hellboy_mcqueen

Great work!
And thx for sharing

ExMB

Could that rubbing be fixed by adjusting the caster and/or changing ride height?

Joe Weinstein

"We used shims with thrust-arm bushings to get this"...

I assume shims are standard Porsche parts for the purpose. Are thrust-arm bushings also?
For my format I can only use standard stuff. I would have to find an 8.5"x19" front because
we can't go wider than stock... But, yes, all the good tires are in 19".

ShakeNBake

Shims are motorsports parts - not technically OEM, and the caster pucks are aftermarket.

ShakeNBake

I think the fronts would get a little more breathing room with 2-3mm offsetup change, or if I used camber plates to get the negative camber with fewer shims. I'm not worried about this, it worked well. If I order another set of wheels, I will change the offset a bit.

Rears are actually rubbing as you can see below - but the tire has no signs of rubbing - and I was not exactly babying the car around TWS. I am not sure what I would do give the rear some more space - 10.5" wheel is a non starter IMO, and and the offset is as close to that toe arm as I would get. If there were a low profile knuckle, I might change the offset by a couple mm.

Rear running - it looks like a lot, but you can't tell that the tire has touched anything. (Left is rear of car)


Front - again, it looks bad, but you can't tell it was rubbing. (Right is front of car)


Packed up and on the way home.

electron mike

Looks like minimal rubbing from those pics, do the tires show enough to concern you or is it superficial?

How was the grip compared to cup2s and your previous alignment? Any guess how much it improved your lap times?

ShakeNBake

Rubbing:
Only one front tire (front left - I presume due to Turn10) showed signs of rubbing, but it was minimal and didn't pull any rubber off the tire. Hoosiers are pretty rounded on the edges.

Feel:
The whole car felt very good. The understeer is still there if you screw up your corner entry and still require front grip at the apex - but I think at this point I would not change a thing, I'd rather have more balance towards rear grip.

Wear/Alignment:
At TWS, the rear tire wear (-2.5 now) seemed very even with this alignment. The front (-3 now) could use another half degree, for a total of -3.5. This is looking strictly at tire wear, but TWS is like a cheese grater on tires. Temp profile shows that there might be too much negative camber in the rear, so I will be watching closely at COTA. The problem ultimately is that I may be giving up grip when the rear tires are loaded, which might be why the car likes to snap halfway to track-out or at apex under full power.

I corded a front Cup2 within 2 sessions at TWS back in December with the factory alignment. The hooisers look good enough after 7 sessions to survive a weekend at COTA with Chin.

Hoosiers vs Cup2:
LapTime wise, giving how little experience I have on the car, and with cup2s for that matter, it's difficult to tell what the difference is between cup2s and hoosiers is. This was the first time I really pushed the car and tried to have fun with it, and I've still got a lot of learn. It's reflexes are much faster, and it breaks loose much more abruptly than any street car I've driven...more like a race car. I'm not yet thinking ahead of the car, so I'm overly cautious. I would guess both tires are about the same given the level I am driving the car right now. There are at least 2 more "sack-up" seconds on the hoosiers at TWS, it will be easy to find those - but to go further I'm going to have to improve my skills on this platform.

Mostly rambling...sorry

ExMB

What was your aero setup? Would the Gurney Flap from the Clubsport be something you'll look into? Will running less fuel help? Or a combination of both?

ShakeNBake

Max-aero. You know, at this point, I think it's really about my driving style. I'll report back on how it goes at COTA.

Mvez

More spring rate will help. Car is still sprung soft for R7's, or stock tires for that matter. I'd run 400/600 or 500/700 for dual purpose car, at minimum.

I just test fitted a rear BBS CH-R 19x10 ET38, and the fitment is perfect. 10.5" ET44 would be most ideal for 295's, but for off-the-shelf wheels, 10" will be fine.

The 10" gives plenty of room on both sides, matches outside clearance of stock, minus 1mm, so even better clearance.

I have ZERO plans to make compromises and fit an 11" wheel for 19" or 18" diameter, it simply isn't needed. If you are going to buy custom wheels in 18-19" diameter, go with 10-10.5" width in the rear....PERIOD.

Another point, for those with dual purpose cars, Michelin makes Sport Cup 2's in 245-35-19 and 285-35-19 which fit perfect on 8.5"/10" rims and is plenty of tire for the GT4, and a proven setup on 981's. Or go with 235/285 Nitto NT01's....

Mvez

I would assume they would look at shims as standard parts. The stock thrust arm bushings allow for adjustment, you don't need to buy solid caster/thrust arm pucks. When you dial in max shim's on the control arms to increase camber, your caster is going to jump up to 10 deg or so......then when you adjust the thrust arms again, it gets caster back in range and adds more camber.

you can probably get away with changing out the inner tie-rod ends on the front, and inner rear toe links to allow for max camber, and retain the "stock" outer, so upon inspection it looks stock.....lol.

electron mike

Thanks for the insight, much appreciated! Do you feel the abrupt loss of traction is mostly the hoosiers or setup and tires? Mine on cup2s seems to break away predictably, but that could be because I am not going fast enough.

ShakeNBake

That's just a function of the lower polar moment of inertia than any car I've driven in anger. M3s and 911s rotate very slowly in comparison. 911 is a diabolical in that it will always rotate - period, you know its coming long before it happens, and as long as you are on power everything is fine - that's why everyone loves them.

This car is just different, I need to learn it. Takes some cycles. One other person I trust drove it and said it was the best handling car he's been in. He's a much better/faster driver than I am. I don't think it's the setup at this point.

ShakeNBake

You are probably right. My dinosaur brain considers going to a narrow wheel and tire a compromise (i.e. why buy an RS when all it has is wider tires?) - but I don't have the wisdom to know any better, but I will get there through trial and error. At the moment this setup works well, and rubs nothing like my RS did with 335/265 tires.

Jgarvish

ShakeNBake: Thanks so much for all your insight. I've been following your posts and appreciate all of the information you've shared.

I'm hoping to be out on COTA the last weekend in February with MVP. Currently getting my car aligned as well as getting new toe links and adjustable thrust arms (see pic) installed to help with toe and caster adjustment once I get increased camber. Also test fitting my Forgelines (19X9 ET 50 and 19X11 ET 47) and Hoosiers (265/35/19 and 295/30/19). Will update once I get my car back and have a chance to drive it.