Spartan

Spent the weekend getting the GT3 ready for the track. Learned a lot about the 991 in the process and have some very helpful info for all the track guys.

Work begins!



First off after speaking with BBS Motorsports for a long time we fit up one of the first sets of E07 center three piece 19 wheels. These are 18" centers with the taller barrels. The center is a different design than the 997 GT3 centers and the bolts are on the inner instead of the outer. These look much better than the old centers in 19" imo. They did not have any monoblocks in stock and there was no way to get them in time for the event this weekend. Fronts were 9.5 X 19 ET 54 (later switched to 9") and the rears are 12 X 19 ET 48. I'm not worried about RWS issues with the 1mm variation on the rear from the stock offsets. If you actaully measure out three piece wheels you will find they will vary 1-2mm from the BBS drawings!



These would be wrapped in 265/35/19 and 325/30/19 hoosier R6's. The 235's people want to run on here are horribly small and the rolling diff to great. Stock is about 1.5% and the 265 & 325 combo are 2.3%. I drove the car as aggressively I could on the streets of chicago and could not get the ABS light to come on so we should be fine there. All of this is not quite bolt on as I will detail below.

Starting with the front I thought the 265 would fit a 9.5 rim better so that's what we ordered. Once we bolted it on we noticed that the tire looked stretched and it has a very large rim protector bead on it. This caused it to be very close to the spring which was not a big deal. The inner barrel was only about 2mm away from the top spring perch adjustment ring as you can see below. This might have been fine and would fit if you moved the ring by lowering the car. In the end we swapped out the inner barrels from an 8.5 to an 8 and ended up with the 9" front to be safe. The 265 actually fits this better imo which is a surprise since it should fit the 9.5 better. Goes to show that tire specs are not always accurate and you have to try bolting stuff on sometime$. Everything fits perfect now with lots of room. At full lock it might rub on the top brake duct but who cars. You don't full lock cars at the track if you are doing it right.



The rears are a little project but nothing to be afraid of. I still like the hips on the black one a lot better



The problem with the rears is that lower control arm that sticks way out. The bolt head would rub the inner barrel so you must remove and flip it around.



Installed a low profile lock nut (these actually hold torque better than the stock nut) and then trim off the remaining bolt that sticks out. Here is a pic after it has been flipped and trimmed



Now there is plenty of clearance! You need some clearance as the inner barrels on wide three piece wheels flex more than you would realize. It's not a bad thing it just needs room when it happens. Ok now that the bolt is taken care of you must address the brake line bracket which sticks out just as far as the bolt!



Take you time and bend this away without bending the line to much as it comes out of the caliper. You should be able to get your finger between the line and the inner barrel when this is done.

Ok wheels are done now its time for the GMG roll bar. What can I say about that? Well the one they sent me didn't bolt together. The X brace in the back was off by greater than 5/8 inch! Here is what I had to do to dry fit it together out on my deck.




The tension on those straps is scary but it flexed it out enough to dry fit it. Once I proved to myself it would actually bolt together somehow I had to figure out a way to get it that way in the car. This is a challenge as you have to force the bars out away from the car and there is no good way to do that when the bars are in in the car. Spent all day figuring out a pulley system to do that. The interior of that GT3 has heard more cursing that if should! I've been doing this stuff a LONG time and I'm really good at it. My bar was not made correctly imo and I would have returned it if it wasn't for my timeline. God I wish porsche would sell us a factory bar. My advice is to TEST FIT the bar out of the car first. If it doesn't bolt up easily call GMG and get a new one.



Next up was the Recaro halo seat install. No one sells 991 specific brackets yet so I ordered up an assortment. It seems the 991 seat brackets are the same as the 997 mabye a few mm wider. The nice thing is that it the 997 will all bolt up with some slight massaging. Really like how easy it is to remove the stock seats and how they hid all the boxes & wires under the carpet




Next up was oil change. Couldn't get 5w-50 in time so I went with the motul 5w-40. Sorry not good pictures here.


Installed some RS-29's which are my last choice of pads but all thats available at this time. Looking forward to options from endless or pfc. Will be installing some caliper studs to make this easier in the future. SRF flush was next.

My local go to shop (Chicago Performance & Tuning) took care of the alignment for me. The front shims for the lower control arms are the same as the 997 GT3 stuff so no problems there. The rears are a Motorsport part and cannot be purchased from the dealer.



Here she is on the rack with the wheels. Next up today is to install the AIM CAN bus data stuff and the passenger side track seat.



I will up date this post after the first run session this weekend to let everyone know if those hoosier sizes cause any ABS issues. If this works it will be huge to run a 265 front R6 up there.

Zucc

Great info, thanks for posting!

kosmo

awesome.
flipping and trimming the rear bolt was brilliant!

the GMG bar not fitting is crazy. They owe you something

orthojoe

Awesome post. Thanks for sharing!

Spartan

Thanks! Trimming suspension bolts on Porsches nothing new. Teams had to trim that exact bolt on the 2012 RSR's That RSR is where the 991 rear uprights came from to fyi

Dan39

Spartan, thx for this thread. What track are you running at and is it high speed, heavy braking, etc? Are you planning on adding any rear wing? Have you thought about the Cup car front splitter? It looks very similar like it might be not much more than bolt-on? I assume canards will come out later like they did for the prior gen.

EDIT: the reason I ask is I found it to have a bit of high speed oversteer and the braking to not be quite as good as I would have expected. Braking points when I compared the my track video to someone like TRACKCAR's at the same track were nowhere close - like 5 car lengths earlier, which I assume is downforce and maybe slicks on his 4.0 even though the laptime was similar?

Spartan

Road america this weekend. Don't know if cup splitter will fit but this one seems fine imo. You can always lower the car but that's not smart if you drive on the street all the time. If you have high speed oversteer check your alignment. If this is on stock tires you can probably blame them. Those canards are really marketing imo. True canards need to be big to generate the vortex along the side of the car which is their purpose.

Spyerx

Looks like proper track car now with the bbs. Love it.

Elephant Bart

Fantastic info! Thanks

MaxLTV

Excellent info! Finally it began.

SamFromTX

This is one of the most helpful posts, thank you for taking the time to post. Two questions please:
1-Did you drive the car with stock tires on the same track? I would like to know what time savings are gained by going from SC2 to Hoosiers.
2-How much negative camber did you add F/R?
Thanks.

Manifold

Good thread, subscribed. Two more questions:

- What toe settings are you using?

- Did you corner balance the car?

Spartan

Corner balancing is a waste of time if there is any rubber in the suspension. It can't hurt anything though so its really up to you.

For alignment this car will see lots of street time so 2.25 F camber, 1.8 rear, 0 front toe (toe out isn't needed) rear toe is 1.75 mm in per side. This alignment worked perfectly with R6's on a 997 GTS that saw a ton of track use and street use. The GT3 is different and I will post everything we learn from the weekend on tire wear etc

Spartan

No I did not. Street tires are for the street imo. Kind of like all seasons tires are not good in any season R6's are a huge leap from any of the grooved slicks out there. Night and day imo. Alignment settings in the post above!

SamFromTX

Thanks. A very exciting thread.