after taking delivery of my RS, I track the car several times at Laguna and Thunderhill with OEM 19" and pilot sports cup tires. I never felt comfortable with the car. The rear twitches under hard braking and I had no confident with PS cup since it is very slippery when cold and lose traction abruptly on turns. PCCB brakes need time to heat up and some times it grabs and some times not? I remember sitting in the pit at Thunderhill thinking to myself what is wrong with my RS?? This is suppose to be a great track car and I was much more comfortable and had more fun driving my M3 with Yokohama's ADVAN A048. I tried tilting the rear wing up couple degrees which helped stability some what under hard braking but the whole car still felt very nervous. I drift my RS at Thunderhill and PS cup lose traction abruptly without much warning which was confirmed by Drift champ Luke at BRracing.



In an attempt to help my RS drive better, I set out to do the following:

1. Corner balance
2. More aggressive track alignment
3. Better tires

Corner Balance

Shad at Driving Ambition near Sacramento did a great job corner balance my RS. The car felt more stable right away. The factory setting was slightly off and it took about 2 hours to set everything up without lowering the car. The car weigh 3169 lbs with 1/2 tank of gas w/o driver and 3336 lbs with me in it.








Track Alignment

Thanks for the many input from 997gt3north I got couple shims for the front control arm and hook up with G12 alignment at Sacramento to give the car more aggressive camber and toes. First of all, factory alignment setting was all over the place both front and rear even though the car track straight on the road. The rear camber adjustment went without a hitch but we couldn't get more than 1.8 to 1.9 front camber despite of using 7 mm of shims on each side? I left the camber setting at 1.8 both front and rear which is slightly more aggressive than factory setting of 1.2 to 1.6 and set rear toe in at 2.0 mm so the car will be more stable under hard braking (rear tires tend to toe out under hard braking which makes the rear dance from side to side). We set the front toe out at 0.5 mm and the car track pretty aggressive to the right - following natural camber of the road. We confirm this finding with The Racer Group and dial back the front toe to 0.2 mm toe in. The car still track ever so slightly toward the right but not annoying enough to make a fuss




Better tires

I had plan of getting a set of 19" Toyo R888 for my OEM wheels since many had good experience with them but I found a set of 18" CCW wheels with Nitto NT 245/40/18 front and 315/30/18 rear. Pretty funny tire combination but oh well, let's give it a go. The CCW/Nitto wheel combo was 1 lb heavier at the front than OEM with PS cup and 4 lbs lighter each wheel for the rear. The speedometer was not affected since the front hight is the same as OEM but engine rev a little higher at speed due to smaller diameter rear wheels.

How does it perform on the track? OMG!!! it was insanely GOOD!!! First of all, you can drive the car really hard even when the tire was cold - it does not slip like PC cup. Once the tire heat up ..... I have no word describing how well it handle. It grabs the turn like a Velcro, accelerate briskly and brake easily. I estimate that I use 50% less braking going into a turn. I was braking wayyyy to early because I was not use to the change. When the tire lose traction, it was super progressive. Couple times I gently drift my RS at 45 degree in a turn and ease on the throttle to bring the tail back. No drama and no surprise. Tire pressure was set around 30 psi hot. I improve my previous best time at Thunderhill by 6 seconds at 2:10

I am an advance novice when it comes to track and my lap time will improve when I get more experience with the tire. I have never felt better about my RS and hope to gain more confidence with time

Typical Thunderhill Lap Times

D Sports Racer race record, John Hill, Stohr WF1, 03/18/2006 1:42.071, 2.866 miles, 16 turns CCW w/o bypass
Spec Miata 2:08.235
Spec Racer Ford 2:02.491
Porsche 944 spec 2:12.9
Porsche 997RSR with professional driver 1:45
Porsche 997 GT3 RS with prof driver 2:02
Stock Acura NSX w/street tires driven by Kenji Morishige 2:09 with bypass, 2:11 w/o bypass
Prima Racing 1992 Civic EG driven by Kenji Morishige 2:09.xx 2005 NASA Race Weekend
Prima Racing 1999 Civic Si driven by Andrie Hartanto 2:02.869 2005 NASA Race Weekend
Shed Racing 1983 VW Rabbit GTI Cup driven by Ron Swett 2:13.567 2005 NASA Race Weekend
2003 Mitsubishi Evo 8 #42 NASA TTB driven by Yang Tang 2:02.254 2007 NASA Track record w/ bypass
Spec E30, Donny Edwards 2:08.712 8/23/2008 NASA Race w/bypass



Thunderhill RS

 

Nice write up. Why didn't the group you were doing the track day with run turn 5 (the hill)?

 

Your the one who got my wheels and tires!!!

Sorry, I am just bitter because the guy selling commited to me and then sold them to you out of practicality (laziness is a better word).

Beautiful RS, have a blast with it.

btw, that is not an odd tire combo at all. However, once you are ready for the next set, I recommend that you go with the R888's. They are the same compound and basically the same tire as R888 except with different tread pattern (I believe they are made in same factory too). Anyway, with the Toyo's you have a much better choice of sizes. Here is what I would highly recommend for your wheels (you now have 9" front wheels):

255/35 F with either 305/35 or 315/30 rear

You can also go with a 265/35 front with the 335/30 rear. The 265 only weighs one pound more than the 255, while the 335 actually weighs 1 lb less than the 305/35, but 2 lbs more than the 315/30.

You might also want to play around with your sway bar settings to help turn in. Some run the GT2 bar in the rear to help with this, but I think you have enough adjustability to get it where you are comfortable. And if you are running more rubber up front, that will help with the understeer.

