powdrhound

400/600 is super soft for the track. Consider that 996Cups run on the order of 1300/1400 or so. My setting are -2.9F/-2.3R camber. Front and rear stock GT2 stays set 1 hole from full soft but I may stiffen the front one hole. I was running 600/800 rates on my JRZs and recently switched to 700/800 rates and different size tires running a 1" taller rear than front. We went from NTO1s 245/40/18 and 315/30/18 to the same 245/40/18 but the taller stiffer 305/35/18. These two items made a huge difference shaving almost two seconds per lap after fine tuning the sways. Incidentally my tire wear is now perfectly even front to rear telling me that we are splitting grip evenly among all 4 tires. Prior to these changes I was getting twice the life on my fronts compared to the rears. I am also able to run slightly lower pressures at 33/34 hot and have zero rollover with the 305/35s compared to the 315/30s. These changes have set the car up toward more understeers and I had to relearn driving it to a certain degree. The new set up resulted in an increase in my minimum speed in all corners since I have to enter all corners carrying more speed / momentum and force to rotate the car through trail braking deeper and delaying the application of power. I feel that 700/800 is still fairly soft and we have decided to narrow the % gap front to rear further by going to 900/1000 rates with slightly different helpers. I still drive the car on the street from time to time and 900/1000 is a pretty good compromise. Here is a video of a lap after the spring and tire changes. You can see by the dot going red in the bulls eye that we are pulling in excess of 1.05G in all the corners and under braking.

http://www.youtube.com/watch?v=ATd0q...ature=youtu.be

Vonschmidt

Luke

Sounds like a good setup on your cR would love some photos. As for your questions.

As we all know spring rate is a function of track design on a super smooth track like COTA or NOLA we would change out our springs for 1000/1200 and reset the sway to 1 notch and run a little lower not he tire presure.

However most of our time is spent on rougher tracks so we did a fair amount of setup changes from track to track. However a happy medium seems to have occurred when AJ and his crew dropped the springs from 600/800 to 500/800 a larger than normal differential however it resolved the bump issues. We also installed a bump steer kit from GMG did wonders on the curve we are looking at less than 17/1000 over 1.5 inch bump travel in the front and less in the rear. Being this tight we were able to maintain a tight camber curve even with the Porsche designed lack of an upper control arm in the front.

Reducing the front springs brought on some issues with power on oversteer so we lowered the rear ride height by almost 1/4 inch and increased rear toe from .10 to .12 and added some length to the rear lower control arms from RSS bringing everything into balance.

So I would agree your existing springs might be to soft and the smoother the track the more you can bump them up however if you want a car that can be driven on virtually every track with great results not optimum but great you might look into our setup.

Please post some photos and let me know if this answers your questions. I like a stiff ride with fast set and this car has it as configured.

LukeSportsman

Thanks for responses. Almost everyone I run with here are either mod'd 7gt3/rs or stockish 7tt's so I really appreciate the feedback. I even got feedback once just plopping into the race seat, "wow your car moves alot dropping in". My air cars aren't anything incredible but at 2200lbs I run 22/28's for street and the GT2 certainly seems softer even with the 18's. Fact (sadly), my GT2 rotates and sets slower then my Mustang AIX does on the NT01's.

I will get some photos posted soon, but as a "builder" I must admit that outside of maintenance I'm not responsible for this build. I've ventured over from PP to spend more time in this specific forum in regards to the GT2. So with winter coming it might be slow, but will start a thread.

Its driving nuts enough to consider a different car for track use, BUT I LOVE the GT2

How is the engine coming along?

Vonschmidt

Glad we could be of help, I am surprised that your gt2 rotates and sets slowly, are you sing Motons or simply relying on stock. Each part of the suspension is so interlaced with the others that in order to get a good set the need to function as a unit. My car has no movement when you get in and out so perhaps it's the springs or interconnecting pieces.

As for the engine we are down to the open case and parts are ordered. Hope to get started with assembly late November when all parts have arrived. Giving some thought to going with the Mahle 3.8 or 4.0 buckets still. Any experience out there on these.

Vonschmidt

Good Afternoon my Friends

Its been a while since I had time to post here and we have made a lot of progress on the motor. This is posted to help catch folks up on the issues.

After tear down has been completed and we discovered that the entire chain of events was caused by a defective or defectively installed left side timing chain gear. This low stress gear should never have failed and is something that we did not have access to unless a complete tear down was done and of course at less than 20,000 street miles I did not think of doing that.



