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mystery of the front end wobble, update with video 06/02/13
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Author:  barnoon [ Thu Jan 10, 2013 4:16 pm ]
Post subject:  mystery of the front end wobble, update with video 06/02/13
hi all, chasing a problem with my 96 leaf sprung Sierra, I run 31" BF Goodrich tyres and have tried them at everything from 15 - 32 PSI to see if it helps the issue. What happens is randomly above 50kmh the steering wheel will start shaking violently from left to right, If I look out the window and look at the tyre its wobbling side to side quite a bit. Took the car to a mechanic they said most likely wheel bearings or front brakes randomly sticking, so they rebuilt the front brakes and replaced the wheel bearings and the problem is still there, they (Bridgestone) ended up giving up after spending a further 3 hours with the car today and have no idea what is causing it, they balanced all the wheels which they say are fine, tried putting the front tyres on the rear, checked the tie rod ends and other suspension components and said nothing has any play in it at all and they have no idea.

Gave up with them and took it to another shop, they spent 2 hours with it and again could not find a solution and just scratched their heads, the problem comes and goes I can be cruising along at say 80kmh and all of a sudden the steering wheel will start shaking violently and the wheels wobbling left to right, then 15 seconds later it will go away and be fine, and randomly come back, only ever does it at above 50kmh, I haven't got the money to keep taking it to mechanics whoand I am a noob with cars, anyone have any suggestions what could be causing my wobble?

thanks :)


UPDATE
ok guys I still haven't solved the wobble, I've gone back to stock rims with 205/70/15 tyres on them, I've got a new pair of front tyres put on, a wheel alignment and inspection of kingpin bearings etc which mechanics said all checked out fine.

I managed to mount my GoPRo to the bottom of the front bar and concentrate it on the front suspension and drivers wheel area, of course now that I've done this it barely wobbled, although around 1 min 18 second mark of the video you can notice it wobble back and forth a bit and a few other various times in the video, this was at 75kmh, its nowhere near as bad as it gets sometimes, It can get so bad I have to slow right down to get out of the 65 - 80kms range.

if anyone recognizes a problem in the video advice would be MUCH appreciated :)

http://youtu.be/LwM4dwkPo3Q
Author:  atari4x4 [ Thu Jan 10, 2013 4:18 pm ]
Post subject:  Re: the mystery of the front end wobble
have a search for death wobbles... can be a number of things, including king pin bearing preload.
Author:  Gwagensteve [ Thu Jan 10, 2013 4:39 pm ]
Post subject:  Re: the mystery of the front end wobble
Most likely:


atari4x4 wrote:
king pin bearing preload.
Author:  want33s [ Fri Jan 11, 2013 6:23 am ]
Post subject:  Re: the mystery of the front end wobble
AS above... Check the kingpin bearing condition and setting.
Check toe in.
Check your tyres are actually round. Sounds obvious that a tyre shop would do this but OH&S says that tyre balancers need to have a flip down cover so you can't get caught in a spinning rim/tyre.... This also means you can't see if the tyre is out of round.
Author:  dzasta [ Fri Jan 11, 2013 7:01 am ]
Post subject:  Re: the mystery of the front end wobble
I had the same problem and got the same kinda answers as you are getting. Spent a fortune on wheel bearings and king pin bearings and did not fix the problem, eventually I replaced the steering damper and that fixed the problem.
Author:  Built4thrashing [ Fri Jan 11, 2013 7:13 am ]
Post subject:  Re: the mystery of the front end wobble
Adjust your toe in. had similar issues and the alignment specs were within the limits... I gave it an extra 3mm of toe in and problem was fixed.
Author:  Gwagensteve [ Fri Jan 11, 2013 7:43 am ]
Post subject:  Re: the mystery of the front end wobble
For the record, Here is is troubleshooting table for wheel shimmy from the factory service manual:

