First a little introduction:
I'm an Automotive Engineer whos worked for a few OEMs. Including Jaguar and Aston during the 'PAG' era.
I'm a huge fan of vintage BMWs, and own a Euro spec E24 M635CSi and my first car, an E21 323i.
In the future I may get a beaten up E46 M3 as a track rat.
But anyway, for this post, I've always admired the E39 M5. We used it as a benchmark while developing cars I've been involved in.
My memories of the ride and handling compromise over UK roads were remarkable. Recently I drove one again, over the terrible roads up here in the Midwest and I was very impressed. The car in question had had most of the suspension components renewed. The ride was great but also the body control.
My plan is to get the same body control and ride compromise on my Jaguar X308 XJR.
Before anyone patronises me, I can preface this by saying I've looked into this very deeply and it is possible.
BMWs- even the older ones- put a lot of effort into certain vehicle dynamics fundamentals- they look at the yaw inertia relative to the centre of gravity to give the handling characteristics we're all so fond of. Typically their dynamic index (a term that relates the yaw inertia to the centre of gravity) is close to 1- this is the case for an old BMW 2002, An E30 BMW M3 and an E46 M3 etc. By comparison my 1970 Challenger has a D.I of about 1.28!
Fortunately for me- The X308 chassis Jaguar has a Dyn. In in line with BMWs- at around 1 with 52% front weight bias. Its torsional rigidity is about 13,000 nm/deg vs the E39 M5 at 16,000. Its just that Jaguar chose to market the X308 to a different clientele
So this should all be possible.
I need to know either the spring rates or the wheel rates of a STOCK OEM BMW E39 M5.
I tried to measure them with a vibration app on my phone during a test drive and that didn't work. I did a search online and I only came across these two threads:
If this doesn't work, I may even beg/borrow or steal OEM style springs from an M5 and have them measured.
Is anyone selling or willing to lend me a front and rear spring in the Wisconsin/Minnesota area?
Seeing as someone from here supercharged a BMW M60 V8 using an intercooler/supercharger pack from a Jag and I helped, I think its time to cash in the favour!