Earlierapex

I know "use search," but the search feature on rennlist is, um, discomboblooluss, and Orthojoe's "war and peace" tome is awesome, but longer than the bikini pic thread in off topic.

I have a few basic questions if you know them off the top of your head and don't mind:
1) can you get -3 camber? If not, what do you need to do to get there?
2) what are the best 19in wheels to run with PCCBs for hoosiers? Running with TC off is fine.
3) which half cage has the most robust attachment points?
4) which front and rear rollbar setttings are best? a little "loose" is way better than a little tight.
5) which are the stickiest tires in stock 20in size?
6) can you shutoff the airbag light for the seat side bags with an OBDII code reader if you replace the stock seats?

Any other basics you would advise? Has anyone used one of those cute, little track-tire trailers with a 991?

Thank you!

Hams955

1) can you get -3 camber? If not, what do you need to do to get there?
- Yes but not with the OEM hardware. You will need extended length monoball LCA inners from RSS to achieve that kind of camber. You will also need adjustable thrust arms or the adjustable LCA pucks. I'd recommend the pucks.
2) what are the best 19in wheels to run with PCCBs for hoosiers? Running with TC off is fine.
- Finspeed or Forgeline GA1R's. VERY tight fitment; be prepared to score your barrels and thrash your calipers.
3) which half cage has the most robust attachment points?
- GMG WEC cage they made for GT2RS, or BBi.
4) which front and rear rollbar setttings are best? a little "loose" is way better than a little tight.
- loose front and third hole rear. I'd recommend middle front and third hole rear
5) which are the stickiest tires in stock 20in size?
- Depends. Street alignment the Dunlops hold up better than SC2's. Aggressive alignment the SC2's perform better. Trofeo R's perform the best on track but wear out the fastest of the three.
6) can you shutoff the airbag light for the seat side bags with an OBDII code reader if you replace the stock seats?
- You have to code out the modules with a PIWIS-II that can load into engineering mode to permanently remove the light. A simple OBD-II reader will clear a code but the code will return immediately.

- Chris.

porscheflat6

Agree with all thee above

Mvez

1) You do NOT need pucks or adjustable thrust arms to get over -3 front camber. All you need are Tarett "Race" monoball front camber plates, which provide 1 degree of EXTRA camber over the stock top mounts, which allow you to use WAY less shims and thus keep caster in spec. This means no pucks or thrust arms are required. It's an easier way to achieve this type of camber with stock arms if you so choose.

Most people simply don't know this part is an option or even exists for the GT3. Plus it's a lot less expensive than a set of pucks and thrust arms, and safer as you don't have to shim the hell out of the lower control arm. These parts are the same for the GT3/GT4.

Hams955

Wrong information.

You can get the camber with the camber plates to -3 or more alone, but your caster will be too high. The stock LCA's and inners will get you to around -2.6 with full engagement on the studs and retain the hardened shims of the LCA. Technically you could accomplish it with upper plates, but you'd still need either pucks or adjustable thrust arms to keep the caster in check.

The only advantage camber plates offer over the monoball inners is that it will not increase track width as camber increases. The installation on the monoball LCA inner is simpler as well. It does not require you to remove the strut and R&R the camber plate; require more labor hours as well.

Your suggestion is almost the same price. $500 for a set of the monoball inner LCA's or $450 for camber plates.

- Chris.

orthojoe

1) Yes, but you will need shims for the LCA. Once you go over about -2.4 camber you'll get too much caster and rub the fender liner. You'll need adjustable thrust arm bushings to roll back the caster.
2) The best are the ones that will fit over those calipers. LOL
3) I'm a cantrell fan myself.
4) This is a very personal choice. I know some people that like soft front and stiff rear, while I like stiff front and soft rear. It's totally up to your driving style.
5) I think cup2 are still the best choice. Dunlops are a touch faster, but they wear faster, so the few tenths aren't worth it. I hate trofeoR. hate them.
6) No. You'll need the super fancy and expensive porsche module that the dealers have