Factory service manual page 2-13 wrote:
1: Wheel tyres inflated unequally
2: Wobbly wheels
3. Large difference in tire diameter between right and left wheels
4. Loose hub nuts
5. Damaged or worn wheel bearings
6. Worn or loose tie rod ends
7. steering gearbox out of adjustment
8. Steering gearbox mounted loose
9. Worn steering knuckle oil seal
10. Tire or wheel out of balance
11. Blister or bump in tire
12. Disturbed front wheel alignment


So changing to a known good set of tyres will eliminate 1,2,3,4,10,11,12

Kingpin preload is not specifically mentioned in this list, although play at the road wheel will be either due to loose wheelbearings or kingpins, so they have to be considered together in my opnion.

You'll note that "worn steering knuckle oil seal" is mentioned in this list. It's there because it has a significant role in damping wheel vibration - it adds friction to the steering. When checking kingpin preload, it has to be done with the oil seal and tie rod removed. Starting torque with a fish scale on the steering arm is 1.0-1.8kg. that's with no seals in. That's tight with the seals in, that would make the knuckle really surprisingly stiff to turn.

The problem is far worse in Jimny's, and factory fix for them is stiffer radius arm bushes and careful checking of kingpin bearing preload.

For the record, preload isn't play. I think that most people adjust wheelbearings, kingpins and steering box by feel. This will generally leave them far too loose. Each of these items has a starting torque and it's much, much tighter than you'd ever set these by feel.

If I was chasing death wobble, I would take the steering damper off until I got rid of the wobble, and then replace it if I felt like it. Because it masks the problem, you won't know if you've found the cause or not. Because a steering damper adds some "starting torque" to the steering system, it can cover the kingpins and oil seals being out of spec.

I'll add that everyone is willing to point the finger at large/out of balance tyres when it comes to wobble, but it's not often the case. The trolley tug death wobbled with stock tyres on it, but never did with offset rims and 35.5" swampers. The cause of the wobble with stock tyres on was a broken kingpin. The tug doesn't run a steering damper.
Author:  barnoon [ Fri Jan 11, 2013 9:14 am ]
Post subject:  Re: the mystery of the front end wobble
very informative, thanks heaps everyone, will have a play with it this weekend and report back
Author:  barnoon [ Fri Jan 11, 2013 5:44 pm ]
Post subject:  Re: the mystery of the front end wobble
this yellow thing is my steering damper right guys?

Image
Author:  Gwagensteve [ Fri Jan 11, 2013 5:47 pm ]
Post subject:  Re: the mystery of the front end wobble
Yes. Take it off and hide it until you get rid of your wobble. Many people prefer the feel of the steering without a damper.

It's already an aftermarket one, and there's no sign it's dribbling oil out so I'm sure it's fine.

Steve.
Author:  Lukeszook [ Fri Jan 11, 2013 10:52 pm ]
Post subject:  Re: the mystery of the front end wobble
I have the same problem on my 93. i have Maxxis Bighorn's on it with the bigger wheels. i have just put it down to their size being to much for the car.
Author:  atari4x4 [ Fri Jan 11, 2013 11:14 pm ]
Post subject:  Re: the mystery of the front end wobble
nope, you have underlying problems :wink:

steve's post pretty much covers it & there are a heap of other threads with more info/details
Author:  Gwagensteve [ Sat Jan 12, 2013 6:45 am ]
Post subject:  Re: the mystery of the front end wobble
atari4x4 wrote:
nope, you have underlying problems :wink:


Definitely.

None of the guys running 35's in the vic club have ever balanced their tyres, and I can assure you, 35" Krawlers on beadlocked rims are insanely heavy. Heavy/big tyres do not cause death wobble. They might help it start, but they're not the cause - the conditions that allow it to start already existed.

