New Suspension Sloppy

[Schalldampfer1]

Just got brand new Bilstein Touring (match for OEM Msport) shocks and struts and slightly used Cobb/Eibach lowering springs (9k miles) installed along with new mounting hardware. An alignment was done by BMW after install. Everything checked out for them. I took the car home and noticed a slightly more comfortable ride (as old suspension was worn out) but the steering and handling was sloppy. I would floor it from a stop light and the rear end would squat more to the right rear side. Same thing would happen when flooring it in a lower gear on the highway. It also did not seem precise when changing lanes on the highway. Keep in mind I have winter "performance" tires on but the car did not behave like this last year with the winter tires. Could it be the tires? Do the springs and suspension still need to settle for a few days? Anyone have this happen before? Any ideas? Thanks in advance.

How the car sits now


Front


Rear

[mackeroni]

What did your installer/dealer say when you asked them about the rear squat and sloppy steering? You should at least let them know of your concerns in case this situation does not improve when you remount your performance wheels and tires. Spring is only a few weeks away, but you should not wait until then to express your concerns.

Peace... Mack

[swagon]

Bilstein B4?

[Schalldampfer1]

Originally Posted by mackeroni

What did your installer/dealer say when you asked them about the rear squat and sloppy steering? You should at least let them know of your concerns in case this situation does not improve when you remount your performance wheels and tires. Spring is only a few weeks away, but you should not wait until then to express your concerns.

Peace... Mack

Yeah I spoke to my tech. He thinks the tires are part of the problem with the non-precise steering but he is not sure about the squatting yet.

Originally Posted by swagon

Bilstein B4?

Yes the B4 Sport.

[swagon]

I mean, you can have the technicians have a look at the car once again and see if there is anything wrong... but my uneducated guess is that it's caused by the dampers. Should've gone for the B8's, man. Installed the B12 Pro-Kit on our E90 last year and there's no dissatisfaction with the performance of B8 + Eibach combination.

Search through the suspension section, too.

[tock172]

Originally Posted by Schalldampfer1

Just got brand new Bilstein Touring (match for OEM Msport)

Originally Posted by Schalldampfer1

Yes the B4 Sport.

You bought the wrong dampers. You purchased B4 OE Replacement dampers, which are meant to replace the standard suspension dampers, which no US-spec 135i came with.

Your Bilsteins should be yellow. B6 HD (performance) is one choice, but the B8 Sport dampers (now called Performance Plus) are what you really want to pair with M-sport or aftermarket lowering springs.

[Schalldampfer1]

Originally Posted by tock172

You bought the wrong dampers. You purchased B4 OE Replacement dampers, which are meant to replace the standard suspension dampers, which no US-spec 135i came with.

Your Bilsteins should be yellow. B6 HD (performance) is one choice, but the B8 Sport dampers (now called Performance Plus) are what you really want to pair with M-sport or aftermarket lowering springs.

When I ordered the Shocks and struts there were two options available for the Bilstein B4's, Standard Suspension and Sport. I chose the Sport.

These are the exact ones.

https://www.fcpeuro.com/products/bmw...135i-22-152770

https://www.fcpeuro.com/products/bmw...135i-22-152787

https://www.fcpeuro.com/products/bmw...135i-19-152790

[ianc]

Rear end wiggliness is usually a symptom of the crap rear subframe bushings. Look at inserts or the M3 parts ($$$).

Sloppy lateral motion is likewise usually addressed with the M3 control arms, which have ball joints rather than bushed joints...

Slippery slope...

ianc

[tock172]

Originally Posted by Schalldampfer1

When I ordered the Shocks and struts there were two options available for the Bilstein B4's, Standard Suspension and Sport. I chose the Sport.

These are the exact ones.

https://www.fcpeuro.com/products/bmw...135i-22-152770

https://www.fcpeuro.com/products/bmw...135i-22-152787

https://www.fcpeuro.com/products/bmw...135i-19-152790

Should have bought these:

https://www.fcpeuro.com/products/bmw...135i-35-115939

https://www.fcpeuro.com/products/bmw...135i-35-115946

https://www.fcpeuro.com/products/bmw...135i-24-115957

Did the techs say anything about other worn components on the rear suspension?

[Schalldampfer1]

Originally Posted by tock172

Did the techs say anything about other worn components on the rear suspension?

No, he didn't mention anything else needed to be replaced.

I think the tires were mostly to blame. I swapped them out for my summer wheels and tires and noticed a big improvement. The winter tires must be going bad. Seems like the alignment may need a slight tweeking, but it is much better.

[tock172]

Originally Posted by Schalldampfer1

No, he didn't mention anything else needed to be replaced.

I think the tires were mostly to blame. I swapped them out for my summer wheels and tires and noticed a big improvement. The winter tires must be going bad. Seems like the alignment may need a slight tweeking, but it is much better.

Interesting. Well, I'd still give some thought to purchasing the correct Bilstein dampers. The ones you have paired with the Eibach/Cobb lowering springs are likely not valved to handle those things and may blow, leak or wear prematurely.

[swagon]

What winter tires do you have? I run a 17" 205/225 set of Dunlops and the car is all over the place when I apply more than half throttle.

But still, I'd consider getting new dampers if I were you. Like tock said, the B8s are paired to Eibach springs.

[ShocknAwe]

Fair amount of misinformation here. The issue you're having is the suspension is now underdamped by using stock dampers with springs that have a higher spring rate. Can't recall if the cobb springs are progressive or not, but if they are, that's another issue.

B6 is a high pressure gas damper and is a suitable replacement for stock or near stock ride height.

B8 is the same valving, but with a shorter stroke. Better to use those if you opt for more than 1/2" off stock.

The 135i was not sold (at least in the US) without the sport suspension. RSFBs will not cause the issues he's describing, if so, it would be much more, well, subtle. Can't comment on the tires, but it's plausible that they were contributing to the bad rear feel. Good tires are critical. Also, you want some squat. Helps with grip. Have fun.

[Mr Rooty Von Tooty]

The M-Sport is 20 mm lower than the non-sport. The proper shock is the Bilstein B8 which has a slightly shorter stroke than the B6. Both have a yellow body. The cheap OEM is black.

Anyway, don't take my advice. Bilstein has a great tech center with human beings who'll give you the straight poop! I've used them many times over the years.

When you change springs, compare them to the stock ones for length. This will help you determine the correct shock. Bilstein recommends the B8 for lowered ride (and the M-Sport).

[MightyMouseTech]

Also, the temperature makes a big difference in both the shocks and the tires. It is pretty warm out there. Google says it is 17 C there right now. Way too warm for winter tires, going to feel like driving on jello.

Also, have you checked the tire pressures? Absolute first thing to always check.