Tramlining

Just been to the local dealer with my year-old 320d Touring (200 yards away - a lucky side-effect of switching to BMW) and he reckons it's had new suspension arms as they look v squeaky clean - and that they've not been aligned correctly, as the (new) tyres are wearing on the outer edge.

He reckons it's got too much toe-in, whereas I'd thought toe-out was more likely to make it inclined to turn too easily, but hey the upshot is it needs wheel alignment checking and I've just got to persuade the dealer I bought it from 3 weeks ago (closer to 200 miles away - well, 130 at least) to cough up.

Ian

Well, mine had its wheel balancing (didn't work the first time as front tyres had been so worn down they couldn't get a fix, so had to rebook and confirm that the dealer I bought from would give me new tyres too) - but still not right.

It doesn't actually go off-line by itself any more, but whenever the road surface has any imperfections the steering lightens and wobbles so that it's very easy to accidentally direct it off course (but if left alone it does in fact keep going straight ahead); and under acceleration or braking on a poor road surface again it all just feels wobbly - without actually taking itself off-course.

Suspect it's going to have to go back for another check... but any ideas?

Ian

Well, the lower front suspension arms have been replaced (I think that's what they said) and there's no play in the steering generally; on a lovely smooth road surface it seems fine, but on a dodgy road surface it comes over all wobbly - at high motorway speeds and slow town speeds alike.

Having had a wheel alignment once I guess I probably need to get someone from the dealership out with me to see what they think...

Ian

Just to get back to the difference a tyre can make.

I have 215/40/17 tyres on the front of my car (and the back for that matter ). I have used a couple of sets of Bridgestone SO3's now, and as much as I like them, they did used to tramline like crazy. I was advised to try the new Goodyear F1 GSD3 to cure (or at least reduce) the tramlining problem.

Now I have the Goodyears fitted (same size, same pressures etc). The tramlining has virtually dissapeared. This just goes to show that different tyres of the same size can indeed make a big difference.

Cheers,

Ian.

Well, had a road test with a BMW technician yesterday and couldn't find anything wrong except tyre pressures, which were too high (34/39 psi f/r on std 16" wheels - should be 31/37 apparently). Does make a difference, but suspect that was exacerbating rather than creating the problem.

But they took it up on the ramps and checked the suspension bushings for wear and there isn't any, no play in the steering, full wheel alignment all done. It does run straight, so I don't think there's anything knocked out of place; but just steering wheel rocks over bumps (before returning to straightahead OK), steering lightens up on bad roads at any speed, making it easier to steer off course accidentally; and whole car feels wobbly when braking on rougher surfaces.

Running out of ideas... the only thing is when they talked me through the wheel alignment they didn't actually specify what the castor was and should have been and had been adjusted to etc, unlike the camber and toe-in which were causing the obvious problem. So I wonder if this got overlooked? Anyone know if it would be a likely cause of this sort of problem?

Ian

OK, back to the garage again last week. New technician reckons it's a characteristic and he's had 5 or 6 customers notice it. Well maybe it is but I must say I hope mine's worse than most, because I can't believe BMW 3-series would keep on winning every single group test in any magazine if they all wobbled like mine does when the road gets bumpy!

As stated before, I've only got 16" wheels on there, and the steering wheel kicks back and forth in your hands over bumps even though the car still does end up going straight.

Still wondering about the castor, although maybe the tyres (Dunlop SP2000) aren't helping? Presumably some tyres might be more likely to be affected by bumps, eg. stiff sidewalls might make them deflect more readily?

Ian

I should have finished of my last post by saying that this trait may be the price you pay for having such comunicative steering. I have never driven a car that provides you with so much information about the road surface and levels of grip availible. The fact that it puts me off thrashing down roads with pot holes and poor surfaces is to be honest probably a good thing. Crashing through potholes can't be good for the suspension and if the surface is poor then the way any car will behave can become unpredictable which is dangerous.

As for tramlining, any car on 225 tyres is going to do this.