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  #1  
Old December 4th, 2017, 07:34
burntkat burntkat is offline
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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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  #2  
Old December 4th, 2017, 07:46
Bent's Avatar
Bent Bent is offline
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Re: Death Wobble after lift

Castor too far forward/positive?
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'01 XJ 4.0 AW4 231 Modified
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  #3  
Old December 4th, 2017, 07:49
BenWheelin BenWheelin is offline
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Re: Death Wobble after lift

You didn't mention the steering stabilizer, cheap enough to start. New or used tires?

Maybe try it on your old tires, I had it start suddenly one day but didn't notice the knot in a tire for months. Looked and looked, went over everything, and it was a tire.
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  #4  
Old December 4th, 2017, 08:17
burntkat burntkat is offline
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Re: Death Wobble after lift

Quote:
Originally Posted by Bent View Post
Castor too far forward/positive?
Good catch. I meaasured it at 6deg pos (top toward back). This is about spot-on IIRC.
__________________
-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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  #5  
Old December 4th, 2017, 08:17
burntkat burntkat is offline
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Posts: 886
Re: Death Wobble after lift

Quote:
Originally Posted by BenWheelin View Post
You didn't mention the steering stabilizer, cheap enough to start. New or used tires?

Maybe try it on your old tires, I had it start suddenly one day but didn't notice the knot in a tire for months. Looked and looked, went over everything, and it was a tire.
Steering stab was replaced after purchase of the vehicle, 4 months ago. Besides, they mask DW, don't cause it.

Tires are new.
__________________
-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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  #6  
Old December 4th, 2017, 08:39
burntkat burntkat is offline
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Re: Death Wobble after lift

More information:
I aligned the vehicle by tape measure. This isn't the first time I've done it, and my SAS'd S10 and the wife's 4" lifted ZJ both are able to roll out at 70MPH without issue. (granted the SAS'd S10 has a leaf front suspension, but the point is my alignment and balance is good).

BTW- wheel balance- wheels are balanced with a combination of a static balance job (weights taped to the inside of the rim to do the heavy lifting part of the balance job), and use of Centramatic balancers (to put a fine polish on the balance, actively as the wheel rolls down the highway). I've never had a problem with this method, even using just the centramtics up to a 33" tire.
__________________
-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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  #7  
Old December 4th, 2017, 10:18
RCP Phx RCP Phx is offline
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Re: Death Wobble after lift

4" is a lot when using the factory control arm mounts and that carries thru to drag link angles!
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  #8  
Old December 4th, 2017, 10:36
burntkat burntkat is offline
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Join Date: Apr 2003
Location: Charleston, SC
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Re: Death Wobble after lift

Quote:
Originally Posted by RCP Phx View Post
4" is a lot when using the factory control arm mounts and that carries thru to drag link angles!
True, but I'm using the same setup on the wife's ZJ at 4", and my 90 XJ at 6".

Sub-optimum, certainly agree. But it isn't a guaranteed no-go.
__________________
-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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  #9  
Old December 5th, 2017, 18:14
BenWheelin BenWheelin is offline
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Join Date: Oct 2017
Location: Texas
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Re: Death Wobble after lift

Quote:
Originally Posted by burntkat View Post
More information:
I aligned the vehicle by tape measure. This isn't the first time I've done it, and my SAS'd S10 and the wife's 4" lifted ZJ both are able to roll out at 70MPH without issue. (granted the SAS'd S10 has a leaf front suspension, but the point is my alignment and balance is good).

BTW- wheel balance- wheels are balanced with a combination of a static balance job (weights taped to the inside of the rim to do the heavy lifting part of the balance job), and use of Centramatic balancers (to put a fine polish on the balance, actively as the wheel rolls down the highway). I've never had a problem with this method, even using just the centramtics up to a 33" tire.
Tape measure method should be fine if it doesn't pull. Did you relieve the control arm bolts at the new ride height to let the bushings unload?

I've experienced it from a bad steering box, but it was already leaking from the pitman shaft, and from wheel bearings. I'm sure you would have noticed play there by now.

Last edited by BenWheelin; December 5th, 2017 at 18:18.
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  #10  
Old December 6th, 2017, 07:16
burntkat burntkat is offline
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Location: Charleston, SC
Posts: 886
Re: Death Wobble after lift

I haven't relieved the stress on the bushings- hadn't even thought about that.

Steering box is brand new rebuilt unit from Oreilly. There are no leaks in it- however I think there may be a little bit of movement in the sector shaft. There's no leaks there, as I said, however- not sure how that is even possible.

I have new wheel bearings on the way, although I'm not convinced they're bad. The DSPO told me the vehicle was "well maintained"... I've come to the conclusion he's a damn liar. The shocks were the OEM units, FFS! I could tell because they were 1- rusted to crap, and 2- had Chrysler emblems on them. Even with that, it still rode well. It rides much better now, except for the 40mph limitation.
__________________
-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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  #11  
Old December 6th, 2017, 20:28
Green XJ Jeep Green XJ Jeep is offline
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Re: Death Wobble after lift

Moog lower control arms are $30 at rockauto.

Chances are the bushings in the control arms are a little worse for wear. Especially with the new angles
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  #12  
Old December 6th, 2017, 21:37
burntkat burntkat is offline
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Re: Death Wobble after lift

Yep, that's the way I'm leaning as well. I'm just going to replace the bushings though. I have the tools to do the job. My only concern is rust on the fasteners
__________________
-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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  #13  
Old December 11th, 2017, 05:07
burntkat burntkat is offline
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Join Date: Apr 2003
Location: Charleston, SC
Posts: 886
Re: Death Wobble after lift

Replaced all the steering rods and ends yesterday. Literally everything from side to side that bolts to the pitman to the knuckles. MUCH improvement, I've had the truck to 60 briefly now. It's smooth but I do get an occasional heavy vibration (like a heavy shimmy, or moderate DW) from 45-50, however it is intermittent. Comes and goes, without apparent reason (ie, bumps or potholes don't appear to have anything to do with it).

I think it may be a harmonic of my wheel balance occasionally coinciding with a flaw in a wheel bearing... These are 20 years old after all. I balanced my wheels on a static balancer, and will switch over some Centramatic balancers from the wife's ZJ this evening. If the problem goes away I'll leave them on for a bit till I can get him his own set. Meanwhile I have new bearings to go on the jeep, just didn't have time to install them this weekend. I'll also do ball joints in a week or two as a precaution, and I have a set of poly bushes arriving today. Yes I understand they will limit flex, this is not a trail vehicle. I'll grease the snot out of them and install, and won't have to worry about them again until we are ready to consider a more major suspension upgrade (longarms). He wants to pursue a career in automobile customization and will be beginning work on his welding certification next year.... Once he has that we will look into our own take on a Clayton longarm system like I have in the 90.
__________________
-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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