NOPDK

Have 8+ track days on my GT4 now. Was up at Sebring this past weekend running with Chin. Had some initial impressions on tracking the GT4 a few months ago but now have much better feel for the car. Have been daily driving it and tracking around 3 times a month.

Had my alignment shop max out the stock camber range. Around 1.5 front and 1.1 rear. Past that and you lose toe. With that setup I found the rear end unstable under hard breaking. It will wiggle around a good bit. Not hard to control but also not confidence inspiring.

Have been speaking to John at BGB about advice for street/track alignment settings and different parts. He recommended camber of negative 2.75 front and negative 2.25 rear as a good dual use starting point. Some toe out up front and some toe in for the rear. Have 3 track days in on this new alignment which required installing Tarett engineering front toe links with bump steer and rear toe links. Installing the front also required a bunch of shims. My local shop underestimated how many and I had to reorder extras.

On track BGB's recommended specs worked great. Car turns in sharper, good bite and the rear end doesn't dance around on braking. Car is on stock middle position on roll bars. At Sebring car did not understeer except in Turn 5. Loads of understeer in this corner. Tried a bunch of lines through and all had some degree of understeer. Other corners car felt great. The aero downforce was really confidence inspiring in Bishops bend and car felt much more planted than my 991S ever did through here. I texted John after my first season and he was good enough to get back to me with some advice. As sebring is very bumpy I don't want to go too hard on the rear of the car as it will likely dance around in 17. For my next Sebring outing in November I'm going to go one step softer in the front and keep the rear in the stock middle position. Will see what that accomplishes. On the road at around town speeds the extra camber is transparent. On the highway car doesn't track as straight as stock alignment. Not a problem but it will drift more easily following seams. I figure with my dual track and commuting the tire wear should even out over time. Tires are wearing fine this far.

At Rennsport I spoke with Andreas Preuninger for 20 minutes. Great, great resource and very passionate. He seemed very open with my questions and just asked that I didn't post specifics. One of the things I decided was a worthy point of upgrade is the headers. Compared to this motor when it was in my previous 991S I feel that the midrange torque is flat. Also in the 991S the motor pulled strongly to redline whereas in the GT4 it runs out of breath 3-400 rpm below redline. Motor would benefit from better breathing. The extra exhaust pipe that kinks over the rear axle must add a good bit of back pressure and I think opening up the exhaust can only do good things for the power. It should add back that midrange torque and hopefully help it breath better at the top end. As the Cargraphics cayman headers have been raced for years with BGB I felt comfortable ordering a set. They should ship this week from Germany and I'm really looking forward to seeing what they accomplish. I'm cautious on changes to the intake side of the equation and I don't want to risk warranty issues with software changes. The larger 82mm throttle body and IPD plenum are tempting but I'm going to let a few people try those mods first to make sure they don't throw any codes and produce a real power benefit. I did order a set of K & N air filters from John as that might reduce the intake restriction a bit? Figured it couldn't hurt. I've been running the new filters for 10 days and have noticed the crackles and pops on overrun when lifting off throttle are nicely more prominent. Sounds great. Intake sound is a little louder but you soon become used to the change. Can't feel any power difference, not that I was expecting to but the extra sound track was worth the cost.

I've been pleased with the guidance from John at BGB and have purchased my parts through him as his expertise has been a great value added. (note I have no affiliation with BGB and have never met John in person, just appreciate when a vendor goes the extra step of not just selling a part but also educating you along the way. Was pleasantly surprised that he responded so quickly to my text on Saturday when I was at Sebring).

Pict of car sitting in pits at Sebring on Saturday just before a nasty storm rolled in.

vantage

Great info, thanks. Do you know how much toe-in is appropriate for the rear? 1/16" total?

mooty

concur, as stated in another thread, most track used cayman needs the toe link and tie rods due to camber.

john at BGB is well versed with all things cayman.

NOPDK

Per John at BGB

Set up alignment from
Front:
camber: -2.75
Toe: 1-1.5 mm out per corner

Rear
Camber: -2.25
Toe: 1-1.5 mm in (up to 2mm if dancing under braking) per corner

supercup

Love the color of your car!

mgerber

Thanks for sharing the info and experience. Sounds like the car with the most recent alignment specs is a reasonable street/track compromise.

usctrojanGT3

I was going to do -3 to -2.7 front and -2.5 to 2.2 rear on my camber. Thanks for the info on the toe settings. I was also thinking about going 1 more setting softer on the front sway bar but I might leave that alone and see how the car does with the proper alignment first.

RealityGT

Thanks for sharing Sub'd

BGB Motorsports

I think that you will like the setup like this. The OP was curious about going 1 hole softer on the front bar to full soft but i told him that Sebring is both fast and bumpy and that it would be worth trying it once with the bars set as is and then going back. His only complaint was push in the carousel and I was hesitant to tell him to go to full soft on the front bar because the front bar on the Cayman and any Porsche for that matter is the most powerful tuning tool on the whole car. It can make the car tight or loose when you're in the window and you go stiffer or softer. Sebring has long fast corners where you want more front bar rate to keep the rear planted in fast corners and when attacking on corner entry.

I made some revisions to Orthojoe's 991 GT3 setup from 2700 miles away and he was digging it so it's not just Caymans that we love to tune on and tinker with, we love all Porshies!

4carl

"Have 8+ track days on my GT4 now. Was up at Sebring this past weekend running with Chin. Had some initial impressions on tracking the GT4 a few months ago but now have much better feel for the car. Have been daily driving it and tracking around 3 times a month."

What type of oil and coolant temps did you see? Any other issues from the track use? tire ware?
thanks carl

Quikag

Great write-up and thanks for the tech! I have stock parts, so I got -1.1 rear and -1.6 front with a few shims with zero toe front and 1/16" total toe on back. Also did the aero tweak and full soft front, full hard rear on sways. I hope the car isn't too loose on the track this weekend. I'll find out soon and adjust accordingly.

ChrisF

NOPDK - thanks for the write up. Really appreciated. I love the fact that between you and BGB, I'm getting some of my Winterfest R&D out of the way! I've also had really positive experiences with BGB even from thousands of miles away. I just need to figure out how to give them some of my money.

What kind of laptimes are you doing at Sebring?

usctrojanGT3

Yeah, I think that's good advice. I'll leave the sway bars alone and see how having a proper alignment helps with the understeering issues I had last month. I'll be running 19" BBS wheels with Trofeo Rs so that's why I figured I'd go up to -3 front and -2.5 rear on the camber. I also had Spyerx help me make the aero adjusments (higher rake on the wing and took out the plastic blockers).

NOPDK

Oil and coolant temps maxed out at 2/3rd's up the scale. Never an issue. Car ran solid. It was warm but not crazy hot on Saturday. Have run Palm Beach when it was low 90's and HOT with zero coolant issues. Car is amply cooled for hard running. Tire wear was even. Start cool around 28 degrees at all corners. had even temp rise front to rear so balance was good. Got up to around 35/36 temps. To me tires have best grip around 33/34 and start to fall off above 35. I've been told that up to 38 is ok with the sport cup 2's but personally I'm feeling 33-35 square is a good range.

NOPDK

What track will you be running? If the rear of the car dances around under braking then you may need more toe in which won't be possible at that camber without adding the toe links. Post how the car handles with the roll bars adjusted as you mention. If the track is bumpy the rear might get unsettled. Do report back.