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Posted By: Neil_c Advice on lowering springs and stiff suspension - 29th Jan 2012 11:03pm
I've got quite stiff suspension on my BMW (Eibach springs and Bilstein shocks). shocks are new.

Would you say it's normal to feel imperfections in the road a bit more under breaking? My gilf has a K.A. which is obviously a bit pot of treakle and can go over any pothole under braking without much feedback into the steering wheel.

Naturally when the car brakes, the weight will transfer to the front but would you say it's fairly normal to get some feedback under braking through the wheel on a lowered car?

On a flat surface I don't notice much. Discs runout is within tolerance and reaction bushes have been replaced.

Thanks.

Neil.
Posted By: dave_g Re: Advice on lowering springs and stiff suspension - 29th Jan 2012 11:32pm
my old golf used to really crash into potholes and tramlined quite a bit,its just part of having a stiff lowered car!
Posted By: _Ste_ Re: Advice on lowering springs and stiff suspension - 29th Jan 2012 11:39pm
Tis normal mate my Astra gsi has hardened dampers and lowering springs and I feel everything in the road, that's with all new tires on too.

My old ac schnitzer e36 was the same too.
Posted By: Neil_c Re: Advice on lowering springs and stiff suspension - 30th Jan 2012 12:08pm
On freshly laid motorway tarmac even at speed the braking feels reasonably smooth, it's just on rough side streets, usually at lower speeds.

It is a bit more noticeable when the car is loaded (i.e. with more passengers).

Do you find you get any feedback yourselves through the steering wheel if the motorway is flat? (I get very little myself if the road is smooth).

I did some research on it last night and it's called "bump steer". Apparently it can be minimised by changing the geometry of the track rod ends.

http://forums.bimmerforums.com/forum/showthread.php?t=178221


do you have very low profile tyres on large wheels??
When I had 19" wheels on my 330i, and when I had 20" wheels on my 350z the results where as you're experiencing. I went to 18's on both cars when tyres needed changing, couldn't put up with it in the end just, for improved looks.
215/45/r17 on back and 205/40/r17 on front. 17" wheels basically with low profile tyres. I might even them out to 215/45 once the front tyres wear out.
Similar on mine mate lowered on Schnitzer springs and cant clear most speed bumps over 3 mph, car can bottom out, car is also on low profiles 255 35zr r18's - not sure if that helps with anything
Posted By: Neil_c Re: Advice on lowering springs and stiff suspension - 31st Jan 2012 12:10pm
I think having wider & taller tyres on the back than the front is likely to be a factor in bump steer.

Prob not worth the hassle of doing anything with it though. I did try large tyres all round but you're quite limited with lowering springs and the ability to steer!
my bmw is prone to bump steer and what i call tramlining ie it wants to follow imperfections in the road being in motor trade i drive a lot of different cars but bmw,s with big wheels do seem to be prone to these sort of problems i recently drove a 330 and it was almost frightening check the bushes on the rear of the front wishbones they can apear to be ok but be quite soft this can exagerate the problem
I had the reaction bushes replaced a few years ago by bmw. you're right abouth the tramlining. the car does handle really well though, you just have to put up with the road feedback. Getting it tracked on a Hunter at Buckley tyres really helped and having the wheels balanced on a modern machine made a huge difference.

How do you find the steering on your bmw under braking? do you feel the road more than under throttle?
Mine is only lowers 60 mil and yes every bump on the road I feel no matter how big all small
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