ipse dixit

CIFY

Mvez

No, it's correct actually. When you increase camber with shims you pull the wheel toward the front liner, adding caster too. When you increase camber from the strut top, you pull the wheel back toward the rear liner, without adding track width. Both add caster. Sowhen you use the Tarett plate with just a few shims, you then pull the wheel back toward the center of the wheel well, and can achieve an acceptable caster value without fender liner rubbing. That's why Tarett redesigned their "Race" plate for the GT4/GT3 because people found out you can place the camber plate somewhere in the middle of the slots, then use shims to pull the wheel back into the middle, thus achieving an acceptable caster spec. It just takes a competent shop to know what they are doing, or somebody who isn't lazy.

Not to mention you avoid all the safety issues with engagement. So if you want race spec camber via shims, be prepared the change the whole front suspension with monoballs, thrust arms, and tie rods. Or just use a properly designed camber plate, with just a few shims, and achieve a high camber alignment with acceptable caster without fender liner rubbing.

Hams955

Even with the Tarett camber plates, you end up with caster above 11 degrees if you go beyond -2.8 camber. That's too much caster for these cars. More caster isn't always better. You don't need thrust arms and pucks, you can use either. If you read my original post - I suggested the use of pucks over thrust arms.

Even with your camber plate suggestion you still need pucks or thrust arms to bring caster within a good spec for the car.

YES; caster is higher on a GT car and it is a good thing. But you can have too much of a good thing.

- Chris.

Hams955

Nice edit.

Still wrong however.

- Chris.

Hams955

I will correct your statement simply by saying I agree with you that camber plate is a method to achieve -3 camber from the top without increasing track width. It is perfectly fine to do so. Your mistake is assuming that you can hit caster spec on camber plates alone at that level of camber. You would need to press in pucks or run an adjustable thrust arm.

By the way - these guys are great in that they allow you a great range of caster adjustment without the harshness of a solid puck: http://www.rennline.com/HD-Thrust-Ar...info/S-05028P/

Kind regards,

Chris.

Mvez

All good. I'm trying to refresh my memory from when we did all the GT4 alignments with these top mounts. I believe you are correct in that the actual "spec" number can't be hit, what I mean is that you can center the wheel as such that you don't get front fender liner rub, with acceptable caster, for a high camber value. The additional camber it gives lets you "use" a few shims to pull the wheel back toward the center of the wheel well, giving more ideal wheel placement, without having to use caster pucks.

We've got a number of GT4's proving this, running big 265-35-19 tires, on stock arms/pucks, and the cars handle superbly with higher caster. I'd rather deal with the geometry change from just the higher caster than shimming a ton and also increasing track width and caster, not to mention wider wheels also being used. I do like those Rennline ones, it just makes me mad that Porsche doesn't give us the old 997 style pucks from the get-go.

Earlierapex

Hams955

MPSC2 likes camber for sure. I'd shoot for around -2.8 front and -2.5-2.6 rear. I assume this is a .2 car right? If so, run zero toe front and run on the tighter side of toe in on the factory spec. You'll like the result. The rear doesn't need as much camber since it is a mulit-link setup; it will gain more camber on compression than the front strut type setup will.

As for caster - yes it's possible have enough caster to have negative impact. Given the RR platform, a lot of caster will cause skipping on rough pavement. It will also make the car push mid corner and slower corners on entry. It will also make the car hard to turn in. Keep caster around 9.5 - 10 on the new car and see what you think.

Camber plates are a great idea if you're thinking about running the Swift spring package. Kind of one of those "while you're in there" things to do. Just a thought.

- Chris.

Earlierapex

Thanks Chris. It's a 991.1 that I've been tracking some (5 days). I was going back and forth on whether to to get more serious about making it more track worthy. After last weekend at Sebring, I finally decided I was crazy not to spend more time at the track in this car. It's just sublime, but also very fast. I've got 20 years of experience, and even though it is very easy to drive, this car is too fast for 3 point belts.