Steve.
Author:  scottiej [ Sat Jan 12, 2013 7:25 am ]
Post subject:  Re: the mystery of the front end wobble
I've had it before and it turned out to be the U-bolts had come slightly loose, torqued them back up and it disappeared.
Author:  barnoon [ Tue Jan 15, 2013 6:52 pm ]
Post subject:  Re: the mystery of the front end wobble
fitted some known good stock rims with 205 70 15 tyres on them, wobble is still there so can rule the 31s out as being the problem, will look into the other options when i get chance
Author:  barnoon [ Wed Feb 06, 2013 5:25 pm ]
Post subject:  Re: mystery of the front end wobble, update with video 06/02
UPDATE
ok guys I still haven't solved the wobble, I've gone back to stock rims with 205/70/15 tyres on them, I've got a new pair of front tyres put on, a wheel alignment and inspection of kingpin bearings etc which mechanics said all checked out fine.

I managed to mount my GoPRo to the bottom of the front bar and concentrate it on the front suspension and drivers wheel area, of course now that I've done this it barely wobbled, although around 1 min 18 second mark of the video you can notice it wobble back and forth a bit and a few other various times in the video, this was at 75kmh, its nowhere near as bad as it gets sometimes, It can get so bad I have to slow right down to get out of the 65 - 80kms range.

if anyone recognizes a problem in the video advice would be MUCH appreciated :)

http://youtu.be/LwM4dwkPo3Q
Author:  atari4x4 [ Wed Feb 06, 2013 5:30 pm ]
Post subject:  Re: mystery of the front end wobble, update with video 06/02
did the mechanics pull the front end apart to check the kingpin bearing preload?
Author:  Gwagensteve [ Wed Feb 06, 2013 5:41 pm ]
Post subject:  Re: mystery of the front end wobble, update with video 06/02
Did they remove the tie rod and knuckle seals, check for starting torque on the knuckles, and then replace the knuckle seals with new, tight ones?

How much would you pay for someone to do that? Because its going to take a couple of hours minimum, plus new seals.

The quick and easy stuff is easy to rule out, and that leaves the stuff that's expensive and fiddly to check/rectify.

I haven't watched the video. I know what death wobble is. I also know what's most likely to fix it.

Steve.
Author:  barnoon [ Wed Feb 06, 2013 5:53 pm ]
Post subject:  Re: mystery of the front end wobble, update with video 06/02
According to what they told me they inspected the king pins and could not find any play at all nor any problems with any other component, I was charged 3 hours labour for whatever it was they did. I'd probably be better off paying someone on this forum who knows what they are doing to look at it rather than keep paying these grease monkeys who never seem to find a problem.
Author:  christover1 [ Wed Feb 06, 2013 6:23 pm ]
Post subject:  Re: mystery of the front end wobble, update with video 06/02
I could only see wobble at the wheel/tire.
Which to me suggests the area of tie rods/king pins/bearings area.
I did not see any flex in tie bar or drag link, which is good.
Author:  Gwagensteve [ Wed Feb 06, 2013 6:26 pm ]
Post subject:  Re: mystery of the front end wobble, update with video 06/02
Please don't think I'm being a shit about this.

There's two problems with this.

1) If they're right, there's no worn/loose things associated with the front end. Therefore death wobble is normal and nothing to be concerned about. That doesn't seem right, you think?

2) If there is any play, the kingpins are already far too loose. The requirement is for starting torque with the seals stripped off the knuckle. For a bearing, that's tight. Really tight. That's a long way from "no play"

Once starting torque is in spec, and new knuckle seals have been installed, imagine how tight the knuckles will feel! That's what damps the wobble.

We had a club member whose car (running unbalanced swampers) had never, ever wobbled. It runs a steering damper and the car is in excellent condition. After a very hard recovery with a front wheel jammed against a bank, the car started wobbling really badly.

The owner pulled the front end down and found a damaged kingpin bearing, just on that side. He replaced it, and the wobble disappeared and has not come back.

Steve.
Author:  barnoon [ Wed Feb 06, 2013 6:55 pm ]
Post subject:  Re: mystery of the front end wobble, update with video 06/02
Gwagensteve wrote:
Please don't think I'm being a shit about this.

