Strange suspension problem that I can't solve
Discussion
I've got a w208 clk55. Late last year it starting acting weird when I turned right. The front left tyre would scrub or drag during slow manoeuvres such as when parking or moving off with the wheel turned right full lock. It was more apparent on cold roads or low grip surfaces such as ice or snow or gravel. The car would plough on as if the wheel wasn't turned. It would also understeer on the limit on fast right handers.
I ended up changing the lower arm bushes for poly bushes, replacing the ball joints, replaced the upper arms entirely, and a new drag link. I also put on new Michelin ps4's all round and then had a wheel alignment.
This didn't solve it.
This summer I flushed the steering fluid, changed the steering damper and adjusted any play out of the steering box.
I took it out for a spirited drive and it's still acting up on fast right handers. I remember the left wheel juddering and losing grip when on a large roundabout. I wasn't on the limit, but I was having fun. I could feel it through the steering wheel and from the way the car handled.
For the life of me I can't figure out what's wrong. The only things I haven't changed are the ARB mounts, shocks and top mounts. None of which would be the obvious cause of my woe.
Thinking out loud, the double wishbone suspension's only point of failure would be the bushes or ball joints. These are new. I can't see the shocks or top mounts having an effect such as this. And there is no play in the wheel bearings.
The only logical thing I can think of is that something has cracked, such as part of the chassis or the upright. But then surely this would have gotten worse over time and made itself more apparent? I can't physically see anything wrong with the chassis.
I don't like being defeated, but here I am. Help?
I ended up changing the lower arm bushes for poly bushes, replacing the ball joints, replaced the upper arms entirely, and a new drag link. I also put on new Michelin ps4's all round and then had a wheel alignment.
This didn't solve it.
This summer I flushed the steering fluid, changed the steering damper and adjusted any play out of the steering box.
I took it out for a spirited drive and it's still acting up on fast right handers. I remember the left wheel juddering and losing grip when on a large roundabout. I wasn't on the limit, but I was having fun. I could feel it through the steering wheel and from the way the car handled.
For the life of me I can't figure out what's wrong. The only things I haven't changed are the ARB mounts, shocks and top mounts. None of which would be the obvious cause of my woe.
Thinking out loud, the double wishbone suspension's only point of failure would be the bushes or ball joints. These are new. I can't see the shocks or top mounts having an effect such as this. And there is no play in the wheel bearings.
The only logical thing I can think of is that something has cracked, such as part of the chassis or the upright. But then surely this would have gotten worse over time and made itself more apparent? I can't physically see anything wrong with the chassis.
I don't like being defeated, but here I am. Help?
Edited by goldar on Thursday 13th October 19:48
Ride height is the same on both sides.
Spring aids are fine.
I fail to see how suspension geometry could have changed itself. Regardless, an alignment has been carried out.
Camber gain was a thought. But how would this have changed suddenly? Although it doesn't explain the low speed effect where spring compression is minimal.
Spring aids are fine.
I fail to see how suspension geometry could have changed itself. Regardless, an alignment has been carried out.
Camber gain was a thought. But how would this have changed suddenly? Although it doesn't explain the low speed effect where spring compression is minimal.
Did the alignment check include camber and castor settings as well as standard alignment, front and rear.
Could the nsf wheel have had a clout against a kerb or pot hole sometime in the past, even accurate measuring of the wheelbase each side might give a clue here.
Some BMW's can suffer with worn rear lower bushes allowing a front wheel to be forced back out of alignment as speed rises, could this be happening here.
Obviously you've been right through the brakes and there's no sticking happening, ditto wheel bearings all tickety boo, whilst up in the air spin each wheel and observe they and the tyres are round, sounds silly but you know what i mean.
Its sitting on OE correct sized and offset wheels with the correct sized tyres for the car?
For difficult to diagnose cases it can be worth getting someone else to drive your car on quiet roads (swap drivers, they might see something you don't), doing their best to replicate the symptoms, whilst you drive around each other and observe from all angles, try and find some not rough but undulating roads which cause the dampers to have to do some work but slower easier to see than over just rough roads if that makes sense.
Could the nsf wheel have had a clout against a kerb or pot hole sometime in the past, even accurate measuring of the wheelbase each side might give a clue here.
Some BMW's can suffer with worn rear lower bushes allowing a front wheel to be forced back out of alignment as speed rises, could this be happening here.
Obviously you've been right through the brakes and there's no sticking happening, ditto wheel bearings all tickety boo, whilst up in the air spin each wheel and observe they and the tyres are round, sounds silly but you know what i mean.
Its sitting on OE correct sized and offset wheels with the correct sized tyres for the car?