This timing gear is in a majority of our cars and in speaking to several shops no one has come across this particular failure. if you look at the break you will note the discoloration which is either due to the heat of being flexed for many miles or perhaps the factory used heat to do the initial install. Since this is unlikely as the factory and even after market shops use a press to install these we are left with the conclusion that as the miles passed this piece flexed constantly on each revolution and eventually failed.



A closer view shows the material actually seems to have an abundance of carbon on it in what should have been solid metal again suggesting that this was a long term latent defect.

Unfortunately no mater what the cause the effects of this breaking were spectacular. As the gear gave way it allowed the chain to slip from its normal position and swing around for a few rotations bashing everything in reach before falling to the bottom of the housing This in turn caused a chain reaction resulting in an intermediate shaft failure, bent valves, damaged pistons and heads.

The process of the rebuild is already underway and I will try and post some photos of the work already done and that which is ahead so those that are interested can see.

Bottom line we hope to have the new improved motor on line by Mid February and then see what the improvement in my skills as a drive from the Spec Boxster translate to with all this power.

TrackDays247.com

Definitely one of the most interesting threads on a spiritual successor to my car. Nice.

My 930 engine issues/rebuild - several years back: https://rennlist.com/forums/911-turb...-pictures.html

Vonschmidt

Got an offer from a fellow RL member that I track with to drop the parts off and he will ask his metallurgy folks to take a look at this failure. What a great forum that's exactly what I'm looking for.

Don't have any illusions that even if defective there will be much recourse the car is way outside Warntee however it might help porsche look at this part and insure future runs address any issues discovered to insure that others don't suffer the same fate.

Thanks Tor see you next week.

powdrhound

Unfortunately, I'm pretty sure Porsche could care less, a fact solidly proven by their response to the coolant pipe fiasco.

Vonschmidt

I realize that you are correct but guess I can always hope. Our cars are so well designed and engineered it just seems unbelievable to me that they don't go the few extra feet to a make them perfect.

Of course its kind of like my F-450 with 63,000 miles completely blowing up internally and ford basically telling me its my fault., we have been waiting four weeks for the tear down and review, And then a week later I had my Escalade fail and the Caddilac dealer gave me a Escalade to drive and had the cracked piston replaced in less than 7 days. No cost, no hassle.

Texgirl

My husband and I are looking for a GT2 he has driven for years and has a 2010 cup. I have an Audi but we have always wanted one of these.

Sounds like yours is too highly modified to drive on the street so we would not go that far but just the raw power is a real turn on.

If you have a GT2 and a Spec Boxster how do you chose which to drive at a track event and what is your daily driver.

mooty

^boxster spec for racing GT2 for DE
if u want 997GT2, i have one for sale.

Vonschmidt

Ran into a snag with the build and am looking for a new part that porsche does not seem to have in the country now and estimated arrival time in US is Jan 14th.

We need the right side Guide rail PNA 996 105 166 70

Does anyone have one they would be willing to sell me.

Vonschmidt

[QUOTE=Texgirl;10987228]My husband and I are looking for a GT2 he has driven for years and has a 2010 cup. I have an Audi but we have always wanted one of these.

Sounds like yours is too highly modified to drive on the street so we would not go that far but just the raw power is a real turn on.

If you have a GT2 and a Spec Boxster how do you chose which to drive at a track event and what is your daily driver.[/

The last question first. The GT2 is a DE car you would need to install a cage and look for a class. With all the CF that's just a crime. If you were to buy one most of the changes we have made coud be implemented and retain its street driving, primarily just putting some rubber back in the suspension and a stree alignment.

The Spec Boxster is a great class for racing and if you guys have any interest I'll be at TWS in College station tthis weekend with the SPB. You can come by and see for yourself the fun this little car can provide.

As a spec class all the cars running have to be the same so it really comes down to driver ability, some luck, and race craft. Doubt your cup car driver would be interested but perhaps we can entice you to join our ranks. As for the cup car driver the SPB is a great learning tool it really keeps you on your toes in corners as you have no HP to make up for mistakes. Makes you a better high HP car driver by far.

Texgirl

Thanks I guess when we get one it will just be a street car with occasional DE events.

Vonschmidt

The motor is going back together great. I have not posted photos for a while just trying to find an good online storage media that I can link to any thoughts.

As for the car we will be loading the car and taking it down to Houston where they should be able to start putting the final parts back on and reinstall the motor itself. I'll try and post a few photos tommorow.