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now that the OP is not amongst us anymore we should continue the wiki (for both selfish reasons as well as to continue the work he started)
how can we get control of the wiki so we can keep updating the original post
if we need volunteers I am willing.... if there are more appropriate people that if fine too.
Changed front sway bar back to medium and the bit of oversteer I had went away. I was at medium-medium. I think I'll change rear to hard next time and see how that changes things.
now that the OP is not amongst us anymore we should continue the wiki (for both selfish reasons as well as to continue the work he started)
how can we get control of the wiki so we can keep updating the original post
if we need volunteers I am willing.... if there are more appropriate people that if fine too.
I think a key step for us is to get the alignments nailed. A track focused, track focused + springs, street focused, and dual-use focused alignments. This would need to cover ride heights, caster, sways, aero, tire compound, tire size and track widths.
Installed the higher BBI wing uprights and I could definitely feel the downforce in a few high speed turns at Buttonwillow. Improved by personal best with RE71Rs by .50 second but I could have done a second faster if I didn't mess up a few turns.
I have my sway at medium / medium, -3F/-2.2R on tarret swift spring rates and 4 mm toe in rear. Still felt midcorner under steer where I had to throttle steer to make it rotate. I'm on oem Dunlop. Getting re71r for this sat on oem 20s.... let's see how better tires feel.
I have not adjust front or rear aero. Leaving them how they came from factory
Car feels pretty good overall.. just need to track it more and learn mid engine platform.
I had MSI wheel studs/nuts on the car for the past year and only a handful of track days. Discovered they were not properly mating with my wheels, and in fact the dimensions and shape are wrong.
Four studs backed out when I was removing studs to take off wheels for brake flush. I checked the remaining studs and another 4 were finger tight - I unscrewed them by hand.
Ended up taking off all studs and going back to OEM fasteners. There was considerable rust on the studs and nuts, and where they met at the wheel. The rust had embedded into the alumin wheel and it took some chemicals and elbow grease to get it off (which we did).
I used MSI studs/nuts on my Cayman R OEM wheels for two seasons without issue. There is a thread on RL about wheel studs and I've posted details there. I'm currently investigating to see why the product didn't fit (did MSI send the wrong item? Was the wrong item ordered? Etc). If I can figure out what went wrong I'll post - but clearly the MSI were incorrect dimensions, taper, shape and did not mate correctly with the OEM wheel which means the nut was contacting the wheel at what appears to be less than 50% of the surface area that should be in contact.
A couple photos here including the measurements I took at the widest part of each wheel nut (the MSI is wider than Porsche's). And the link to the wheel stud thread.
The last two photos (one is a photo, the other is a small diagram) are courtesy of APEX-COMP, a RL sponsor and manufacturer of wheel studs (and also a local friend). He does a great job of describing what to look for if you are going to use wheel studs. Getting it right is critical. I have no stake in APEX Competition - just appreciated his detailed post which is post #23 on the thread below:
^yes loctite
they look like ball seat but the shape doesn't match.
Backtracking to learn what happened.
In wheel stud thread someone posted that MSI had a "weird batch". Maybe this was part of that group of product
Car is set up as under steering (as any modern car is), more contact patch under load (steering plus going through a corner) on the front can help (plus other measures...). You will notice that with -1.7° camber front your tires will wear heavily on the outer edges, even with -2° they do that, hence I max out the camber. Again, camber is not the only aspect but one you can influence with stock suspension and I am not yet ready to mod the car.
If your tire does not look like the one above, you are either not pushing by he car hard enough or have a miraculous suspension.
Why the difference between front and rear: I like my car to break loose at the back end if I overpower it or induce a change in weight distribution (e.g. lift of oversteer). This should all happen very controllable. With the same camber front and rear, a pro known for his drift abilities (google Tim Schrick, probably not known in the US but well known in Germany, he belongs to the family which owns Schrick camshafts) took PSM back on and told me to get a new alignment quickly...
In the end, you need to try different setting out (and go with 0.5° changed to feel the difference) and find out what suits you driving style most.
I just want to leave this here regarding what I just posted on GT3 forum.
I suspect the same applies..
There seems to be a lot of time in just killing the outside of the tires.
CUP2 tires are weird.
I probably would try the Bridgestone RE71 if I wouldn’t drive so much in hard rain from what I read on Rennlist (GT4 section, where the track guys go...) but they don’t make them in RS size yet anyway.
Or go Hoosier or slicks with 19" but that means trailering, tools, wheels etc.
The CUP2 tires…
Some get many track days out of them. I get 4 at best.
So, the construction is about 25% slick and about 75% harder (like a Supersport I guess): http://www.michelinman.com/US/en/tir...rt-cup-2.html#
Everyone probably know this already.
For me it’s perfect because I always have a Michelin Super Sport to drive home on, it basically never wears out.
Only the OUTER 25% wears and eventually cords but not until the tire is as slow as a MSS. The inside looks like new.
For example when I ran Dunlops, same lap time but the entire tire goes to slick and It’s a handful to drive home in the wet. They also cant take the heat / weight on the RS and they fall apart. I've seen GT4 drivers post about that as well.
So I read about 991 GT3's and GT4's adding camber. Just like I tried -2.7/-3 and the tire just gets slower because you use the inner 75% so you end up with a MSS.
I have backed off more and more. Now -2camber all around and they still get heat cycled out before I cord them.
I don’t bother cording the fronts because pushy and slower.
I am running stiff sway bars to keep them from cording on day 1 or 2.
Now with new DSC box I think the bars can be middle (only 3 holes front and rear on 991RS).
But because the shocks dynamically stiffen the car leans less and so I hope to still get 4 days out of them. The first test day looked very promising.
Back to Sebring on Saturday for more testing.
Although I do think the difference in compound across a cup2 adds to the uneven wear, I would caution against the conclusion that camber up to -3 front makes the car any slower on cup2s. Supposedly the best lap time at thill done by a GT4 (by a good margin) was done with cup2s and -3/-2.5 camber.
03-27-2017, 01:22 PM
how to continue the Wiki