For difficult to diagnose cases it can be worth getting someone else to drive your car on quiet roads (swap drivers, they might see something you don't), doing their best to replicate the symptoms, whilst you drive around each other and observe from all angles, try and find some not rough but undulating roads which cause the dampers to have to do some work but slower easier to see than over just rough roads if that makes sense.
Edited by Smint on Thursday 13th October 21:17
Smint said:
Did the alignment check include camber and castor settings as well as standard alignment, front and rear.
Could the nsf wheel have had a clout against a kerb or pot hole sometime in the past, even accurate measuring of the wheelbase each side might give a clue here.
Some BMW's can suffer with worn rear lower bushes allowing a front wheel to be forced back out of alignment as speed rises, could this be happening here.
Obviously you've been right through the brakes and there's no sticking happening, ditto wheel bearings all tickety boo, whilst up in the air spin each wheel and observe they and the tyres are round, sounds silly but you know what i mean.
Its sitting on OE correct sized and offset wheels with the correct sized tyres for the car?
For difficult to diagnose cases it can be worth getting someone else to drive your car on quiet roads (swap drivers, they might see something you don't), doing their best to replicate the symptoms, whilst you drive around each other and observe from all angles, try and find some not rough but undulating roads which cause the dampers to have to do some work but slower easier to see than over just rough roads if that makes sense.
All of this is fine. Could the nsf wheel have had a clout against a kerb or pot hole sometime in the past, even accurate measuring of the wheelbase each side might give a clue here.
Some BMW's can suffer with worn rear lower bushes allowing a front wheel to be forced back out of alignment as speed rises, could this be happening here.
Obviously you've been right through the brakes and there's no sticking happening, ditto wheel bearings all tickety boo, whilst up in the air spin each wheel and observe they and the tyres are round, sounds silly but you know what i mean.
Its sitting on OE correct sized and offset wheels with the correct sized tyres for the car?
For difficult to diagnose cases it can be worth getting someone else to drive your car on quiet roads (swap drivers, they might see something you don't), doing their best to replicate the symptoms, whilst you drive around each other and observe from all angles, try and find some not rough but undulating roads which cause the dampers to have to do some work but slower easier to see than over just rough roads if that makes sense.
Edited by Smint on Thursday 13th October 21:17
finlo said:
Google Mercedes front wheel hop it's a well documented issue.
It's not an issue on w208's as far as I'm aware. It was fine one day, and then it starts doing this. And I've changed so much, there's not much left to change. The bits that remain to be changed wouldn't cause such an issue. Key points below are all related:
What would cause the front left to to lose all grip when turning right at slow speeds?
What would cause the front end to understeer on fast right handers?
What would cause the front left to judder on fast right handers?
Edited by goldar on Friday 14th October 08:41
goldar said:
Ride height is the same on both sides.
Spring aids are fine.
I fail to see how suspension geometry could have changed itself. Regardless, an alignment has been carried out.
Camber gain was a thought. But how would this have changed suddenly? Although it doesn't explain the low speed effect where spring compression is minimal.
Alignment only shows straight ahead, Ackerman is off centre.Spring aids are fine.
I fail to see how suspension geometry could have changed itself. Regardless, an alignment has been carried out.
Camber gain was a thought. But how would this have changed suddenly? Although it doesn't explain the low speed effect where spring compression is minimal.
Smint said:
Can you turn all traction controls of every type completely off, even if it means removing fuses, eliminate completely the possibility of electronic interference.
I regularly switch off traction control. I don't believe it makes a difference. I haven't tried pulling fuses, but it's not the ABS that's causing issues, so a bit of a pointless exercise. goldar said:
Key points below are all related:
What would cause the front left to to lose all grip when turning right at slow speeds?
What would cause the front end to understeer on fast right handers?
What would cause the front left to judder on fast right handers?
You said in an earlier post that it can't be shocks.What would cause the front left to to lose all grip when turning right at slow speeds?
What would cause the front end to understeer on fast right handers?
What would cause the front left to judder on fast right handers?
Edited by goldar on Friday 14th October 08:41
2 & 3 above 100% can be caused by a knackered shock on that corner.
On top of that if it is that obvious at very slow speeds, why not get a trusted friend to drive it round a quiet mini roundabout while you view it.
goldar said:
I regularly switch off traction control. I don't believe it makes a difference. I haven't tried pulling fuses, but it's not the ABS that's causing issues, so a bit of a pointless exercise.
I wasn't thinking about ABS, more about other stability controls which can apply individual brakes when the system senses loss of traction.Gassing Station | Suspension, Brakes & Tyres | Top of Page | What's New | My Stuff