Front end suspension refresh?

I

itguy

Member
 Melton Mowbray, Leics
Hi Everyone

Right, I'm getting annoyed with the Zed now. Have had the wheels balanced on the car 4 times now and at two different places and STILL I get a 55mph occasional steering wheel shake.

This cannot be down to wheel balance now surely.

Doesn't do it all the time, just sometimes and tends to be when the car is warmer.

So - thinking things through logically;

1) It's got new front disks and pads on and I replaced the nearside calliper 2k miles ago because it was sticking. The offside one is a little stiff but not binding (car still does 40mpg on a motorway run)

2) 4 wheel alignment has been done and front end is all true and in tolerance

3) I can't feel any play anywhere in the suspension when I jack the car up and move the wheel 12-6, 3-9 etc

So, what next to replace/try?

Replace offside calliper in case of slight bind?
New lower control arms and bushes?
New ARB drop links?
New steering rack arms and track rod ends?
New front dampers (and strut tops??)?

Help!!
 
I'd check the wheels are true and straight. They can be balanced even when bent.
Check the mounting surfaces of wheel to rim are spotlessly clean.
Replace the lollipops, wishbones, drop links and ARB bushes. Common wear items and affect the system badly
Tyre pressures set correctly

If the disc is not getting when not braking then the caliper is OK. Since it's not happening when braking I'd not be inclined to be looking at pads, calipers, discs, etc.

Only after that would I be going for shocks, track rod ends, rack, etc.

Was the car weighted when the alignment was done? Need full fuel, weight in both seats and boot, else it's a waste of time.
 
Whip the caliper off , if you have it put an old disc and pad back on and lever the piston in then pump it out a few times and check it's retracting properly , this may work. At least it's free before you start buying new parts
 
Haven't got the old discs/pads unfortunately.

One thing that I have just read elsewhere is to try rotating the disks round a couple of holes - just in case they are slightly out of balance - I can do this but would need to take out the retaining torx bolt of course.

I watched like a hawk when they were balancing the wheels and I could see no evidence at all of the rims being bent or miss-shaped in any way - admittedly I haven't had a dial gauge on them yet.

Car wasn't weighted when the 4 wheel was done, would that make such a difference that would cause a wheel wobble?
 
itguy said:
Haven't got the old discs/pads unfortunately.

One thing that I have just read elsewhere is to try rotating the disks round a couple of holes - just in case they are slightly out of balance - I can do this but would need to take out the retaining torx bolt of course.

I watched like a hawk when they were balancing the wheels and I could see no evidence at all of the rims being bent or miss-shaped in any way - admittedly I haven't had a dial gauge on them yet.

Car wasn't weighted when the 4 wheel was done, would that make such a difference that would cause a wheel wobble?
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You can't possibly tell if a wheel is out of true unless you spin it on the car or a balancing machine with a simple pointer on the inner and outer rims. 1st Class alloys just did all my wheels (Jaguar XF) and Paul found 3 of the 4 bent...He could have balanced them, but I'll bet it would still have shimmied at 50-70 so we had then straightened.

If the car is not weighted then the alignment is a total failure. It may not wobble, but it will tramline and be way out off tolerance. Any balance shop with something like 'Hunter' would have done it correctly. I'd ask for my money back or have it done again correctly (after you make all the suspension changes)

If you do not have a staggered wheel set up you could swap the fronts and rears to see if it makes any difference.

Frankly I think your going to have to eliminate any issues over the second caliper then start swapping suspension parts out on the front next and unless recently done the parts I listed above. They'll benefit from doing anyway and make the car feel like new.
 
Corner weighting won't make a difference , it's for race cars only , is it only when braking , if so you could try re bedding the pads , 60 mph and down to 20 a dozen times and drive home the long way , or get the disc skimmed on the car to take out any run out , you will be surprised how much may come off .
Is it always on the same road surface , as mentioned before me , it's gonna be slight play in a bush , lollipop to start with , same on most bmws , or the tiniest bit play in a joint that you can't feel on a jack through the wheel , lever everything against each other with a flat bar , like the mot tester does , you may find something that way .
Good luck because it's a pain in the arse when it doesn't happen all the time .
If you were anywhere near you could have had my old disc
 
Cheers everyone.

