Is ti just me?

mmm-five

mmm-five

Lifer
 Liverpool
Site Supporter
I've got a couple of nice, empty roads not far from where I live, and I like a good blast on them. The only problem is the roads getting to them are not the best (not the worst either, but just a bit rough & lumpy).

Now, my M5s have never had a problem with these rougher roads - my '94 had EDC and absorbed everything, my '90 has a custom Bilstein kit which works as well on the 'Ring as it does on country roads. However the Z is useless over the same road and I have to take it so easy for 20 minutes to get to the nicer roads - otherwise some of my sweeping & lumpy corners are an excercise in left-right opposite lock to avoid being bounced into hedges/ditches/stone walls!

Is the car this bad all the time or it is just my CSL wheels and low profile tyres overloading the suspension.

If it's not the CSL wheels and it's just the nature of the car, then swapping the CSLs for original 18" wheels is not going to cure this 'trait' is it? I don't want to have to replan all my regular routes just to avoid being bucked off the road by the chopy ride.
 
The CSL wheels make very little difference and if anything help slightly. It's a trait of the car but I have heard people who have fitted the H & R lowering springs say that they help.
 
Ah well, looks like I'll just have to decide whether or not to risk trying the 18s then :headbang:
 
I run 18 ellipsoids with run flats at the moment.

I bought some 16 inch rims to test over the very bumpy and undulating roads where I live.


All I can say is that the bump steer has completely gone away and the car is not thrown towards hedges and ditches!

18's for smooth roads and tracks. Smaller for rough terrain

Sceptre
 
mmm-five said:
Ah well, looks like I'll just have to decide whether or not to risk trying the 18s then :headbang:
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TBH I would put the money towards a change of suspension myself, I know exactly what your getting at as I find the same thing on some of the local back roads you simply end up slowing down before you get bounced off the road (I think the rear srings are to stiff?). I did a couple of thousand miles on the original wheels before fitting the CSL's and I don't think they will make the improvement your looking for.
 
Sceptre said:
I run 18 ellipsoids with run flats at the moment.

I bought some 16 inch rims to test over the very bumpy and undulating roads where I live.


All I can say is that the bump steer has completely gone away and the car is not thrown towards hedges and ditches!

18's for smooth roads and tracks. Smaller for rough terrain

Sceptre
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I know what your saying as that was exactly what happened on my old E36 coupe, I had a set of 15" and and 18" wheels and the car used to tramline and follow the road camber really bad on the 18"s, yet was fine on the 15"s. It was one of the things I worried about before getting the CSL's but if anything the car tramlines less with them fitted, I think the PS2 tyres help matters slightly.
 
The wheels will make no difference. I regularly swap between CSL and standard wheels. In my opinion the suspension is fine on smooth roads however when things become a little more 'real world' the Z4MC does bounce around far too much.
 
Top pup said:
mmm-five said:
Ah well, looks like I'll just have to decide whether or not to risk trying the 18s then :headbang:
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TBH I would put the money towards a change of suspension myself, I know exactly what your getting at as I find the same thing on some of the local back roads you simply end up slowing down before you get bounced off the road (I think the rear srings are to stiff?). I did a couple of thousand miles on the original wheels before fitting the CSL's and I don't think they will make the improvement your looking for.
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Don't really want to get into modifying anything, as I know from experience how much loading is put on the insurance if you're honest with them. I've got a custom Bilstein kit on my e34 M5 and that alone raised the price by 25%.

Can't fit 16" wheels on the M, although I'm sure certain 17" wheels will go over the discs/calipers. I may just buy a cheap set of 17s to try with 45 profile rears and 50 profile fronts - can always use them for winter then - plus I can get much cheaper track rubber in 17s, but will have to invest in a trailer/rack to take a set of spare wheels to track with me - the benefit of the M5 is that I can get 4 wheels across (a suitably protected) rear seat.

I bet there's a lot of drivers (not specifically of our cars) who don't declare exhausts, chips, CSL wheels, coilover suspension to their insurance companies - wonder whether these same people cry the loudest when the insurance company refuses to pay out, or cuts the payout drastically?
 
I'm not sure 17" wheels will go over the discs/calipers, there's very little clearance between the caliper and wheel on the the OEM 18" wheels at the front to start with. I'd certainly try a set before parting with any money.
If you don't want to modify your car perhaps you could look into Z4MR springs/dampers? I'm not sure of the exact difference but they are softer than the Z4MC setup.
 
I wasn't sure about the 17" wheels as my M5 with 343mm brakes used 18" wheels for the road and 17" wheels for the track and there was still 5mm of clearance.

I'm sure I'll get used to the mid-corner loss of composure, but surely suspension has progressed to a point where they can tune it for good manners in most conditions? Here's hoping that it was tested at the 'Ring and I won't have to worry about it over there :D
 
mmm-five said:
Here's hoping that it was tested at the 'Ring and I won't have to worry about it over there :D
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It's not too bad at the Ring.

Caution required at Flugplatz,Wipperman and Pflanzgarten 1 and 2.

Have fun.
 
Blacklines said:
mmm-five said:
Here's hoping that it was tested at the 'Ring and I won't have to worry about it over there :D
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It's not too bad at the Ring.

Caution required at Flugplatz,Wipperman and Pflanzgarten 1 and 2.

Have fun.
Click to expand...

So I can just floor it through Schwedenkruez & Crünchen then :driving:
 
mmm-five said:
I wasn't sure about the 17" wheels as my M5 with 343mm brakes used 18" wheels for the road and 17" wheels for the track and there was still 5mm of clearance.
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They might fit then, the Z4M front discs are 345mm, so I guess it will depend on the caliper clearance.
 
My friends thought i was mad, but i used to have a Mini Cooper S and ran it for a short time on 15" steel wheels. The car was an absolute riot and far better than with the standard wheels. Looked rubbish though!
 
Sixpspeed was going down the KW V3's route which is meant to improve the traits you mention.

I find the low speed ride poor, but at speed I just ignore the stiffness (oo-er)and haven't had a problem yet on rough roads, but it does seem harder work with aless compliant ride than it should be be.
 
Thanks all.

I think I'm going to try OEM 18's first and then go from there. I really don't want to start modifying the car after only a couple of weeks of ownership - although the KWv3 or Bilstein PSS10/B16 kits look great :D
 
Have a look at the "Buy and Sell" section, Senwar has some OEM 18s for sale in Sheffield, not too far from you.
 
I think that a lot of you people are comparing apples with oranges...

The Z4MC has a very, very short wheel base when compared to a E34 M5...

The fact that it worked at the Ring means nothing - there are no bumpy corners there. A lot of camber transitions like Hocheichen, Wipperman, Pflanzgarten 3 and a lot of jumps - Quidderbacher Hoche into Flugplatz, Flugplatz into Schweden Kreuz, Pflanzgarten 2 + 3, but no real mid corner bumps like the ones typical on a British B-road.

Having done 35k miles in mine, with ahem, maybe around 20% of them getting lost around that one way toll road up in the Eifel mountains :lol: , I have to say that the suspension is amazingly well engineered for Europe / track driving. I don't really expect BMW to re-engineer it to suit the crap UK roads, having sold only 500 odd cars here. My advice - leave well alone and get adjustable top mounts from KW. Also re-adjust your driving style to suit a car with shorter wheel base and lively back end, when compared to a behemot such as the M5...
 
Cheburator said:
I think that a lot of you people are comparing apples with oranges...

My advice - leave well alone and get adjustable top mounts from KW. ...
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How will that effect the ride?
 
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