Stock spring rates for all the M3 models.

[Kozy]

I am trying to find out (for very geeky reasons) what the spring rates and motion ratios for all the M3 over the years.

I've found them for the E30, tucked away in a very niche technical blog, but I'm struggling a bit with the E36, E46 and E92. It's not the sort of thing listed in the service manuals (I've downloaded them and read them, it's not there) but the E30 ones were listed on an official looking datasheet which needed translating from German, listing things like the sweep angle of the rear wishbones, all the alignment specifications, srub radius that sort of thing.

Does anyone know of any similar technical data for the later models at all? There's always at least one enthusiast for each marque that knows this sort of stuff!

[stevesingo]

Can you please post up the E30 info. I'd be interssted to see it.

[Kozy]

Sure, I've got the rear spring rates at 250lbin and the motion ratio at .67, the front spring rates at 140lb/in and the motion ratio at .96.

[stevesingo]

That kind of compares to the info I have found

http://www.e30tech.com/forum/showthread.php?s=689e...

Are you using the same source?

Should we expect some great little calculator on your site??

[Kozy]

Maybe at some point, but that's not the purpose at the moment.

I am doing some technical themed artwork for the M3 range and since I had that info for the E30, it would be nice to get the same data for all the models as a comparison of how the relative ride stiffness has changed over the years.

[stevesingo]

Kozy said:

Maybe at some point, but that's not the purpose at the moment.

I am doing some technical themed artwork for the M3 range and since I had that info for the E30, it would be nice to get the same data for all the models as a comparison of how the relative ride stiffness has changed over the years.

Care to share your source?

[Kozy]

Of the motion ratio information? Christ I'll have to dig that out. It was photographed from what looked like an original workshop manual (not the user service manual), I think I've got it on my laptop at home. Had the scrub radius, arb motion ratios and all sorts listed. Took a bit of work to translate though!

[stevesingo]

Ah,

I think I have seen that photocopy on the web somewhere.

[mlhj83]

Note that spring rates differ even amongst the same generation and version of M3 or any BMW. For example, a manual E92 M3 with standard CF roof will have different springs to that of another E92 M3 with M-DCT and a sunroof. This is a stated fact in many of BMW's technical documents.

[stevesingo]

Good point. Even the E30 M3 spring rates are different between aircon and non-aircon cars. Dont know by how much though.

[Kozy]

Oh arse biscuits.

Does anyone know of a way to find those out? If they only vary by a few lbs it's not a major concern.

Edited by Kozy on Friday 23 May 12:47

[mlhj83]

Kozy said:

Oh arse biscuits.

Does anyone know of a way to find those out? If they only vary by a few lbs it's not a major concern.

Edited by Kozy on Friday 23 May 12:47

I don't think anyone in the UK can tell you. BMW parts department can only provide you with the right springs for your car if you give them the chassis number, but certainly can't tell you the rates.

Safe to say, only M in Garching will know.

[Kozy]

Well that's a shame!