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Shaping up a new-to-me 07 GT3

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Old 06-09-2014, 11:51 PM   #61
Tom-TPC Racing
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Bilstein clubsport?
Nope. They're Damptronics.
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Old 06-10-2014, 12:43 AM   #62
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Default Shocks & Springs

I am using Bilstein Damptronics because I like the versatility of PASM. I don't have a truck and trailer so I drive to/from tracks, and occasionally I like driving my only Porsche out to dinner. And what if I told you there's an aftermarket PASM control box available to drive any PASM shock to poduce the compression/rebound curve of a race shock? And the button can be used to toggle different curves/peak stiffness. On top of that, the software can change the shape of the curve by controlling the oil bypass valve in the shock. This is what I want!

Conventional adjustable race shocks create more resistance to oil flow which make the valving stiffer by turning the ****(s) to reduce the size of the oil flow path and forcing the oil through a series of shims. Re-valving to make stiffer usually means add more shims or thicker shims. I work JRZ's almost daily and would definitely use them if I was building a pro car to run endurance races. But for my streetable track car I'm going with electronic.

I installed GT3 Damptronics on my previous street/track car, which was a 997.1 Carrera S. On that car, I first installed the Damptronics as they were right out of the box which came with 330/717 in-lb springs(I tested the springs myself). I found the front to be very harsh over bumps and bouncy, and didn't have good support for high g-loads so I got rid of the short Bilstein 330 main springs and tender springs for a longer Eibach 450 front springs. The ride was improved! The taller spring made with longer length of spring wire absorbed the bumps much better AND have more support and improved stability under heavy braking. My conclusion is that tender springs are not needed unless the main springs are stiffer than 800. Tenders are used to soften the compression ever so lightly should you take a wheel off ground, this reduces weird harmonic in very stiff main springs. Anyway, I increased the front to 500 and shortly after I sold that car. It was a great handling car.

Interesting fact- this new set of Damptronics I just got have stiffer springs that the previous set all the way around. +20 front/+10 rear. They have the same part number but different production date. My guess is in from Bilstein to sell the same coilover kit to the .2GT3 and GT2 they have to increase the rate and make a one-fit-all kit.

On the GT3, I am going with 500 fronts from the get go. I don't use 60mm ID metric springs. I use 2.25" so the front spring change requires 2.25" ID hats and perches. Easy direct fit stuff.
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Old 06-10-2014, 12:43 AM   #63
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I bought my first cup car (2000 MY) factory yellow from mike at TPC and Tom helped with setup. That car was full stiff front and full soft rear. It handled so much better than the other 996 cup cars.... Even being a few hp down on newer cars it was easy to be competitive in pca.

Hope TPC guys doing well.
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Old 06-10-2014, 01:50 AM   #64
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amazing!

what product did you use to clean the alcantara steering wheel and shift ***? before and after pics?
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Old 06-10-2014, 01:50 AM   #65
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This was the shirt I used to clean 7 years of thilth off the alcantara steering wheel and shift ****. .........
Can I ask what you used to clean it up, other than the shirt?
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Old 06-10-2014, 01:52 AM   #66
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Default Getting more interesting

The rear is where it gets more interesting... The Damptronic rear uses the factory upper mount. Which works fantastically well for what it is. It is an aluminum mount which transfers the energy of the spring to the body of the car. The mount does have some kind of elasto foam/rubber doughnut to "center"(well, to locate is a better description) the top of the rear shock. This is the same type of rear upper found even on a GT3 RS. Again, not complaining as the Damptronics with factory rear mounts worked very well on my old car and on every car that's been tracked with those mounts.

With that said, I think it can be made to work even better by keeping the top of the rear shocks centered AND stable during compression/rebound. As you can see from the first two pics there is angle of misalignment when the car is sitting still with only -2.0 degrees of rear camber. The aluminum mount has a built-in angle of around -4.0 degrees, factoring in the camber the shock sits at 6.0 degrees. Unlike the front shocks, the angle of the rear shocks doesn't affect wheel camber.

I believe that some of the dampening control of the rear shock is loss during travel as the shock side thrust a little bit. As more negative camber is added that put more stress on the top rubber, forcing it to go toward the inside of the circle. And the bottom mount is also rubber(except for RS 4.0 and GT2 RS, which have solid bearings on the uprights). Still, it is amazing how good the rubber works, I've seen people run crazy fast lap times!

