Vibes after 1" lift, what to do??

Hi Y'all, I did a bastard pack just to fix the sagging leafs and ended up 1" above stock (I think), I did the right up here:
http://www.naxja.org/forum/showthread.php?t=957617

BTW, it's a 1999.

Measured at the flare the rear is now 1" higher than the front. IIRC stock is .5" lower. Before the swap the rear was 1.5" lower than the front, so it was sagging 1 inch and now it 1" high. So it's 2" higher than it was but only 1" higher than stock. But measured from the bumpstops to the axle tube there's now almost 5" clearance whereas before I think there was only 2", but I may be miss-remembering.

Anyways I now get vibes right around 40 mph especially when accelerating. :tears:
The vibes wouldn't really bother me except I'm worrying that the tcase is in danger of premature waring and catastrophic failure. I suspected pinion angle was responsible but I just don't know now. I wan't to do a SYE but it isn't in the budget now. (SYE kit, new driveshaft, move spring perches). I don't really want to drop the tcase either. 1" boost and 1" tcase drop, why bother? I'll pull out a leaf and go back to dragging ass before I do that.

Suggestions? Help? I worked all weekend on the spring swap and was happy with the results until I noticed the vibes on the way to work this morning. I have a 50 mile round trip commute and this is my daily driver. Please :helpme:

once again, degree shims.Use the type that slip in,it's overkill in your application to use the $30.00 ones that use the center bolt & become part of the springpack.Just loosen up your freshly tightened u-bolts & slide them in. $10. to $15. Your'e right, dropping the t/c is not nec. goodluck

cherokee chuck said:

once again, degree shims.Use the type that slip in,it's overkill in your application to use the $30.00 ones that use the center bolt & become part of the springpack.Just loosen up your freshly tightened u-bolts & slide them in. $10. to $15. Your'e right, dropping the t/c is not nec. goodluck

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Any suggestion on where to find them?

Check your U-joints before you do anything else.
I went 1 3/4 inches and got vibs.
Turned out I had a bad joint, just did not show till the lift.

I found no play in the driveshaft, so the u-joints are good, right?

I got an angle finder and measured the angles of the driveline:

tc yoke: 6*
driveshaft: 16*
pinion: 4*

I measured the tc and pinion angles from the end of the u-joint socket. On the tc end that's fine but on the rear there isn't much of a flat to measure from as there's a strap for the u-joint.

Should the pinion angle be lower? If so, how much? Right now it 2* down from the tcase, how much does it move on acceleration? Or is the pinon angle not the problem?

you should be able to find degree shims at any offroad shop. R.E, quadratech & 4WD Hardware all have them in their catalogs.

Spring shop for shims also, though that might not be your issue. We really need to know where you're at for lift, then we can look at the yoke angles.

And though it's not a surefire method, measure center of the wheel/hub to the bottom edge of the flare, straight above. The stock measurement is in bowels of the forum search, so check there. IIRC, it's something like 17.25" or so front and back.

srimes said:

I found no play in the driveshaft, so the u-joints are good, right?

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I had zero play in mine.
One joint had a rather large flat spot where the needle bearings once were.
(there was just dust in the cap)
I was really suprised to find it in as bad of shape as it was.
I had zero vibs and no noise before the lift.

drifto77 said:

I had zero play in mine.
One joint had a rather large flat spot where the needle bearings once were.
(there was just dust in the cap)
I was really suprised to find it in as bad of shape as it was.
I had zero vibs and no noise before the lift.

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So how did you find the flat spots? Did you just decide to change them and found they were bad afterwards?

ECKSJAY said:

Spring shop for shims also, though that might not be your issue. We really need to know where you're at for lift, then we can look at the yoke angles.

And though it's not a surefire method, measure center of the wheel/hub to the bottom edge of the flare, straight above. The stock measurement is in bowels of the forum search, so check there. IIRC, it's something like 17.25" or so front and back.

Click to expand...

Front is 17.5"
Rear is 18.75"

jeez first thing I would after checking for the obvious, is drop the t-case, shim the axle and get a sye if all fails. Ive done all in progression. But dropping the t-case will be the easiest most cost effective way.

srimes said:

So how did you find the flat spots? Did you just decide to change them and found they were bad afterwards?