There's two problems with this.

1) If they're right, there's no worn/loose things associated with the front end. Therefore death wobble is normal and nothing to be concerned about. That doesn't seem right, you think?

2) If there is any play, the kingpins are already far too loose. The requirement is for starting torque with the seals stripped off the knuckle. For a bearing, that's tight. Really tight. That's a long way from "no play"

Once starting torque is in spec, and new knuckle seals have been installed, imagine how tight the knuckles will feel! That's what damps the wobble.

We had a club member whose car (running unbalanced swampers) had never, ever wobbled. It runs a steering damper and the car is in excellent condition. After a very hard recovery with a front wheel jammed against a bank, the car started wobbling really badly.

The owner pulled the front end down and found a damaged kingpin bearing, just on that side. He replaced it, and the wobble disappeared and has not come back.

Steve.


No I don't think you're being shit at all mate, I really value opinions from people like you who know what they are talking about, unfortunately for me I know next to nothing about this stuff and I've had it at 3 different mechanics now who all say everything is fine and they have no idea why it wobbles. There obviously is a problem somewhere within the kingpins / bearings etc its just a matter of finding a competent mechanic to find the issue:(
Author:  Built4thrashing [ Wed Feb 06, 2013 7:38 pm ]
Post subject:  Re: mystery of the front end wobble, update with video 06/02
Make the echanic drive it so they can experiance the wobble themself.....

I think you would have better luck with a specalist suspension place as a general mechanic wouldnt know enough about it to fix it.
Author:  barnoon [ Wed Feb 06, 2013 7:50 pm ]
Post subject:  Re: mystery of the front end wobble, update with video 06/02
Have got them to drive it, they all agree its terrible but can't find why :( first place was Bridgestone, second was a 4wd shop and 3rd was a suspension specialist. Not sure where to turn now, hopefully somsone in Sydney can reccomend someone who understands Sierras :)
Author:  christover1 [ Wed Feb 06, 2013 8:00 pm ]
Post subject:  Re: mystery of the front end wobble, update with video 06/02
I replaced my steering damper with a ARB one, and my wobble never came back.
I know it only masks the problem, but in my case it masked it well.
I never found any faults in anything.
Make sure all parts are safe is all you can do.
Author:  barnoon [ Wed Feb 06, 2013 8:24 pm ]
Post subject:  Re: mystery of the front end wobble, update with video 06/02
christover1 wrote:
I replaced my steering damper with a ARB one, and my wobble never came back.
I know it only masks the problem, but in my case it masked it well.
I never found any faults in anything.
Make sure all parts are safe is all you can do.


It currently has a TJM damper on it but it looks pretty old, won't hurt to swap it out for a new one, even though I know it will just be masking the problem.
Author:  barnoon [ Wed Feb 06, 2013 8:50 pm ]
Post subject:  Re: mystery of the front end wobble, update with video 06/02
would something like this be worthwhile to get? http://www.ebay.com.au/itm/Suzuki-Sierr ... 53f494df61
Author:  Gwagensteve [ Wed Feb 06, 2013 9:00 pm ]
Post subject:  Re: mystery of the front end wobble, update with video 06/02
Yes, although there's no shims in the kit to adjust kingpin preload as fas as I could see. It's a good start though.


Steve.
Author:  dzasta [ Thu Feb 07, 2013 6:29 am ]
Post subject:  Re: mystery of the front end wobble, update with video 06/02
I paid $700 to have the King pins done on my Sierra and it did NOT stop the wobble. I changed the damper and the wobble has gone.
Author:  barnoon [ Thu Feb 07, 2013 6:33 am ]
Post subject:  Re: mystery of the front end wobble, update with video 06/02
dzasta wrote:
I paid $700 to have the King pins done on my Sierra and it did NOT stop the wobble. I changed the damper and the wobble has gone.


Which damper did you have originally and which one did you change it too? cheers
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