Can't cure the poor ride quality

[Gaffertetley]

Hi guys, I need help I've run out of ideas to solve or improve the horrendously crap ride quality in my car.......my E85 when bought was stock, usual bouncy harsh ride.
Junked runflats, replaced shocks with new Bilstein B4 all round.
Only minor improvement.
So....then I stalled Eibach springs.....no change.
Got onto Bilstein about damping rates, they insisted for the Eibach springs to use B8's....better damping control sounded sensible.
So.....much ££ and B8's later......no damned change.
Still bouncy as buggery.
Now for comparison, my son's 3.0Si on cheapo stance coilovers rides loads better and he's got it about an inch off the floor.
My brother in law's 3.0 standard suspension is better.
My Z3 on Eibach Bilstein B8 is like a limo......my E36 coupe on same setup is good too, but it has a roof.
There's no damage.......so what the hell is going on.....??

[enuff_zed]

What size wheels?

[thecremeegg]

Mine's on B4s with Eibach springs and rides really nicely! Is it bouncy on a smooth road, in corners, or on bumps?

[john-e89]

Tyre pressures…? Which brand of tyre you have pressures make quite a difference to ride quality. Maybe have a play around with them, a few psi either side of what is recommended has a definite impact.

[swissfraser]

I've only had a Z4 a few weeks and live on a scottish island - the roads here are even worse than on the mainland. It was pretty much impossible to drive it. I picked up a set of 16" wheels on ebay and stuck some non-run-flats on and it's completely transformed the ride. I'm keeping the 18" wheels in the hope that at some point before the end of summer the roads get patched up, but I'm not holding my breath for that...

[9designs]

Brand of tyres, some non run flat are no better than good run flats. Ultra higher performance tyres are just as stiff on the side wall as run flat.

[coldel]

If a tyre has XL on it, generally has tougher side walls and if you are running lower profiles it will cause rough ride.

But given the Stance lowered suspension is better than your car on Billies it does sound really odd.

[tomscott]

Aren't all those kits lowering kits?

Part of the problem with the poor ride is there is so little rebound in the back?

[Gaffertetley]

Thanks for the feedback guys, all cars are on standard wheels, it's not tyres pressures, and it's not tyres.....just went up from uniroyals to softer Michelin's,.......if it was a motorbike, I'd assume the springs were to high rated for the weight of the car, and the dampers can't control the movement.
Am going to try the standard springs back in it with the B8's I think......I'll keep you posted

[MikeyH]

My e85 is on Bilstein B4s, sport springs, 18” wheels and 40 profiles front and rear. Yes it is a bit bouncy and crashy in potholes but not that bad. At first it seemed a bit uncomfortable but I must have become used to it as it seems okay now. I wouldn’t want 19” wheels. Ouch.

[Zulu4]

I'm going to try a slightly less low profile tyre next time on my 18" wheels. I know the speedo will be slightly out, but I don't care.

[MikeyH]

With 40 profiles on the back, my speedo reads spot when driving past those speed signs.

[coldel]

https://www.tyresizecalculator.com/tyre ... calculator

[Zulu4]

With 40 profiles on the back, my speedo reads spot when driving past those speed signs.

Nice.
Does it make the ride a little softer ?

[MikeyH]

I don’t know as it came with 40s when I bought it.