With the autox season over, I'm reflecting on the cars performance this year trying to understand where I can improve the car or myself. I thought it would be beneficial to get some ideas and feedback from the group.

The Car -
987.1 (not a daily, but not a race car; primarily used for the AutoX)
19x8 235/35/19 PSS
19.95 265/35/19 PSS
Numeric Shift Cables
Numeric Short Shifter
Cargraphic Exhaust
Softronics 93 Oct Sport Chronos Flash
Tarret GT3 Front LCAs - Installed for increase caster (cup setting)
Pagid Orange (F/R)

Alignment -
Front:
Camber -1.8 (L/R)
Toe Out 1/32 (L/R) Total toe Out 1/16
Rear:
Camber -1.0 (L/R)
Toe In 1.32(L/R) Total Toe In 1/16

The first half of the season the car felt like it was pushing a lot. I also ended up chewing through my front tire's shoulders. I upgraded to the Tarret GT3 LCAs, gave it some more camber, and bought fresh rubber (PSS). The tires are now wearing very good now. I think the camber is perfect.

Following the upgrade to the front, the car went from pushing to rotating. Its nice and makes for an entertaining lap at the autox but I find myself having to wait for the car. Best described as: A period where I'm not on the brakes and not on the gas because the moment I touch the gas the rear immediately slides out.

I want to fix this problem for next year, because I think this is causing me to lose half a second. The thing is, my rear PS tires are on the wear bars. The tires are also 2 years old. I'm thinking of making a few changes to the rear. I'll definitely be adding a tiny bit of camber, I'm just over the shoulder in terms of wear. But what about the oversteer?

Do I:
1. Get new tires in 265, add some rear camber, and leave the rest alone?
2. Get new tires in 275, add some rear camber, and leave the rest alone?
3. Reduce front caster, get new tires in 265, and add some rear camber?
4. Reduce front caster, get new tires in 275, and add some rear camber?

Decisions decision.... And input is appreciated!

Thanks in advance!
Syeo86

 

Two year old tires on the rear with new on the front? Effectively, you have no useful baseline.

5. Get new rear tires, do nothing else. See what it does then before even thinking about changing anything. Once you do this, for all you know, you could have understeer again.

 

Fair point.

I just assumed the added front caster and camber would result in more oversteer. I'll order up new 265 PSS tires.

 

If its within reach, go for wider front rims and try a square setup. I'd also try -3.0 camber up front and -2.5 in the rear. It is a bit tricky to drive a mid engined car with a square setup, but I feel its much faster than a staggered setup.

If you're looking for something subtle, a fresh set of rear tires will help a bit.

 

My understanding, and correct me if I'm wrong, is that a square setup will let the car rotate even more. I'm trying to fight the oversteer, so that may not be the direction I want to head in.

I'm torn with running 265 or 275. I'm leaning to 275(because 9.5 inch rear rim vs 9), then tweaking the rear camber and toe to dial the car in.

 

Of course, you'll need to modify the car to suit your driving style. My car is on coil overs and I AutoX on DOT legal slicks.

In my case, after going to a square setup, I ended up disconnecting the rear sway bar at first because the totally uncalled for over steer. After 3 seasons with a square setup, a lot of driving, and a few driving schools, I'm ready to reconnect the rear bar. In my situation, a lot of the over steer I was experiencing was because of my driving style ( braking too late, lifting mid corner, and not cancelling over steer ). After gaining some more experience (I'd say I'm about average skill by now ), I now experience slight under steer on corner entry.

Replacing worn, old rear tires will give you more traction in the rear. Might I also suggest replacing all 4 with 200TW tires, perhaps in the Bridgestone Flavor that everyone is raving about?

 

You are describing my driving style to a T. I brake as late as possible, sometimes trail braking to letting the car to rotate, which causes me to pause and wait before I can get on the throttle. If I'm too early, the rear washes, and then I'm stuck trying to manage the rear through the rest of the corner.

To be honest, the oversteer isn't extreme. It just a little more than what I want it to be. On top of all of this, I'm trying to stay in the class my car is in now. Changing to 200 tires, will bump me out.

I have a feeling, I'll shoot for the 275, bring the rear to -1.4 with 1/16 or 1/8 Toe In. And see how she does next season. If its still tail happy, I'll disconnect the rear sway and see what happens.

One quick question, what was your wheel setup when squared? I don't think the car can take more than 245 in front, so I assume I need to reduce the width of rim in the rear.

Did you run the same rim all around? 19x8 or 18x8 with the same offset?

 

200 tw tires will bump you out of your class? Thats strange, the SCCA has a 200tw limit for stock classes and the PCA will let you stay in Showroom stock and Production with up to 140tw. Thinking about it, Im pretty sure the Tarret LCA's already did that for you... In fact, you'd be stuck racing with in ASP against fast Evos, STIs, and RX7s like I am in the SCCA just for that mod.

