E91, rear sag from worn shock?

[PLuKE]

My E91 pre LCI 330i has been going great. But I have noticed that the rear o/s has had a new shock when I bought it, and the n/s seems to sit lower, and that shock is the original 112k on it. No bangs/squeaks etc etc.

Can a worn shock give the rear more sag on that size?

Thanks for you input.

[Dave Brand]

Is it a self-levelling system which uses the damper ("shock absorber") struts to level the car? If not, ride height is determined by the springs.

A new damper on one side was not a good idea. They should be replaced in pairs, as should springs.

[PLuKE]

There just plain shock and spring setup.

I willl buy a new shock so the rear axle has a fresh setup.

I thought fthat compression would play a part in the sag of the car?

Like

[kev b]

Firstly I would check the spring is not broken, it is not unusual for these to snap.

[227bhp]

Height is dictated by spring, not damper.

[Digitalize]

BMW's tend to sit a little lower on the right side than the left, supposedly because BMW never rebalance the car after moving the steering column over to the right.

Either way springs will effect the height the car sits not damper. You might have a snapped spring if it's significantly lower on one side.

[PLuKE]

The rear left sits lower than the rear right.

So, it's only around 1cm lower. I shall change the shock on that side, so at least the dampening is the same.

Thanks chaps, will have a check anyway of the spring.

Luke

[CarsOrBikes]

it may have had only one aftermarket spring, rather common

[SebringMan]

CarsOrBikes said:

it may have had only one aftermarket spring, rather common

This.

IME almost no aftermarket spring "keeps" as good as genuine.

As an example:

I had a 2004 Mondeo V6 Auto. It had Lesjofer springs fitted to the front of the car. 20,000 miles later and the front of the car had a rake with an alarming amount of wear to the inside of the tyres. We eventually changed the front dampers and springs (for the second time) but fitted genuine Ford parts). 100,000 miles later the springs did not sag at all.

Towards the end of that car's life we changed the rear springs for heavy duty items with B4 shocks. Besides having interesting handling to say the least the rear of the car began to sag later on with the new owner! Front of the car? Still nice and high.

If people are confused about the mileage quoted we had the car from 114,000 to 284,000, with a friend then taking it to 330k.

I did once say this on another forum and they claimed it wouldn't happen to BMWs because "They are a BMW and not a Ford". IMO that is complete rubbish. For the M3 as an example BMW specify two different dampers, for the Coupe and Convertible ECP? 1 damper for both. Likewise, ECP only specify 1 spring and damper for a normal Mondeo. Go to Ford and they offer about 7 different choices dependant on engine size and spec ; there is a big difference in weight between the 1.8 and say a 3.0 Auto.

The truth is that for most people anything new will make a nice difference over something pretty old, making them think "OE" stuff is good value. To be fair it is case but with searching.