60+ mph vibes after lift

[Fred85]

2001 XJ with 2" OME lift

The vibes are really diminished if i let off the gas, so i think that narrows it down to the driveline?

I've ruled out wheel balance, and alignment is recent and within spec. I have an SYE installed with a front DS, 2.5* shims on the rear axle, joints are relatively new and there is no play that i can detect between the transfer case and the axle. I have also removed the front shaft and driven around just to eliminate that as a variable.

What I'm thinking: DS was from a '95 or so in the junkyard and it was never inspected or balanced, could this cause these sort of vibes? What else can i look for here?

 

[89xj]

too much pinion angle if the vib stops when you let off the gas.

 

[Talyn]

Usually, if the drive shaft was in question you would have vibes all the time, not just while on the gas. I suggest you take a look at your drive line angles.

 

[RCP Phx]

What t-case and SYE kit?

 

[Tim_MN]

DS was from a '95 or so in the junkyard and it was never inspected or balanced, could this cause these sort of vibes?

Yes.


Install your 2001 front DS on the rear and go for a test drive. The u-joints, slip yoke, or the centering ball may may be the source of the vibes.

 

[ZomBrady]

Did you re-gear?

Sometimes if the gears aren't setup properly, you can and will get some weird driveline vibrations. Ask me how I know. . . .

Check to see how much backlash you have in the rear-end. If you have more than a wiggle (1/8th of a turn), have a specialist look at it.

 

[Fred85]

no regear...i really need to get an angle finder to check angles though

i'll swap the shafts and see the results

any idea of driveshaft balancing cost?

 

[DeftwillP]

I had my front shaft balanced a few months ago for $50. Now I just figured outthat I need it lengthened too. :banghead:

 

[Fred85]

ok, i haven't yet checked the pinion angle....but it looks pretty good, i would think 2.5* shims would be sufficient for a 2" lift?

i did however take the front shaft and move it to the back, which actually was a marginal improvement in the vibrations......but they are still there, just to a lesser degree

what else could i look for here? How do i know if TC bearings and pinion bearings are bad? i always assumed they had play in them....

 

[Fred85]

i felt a need to bump this thread

I have since corrected my pinion with 5* shims (took out the 2.5* ones) and had my driveshaft balanced by fleetpride. I now have smooth acceleration up until past 70 mph, where i'm getting what sounds like rotational noise by the driveshaft. There aren't really vibes, especially not in the front end because the the steering wheel is as smooth as can be....

What else can i look for here? The noise isn't pronounced enough to really drive me crazy, but if i can fix it i would prefer to....

 

[bigd423]

could be bend driveshaft, bad ujoint, or the gears could be bad in the rear end..

 

[Jeepguy03]

Did you try taking the shims out? I'd think with a 2" lift that a SYE should be plenty. Maybe its the shims that are affecting your driveline angle. Maybe a pic of the rear driveshaft angle would help?

What T-case do you have?

 

[MrShaft696]

I would go to the junk yard and grab a different driveshaft to try.

 

[uk captain]

had this problem on my 98

changed to a pre 95 transfer case which has a longer prop

 

[Fred85]

^^^i thought the same thing, but with my setup 5* shims put my pinion in proper alignment (checked with angle gauge)

i guess i could swap the front and rear shafts, but i've done this before without any change. Could the driveshaft being "out of phase" have any effect?? i've seen some cases of rotating the shaft 180* curing some vibes...

also, what about the transmission mount??

 

[RCP Phx]

What t-case and SYE kit?

 

[Redsnake]

Interesting read. I'm in the works of getting the $ together for an OME 2" lift too, but I didn't think my '96 would need much other additions for such a small lift. If you could PM or post up where and how much your OME 2" cost I'd appreciate the info.

I'm curious and hope you solve this issue as it may be something I have to do in the near future also.

 

[mrtosh]

I'm in the same boat. Granted I'm at around 7" of lift with a zj front DS in the rear. I've switched back to the xj DS and its the same. Smooth as silk up until 70 and then I get a rotational noise that isn't constant. No vibes more of an on/off rotational noise. Weird how everything is fine up to 70. I do also have a AA SYE,shims, and 4.56 gears. Definitely not a consistent gear noise. I do know I need to replace the front output bearing on the TC. It is pretty growly especially in 4hi. Wouldnt think that would effect normal 2wd operation though. Just very odd its not a constant vibe noise, almost like every other second there's a vibe noise.

i felt a need to bump this thread

I have since corrected my pinion with 5* shims (took out the 2.5* ones) and had my driveshaft balanced by fleetpride. I now have smooth acceleration up until past 70 mph, where i'm getting what sounds like rotational noise by the driveshaft. There aren't really vibes, especially not in the front end because the the steering wheel is as smooth as can be....

What else can i look for here? The noise isn't pronounced enough to really drive me crazy, but if i can fix it i would prefer to....

 

[longarm]

On my 99' XJ I did a Rocky Road 2" lift to clear my 10.50 x 31's on Wrangler/Ravine 8" wheels. This kit was poly blocks in front and 3" longer shackles in rear with 1/2" blocks. I added another 1/2 " block in the rear for more clearance when I tow. Got vibes between 30 and 40 and again at 55. Also had growl when I let-off throttle. I took the block out and machined it to 3* and put it in with big end forward so as to drop the nose of the diff. Bingo, no more vibes and no more growling.
I don't know jack, I'm just a very old gear head.

 

[Fred85]

I wanted to bump this thread to see if i could get any new insight.

I have since determined that this noise isn't driveshaft related. I've removed the front shaft and tested: no change in noise. I've also installed a new Tom Woods shaft in the rear and played with the "phasing" of the shaft with the diff/tcase yokes: no change in noise.

Since this last post I had another alignment and my old tires rebalanced: no change in noise.
I got new tires and an alignment a few months ago: no change in noise.

To refresh everyone's memory, from about 70 mph up i'm getting a constant droning/humming noise. There is a slight amount of vibration (I can feel it with my arm on the center console), but its more audible than it is vibrational...and it's pretty loud.

I guess i was going to replace control arms next...i'm throwing money at it now