bar when I replace the tyres with 31's at the moment with 30's there's no real rubbing but the front end is definatley offset to the drivers side.

Also haven't regeared, still running the 3.55's, I've also gone back to my standard lower control arms for now to help in the process of elimination. Basically what I have is 4" of lift (made up from numerous bits and pieces so no particular supplier), Rubicon Hack'n'tap SYE along with a Offroad Only heavy duty rear driveshaft.

I had the vibes prior to the SYE but much worse and at only 2.5" of lift, I'm beginning to think it has nothing to do with the lift but is possibly something worn out somewhere. The front Uni's seem fine but I guess it could possibly be a rubber bushing somewhere like in the UCA's. I also seem to think I first noticed the vibes after the Jambo coming back on the freeway.

Would a wheel alignment make any difference? I did try a second set of tyres a while ago but that was prior to the SYE so I could have had vibes from 2 places then but now with the SYE narrowed it down to 1. I guess an alignment and balance is next on the list unless anyone can think of something else I should try first.

Cheers
Steve

[Hic]

OK Steve
- Front Control arms will make no difference
(you have removed your front shaft and the vibration is still there so you can bet it is not the front of the vehicle)
- Track bar will make no difference
- Alignment no difference
- Balance will make no difference
- Regeared the vibration will be in earlier say 70kph due to higher tailshaft speeds (problem will be worse)
- We have had problems with balance and vibration in all U.S shafts (Cheep), so now have them locally made by DANA Spicer.
- Check the carden and uni's,
- Is it a carden shaft, if not why are you installing degree shims ?
- Was the shaft cut square i.e. in a lathe,
- check the new fixed flange on the back to the box for runout with a dial gauge.
- Did the 2.5" kit run T-Case packers
- Check rear wheel bearings / axels
- Check condition of rear LSD, clutch packs and spider / sun gears
- Pull the rear shaft and drive on the front (carefully) and asses vibrations, @ 4" should be worse from the front with no rear shaft fitted.

Is you vehicle a newer XJ, ie rounder shape ?v90% the problem will be between the T-Case and the Wheels

[Steve F]

Originally Posted by Hic

OK Steve
- Front Control arms will make no difference
(you have removed your front shaft and the vibration is still there so you can bet it is not the front of the vehicle)
- Track bar will make no difference
- Alignment no difference
- Balance will make no difference
- Regeared the vibration will be in earlier say 70kph due to higher tailshaft speeds (problem will be worse)

Thanks, at least that eliminates a few things

Originally Posted by Hic

- We have had problems with balance and vibration in all U.S shafts (Cheep), so now have them locally made by DANA Spicer.
- Check the carden and uni's,
- Is it a carden shaft, if not why are you installing degree shims ?

Yep, its a cardan shaft.

Originally Posted by Hic

- Was the shaft cut square i.e. in a lathe,
- check the new fixed flange on the back to the box for runout with a dial gauge.

I'll check the runout on the flange, I guess this could be it.

Originally Posted by Hic

- Did the 2.5" kit run T-Case packers

Yep it ran a T-case drop and was fine for about 2 years, the vibe suddenly developed after Jambo, with the SYE it's comparatively mild

Originally Posted by Hic

- Check rear wheel bearings / axels
- Check condition of rear LSD, clutch packs and spider / sun gears
- Pull the rear shaft and drive on the front (carefully) and asses vibrations, @ 4" should be worse from the front with no rear shaft fitted.
Is you vehicle a newer XJ, ie rounder shape ?v90% the problem will be between the T-Case and the Wheels

I'll pull the rear shaft and start with that as a process of elimination.
Yep it's the post 97 XJ (rounder)

Cheers
Steve

[Steve F]

Fixed

Measured the angles and went back to 4 degree shims and then with some inspection noticed the flange on the output shaft had a tiny bit of movement in it and then realised the bolt may have been bottoming out before it was 100% tight. I didn't notice this until some load had been put on it. I tapped the hole a few turns deeper so the bolt wouldn't bottom out and now with the 4 degree shims the vibes have gone

Thanks for all the info Mark, it pointed me in the right direction and kept me looking at the rear and not the front.

Cheers
Steve