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M135 chassis/steering unstable

2K views 20 replies 9 participants last post by  m20b25 
#1 ·
Hi all. I've recently got a 2012 m135i with adaptive suspension and eibach pro springs. After a few days I noticed how badly the car feels on ruts and the front feels disconnected from the back. Going around a corner and hitting any form of hole causes the car to twitch. I sent it to BMW main dealer for a full kds set up to ensure the toe and camber etc are set for the springs and it's all good. I've had virtually in excess of 30 bmws mainly m3s m5s and 330s 130s etc and I've never had one feel as bad as this. It's not even at high speeds but just drags me anywhere in ruts and twitches at slow speeds. It's got mpss on the rear and Bridgestone on front. The wheels did have slight buckles which BMW straightened and one has a minor buckle still. Surely that and the different front to rear tyre(all non run flat) can't cause such a scary feeling ride????
Any help would be much appreciated. Thanks guys.
 
#2 ·
Any buckle in the wheel or wheels will cause this, as everything else checked out I'd be getting it replaced or fixed and hopefully you should see improvements.
 
#5 ·
Rixstas2 said:
Anyone got 1 front wheel for sale? Ha. The other 3 were perfect after straightening. Some of the eBay ones are ridiculous price for 1 wheel and I may as well buy new .
I have a complete set of OE 18" 461m silver alloys that are great condition.

PM me if you want a complete OE set that are free of buckles/dents/repairs
 
#6 ·
I feel like I get a similar thing with mine occasionally. It doesn't feel like the tyres actually lose grip or there is any level of oversteer coming into play at all, more just that the body over the rear axle feels like it shimmies slightly from side to side.

Very difficult to explain but yeah I only ever experience it on rough road surfaces/crossing the central camber peak on a B road for example. Running run flats on the rear at the moment though which could be a culprit.

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#7 ·
If it's a 5 door, the rear of the car genuinely isn't connected to the chassis, like the various 3 door versions.

 
#8 ·
I think I'm having this exact problem in a brand new m140 5 door. Just fitted eibach springs and spacers and at speeds above 60 mph, the rear almost feels detatched.

If you twitch the steering wheel either left or right, it feels like there is 0.5 second delay between the steering input and the rear followong the front, almost like there is a worn rear joint or a knackered control arm bush.

I'm going to fit the rear bracing from a 3 door and I'll report back to you to see if it's made any improvement.

I wonder if the change in spring rate has softened the rear and made it less responsive?
 
#9 ·
G1_rpc said:
I think I'm having this exact problem in a brand new m140 5 door. Just fitted eibach springs and spacers and at speeds above 60 mph, the rear almost feels detatched.

I'm going to fit the rear bracing from a 3 door and I'll report back to you to see if it's made any improvement.
Those that have retrofitted the underbody V brace have fedback positively about rear feeling more responsive and better connection to steering inputs. Myself, as an early adopter, included.
 
#10 ·
The issue is, bmw have really gone cheap on the dampers on these cars. You've got new springs, but are expecting the boggo dampers to work.....they never will, especially the rears which make the car dance around like a cork in a storm. If you still have the crappy bmw 'bump stops' *sic, then you in effect have almost no damping on the rear, just mushy foam to control your ride after a set amount of proper damper travel.

I concur regarding straight wheels and matched tyres. Tyres have a built in 'slip angle' which can differ make to make. So if the fronts and rears don't match, you'll get a car that feels very odd at different cornering loads.

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#12 ·
Really appreciate the comments from everyone. I'm definitely going to get a front wheel and 2 x new front mpss. It's so bleeding annoying as it's just making me not want to drive it whereas I love everything else about it. As soon as I change wheel and tyre il let you all know how it feels and if need be look at dampers as next point. Cheers.
 
#13 ·
Rixstas2 said:
Really appreciate the comments from everyone. I'm definitely going to get a front wheel and 2 x new front mpss. It's so bleeding annoying as it's just making me not want to drive it whereas I love everything else about it. As soon as I change wheel and tyre il let you all know how it feels and if need be look at dampers as next point. Cheers.
Is it a 3 door or 5 door?
 
#20 ·
I'm not so sure it's the dampners as was previously commented. Sure... they probably are a load of poop, but it only seems to be the 5 door f20 that suffer from the problem described by the OP.

I rang up a breakers yard today and I've got all the bits to carry out the improvements for £40, not that £150 is massively expensive.
 
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