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If I get a drive line vib, thats where I start.
Dropped the drive shaft and pulled the caps.

I also have 1" of lift on my 2000 XJ. I obtained it via Quadratec's HD leaf springs and V8 ZJ coil springs. I am also experiencing DS vibes on acceleration. I just replaced both u-joints and the vibes are still there. Any suggestion on what degree shims I should use? I'm sitting at 18.5" in the front and 18.75" in the rear, from center of hub to bottom of fender flare. No idea on angles of the DS, I don't have an angle finder.

I tried a TC drop, but ended up snapping the one bolt off, and I couldn't get the studs out, so I welded the corner of the crossmember where I snapped the bolt, and decided TC drop isn't going to happen. I've had alot of aggrivation with the XJ lately, and I'm tired of everything going wrong. I will not drill out the bolts to drop the TC.

Who makes shims you just loosen the u-bolts and slide them in? RE makes nice steel shims, but they're the ones you bolt into the pack. They do come with the longer center bolts though, so that's kind of nice.

pro-comp has 4 degree aluminum #PCS99-400b,skyjacker #SKJWS325 also 6 & 8 degree shims are available from skyjacker. I know people dis aluminum shims ,but I have used them on moderate rigs with no problems. I suppose after a few years they might wear but on anything serious I use the steel centerbolt type.You can check the pinion angle with a piece of rod bent to match the angle at the t/c & then comparing it to the dif end. you just need to make sure the angles are the same.neat trick with the piece of rod,I learned it from t.v.[extreme 4x4 or trucks I forget which one].those are good part #.I didn't give the # for the 6 & 8 degree shims because you should not need them. If you do, go for the bolt thru type

Did you get the back wheels in the air before you checked for play in the rear driveshaft u-joints? On the ground they always will seem tight. jack it up under the pumpkin till the wheels are just off the ground then twist the driveshaft back and forth

cherokee chuck said:

pro-comp has 4 degree aluminum #PCS99-400b,skyjacker #SKJWS325 also 6 & 8 degree shims are available from skyjacker. I know people dis aluminum shims ,but I have used them on moderate rigs with no problems. I suppose after a few years they might wear but on anything serious I use the steel centerbolt type.You can check the pinion angle with a piece of rod bent to match the angle at the t/c & then comparing it to the dif end. you just need to make sure the angles are the same.neat trick with the piece of rod,I learned it from t.v.[extreme 4x4 or trucks I forget which one].those are good part #.I didn't give the # for the 6 & 8 degree shims because you should not need them. If you do, go for the bolt thru type

Click to expand...

So if I were to go with the following shim, I would just take off my u-bolts, and put it between the leaf springs and the axle, then reattach my u-bolts?

http://www.4wheelparts.com/Lift-Kit...=1&t_s=64&t_pt=5502&t_pl=1811&t_pn=EXP99-400B

cherokee chuck said:

pro-comp has 4 degree aluminum #PCS99-400b,skyjacker #SKJWS325 also 6 & 8 degree shims are available from skyjacker.

Click to expand...

That is WAY too much for these applications. 2.5 degrees max for only a couple inches. :doh:

Okay then, if I go with the following shim, do I just pull out my u-bolts and slide it in between the leaf spring and the axle plate then reattach my u-bolts?

http://www.4wheelparts.com/Lift-Kit...=1&t_s=64&t_pt=5502&t_pl=1811&t_pn=EXP99-250B

With that you have to remove the center pins, no big deal, just use a c-clamp.

There doesn't necessarily have to be play in the driveshaft even if the u-joints are bad. I had the same vibe with my 4.5" lift and it turned out my u-joint was REALLY bad, but there was no play in my DS when I checked it manually. After replacing it the vibes went away, but came back after about 5 months, so I finally got the SYE. You dont have to but the rear DS right away, you can get away with using the front DS as a rear after teh SYE install...that would save you about $250-$300. You could even get one from a junkyard and keep your 4wd.