I've seen and used aftermarket rear spring adapter which allows for switching out springs, in fact the company I work for makes them too. They work as good as the factory cars as the spring adaptor encapsulates the factory aluminum mount and the top of the shock is located by the rubber in the same manner. But I've seen one aftermarket rear spring adapter that "locks" to a rear solid monoball top plate. And while its great to have the rear shock top centered but how does this arrangement articulate when the spring adaptor is seated and "locked" flat onto the plate? If it doesn't articulate at the top because its side movement is locked, does it then put all the stress on the small rubber bushing at the bottom of the shocks? I don't know!!!

What I am going to do is install a monoball plate that articulates. Only way to do this is with a racing type spring hat. This is going to present a challenge because the stem of the Damptronic rear shock is not long enough of this arrange;no threaded stem protruding above the monoball for a standard nut to thread on to. After some thinking I sleeve nut(aka threaded bushing nut) is worth a shot. Unfortunately after hours of internet search, no one makes a sleeve nut like this. So, I'm going to have to custom make it. Its going to be a lot of work which may not make a difference in lap times but knowing that it works better is good enough for me.
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Last edited by Tom-TPC Racing; 06-10-2014 at 06:49 PM. Reason: Reworded to sound more clear
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Old 06-10-2014, 02:09 AM   #67
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Default So much rear shock drama

There isn't much thread to grab so the thickness of the hat matters! Also I want to use the hat that puts the spring nearest to the original height AND mount the shock so that the travel(stroke) is not compromised.

The black hat is JRZ. The short gold hat is .2GT3. The tall one with the long skirt is .1GT3/Cup. I'm going with the one with the shallowest middle hole to get as more grip on the threaded shock stem.

I ended up shaving down the lower monoball bushing to get additional(sufficient) thread grip.
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Old 06-10-2014, 02:24 AM   #68
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Default Let the fabrication begin

Got a stainless steel hex bar stock and a the unusual size tap from ebay. Let's go to work. The sleeve nuts took So Much Time to manually make machine but I am happy with the way they turned out.

After machining I had to choice a top plate that will give the shock proper travel(stroke) so the piston won't bottom out. The red one is JRZ. The silver one is Cup/RSR which won't work because it I'll lose ~20mm of travel with this particular shock.
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Old 06-10-2014, 02:36 AM   #69
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Default Final assembly

The closest I can come to the original spring install height is 1.0" off. Luckily I order a pair of 1.0" Genesis spring spacers just in case.

Spring height is perfect and the shock height is with 0.1" of its original height in relation to the body. Oh, and I had to modify a socket to tighten the nut with a slit for the cable. It was A LOT of work but I love it when a plan comes together!

Good night. ZZZZZZZ
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Old 06-10-2014, 02:49 AM   #70
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Just tuning in, this is really cool seeing everything laid out!
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Old 06-10-2014, 06:12 AM   #71
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Default Did the same process with my KW's...

Had the same problem and came up with a similar solution of spacers and nuts on my KW's so I could run mono *****. It was an unexpected pain in the a**
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Old 06-10-2014, 01:23 PM   #72
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Originally Posted by Tom-TPC Racing View Post
I dyno'ed it after installing plugs, coils, and fuel filter made no difference in power but it did run smoother. The new MAF and airbox made the improvement.
Excellent!
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Old 06-10-2014, 01:45 PM   #73
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Tom, there is a centering tool for the tap such that you chuck the centering tool in a drill press and use it to center your tap. Put the soon to be nut in a vise, lower and engage the tool into the tap's chamfer and you end up with a very well centered hole with less effort. Obviously the drill doesn't get turned on.
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Old 06-10-2014, 01:48 PM   #74
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Originally Posted by RSRRacer View Post
I bought my first cup car (2000 MY) factory yellow from mike at TPC and Tom helped with setup. That car was full stiff front and full soft rear. It handled so much better than the other 996 cup cars.... Even being a few hp down on newer cars it was easy to be competitive in pca.

Hope TPC guys doing well.
That was our #23 GrandAm car. Great car! Glad you enjoyed it. That car was raced by Maassen, Pobst, Auberlen, and couple of old timers named John Morton and Bill Adam...it was Setup! Had the time of my life crewing back then.

We're doing well. Hope you are too.
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Old 06-10-2014, 01:53 PM   #75
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Originally Posted by dsu* View Post
amazing!

what product did you use to clean the alcantara steering wheel and shift ***? before and after pics?
Quote:
Originally Posted by azcarguy View Post
Can I ask what you used to clean it up, other than the shirt?
I used only the cotton t-shirt and water. I soaked half the shirt and lightly buff with the dry half. Then air dry. It felt so good to the touch afterwards. Sorry I didn't take pics.
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