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Old December 4th, 2017, 06:34
burntkat burntkat is offline
NAXJA Member #1145
Join Date: Apr 2003
Location: Charleston, SC
Posts: 1,164
Death Wobble after lift

I have a 1997 XJ, 4X4, 4.0, AW4, etc. I just "forklifted" the suspension- meaning I replaced every component of it- 4" rear springs, shocks, Upcountry front coils, added ACOS, Iron Rock Offroad trackbar, 31" tires, etc.

The vehicle is fine to drive up to 45MPH. After that, I either have a bad shimmy, or mild death wobble- not sure of the defining line between the two. I know that at around 45 it'll start shaking a little, and it feels as though if I don't brake smoothly it will continue to get worse. This is my son's vehicle and he regularly commutes a mile in a 50mph zone to get to school and work. I want to solve this problem ASAP.

I've examined the front end while my son steers- the trackbar seems to be hoding the axle in place just fine (I've got 150ftlbs at the axle bolt- upgraded to the Clayton H/D bolt kit and 80 at the frame bracket. Frame bracket bolts are tight, and the bracket doesn't appear to be moving. I've replaced the pitman arm TRE as I saw a little movement there. I'm not sure I trust the other TREs although I'm not seeing any movement in them. I have them on order at Oreilly's, going to replace as soon as I get time to realign the vehicle.

I tested the balljoints by using a long lever with a piece of 4X6 in front of the raised tire and looking/listening for movement or clunking. Nothing appears evident.

All control arm bushings appear intact, with the bolt centered in the bushing body.

Wheel bearings were tested as well, by lifting the wheel and trying to shake side to side. I see a *little* bit of movement in one wheel but I'm not sure it's out of spec. It may be the TREs. As I said, not sure I trust them- at the very least, they all have ruptured boots and so I'm replacing them out of due diligence. I don't get any shake out of them, and when I rotate the bars they stay in place.

I noticed this vehicle doesn't have a disconnect in the front axle. Thus, front propshaft rotates as the tires do. Might that have an impact on DW? At any rate, the joints all appear fine.

Kind of at a loss where to go here. I had a similar issue with the wife's ZJ last year, of course it's basically the same suspension. I solved that problem by forklifting everythng in the front axle- hub bearings, control arms (full set F/R of Core4X4 arms with poly bushings), ball joints, TREs, axle shaft u-joints, wheels and tires. I just can't afford the Parts Shotgun approach on this vehicle at the moment, as I've already put $2000 into the suspension for a vehicle I paid $1000 for. Admittedly I got a steal of a deal, but still.

Anyone have any insight? Is it possible for balljoints to be bad even after passing the shake/lever test? How about control arm bushings- is there a more definitive test for them than "that looks right"?
-89 S-10: SAS, D44s front/rear. 5.7L V8. 700R4 with 4L60E upgrades. Built in my driveway.
-90 XJ 4.0, AW4, 231J: Clayton's longarms, RE 5.5" coils, hybrid 6" leaf pack, 33/12.50/15" MTs, Rancho 99012s and 99624s, Tera HD SYE, custom sliders, BW flares. Rehabbing with D44s, RE spring packs, RE 4.5" coils, and ACOS.
-94 ZJ: Budget boost, 31s. The wife's DD.
-97 XJ: Son's DD. 4" lift, ACOS, 4" spring pack, Upcountry coils, 31s
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