RoadsterSport Springs on Bilstein B8's

[AndrewD459]

I recently acquired some Bilstein B8's with the intention of getting the Roadstersport springs on the next shipment to Australia. As I already had some eibach springs I thought I would at least fit them and give them a try at a recent track day. The factory front shock/Spring installed measurement was 260mm (top hat to bottom tip of Spring in lower shock retainer) and 238mm in the B8's (clearly more Spring preload). My hope was that this would be a sufficient set-up for the occasional track day and maybe save on buying the Roadstersport springs. My observation was that the additional preload was firmer on small road bumps but still similarly compliant on bigger bumps, however, there was little noticeable difference on the track as the additional preload isn't enough to overcome the lower Spring rate of the eibach's. Originally the eibach's dropped the car by 1/2" and with the B8's, dropped the height another 1/2" to 13 1/2" all round.

So my question is if the B8's are shorter than the Koni's and there is additional preload particularly on the 300 front springs will this be too much preload? By my calculation, if the B8 is 22mm shorter than the Koni, the front springs will have over 500lb initial preload? And is this a good or bad thing?

[AndrewD459]

Hi Brian. I was looking for some feedback regards the Roadstersport springs on B8's, as all the comments I have seen so far are regards the springs mounted on Koni's or Standard Bilsteins. I don't know the installed height of the Koni's (compared to the standard Bilsteins) and if it is the same, what effect would there be mounting the Roadstersport springs on the B8's as these are 22mm shorter than the base model shock/Spring setup. Your feedback would be appreciated as my order will likely need to be placed soon for the next delivery to Australia.

[Brian]

We plan to try a set of RoadsterSport springs on the B8 shocks in our RF in early May.

[AndrewD459]

Thanks Brian. Looking forward to your assessment of the Roadstersport Spring/Bilstein B8's combination.

For reference the Eibachs on factory stock shocks dropped my car 1/2" all round. The Eibachs on B8's dropped the car another 1/2" to 13 1/2" all round. I measured the front shock installed spring height (top of top mount to bottom tip of Spring in lower retainer) at 260mm in the factory shock and 238mm in the B8 (forgot to do the back). The ride is firmer over small road imperfections and still compliant on larger road imperfections. On the track even with the higher spring preload there feels to be minimal change in stiffness around the track (based on 10 laps so far). Hope this is of some assistance.

[BillK336]

^^^ Comparing to factory black(Tokico?) or factory Bilstein?

[AndrewD459]

Compared to factory black shocks (currently there are no factory Bilstein options in Australia). We get a base model (with LSD in manuals) or a GT model (with LSD in manuals), no club option.

I finally got to do a comprehensive road drive (on the famous 'putty road') on this set-up and need to correct my initial observations. The ride is firmer across the whole spectrum without being uncomfortable but would still likely only qualify as a 'soft' track set-up in most people's eyes. I can still get a little nose dive on very hard braking (track pads) but significantly less roll compared to standard. The roll part was confirmed by a club member at a recent hill climb event when observing my car and 2 other stock ND's on the track. It will be interesting to see the Roadstersports performance on the B8's.

[BillK336]

Interesting the Bilsteins caused a 1/2" drop. I'd expected that only from the Konis.
See Brian's 26 May and 29 May posts in the main thread.
viewtopic.php?f=10&t=3323&start=420

[Brian]

Interesting the Bilsteins caused a 1/2" drop. I'd expected that only from the Konis.
See Brian's 26 May and 29 May posts in the main thread.
viewtopic.php?f=10&t=3323&start=420

Talking extra travel at that link...not lowering. Indeed only the KONI gave us more lowering.

Both versions of the Bilsteins we have tried so far, Club OEM Bilstein and B8, result in same heights....but B8 gives you about half an inch extra travel.

[BillK336]

^^^ My comment was based on Andrew's 01 May post. I interpreted it as 1/2" drop from the Eibach springs, another 1/2" drop from the B8's.
A total of 1/2" would be preferable for me.

[BillK336]

...But 1" would be OK.
I'll assume this combo (RS springs and B8's, short bumpstops) will reduce the Bilstein jiggle.