Big Death Wobble

[baddboy]

Interesting one?????
Got a 75 series with all the gear including extended front shackles etc. It has always driven well until the last few weeks. It has happened about 5 times now. When you come around a corner at relatively low speed (30kms) and then staighten the steering wheel starts to wobble and the front wheels feel like they are about to fall off. I have checked everyting and can't find a problem? I am at a loss to explain it. Aybody got any ideas? It has also been checked by mechanics and they can't see a problem. All the bearings etc etc are all good. Maybe a little wear in the suspension bushes, but steering and everything else is fine.

[Rhett]

front shackels would be my first guess put new bushes in and tighten them up a litle more.

[Modified Toy]

Are you talking side to side steering wheel wobble? Does the wobble get worse when you accel or decel?few things to check tyre balance look at the rims and see if any weights missing no deformations in the tyres eggs etc and check the bolts on the upper and lower king pin bearings.

[MART]

Are your spring saddles slightly rolled , this can cause the diff to move arround , also are your drop shackles pinned driving on the road as the diff moves it can make the suspension hop and make the steering jerk side to side as with a suspension lift the angle of the drag link increases and while driving it normally you only feel it as bump steer , but it is usually associated with hitting a bump while braking as braking can make the diff rotate forward and backwards , and it gets worse as it goes also drop shackles allow sideways movement as well so you get a massive steering shimmey , hope that makes sense , maybe check saddles and U-bolts , also steering damper if you have one , also how old your shocks are , also when you hit the brakes and stop does the car rock back and forth , maybe get someone to have a look at front diff for you while stopping from a distance and finally are your springs okay , Cheers Paul.

[baddboy]

Are your spring saddles slightly rolled , this can cause the diff to move arround , also are your drop shackles pinned driving on the road as the diff moves it can make the suspension hop and make the steering jerk side to side as with a suspension lift the angle of the drag link increases and while driving it normally you only feel it as bump steer , but it is usually associated with hitting a bump while braking as braking can make the diff rotate forward and backwards , and it gets worse as it goes also drop shackles allow sideways movement as well so you get a massive steering shimmey , hope that makes sense , maybe check saddles and U-bolts , also steering damper if you have one , also how old your shocks are , also when you hit the brakes and stop does the car rock back and forth , maybe get someone to have a look at front diff for you while stopping from a distance and finally are your springs okay , Cheers Paul.

Saddles look good.
I just checked the ubolts and got 1/2 a turn on a couple of bolts.
No shackles not pinned but never have been and only just started doing it.
Steering damper is new, shocks 6 months old.
When it does the crazy ivan hitting the breaks does not affect it. It goes away after nearly coming to a stop.
It fees like youve left the wheel nuts off and the wheel is about to drop of. Very violent. I have noticed I seem to feel more in the steering wheel than I used too. Ihave just had the wheels rebalanced but they were also fine.

[chunderlicious]

ok, i just fitted powersteer to flynns car and put the lines on the wrong way (which was the logical way) and it was fine till i touched the wheel when it would go psycho...... check your powersteer and shit associated with the box and pump

[MART]

Mine is a coily and mine used to do the same thing , tell me does it happen going straight , left , right , all. Check your wheel bearings as mine only did it going right and I found my left wheel bearing loose and also what tyre pressure do you run as the higher the tyre pressure the easier it seemed to happen to mine so I run 28 psi and haven't had a problem since , also I found that when it happened I was slowing at about 30 , turning slightly right and if I held the steering wheel really tight it would stop. You haven't used one of those servo pumps where the machine automatically pumps up your tyre as some of them can be 12 psi out , so if you put 35 you get 48 psi , just some ideas , Cheers Paul.

P.S. Some mechanics check the bearings by jacking up front wheels , but with 35's the tyres are very heavy so it might be worth checking it and really yank on the tyres up and down.

[baddboy]

Mine is a coily and mine used to do the same thing , tell me does it happen going straight , left , right , all. Check your wheel bearings as mine only did it going right and I found my left wheel bearing loose and also what tyre pressure do you run as the higher the tyre pressure the easier it seemed to happen to mine so I run 28 psi and haven't had a problem since , also I found that when it happened I was slowing at about 30 , turning slightly right and if I held the steering wheel really tight it would stop. You haven't used one of those servo pumps where the machine automatically pumps up your tyre as some of them can be 12 psi out , so if you put 35 you get 48 psi , just some ideas , Cheers Paul.

