Geometry Issue

[paultv]

I've had the geometry checked by a garage and aligned - new BMW lollipops - track ends are new - new roll bar rubbers -

Garage receipts for two new front springs - two new front shocks, and new top mounts in 2008 - about 25K miles ago - but I suspect this is all bollox as the OS spring is rusty and dropped - NS looks clean and shiny etc etc - the bloke I bought the car off was a total blagger it turns out...

anyhooo, long short - after alignment car feels great - centers well, doesn't tramline - but after two weeks it starts to wander and feel less predictable - so the track etc is shifting or the something is worn - it's really hard to know where to start - just replace the whole lot or how the hell do I measure or test tiny errors that develop over time - maybe the shell is flexing too.

Any thoughts - pointers.

Paul

[Supafly]

I would check that everything is tight and then look at the rear sub frame bushes as when mine were worn the car drove strangely.

[paultv]

I agree, that's where I would go first, but the sub rear bushes are new - but as you say, I'll check all is tight.

Paul

[Brianmoooore]

If someone's been playing with the track rod ends, the first thing I'd check is that the clamps have been refitted, and they're not slowly realigning themselves!

[paultv]

mmmm, found a top mount nut on the NS which won't tighten, the stud spins with the nut - the stud should be captive?

Paul

[biffer]

bolts are removable from clamp, and they also should have a finer thread than standard bolts.

[Carmo13]

The "stud" will turn as it is the shaft of the shock absorber. There is usually an allen key socket in the end of the shaft to enable you to stop it spinning whilst tightening the top nut.
Worn track rod ends will give the symptoms you are describing.
Jack a corner of the car of the ground and try to move the wheel when holding it top and bottom and also on the sides. There shouldnt be any movement or clunking.

[paultv]

Just to be clear, its not the center stud I was referring to, but one of the three mounting nuts which hold the strut to the body.

Paul

[Brianmoooore]

Stud has a square section under its head, which should locate tightly in a square hole in the top mount itself, which has become damaged, probably when the springs were changed.
Whereas this should be fixed to prevent long term damage, I can't see it being relevant to your current problem. The top mount is pushed hard into the underside of the turret by the weight of the car, and won't be moving about if the other two nuts are tight.
Check the condition of your brand new lollipops. If the garage that did the work has used a permanent lubricant to fit the bushes on the control arm pins, and the bushes are now turning on the pins, their life will be short.

[paultv]

Good point Brian, I'll have a look - the pops are real BMW ones - but as you say - could be seized it the pins.

Paul

[Brianmoooore]

Seized on the pins is what they must be! Suspension movement takes place by twisting the rubber - if they move on the pins, they will wear quickly.