[PranK]

Hi Folks,

My 330i has some handling issues and I'm not convinced its all RFT related.

I did have the Bridgestone Potenza RFT's when I bought the car and then changed to Turanza (F) and P-Zero (R) when I got my M-Sports. There was quite a big improvement in stability but I'm still getting a lot of issues and combined with the steering wheel shake/vibrate when braking at over 100kph (~60mph) I wanted to ask some q's.

So, the first thing should be simple. The steering wheel vibrates and shakes a bit when braking at highway speeds. This doesn't happen at low speeds or when not braking. I'm certain its going to be disks and pads but considering the other issues below there might be a connection.

When I have a nice, clean piece of road the car is beautiful, its true and straight and theres no problems letting go of the wheel, it will continue straight. But as soon as it gets rough, it becomes almost dangerous. The thing is it doesn't tend to tramline as much as become unsettled laterally. It seems to go left to right - not in the steering, just in the bump handling. Instead of bumping up and down it seems to bump up and sideways. Its really hard to explain. If you were going around a right hander and the road got rough you may end up a few inches to the left.

I have had a few GTR's in my time and once had 10" wide front tyres, so tramlining I understand. My car doesn't seem to grab the road like a car tramlining.

It's a little bit 'crashy' on hard bumps, but this doesn't concern me as much as the unsettling.

The car has < 60,000k's (~37,000 miles). Could the bushings and any other rubber components be dead due to age? I'm not sure if I've done enough milage to wear through any bushings but maybe they age and get stiffer?

Maybe there is some suspension maintenance I should do? The car was neglected by original owner, so I'm trying to nurse it back to health.

Thanks very much for any help.

Christian

[maddmatth]

I definitely remember bump-steer being an issue I felt with runflats. Pretty normal I think, at least with the larger wheels where you have low profile tyres.
Switching to regular tyres was a huge handling upgrade for me.

[bluewater328]

Originally Posted by maddmatth

I definitely remember bump-steer being an issue I felt with runflats. Pretty normal I think, at least with the larger wheels where you have low profile tyres.
Switching to regular tyres was a huge handling upgrade for me.

I would check your suspension to make sure everything was secured to spec. I think you're on the money suspecting bushings/control arms as that is the nuances that start happening as they go bad but are not catastrophically unsafe. I don't think it is as severe as yours but I had similar experiences when my bushings went: goes straight fine, but ever so slight drift on occasion or on rough road.

That said, I was at 80k miles when that happened so dunno why yours would have gone bad that early unless you drive rough a lot.

EDIT: Just re-read and could be a warped rotor or something else I've seen is a stuck brake piston so your brake could be activated permanently on something like the inside pad (also happened to me). But I also got some warning lights occasionally that helped to diagnose. It does take some looking tho as you typically cheek the outside as a primary check (assuming that they wear the same). But if piston is stuck (and it does happen) your inside could be worn down and activated (and thus affecting your steering while on turns or slowing down).

[PranK]

Thanks guys!!

Damn I'd love to switch the front tyres with some regular non RFT's to test with. That would rule in/out the RFT's once and for all. I'm tempted to switch to non RFT's but I'd be mighty irritated if I spent $800 on a set of tyres only to find it still behaved badly on rough surfaces.

bluewater328 I think I'll get my local suspension joint to give the whole underbody a going-over to try and remove (or confirm) bushings/arm wearing.

Thanks again guys.