Hi Watty
Everyone has an opinion on this. I think the standard jeep specs for a standard height JK are castor - 4.2, and either zero toe, or up to 1mm toe in. Without adjustable control arms, or can bolts, you cannot adjust Castor anyway so all you can adjust is Toe 0 deg to +1mm. i think. I would also be checking other components if you have a wobble. there are a heap of threads on DW both here and in the US. Check out the below
1. Diagnosing Death Wobble and Fixing Non-DW Shimmies and Wobbles
Because my DW posts are buried in other members' threads and in some PMs, here is a thread of its own.
I will also include info on non-DW shimmies and wobbles in the thread.
I will clean it up as I go, but it should be helpful nonetheless.
Death Wobble is no mystery.
It is caused by loose bolts, damaged components, or improper installation.
Look at the picture below and follow along:
First, the tie rod (green) has ends that attach to a knuckle on each side. As you could imagine, if either ends of the tie rod were broken or bad, that could be a culprit for a shimmy (not Death Wobble). A common place to damage the tie rod is on the driver's side at the adjusting sleeve (in the picture, just to the right of the red swaybar link). That sleeve (maybe not the correct term for it, but you can see what I am talking about) allows the width of the tie rod to be expanded or contracted. There are threads on that end that can be damaged, causing play on that driver's side and allow an up and down, or circular play movement. Again, this would cause a shimmy, not Death Wobble.
Next, look at the drag link (purple). On one end, it attaches to the pitman arm (lavender), that attaches to the steering gear box. On the other end, the drag link attaches to the passenger side knuckle. When you turn your steering wheel, a shaft turns that goes to the steering gear box. The steering gear box turns the pitman arm, and the pitman arm pushes or pulls the drag link, which pushes or pulls the knuckle. Your steering wheel is straitened by loosening the two nuts on the sleeve/turnbuckle on the drag link and rotating the sleeve/turnbuckle to lengthen or contract the length of the drag link. If either end of the drag link is damaged, this would cause a wobble or shimmy, but not Death Wobble.
Next, look at the trackbar (aqua). It attaches to a bracket on the frame on the driver's side and to the axle on the passenger side. The purpose of the trackbar is to center the axle on the frame. With the axle centered on the frame, it provides some resistance to the steering system to allow you to turn. If there was no trackbar and you turned the steering, the whole front frame would shift. As a result, there is significant force applied to the trackbar in driving and steering.
Now, imagine that the bolts that hold the trackbar are loose in their bolt holes, or that the bolt holes are wallowed out (oval), or that the bushings at the trackbar ends are damaged, or that the bracket at the axle side has come loose because the weld has broken, or that the bushings are all twisted up because the rig has been lifted without the installer loosening the bolts and then retightened them at the new ride height. All these things would allow play in the front trackbar. When you steer or go around a corner, these loose or broken things would allow the axle to shake or slide side to side. If you hit a bump in the road, it could knock the trackbar towards the driver's side. Then, the rest of the suspension (springs, etc.) would try to bring the trackbar back to the passenger side. If you were going at any sort of speed, you could develop a kind of harmonic resonance as the axle more and more violently slide/rocked/shaked from side to side. It would feel like your whole front end was being voilently torn apart. You would have to bring your vehicle to a complete standstill to stop the harmonic resonance. This is Death Wobble.
Even one incident of violent Death Wobble related to the front trackbar can cause significant damage. The voilent harmonic resonance of the back and forth shaking is more than the trackbar bushings, bolt holes, and brackets are designed to handle. A severe Death Wobble occurance can crack or break the welds on the axle side trackbar bracket, or the bolt can wallow out the bolt hole in the bracket, or the bushing can be permanently damaged.
This is the most common source of Death Wobble because inexperienced installers either do not remove the bolt from the trackbar when they install a lift--leaving the bushing pinched in the bracket and bound up, or they do not properly torque the bolts after the lift has been installed with the tires on and the full weight of the vehicle on the ground at ride height, or (maybe the most common) they do not retorque the trackbar bolts after the first 50 miles, after every heavy wheeling trip, and at every oil change interval.
Next, look at the lower control arms (purple) and the upper control arms (light blue). In the picture, they are aftermarket arms with a heim joint on one end. However, the stock control arms have a rubber bushing at each end. When the control arms are properly torqued, the bushing is somewhat pinched in the mounting brackets on the axle and the frame. Sometimes, an installer will make the mistake of not loosening the bolts for the control arms when they install a lift. What happens sometimes is they really bind up the bushings because they are pinched/sandwiched at stock ride height, but then forced to the new lifted ride height. These bound up bushings can cause weird handling, bushing failure, and lead to Death Wobble. The proper way is to loosen the bolts, install the lift, reinstall the wheels so the suspension and jeep are at the new ride height, rock the vehicle/suspension back and forth and side to side, then re-torque the bolts to spec, then after 50 miles re-torque them to spec, then after every oil change or very heavy wheeling trip re-torque them to spec.
