Rear Spring Length

[david.rice]

A couple of years ago a garage replaced both the rear springs on my Z3 3.0 Roadster as one of them had broken. Since then its always looked lower at the back. I checked the length of the new springs against the old one and the old one is definitely longer!
KYB (replacement) 223mm
Original 240mm

Can anyone confirm that 240mm is the correct spring length and does anyone know where I can obtain a pair of 240mm springs? I've scoured the internet but so far to no avail!

Many Thanks

David

 

[t-tony]

Does your car by any chance have Sport suspension? That could possibly be the reason. KYB are aftermarket products and although are decent quality often these products are not exactly the same as original parts. Usually this is why customers are sold a pair so that you don't end up with one side higher than the other. A garage would be able to buy a pair of KYB springs for less than the cost of one genuine BMW Sport spring. You could "adjust" the height of the car by buying some thicker spring rubber seats from BMW which you fit under the bottom of the rear springs.

Tony.

 

[david.rice]

As far as I am aware I don't have sport suspension- its not a Z3 sport. According to Autodoc there are lots of different spring lengths available but non as long as my original spring!

Thanks for the tip about the thicker spring seats - I will investigate these.

 

[Eddie Zedder]

I have some used springs in my garage, I'll check the length later and let you know.

 

[Lee]

Does it state on the spring a brand or part number ?

Trouble is different company's will use different quality metal which will have an effect on spring rate, thus in turn the length being different.

 

[Stevo7682]

I'm with Lee different brands may design a spring slightly differently ( different thickness or profile) for the same application.
The big stand out one i used to see all the time was rear springs on Vauxhall ( especially astra ) .
The original pig tale springs were variable thickness ( ends thinning from central coils) but they would break easily aftermarket springs used same thickness full length and as such were several inches shorter but would give same compression rate in position.
Also spring could have compressed slightly from new especially being an aftermarket quality likely to be slightly lower.
Stephen.

 

[t-tony]

As far as I am aware I don't have sport suspension- its not a Z3 sport. According to Autodoc there are lots of different spring lengths available but non as long as my original spring!

Thanks for the tip about the thicker spring seats - I will investigate these.

You can find out what suspension your car left the factory with by entering uour Vin. No. on a vin. decoding site. Being a 3.0 I suspect it will have Sport Suspension.

Tony.

 

[t-tony]

Does it state on the spring a brand or part number ?

Trouble is different company's will use different quality metal which will have an effect on spring rate, thus in turn the length being different.

OP said they're KYB springs Lee.

Tony.

 

[Eddie Zedder]

So I have 4 rear springs in my collection 3 are 240mm and 1 is 220mm. I believe the 220mm one is a sport spring as it is made from slightly thicker material.

 

[Eddie Zedder]

You can find out what suspension your car left the factory with by entering uour Vin. No. on a vin. decoding site. Being a 3.0 I suspect it will have Sport Suspension.

Tony.

I believe early 3.0 had bog standard suspension, Sport versions came along later in the production run.

 

[david.rice]

So I have 4 rear springs in my collection 3 are 240mm and 1 is 220mm. I believe the 220mm one is a sport spring as it is made from slightly thicker material.

Thanks Eddie, that would make sense.

 

[david.rice]

Does it state on the spring a brand or part number ?

Trouble is different company's will use different quality metal which will have an effect on spring rate, thus in turn the length being different.

Hi Lee,
I can't see any part number on the OEM spring though it does have BMW stamped on it. I can't even find a part number for the springs on Realoem.

The difference in the springs is quite obvious when they are side by side.

 

[Ade33]

Interested in this thread as I own a sport..Your photo above shows 3 springs...Are they all a different length?..I can see the one on the right is longer than the others...but the other two?

 

[david.rice]

Interested in this thread as I own a sport..Your photo above shows 3 springs...Are they all a different length?..I can see the one on the right is longer than the others...but the other two?

2 springs are the same length (the KYB ones)- they were purchased by a garage when the car failed it's mot due to a broken spring. The third is the original spring. Original spring is approx 17mm longer than the replacements.

I checked with the bmw dealer and springs are still available (at least for thr non sport model) but they are £250 a pair!!

 

[t-tony]

And that is why even BMW fit aftermarket springs, in pairs.

Tony.

 

[Synclare]

.

 

[Ade33]

Thanks for that Synclare..I see in your profile you have a 1.9 Z3 Sport?...I'm wondering if its the same spring and part numberin the larger and presumably heavier 2.2 and 3.0 engined sport models?