strange shop diagnosis

M

mujaman

New member
so a shop that is looking at my jeep came up with another possible explanation for my ongoing death-wobble:

they say it has a vacuum diaphram (?) that may be leaking when i go over a bump - that lets the 4-wheel drive system try to engage - this then causes the u-joints to allow a hop and lead to the wobble... or something to that effect.

i got the info second hand so didn't get a clear explanation directly from the shop (i'm away at school). just wanted to see if any of you guys had ever heard of something like that...?

oh and i finally got my caster angles set right. one side is right at 5 and the other is at 6... so that should be fine. still wobbling though...
 
No vacuum diaghram on the front axle of a '97, last year for that on a Wrangler was '95. Somebody is feeding you a line.

My guess is a loose/worn front track bar, and/or worn control arm bushings. Inspect the control arm bushings with a flashlight and screwdriver, looking for tears in the bushings.
 

bounty, i have a '97 XJ... does that make a difference with the vacuum diaphram? also... i'm pretty sure the tracbar i put on came with new bushings. i know my control arms (which are also upper and lower BDS, the uppers are adjustable) all have new bushings.

on a slightly different note, how do i go about adjusting my steering box to take out some play? i put on an aftermarket one a few months ago but haven't taken a close look at it. once again, i'm away at school and my jeep is at home, so i can't really go look at stuff on it to double check any of this.
 
Missed the XJ part, it could go either way on the vacuum disco on the front axle.
The steering boxes can be adjusted somewhat, there is a bolt on the top with a allen setscrew inside it. I've never done it, but know it's there.
 
I seriously doubt it's your steering box.

Just to clarify, by "death Wobble" you mean:
Hit a bump then the whole front end shakes violently until you almost completely stop? (this is DW) If not, describe again what it's doing.

Do you have the specs from your front end alignment? How have you determined that the front axle is re-centered via the trackbar? (have you measured each side via a reference to the frame or was it "eyed up")

Ya know, this isn't as common but tires being out of balance can cause this as well. Has a weight been knocked of you wheel? I doubt that's it your BFG AT's usually balance pretty well.

How long have you had the tires on, are they showing any un-even wear?

Just trying to narrow things down
 

hey TC thanks for the reply...

yes i definitely do have death wobble. i mean it shakes like nothing has ever shook before... my tires actually squeel when they come in contact with the pavement sometimes. my question about the steering box was just a side note... i didn't mean for it to sound like i related it to the DW. it just seems my steering is altogether been sloppy lately, and i'd like to tighten it up.

back to the DW subject though, i haven't been able to do any of my own work or even check up on my jeep lately because i've been away at school... so i'm not real sure about how well my axle is centered. i do know my caster angles are supposedly set right though... and thats typically one of the biggest contributors to DW.

tires are definitely a concern and i have looked into that quite a bit. mine are pretty old (35k or so on them), but are worn evenly and seem to be balanced fine. that was one of the first things i tried to fix... i had a dealership lend me a brand new set (with brand new wheels as well) to see if that corrected the problem. it helped a bit, but by no means fixed it. the DW has gotten a lot better lately with some of the newest fixes (notably the adjustable UCA's), so i'm guessing a new set of tires now would get it back to where it should be. the thing is though... i should be able to throw just about any beat up worn out pair of tires on it and drive it without DW. new tires only mask an underlying problem...
 
mujaman said:
. the thing is though... i should be able to throw just about any beat up worn out pair of tires on it and drive it without DW. new tires only mask an underlying problem...
Click to expand...

If you put a badly balanced tire on any vehicle it can make for a hell of a ride.

Does the wobble happen all the time, at all speeds, or just after hitting a bump?

Someone correct me if I'm wrong but I define these problems as:

Shimmy - shaking of front end, usually felt in steering wheel. Can happen at different speeds but usually consistant.

Bump Steer - hitting bumps makes the wheel jerk one way, and you have to counter steer to straighten up

DW - hit a bump, front end shakes violently until you stop or slow down to a near stop. Steering is nearly uncontrollable during this.
 
true... a badly balanced wheel always makes your ride suck, but it still is not a legitimate cause for DW.

and yes, all of your definitions seem to be right on.

i usually only get the DW if i'm going over 45-50 mph and hit a pretty good bump. until i put the control arms on, it would sometimes do it even at a small bump though. it is also much more likely to do it if only one wheel hits the bump or if i hit a bump while in a turn (which makes sense b/c both those situations cause one wheel to react differently than the other...). the only way i can get it to quit is to drop down to about 20 mph... a real pain when you have a semi right on your ass doing 75 mph on the interstate.

once again though... the weird thing is: i drove it without incident for well over a year with my 3" lift and NO STEERING MODIFICATIONS. the DW started up out of nowhere back at the beginning of the summer...
 

Well yeah, that's definately it. Sorry but I wanted to be sure as lots of folks use it as a general desciption. My bad.

Well if your alignment is good it could be your tires, and yes, it can be a legitimate cause for DW.

Are your drag link and trackbar aligned (parallel)?
 
hey TC... i'm not really sure if my tracbar and draglink are lined up how they should be. i'll be sure to look into that next time i'm home though or maybe just call and have my dad check it and see if he can tell. is that something you can just "eyeball" or do you need to make some sort of exact measurements?

i think i'm definitely getting some new tires soon, and maybe some new wheels. i've never liked the steel wheels that i've had on it and i think i'm gonna go back to some alloy ones if i an afford it.

thanks...
 
well my jeep definitely does not have any sort of vacuum diaphram on the front... so the search continues.






anybody want to buy a death-wobbling jeep for about $10k...?
 
You must log in or register to reply here.

Similar threads

cowboy80911
Need info on one that was dragged into my shop
Replies
2
Views
494
cowboy80911
cowboy80911
bradleyheathhays
Sourcing a used AW4 transmission for my XJ
Replies
7
Views
264
superj
superj
bradleyheathhays
1st transmission problem in 28 years
Replies
1
Views
493
superj
superj
bradleyheathhays
No start on the old 96er, with clues
Replies
4
Views
828
superj
superj
XJReaper
Checking in
Replies
5
Views
1K
JPNinPA
JPNinPA
Back
Top