spring thickness query

Finisterre

Senior member
 Buxton Narnia
I just bought a replacement rear spring on ebay (KYB RX6751) and its notably thicker than the one it is meant to replace.-
I know that can't be right but am I wrong? The seller assures me its correct.

The Z4 is a 2006 2.0 SE.
I have replaced 4 springs so far and I cant find any of my old paperwork. Bloody car.

help!
 
I suspect the vendor doesn't differentiate between SE and Sport trim.
Has anyone actually done a side by side comparison?

I'm annoyed with myself for being too blase in the purchase process. I just bought the first one. (idiot)
 
A lot of aftermarket springs are thinker or thinner than OEM.... The actual coil wire rate is different so that the different diameter coil can be used.

Thats why in perfect scenario terms that you should always buy and fit in pairs..
 
Z4M-2006 said:
A lot of aftermarket springs are thinker or thinner than OEM.... The actual coil wire rate is different so that the different diameter coil can be used.

Thats why in perfect scenario terms that you should always buy and fit in pairs..

This is single most likely cause of the broken springs as the non oem are of lower quality materials and fail more regularly. Corrosion protection is the main area of the problem.

As said try to replace them in pairs and then the spring rates and sizes wont play a part but the old adage of you gets what you pay for is definitely true with springs.

:D
 
Nelly Welly said:
Z4M-2006 said:
A lot of aftermarket springs are thinker or thinner than OEM.... The actual coil wire rate is different so that the different diameter coil can be used.

Thats why in perfect scenario terms that you should always buy and fit in pairs..

This is single most likely cause of the broken springs as the non oem are of lower quality materials and fail more regularly. Corrosion protection is the main area of the problem.

As said try to replace them in pairs and then the spring rates and sizes wont play a part but the old adage of you gets what you pay for is definitely true with springs.

:D

I think you'll find it's the OEM springs that have a higher failure rate (on BMW'S at least).

Non OEM replacements last much longer.
 
Probably true but in general terms the oem items are normally the better product, given the frequency of failures on BMWs it may be why the aftermarket ones are so plentiful in supply.. :rofl: :driving: :rofl:
 
I fitted kyb rear springs about 7 years ago, they are the the same thickness top to bottom where as the Bmw ones taper thinner to the end of the coil.
The kyb ones are still perfect
 
So. Check ride height. Fit new spring. Check the ride height. If okay buy another. Fit it.

We have a plan.

Is the ride height a known quantity on an SE? I will look on google. But sometimes just asking the question saves ever so much idiocy.

Cheers for the feedback.
Fin..
 
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