P.S. Some mechanics check the bearings by jacking up front wheels , but with 35's the tyres are very heavy so it might be worth checking it and really yank on the tyres up and down.

It has hapened left and right. Has happened going through a small roundabout with very little wheel movement. I am fairly convinced the bearings etc are good. The mechanic checked them as well. Pump the tyrs at home with own compressor and tyre joint checked them Friday. The only thing I can think off is the suspension bushes, which don't look too bad.
The thing that gets me is how severe it is. I was expecting the diff to fly out the first time it happened. For it to be so severe I would have thought a problem would be relatively obvious?

[Modified Toy]

check the chassis aroud the power steer box for cracks to.

[dogbreath_48]

I have exactly the same problem on my 75 - reared it's head after i got 37's and re-drilled my spring perches to shift the axle 1" forward. I went from 34x11.5" simex on 16x8" rims to 37x13.5" bias claws on 15x10" rims.

I was assuming it was a drag link/tie rod end - but i have had an alignment and they said nothing (though i'm yet to check it out myself). I have std length ome shackles, of which i've tightened the bolts etc. I've also checked/tightened up the u-bolts (which i didn't replace when i did the axle shift ). My steering does have a bit of play in it. Wheel bearings are good, haven't checked king pin bearings - is play in king pin bearings as noticeable as if wheel bearings are shagged?

Like baddboy said it's very violent and only stops when the car is nearly stopped - if it's only just building momentum i can sometimes 'steer it out' with a jerk on the wheel. As stated the shaking seems to build momentum very quickly to the point that the whole car (and steering wheel) is wobbling side to side. Generally happens to me when traveling around 20-30km/h and over small bumps in the road like train lines, though it has happened when i've come off a speed bump (at a decent speed) at a small angle.

Could it be something to do with the power steering system? How could i check it out apart from a visual inspection?

[BundyRumandCoke]

My vote goes for something in the axle/U bolt/spring perch area. I had a similar thing in my Rocky. The U bolts were loose, and the thing went birko after driving over a small bump in the road. Whole front axle was floating around. Very scary.

[MUD EMPIRE]

My opinion is that it will be castor. Go to your local mech. and get the
front end checked. Find out how much degrees that the extended
shackels have put it out....and wedge the diff accordingly.
While you're there, correct any worn bushes and steering gear etc.

This happened to my 60 once and, after pulling our hair out over
it for ages, the solution was quite simple.....

Dave...

[christover1]

The drag link has possibly gone past its best. They are often the thinnest bit of the steering. They can weaken with age, and when adding extra leverage of larger tyres etc, they can spring about. It won't do it at speed, because the faster spinning wheels are like a gyro to stablize it.
This can be a precursor to a drag link bending, also.
After market heavy duty stabilizer fixed mine, but adding power steer has negated the need for one now.

christover

[Guy]

Get em balanced. My swampers used to do this.. found that one was about 500grams out of balance Spinning it on the rim got it down a bit. a 200g weight was enough to get it "reasonable" ... death wobbles occured no more.

[Bad JuJu]

My opinion is that it will be castor. Go to your local mech. and get the
front end checked. Find out how much degrees that the extended
shackels have put it out....and wedge the diff accordingly.
While you're there, correct any worn bushes and steering gear etc.

This happened to my 60 once and, after pulling our hair out over
it for ages, the solution was quite simple.....

Dave...

Correct, it will be castor (or lack of it actually) playing up with the natural return to center effect.

[baddboy]

I note the castor concern. However it has never done it before. Nothing has changed. Why all of a sudden would it start doing it. I could understand castor being the culprit if I had changed something and affected the castor angle.
I have tried to get it to do it by radically steering the vehicle (Left and right). The movement this introduces is nothing like the problem I have. It seriosly feels like the wheels are about to fall off.

[stinger]

Unfortuantely I have had this problem a couple of time before. Most recently, coil sprung 80 series. After rebuilding the entire front end to get rid of it, it came down to new bushes in the Panard bar. It happens every now and then since but I just add a turn to the bolts on the panard and it is gone.

