DEATH WOBBLE ????

[Peter Connan]

Oh and by the way, a lot of people seem to think that death wobble is a problem exclusive to vehicles with a live front axle, but the only car in which I have actually ever experienced a proper death wobble myself was a beetle.

[davejones]

Nice post Peter! It really is a frustrating and time-consuming process to get the front suspension/steering set up 100%..

Tony I've been using Broadacres 4x4 fitment centre at the shopping centre there. They are the first place to balance my wheels properly and are 4x4-vehicle orientated.

[AndriesS]

I've mentioned it before check that when the wheels are balanced that they use the finger thingy and not the cone. That made all the difference on my wobble

That said your wobble definitely sounds more to death wobble than a mere tyre in balance. Do you have patrol wheels fitted or aftermarket and if aftermarket has the center hole been machined to fit the Patrol hubs?

A note on the kingpin bearings, I've heard that the Cruisers pre-load (i.e. the force required to turn the hub) is about twice the Patrols.

[G-MAN]

After reading that, any poepol should understand what's going on.

[Tony]

Thanks Dave, I'll give them a try - a couple of folks have in the meantime told me that they also have experiencesd similar "wobbles" and sorted it out with new tyres. So I will now have to wait it out. I have ordered a new set of 5 Cooper ST MAXX 265 75 16's which should be here in 4 weeks or so.

Anyone had a look at them, they havent been out too long in the States but look great, classified as AT's, leaning towards MT's a little - overall performance seems good too. Will let you guys know when they arrive.

[Wheels]

how about a nice set of Procomp Xtreme at's

[Tinus lotz]

Tony is there a reason that you are putting 265 and not 285 on??????

[Kagiso II]

yoo hoooooooooo Tony?? wher'd that wobble go? gone with the old tyres .. or are thye still "abound" ???

[Clem]

[Grant]

Death Wobble is a difficult thing to diagnose and fix, because for it to happen at least two things have to be wrong, but the list of things that can be wrong is quite long.

The primary cause of death wobble is that there is some play in one of the steering/suspension joints. I would say the primary area for concern is probably the trunnion bearing/kingpin/knuckle flange bearing area. On the patrol, there are two bearings on each trunnion. These are taper roller bearings and are located in the top and bottom of the knuckle flange, with four bolts each.

Now it seems as if yours were recently replaced...
With a taper roller bearing, the outer race is pressed into place. If these were not pressed in deep enough, then usage will cause them to become loose. They also need to be shimmed up during assembly, and if this was done incorrectly, this may also cause the problem. Note that the top and bottom shims must be the same thickness.

The only reliable way to check this joint is to jack the front of the car up, place the front axle on axle stands, remove the wheels and split the steering arm ball joints off (drag link and tie rod). Now see how easily the knuckle flange turns. The manual shows that a draw-scale should be used in the hole where the ball joint is fitted, and the resistance should be between 0.6 and 1.75kg. It is best to be as close as possible to the maximum value.

The other area where play may exist, is in one or all of the steering ball joints. While they have been split off, check their condition by feeling how smoothly and easily the taper pin can be moved inside the ball. The movement should be reasonably smooth with a fairly even friction. They should definately not be loose.

The above are the primary causes of the death wobble, but these conditions may exist for a long time before one ever experiences the death wobble, because to actually set up the death wobble, something else needs to be out of spec or out of balance.

This can be one of the following:
1) Bent rims
2) Rims not mounted correctly
3) Out-of balance tires
4) A bump in the road

The best way to check for conditions 1-3 above would be to perform a wheel balancing operation on the car. However, very few people have the necessary machine to do this check. A normal wheel balance should however show conditions 1and 3. To check for condition 2 without the right equipment, firstly make sure the fitting surfaces both on the rim and on the car are clean. Secondly make sure the hole in the centre of the rim fits correctly on the hub spigot. Now bolt the wheels on, and arrange a scribe on the face of the tire. Rotate the wheel, and make sure the line is the same distance from the edge of the tread pattern all the way round. Do the same on the sidewall as well.

fwa.JPG

Further factors that may axacerbate the death wobble are:
1) Caster angle
2) King pin offset
3) Camber angle
4) Condition of the suspension bushes
5) Steering damper
6) Larger/oversize wheels

The caster and camber on a Patrol are not ordinarily adjustable.
Tha camber angle can only go out of adjustment if the axle tube is bent.
The caster angle is affected by suspension lift. This is normally corrected by using special suspension bushes (caster correction bushes), but can also be altered with drop-boxes or special suspension arms. A reduction in caster, usually caused by a suspension lift without the correct caster correction being used will reduce the stability of the suspension because caster is what causes the steering to self-centralize.
The king pin offset is altered by fitting wider rims, rims with a different offset or wheel spacers. The larger the offset is, the more unstable the suspension becomes.
While the lack of a steering damper cannot cause the death wobble, the steering damper does fight the death wobble and will thus reduce the extent of the death wobble.
Oversize wheels increase the leverage the wheels have over the suspension and steering systems.

Therefore it is important to realize that Tiger Wheel and Tire (and similar service providers) cannot fix the root cause of death wobble, they can only make sure the wheels are correctly balanced. And while this may temporarily remove the wobble, it hasn't actually cured the problem. Note also that the root cause of the problem will also cause other damage in the long run, and must therefore be fixed.

Hi Peter,

Great post. Decided that my Troll needs new bearings and Nissan charge R770.40 each. Have you or anybody got contact for after market options.