It's not only when braking, no - you can set cruise at 55mph and the wheel will shimmy slightly, typically on the smoother road surfaces when the car is warm.

Braking at the same time doesn't stop the shimmy (ie kept speed at 55mph with accel right foot, then applied brake with left)

Sounds like my alignment was a fail then (pity, nice new laser hunter they used). I suppose the trick though is probably to replace the lot if I'm going to do it, so that when I get a decent 4 wheel alignment done it's then done for a while.
 
Paulwirral said:
Corner weighting won't make a difference , it's for race cars only , is it only when braking ,
Click to expand...

Sorry - that is sooo wrong. We are not talking about corner weighting, but as in the BMW TIS manual for set up of the Z4 geometry. I don't have access to it at the moment as on holiday, but it is something of the order of 55kg in each front seat and 50kg in the boot and a full tank of fuel. All Hunter test centres and BMW dealers have the same information built into their systems to advise of such weighting.

This is one of the reasons that few tyre centres can align Z4 suspension.
 
cj10jeeper said:
Paulwirral said:
Corner weighting won't make a difference , it's for race cars only , is it only when braking ,
Click to expand...

Sorry - that is sooo wrong. We are not talking about corner weighting, but as in the BMW TIS manual for set up of the Z4 geometry. I don't have access to it at the moment as on holiday, but it is something of the order of 55kg in each front seat and 50kg in the boot and a full tank of fuel. All Hunter test centres and BMW dealers have the same information built into their systems to advise of such weighting.

This is one of the reasons that few tyre centres can align Z4 suspension.
Click to expand...


I'm not being argumentative but what's the point of having 55kg in both front seats and 50kg in the boot if you always drive the car on your own with nothing in the boot? Complete dross; if you set a car up to be balanced as per those specs, and never drive the car with those weights/distributions, it will not be set up correctly.
 
Ed Doe said:
cj10jeeper said:
Paulwirral said:
Corner weighting won't make a difference , it's for race cars only , is it only when braking ,
Click to expand...

Sorry - that is sooo wrong. We are not talking about corner weighting, but as in the BMW TIS manual for set up of the Z4 geometry. I don't have access to it at the moment as on holiday, but it is something of the order of 55kg in each front seat and 50kg in the boot and a full tank of fuel. All Hunter test centres and BMW dealers have the same information built into their systems to advise of such weighting.

This is one of the reasons that few tyre centres can align Z4 suspension.
Click to expand...


I'm not being argumentative but what's the point of having 55kg in both front seats and 50kg in the boot if you always drive the car on your own with nothing in the boot? Complete dross; if you set a car up to be balanced as per those specs, and never drive the car with those weights/distributions, it will not be set up correctly.
Click to expand...

I was thinking the same but I'm guessing it would have ended up in an argument of who knows best , and the cj guy definitely knows his techy stuff , so I stepped out of it .
I was starting to think for next years ring trip I'd best cut off both legs , take 2 children , 1 in passenger seat , 1 in the boot and have a shell tanker follow me round so I can ensure the best possible set up for optimum lap times , as you no doubt realise I don't take things that seriously :rofl: :thumbsup:
 
I'm merely quoting from the BMW TIS manual as used by BMW.
I'll leave it to others to decide BMW are wrong, but meantime I'll continue to have mine set up by the local Hinter station to BMW spec.

If needed I can check the weights quoted when I'm home as they are from memory.
 
Just to add I really didn't intend for that to come across as a keyboard bashing! Just that I can't understand why BMW would suggest that in the manual, when it would be just as well not to add any weight at all!
 
Ed Doe said:
Just to add I really didn't intend for that to come across as a keyboard bashing! Just that I can't understand why BMW would suggest that in the manual, when it would be just as well not to add any weight at all!
Click to expand...

The weights are to create similar conditions to when the car is on the move where some downforce is acting on it.

You're supposed to put the weight on and measure the ride height. The height has to be max 1cm of
TIS figures for a standard car. You can put the weights anywhere you like until you achieve the required ride height, the BMW chosen locations are easily replicated with different shaped weights so that's what's most used.
 
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