For camber, you can rotate the front strut towers to give you a ton more camber. For the rear I recommend going with the toe steer arm and locking plate and dog bones from either RSS or GMG (both make high quality parts). This, along with your rear shimming capability (the regular GT3 does not have the split lower control arm in the rear to allow shimming), should take care of more than enough camber than you will ever need.

Another good reason to get the toe steer arm and locking plate in the rear is that it will hold your toe settings were you last set them. For the stock bits you pretty much have to reset your rear toe before each track event. This is part of the reason your alignment was all over the place; it is not all the factory's fault.

If you do those parts, then you might as well also do the front bump steer arms, and replace all of the monoballs and thrust arm bushings on lower control arms with semi solid and solid pieces. I have all of this along with GMG's WC sway bars, and the improvment is big (not huge, but big). It also does not ruin the ride of the car for street use. It just tightens everything up, gives you more and easier alignment capability, and holds your alignment in place better.

The final step for suspension is a set of Motons, but I personally have not done this, but hope to do so soon.

Oh, one more item. Wevo now has semi-solid engine mounts for the 997. I also recommend these as they are street friendly and also tighten things up and making shifting more precise, especially under high G loads.

Sharkwerks center muffler delete, or their new system (coming soon) with all mufflers deleted and only two light-weight race mufflers is another good thing for the car. Their new system is about 57 lbs lighter, while their center delete is 16 lbs lighter.

Have fun with your fancy new wheels. Sure wish I had those on my car.

 

We did the "by-pass" over turn 5 which is often used for race configuration. It's scarier this way since you can't see what's coming over turn 5 and once you are over you are off camber. Best way to take this turn is have your car aim slightly toward the right and keep the gas on over the hill so the rear won't get light

Sorry about the wheels. I thought the rear don't fit on a none RS GT3?

Thanks for the advice on tire and suspension - very useful information

Now about the tire. You are saying Toyo R888 and Nitto NT01 are made in the same factory? Interesting. If that is the case how come people are using different hot tire pressure on the track for both tires - 37 psi for R888 and 27 - 30 psi for NT01?

About the suspension. Sounds like OEM links changes after each track event - that really sucks. That explains why my initial alignment was all over the place. The GMG suspension components sounds great but it is expensive after adding everything up - not including labor. I may stay with factory suspension components for a while until I win the next jackpot .... wife told me the only Moton I can have is a vinyl sticker lol

I head about rotating the front strut tower to get more negative camber but I was puzzled that I can not get pass -1.8 with OEM set up. I was told that OEM set up with shim can easily reach -2.4 in the front without rotating the front strut tower??

Here is a picture of the front strut tower. Do I just loosen the three bolts and rotate the strut tower 90 - 180 degrees to reach the desire camber? I like to try -2.4 front and -2.1 rear next time

 

Thanks for sharing. Congrats on the lap! That was some seriously smooth driving. You looked very confident in the car. And that is the key to pushing yourself further. People don't realize, but RS' do require work to dial in. But once you do, it's magical. Keep it up!

 

Thanks. My thought exactly. I thought I could just jump into a RS and drive like Tiff Needell lol. It does require some tinkering and boy do I love my RS now!!

I have a-lot to learn both as a driver and about the car. I found that by tilting the rear wing up really help stabilize the rear at Thunderhill

Tiff Needell RS

 

Most people cannot not get past -1.8 either, but instead of rotating the upper strut tops, I used a pair of 8mm shims from Tarett. Each 0.1 of a mm gains you 0.1 degree camber, so you could max at -2.6, or stack an additional 3 or 4 mm to get you adjustment up to -3.0. The side benefit this method is your front track also widens by an additional ~20 mm helping with understeer. But depending on your tire profile and width, it's very close to almost rubbing the forward fender liner on full steering lock.

In rotating the tops, you press out the studs from their present locations, and rotate the top to the position that brings the strut in closer, and rebolt the studs in the other set of holes.

 

Thanks Steve for the advice. My problem is that I can't get pass -1.8 in the front after having 7 mm of shims on each side with the front strut tower all the way inward?? I was told that our GT3/RS can easily achieve -1.8 front camber without shim so I don't know why I can't get it on my RS? I did notice that my front tires almost rub the wheel well with full steering lock.

 

Are you sure? That doesn't sound right. If both were done, you'd easily exceed -3, and your car had to be a 0 to positive camber before.

BTW, for track use, Dwain Dement of Vision Motorsports recommends 3.0 to 3.5 negative front, and 2.75 to 3.0 rear.

 

Yup ... we could not get pass -1.8 in the front despite using 7 mm shims each side. I have -1.8 camber in the rear and both front and rear cambers are the same by looking at the wheels. This really puzzle me since everyone says I should be able to get at least -1.8 camber front without shims? Did we miss other adjustment point that could give us more negative camber?

I would like to run -2.4 front and -2.1 rear next time. -3 camber front and rear is a bit too aggressive for me at this time

Here is a print out of my final alignment specs

 

Those are the only two. I still think something is not right. Maybe I'm not looking at it right but by the looks of your underside it does not look like the strut was ever rotated - the strut still centers towards the outer side. Are you sure the shims were installed? The control arm factory already has I think a 7 mm shim in there. Take a look and if the extra shim was installed, there should be a stack of two now. Maybe you should find someone else that knows what they are doing. Just do one or the other for now, both would be too much for your target.

 

Thanks for the advice. The shims are installed. I will try rotating the front strut tower next. Will keep you posted