Which class/organization are you racing with?

Also, I ran 4 17X9 cup1 rims on my 986 boxster, and now I am running OZ 18x9 and 18x10 with 275s all around. Youll need to roll your fenders and have coilovers to run this, its a very aggressive fitment. A good friend of mine bought a 987.1 Cayman S and it looked like there was a lot more room for tires than my 986, but I have no idea how much.

 

I run with PCA. I'm not sure if the classification system is standard across all regions or not.

The 9.5 rim, bumped me out of SS, then subsequent ecu flash, Tarett LCA, and exhaust ate up my outstanding points. I really was getting tired of eating the shoulder of my tires.

I'll try new rubber for 2016 and see how it goes. Perhaps the year after, I'll try going square. BTW, thanks for the clarification of "square". I kept thinking the rim had to be the same width, but it seems like we are just talking about tire.

I'm pretty sure the front will be tight. From what I've read, the largest tire that can fit is 255; stock suspension.

 

Thanks for sharing your experience. I am the friend lee101315 mentioned. I’ve been trying to do a lot of research and getting plenty of seat time before determining what setup for A Street I will go with. Since purchasing the car in July I have done absolutely nothing to it, but put over 150 autocross runs to learn the car. I am coming off a fast street tire FWD car and wanted to learn to drive the Cayman (987.1 Cayman S) before making any changes to it.
Personally, I think the car is very balanced in a stock form. I don’t know what camber, or toe setting it has right now. It has some old tires and has very low grip levels, but it helped me learn what the car likes, what unsettles it and what the car hates. Initially I had a lot of issues with over rotating the car and inappropriately applying throttle. The biggest issue I have right now is not having enough thrust coming out of medium and high speed corners. I just can’t put the power down, but I am hoping that will go away with proper 200tw tires and a stiffer front bar.
Next season I will be going with maxed out camber settings in the front, will start with -1.5 in the back and have toe settings similar to yours. I do want to find out the current setting first before making the final decision. GT3 front sway bar and Bilstein B8 dampers should stiffen up the car. For wheels, I will be going with 18X8.5 in the front and 18x10 in the rear (max to stay in street class). As far as tire width, I am waiting to see what becomes available come spring time and what I can fit in. If I can fit 275 in the front, I will go with that, but only if there are 285+ tires available for the rear and I am able to fit them. 265 would be ideal, but no one will make an 18” diameter 265 tire. I don’t believe a square setup will work at all on the car in a “Street” trim. Lee’s car is different and his driving style is also different than mine. I need smaller front tire to balance my corner entry speed. Otherwise, it will be 255/275 as that is what’s currently available from Bridgestone. Most likely I will end up with 255/285 as I do believe a 285/30/18 size is coming next season (don’t quote me on that).
I am also looking to go with HP Plus pads as I love them for autocross on my current car. Cayman has an amazing brake feel, but the bite is terrible on the stock pads.

 

I agree, the car is very well balanced. Then I started touching things... :P

You are absolutely right about inside wheel spin. It happens WAY to easily. The right solution is the stiffer front bar, but I think you need upgraded end links.

In regards to tire, I think you can fit quite a bit of tire, assuming you haven't touched the front caster. With the caster set the way I have it now, my front tire (at full lock) is just 3mm away from touching the fender lining.

 

You need to get stickier rubber, even if you have to put the exhaust back on. RE-71R will be the single biggest improvement you can make to this car. Hoosier A7 would be even better.

 

You made me think, and I started running numbers through the classification system.

If I get a 9inch rim on the rear, and keep everything else. I can run a 200W tire without changing classes!

BUT I just got these front PSS tires! Grumbles. Perhaps new set of rims are in order....hmmmmmmm...

DAMN YOU!

 

It's true that PCA regions seem have various, inconsistent classing rules. I didn't know any used a points system, for instance.

Per the PCR, as I read it and as you say, the 9.5 rear is not legal in SS except with the OEM 19 x 9.5 wheels. It is legal in Production, in fact you can do 18 x 10.5 on the rear as you can go +/-1 on width as well as diameter. A 987.2 can go even bigger. This is all based on the specs in the back of the 2015 PCR. A 255 front tire wants at least an 8.5" wheel to support it, and 9.5 would be much better, but you are limited (in the PCR) to a 9" front to stay in Production with a 987.1

 

The Bridgestone RE71R will really help with power down out of corners, as will more front bar.

Most people think a 275 on 8.5 is no good. I've done it and like it well enough but I'm in the minority. There is an RE71R 265-18 now. It should match up well with a 275 on the rear and preserve a little diameter stagger to not mess up the computers too much. (You may have to research this some more.)

IMHO, if you want to be competitive, get as much tire as you can (given the limitations of wheel support and fit) then tune the car to be as drivable as possible. Don't tune the handling by undersizing the tires at one end or the other.

And, yes, you may have to learn to drive around certain issues!