Improperly balanced tires, too much air in tires, bent wheels, improperly installed wheel spacers, bad tires (with separated plys), and poor alignment specs (caster, camber, and not enough toe-in) can cause wobbles and shimmies that lead to Death Wobble. However, these precipitate Death Wobble, but they are not the cause of Death Wobble.
Although not specifically identified in the picture, the ball joints that are at the top and bottom of each knuckle where it attaches to the axle C can go bad. Bad ball joints can cause shimmies, wobbles, but usually not full on Death Wobble.
Next, allthough not identified in the picture, the unit bearings can go bad and be a cause of shimmy and wobble, but not Death Wobble.
Hope this helps--assuming you read it all.
Death Wobble is no mystery.
The reason that the steering stabilizer masks it is that it can absorb some of the side to side voilent harmonics of a loose trackbar or damaged mounts. However, this masking is dangerous because it will not prevent the eventual failure of trackbar bracket welds and bolt holes from trackbar Death Wobble.
It is extremely important to immediately diagnose and fix Death Wobble.
Even one episode of DW can damage other components.
Multiple episodes of DW are almost guaranteed to damage other components.
Multiple episodes will often damage your:
o ball joints
o tie rod ends--including the adjusting sleeve end on the driver side
o trackbar bushings
o trackbar bracket bolt holes
o steering sector shaft (where the pitman arm attaches to the steering box)
o steering stabilizer
o front lower control arm bracket bolt holes
o unit bearings
o trackbar bracket welds
o drag link ends
Hellbound13 is an example of a member who with 5-6 episodes of trackbar related DW on a stock jeep ended up "chasing his tail" for many, many months. He ended up replacing almost everything in the above list--sometimes more than once.
Without repairing/replacing everything that was damaged at once, the remaining damaged components continued to cause DW problems, further damaging the remaining components.
1.
2. Further Steps to Diagnose and Fix DW and non-DW wobbles and shimmies.
This is a modified version of a PM to RedX08 who was fighting some wobbles:
First, I would re-align your rig with 4 degrees or more caster (assuming you have adjustable front control arms) and the most toe-in within factory specs. If you are doing it yourself using the project-jk write-up, toe-in 1/8" more in the front of the tires than the back.
Also, if you have bent an axle C and your camber is out of stock specs, this may cause some shimmy at certain speeds. You need offset ball joints to fix this.
During the alignment, I would check the tie rod adjusting sleeve to see if it was damaged to the point that it wobbles or is loose when the tie rod got bent. I would also have someone slowly turn the steering wheel from side to side while inspecting the tie rod ends and drag link end to see if their is side-to-side play. Also, with a helper turning the steering side to side, I would inspect the steering shaft (in the engine compartment), the shaft u-joints, the steering box and output shaft, and the pitman arm.
Second, I'd make sure your tire psi was somewhere between 28 and 30, and that you haven't rotated your spare to your front axle (differences in size due to the spare having less wear can cause issues).
Third, I would rotate your tires front to back to see if it is tire/wheel related (never having the spare rotated to the front). While rotating the tires, I would want to know if you have hubcentric wheel spacers from Spidertrax and that you removed the lug retainer clips when you installed the spacers. If your spacers aren't hubcentric, I would replace them. If you did not remove the lug retainer clips, that is the source of your wobble.
Fourth, I would loosen the bolts for your front trackbar and front control arms, rock the vehicle back and forth, then side to side, then re-torque everything to specs to see if it is from bushings that are bound up.
If you have had DW instead of just shimmies/wobbles, each component needs to be removed one-by-one to inspect bolt holes and bushings.
Fifth, I would inspect your ball joints by jacking up your rig with the tires slightly off the ground with the axle on jack stands. Then, while someone uses a crow bar or some other lever underneath a tire, while he person lifts up the tire I would inspect the ball joints to see if there is too much up and down play. There should be less than 1.5mm up and down movement in the lower ball joints.
Also while on the jack stands, I would grab the top of the tire with one hand and the bottom with the other hand to see rock it in and out to see if there is lateral play in the ball joints. There should be almost no lateral movement.
Sixth, while still on the front jack stands, I would remove the tires/wheels and brakes to inspect the unit-bearings to see if they have too much play.
Seventh, I would replace the tie rod with a new one-- Rock Krawler chromoly tie rod.
Eighth, I would make sure you have the upgraded JKS front trackbar or just replace it with a Teraflex forged front trackbar.
Ninth, I would replace my drag link with a chromoly version.
Tenth, if I hadn't gotten rid of it by then, I would sell my front axle and buy a Dynatrac 44 front housing to move my Rubi locker, gears, and my chromoly shafts into.
Tom
Quote:
Originally Posted by watty
I have been searching for the last 2 hours for wheel alignment specs, i want to know what the best are , i get a bit of a wobble every now and then . I have a CRD with standard suspension and a steel bar on the front. I am running tyres at 32PSI the front left is scrubbing out.We dont have a jeep dealer close by so will have to take it to a local bloke any help will greatly be appreciated
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Wheel Alignment
Excellent Advice JKTom
The Jeep
Trailhawk