Prior to this I had a 92 troopie. It had something similar and I tried everything for it. I would find that after a balance and alingnment it would be better, but still get the death sudders. I eventually changed rims and amazingly it went away on closer inspection of the old rims I found they were not running true (buckles in the rim centers) this can be hard to pick up on a balancing machine (apparently).

So given it is leaf sprung I would be taking a very very close look at your rims.... My 2 cents worth... hope it helps...

[lj]

this same problem happens to by dads 75 series troopy. however his is completely stock and still has the 16inch split rims. id be very interested to hear if somefinds the solution to this problem.

[zooki]

Ive seen heaps of sierras do this and 95% of them have been worn out scraper seals, the rubber rings that seal the swivel hub to the ball, they act like a shock absorber

[smileysmoke]

zooki do you know if these rubber seals come in a kit for redoing a wheel bearing? mine just started to do this slight death wobble under acceleration.. nothing too crazy but dont want it getting worse. may check out teh seal you mentioned.

[Snarba]

I've had the same thing with my MK when the swampers are on...I think its a combination of the above plus I've replaced and tightened the wheel bearings and also the king pin bearings were pretty worn, since replacing them I havn't had the same trouble.....farkin scarey on the highway and the looks you get from the people who were behind! also my swampers were way out of balance...hope this helps

[baddboy]

Thanks for the replies guys.
I will do the suspension bushes this week, and gradually replace stuff untill I work it out.
:-)

[dogbreath_48]

My opinion is that it will be castor. Go to your local mech. and get the
front end checked. Find out how much degrees that the extended
shackels have put it out....and wedge the diff accordingly.
While you're there, correct any worn bushes and steering gear etc.

This happened to my 60 once and, after pulling our hair out over
it for ages, the solution was quite simple.....

Dave...

If my castor is out it would be the opposite way to baddboy's. I.e. i've only shifted the axle forward (possibly bringing it onto the arched section of the spring). I wouldn't have thought my caster anfgle would have been affected much.

Dave, can you recommend someone in the area to have it checked out?

I would have thought if it was a tyre balance issue it would be obvious at speed as well?

-Stu

[lay80n]

My vote goes for something in the axle/U bolt/spring perch area. I had a similar thing in my Rocky. The U bolts were loose, and the thing went birko after driving over a small bump in the road. Whole front axle was floating around. Very scary.

Have found simillar issues in leaf sprung foubys, both zook sized and cruiser sized. Usually loose u-bolts, or over stretched u-bolts.

Layto....

[GBC]

http://www.ausfish.com.au/vforum/showth ... p?t=103517

Hope this helps for the 75 owners.

Turned out to be shocks after everything else was tried.

C.J.

[mule75]

mine started to do this when i got my rim offset widened. i put new u bolts in and it fixed it............ for a few weeks. then i put new rod ends on, same thing. was good for few months this time. now i have found that i just have to keep a close eye on everything in the front end. as soon as something starts to loosen up slightly i get the shakes, bad.

[baddboy]

Update:
New suspension bushes = No change
Wheel Balance = No change
Wheel Alignment = No change (Casor etc all okay)
Mechanics can't fault front end i.e. King Pins, bearings etc.

I'm running out of ideas!! Apart from a coil over suspension and new diffs!

[dogbreath_48]

I know you tightened your u-bolts, but when were they last replaced? I plan to replace mine on the weekend, along with bushes and maybe a dampner. Hope like fuck it solves the problem.

-Stu

[baddboy]

I Had them replaced when the Ubolt flip kits went in 6 months ago. Checked and they are tight, Why would replacing them make a difference. I could understand if they were stuffed. Not saying it couldn't be the fault, I am sure someone will explain it to me!!
I have noticed a slight roll or distortion/bow in the U-Bolt plate, although again everything is tight and no movement is evident.

[MART]

I had a torque steer problem in the rear and I couldn't find why , so I bolted my video under the car and found the problem sraight away , I needed solid bushes in my A frame as the noalathane one's where flexing to much , you might be able to do the same , it might show you how all the suspension moves and you may be able to spot your problem , Cheers Paul.