Chassis change in 2009 NC

Hi all,
I am fitting the Bilstein B12 kit to my 2008 2.0 sport. This thread is not about pros cons of this, there is another thread where I made the B12 decision if you want to comment on that.

But there are two B12 kits for the NC, not many suppliers point this out and their ‘part selection tool’ gives one answer for the whole life of the NC. In evitably, the kit I have ordered is specifically for the later car, so I have now also ordered the earlier kit and will return the unused one. But if there is no material difference will crack on and fit the first one to arrive (delivery from Berlin is taking its time…)

After some digging, I have this statement by email from Eibach

On the NC chassis there was a slight change on the 09 onwards model to therefore for TÜV approval purposes we needed to design 2 solutions on this setup. One will fit the other (in terms of the springs, for dampers you would need to check this with Bilstein) but it is not down to weight. We recommend that you stick to the correct kit for your car to maintain the intended ride and handling along, and also to preserve your warranty on the kit.

While I will chase Bilstein for an answer, does anyone know what the difference could be that would require different dampers to maintain TUV on 2009 and later cars? I know there is a slight weight difference, but my 2008 prht is heavier than the rag top yet is recommended the same kit.

So

  • Is there any physical difference to the suspension fitting between the mk3, mk3.5 and mk3.75 ?
  • Is there differences to ABS or any handling characteristics that would require modified damping characteristics?
  • Has anyone found any reason why shocks and springs are not interchangeable between these models.

Many thanks for any input.

The front lower arms were changed for 2009 (lowered roll centre IIRC) and the DSC program was changed. Not sure it springs and damper characteristics where also changed due to those changes.

Thanks for that. Bilstein only list one kit for entire nc range. Weird that Eibach have two options, yet say the springs are the same on both.

I’m looking in the MX-5 NC Facelift training manual and it states…

Lowered front roll centre for optimised driving performance while cornering
Modified Bilstein suspension (only LF engine with 6 speed manual transmission)
Due to suspension changes, revised tuning of the DSC software

In answer to your first bullet point, I’m pretty sure that physically the suspension fit is the same.

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Many thanks - much appreciate you looking that up.
I figure that it was ONLY the LF with 6 speed that had the Bilsteins (i.e. the Sport model). And assume the change was a modification of one or many of the damping rates (Hi/lo speed, comp/rebound) due to new geometry.

I would guess that Bilstein then offered a revised version of the B6/B8 to fit, but subsequently decided to simplify the product line and simply offered the revised shocks across all years. For whatever reason Eibach continues to sell both types, but in all probability they are identical (why would Bilstien provide two options to Eibach when they only sell one themselves).

When the first set arrives, I will look for part numbers/codes on the shock and then cross ref that back to Bilstein. If that corresponds to what Bilstein currently sell, then I will fit it. If it comes up different, then I’ll wait for the second kit to arrive (which was ordered a week later).