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Discussion Starter · #1 ·
spent Friday at Thunderhill -- with RA1s (about 1/2 tread) and the 550/425# GC coilovers was able to equal my best time with the Dinan 3 and fresh Pilot Sport Cups in 2003 (in 2004 the Cups were dead and 5 or 6 seconds slower - same as street tires). i'm still getting used to how much is availavable and substantially over-braking at least 3 corners. there should safely be another 4 or 5 seconds to be had (even more for a good driver, but that's getting pretty fast in a 4000# car).

the suspension/tire combination is extremely predictable and very easy to drive

my sister visited and spent a couple hundred freeway and city street miles in the back seat and pronounce the ride "just fine" (however her daily driver is a '76 911). some of the new freeway construction and re-surfacing have left some pretty nasty macadam/concrete mis-matches -- these make a substantial firm bump at speed but no nasty noises and i've had no incidences of bottoming since raising the car to just below stock ride height. on-ramps, lane changes, etc. are substantially improved

i recommend this combination to anyone at least semi serious about tracking -- and to anyone else i'd recommend the GC setup with 430# front springs to provide noticeable stability improvement in cornering and braking compared to stock (and the Dinan 3 and GC with 350# springs which really aren't enough stiffer than stock to make a difference)
 

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Discussion Starter · #4 ·
14 1/4F/ 14R

also, running the RA1s at 42-44psi hot, i was told this is where the touring car guys run, and it seems to work -- M5 is too heavy to run lower pressures
 

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Josh:

I am envious of your spring rates as I am running on Dinan's that are likely in the low 200#'s. I do need to do a GC set up.

It is tough finding the right pressures for RA1's on a heavy car. They have a soft sidewall which you really feel on transitions so you want to run higher than most but I have also been told that some guys run them at about 28lbs cold, usually high 30lbs' hot. To be honest, I don't notice a huge difference but I tend to just let air out as the day progresses. How much camber do you run on your set up? Also curious about your laptimes for an M5 set up like that. I got to see all the BMW clubracers run Saturday. Their laptimes are at:

http://www.mylaps.com/results/showevent.jsp?id=72117

The BMW and Porsche group ran the cyclone while the other groups ran the bypass. Check out the Porsche guy, Stefanowic, 1:50 and change. Yikes.


You ran with Trackmasters? I was up late Friday to run with NASA the next day. Would have been nice to do a two day but I had some work to do.
 
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