Shopping trolley handling....

[benw]

The handling on my 2003 Roadster Coupe has been gradually getting worse over the past 6 months or so. It tramlines on the motorway really badly which it never used to do and it bump steers terribly. I'm nervous taking a corner at anything other than a sedate pace because if I go over uneven ground the front end suddenly understeers - again something it never used to do so badly. I also get a slight buzzing vibration over certain road surfaces at certain speeds (usually 50mph+) that can be felt through the footwell and very occasionally get a 'clickety-click' noise from the front end if I go over a series of bumps.

I've checked everything outside the car and there is no perceptible movement in any of the suspension components. In the Spring I changed the front wishbones, ball joints, shock absorbers, springs and top mounts. I'm going to change the track rod ends for what it's worth but they don't appear to have any play in them and they passed an MOT. I'm running out of ideas for what it can be. Steering rack mounts? UJ in steering column? Wheel bearings?

Has anyone had anything similar? Any ideas at all?

[10:45PM]

Antiroll bar bushes?

and steering rack itself?

None of this should be guesswork though, you isolate the item and check for play/wear.. if they 'don't appear to have any play in them', then you've not found the right component/area yet !
There are ways and means of checking each area... someway easier with an assistant obviously.

[tolsen]

Cheap after market wishbones that upset wheel geometry. They alter camber by -22 minute.

[tolsen]

Handling will not improve if tracking is off. Did you check tracking after replacing front axle components?

[Mr T]

Does your car have power steering? Could this have an intermittent fault?

[Kapt. Q]

Ball joints should be first suspect. If the mileage is very high and no front end work has been done before and you are capable of doing the work yourself, I'd just swap all four ball joints, both drop links, all four control arm bushings, both anti roll bar bushes and both strut bearings, that way you end up with a rebuilt front suspension for not a lot of money that you can rely on for a long time. Always use genuine Smart parts!

Cheers!

[benw]

Sorry for going quiet. Work got the better of me last week.

Ball joints should be first suspect. If the mileage is very high and no front end work has been done before and you are capable of doing the work yourself, I'd just swap all four ball joints, both drop links, all four control arm bushings, both anti roll bar bushes and both strut bearings, that way you end up with a rebuilt front suspension for not a lot of money that you can rely on for a long time. Always use genuine Smart parts!

Cheers!

That's what I did in the Spring! Didn't use original parts but did use Lemforder branded parts from Euro Car Parts. Lemforder are the OEM supplier for a lot of German cars so I'm pretty sure it's not shoddy parts. And yes I got the tracking done straight after. Had it done again a few weeks ago too just in case. Interestingly the tyres are all wearing normally. I'm on 95k miles by the way so high-ish but not silly.

I had a chance in the week to inspect it again. I'm sure there's no play in the ball joints, suspension mounts and drop links. I've pushed, pulled, bounced, levered, wiggled everything and no obvious movement anywhere. If there is it's so incredibly subtle I just can't imagine it causing this much trouble.

I'm starting to suspect the steering rack. Do they have a history of failure?

[benw]

Does your car have power steering? Could this have an intermittent fault?

Yes. Doesn't feel like it's cutting in and out though. I'd expect it to go heavy/light but not 'loose'?

[Mr T]

A defective steering damper might make you feel the bump steer more.

[10:45PM]

Yes. Doesn't feel like it's cutting in and out though. I'd expect it to go heavy/light but not 'loose'?

If it was intermittent, perhap when it kicks back in you subconsciously adjust to accommodate the change, this could unbalance your ' feel' of the road.

Easy way to isolate is to disable the PAS for a day or two.

[lalli_d1]

have you had the car looked at by a garage? there is no point in fitting parts and it being no better?

[davros7760]

Bit slow in picking up this thread but I do have a question - have you by any chance
replaced 1/2 tyres recently (but not all 4?).

Certain combinations of different manufacturers tyres can induce horrible handling....
its a long shot but you appear to have covered all the bases

[mikerj]

Have you checked the bushes on the rear axle control arms? Quite often a suspension issue at one end of the car can feel like it's coming from the other end. Also worth checking the rubber bushes on the steering rack mounting points.

[Terry Watson]

Had similar problem recently. Check front engine mount for perished rubber. Replaced mine - corners on rails again