Boxster in NASA-TTC

[racer_d]

I guess the real first step is confirming what improvements are allowed for NASA TTC class (or any other groups you would use the car with) before doing anything.

Sticky tires will help immensly, as will reducing tire stagger front/rear. Not sure MPSCs are the best out there but certainly a safe place to start. I would the worthy tires in the following manner, best to worst: Hoosiers, then Khumo V710s, then Victoracers, then RA1/R888 then MPSCs.

the GT3 front sway bar is a popular upgrade for reducing understeer.

5-7mm spacers up front is also helpful to dial out understeer

Alignment is critical. Using factory components, you will never get "enough" negative front camber for use with the tires mentioned above. Most can get between -1.5 and -1.9 degrees, beyond that you need camber plates and/or GT3 Cup lower control arms. Not sure how legal these would be for your class.

IMHO, PSS9s are too much of a compromise (catering to street and track compliance is not easy. They are a good upgrade, but still a compromise). If rules allow, I would search out something more "race" oriented.

[iflyadesk]

If I read you guys correctly, the car needs more tire and camber in the front. So, probably a good first step would be GT3 control arms, 245s, and a strut brace (how much of a factor is the strut brace?). Additionally, I'll get the sways.

To answer one question, the way NASA-TT works is you are assessed points for each mod. So you get to choose your mods, rather than say having springs alone bump you into street prepared, like Solo II. I'm pretty confident I could work in every mod I want and still be within the base class for this car (TTC).

I'm a bit confused on the tires. Are you saying I should run 245s all round, but keep the 7/8.5 wheel staggering? One of the rules for TTC is you are assessed points for the tire width of the widest tire. So, if I had 205/255s, I'd be charged for having 255s. However, if I ran 245s all around, it'd actually be less points than the previous setup.

I was pretty proud of my 1.5 deg neg camber... I guess it needs much more.

Finally is springs. I want more spring, but there are only two available: H&R and Eibach. These are nebulous progressive spring rates, so I have no idea how they compare to a standard racing spring. I noticed the BSR runs 450/500.

I want to avoid the purchase of dedicated coilovers for several reasons. (1) The increased complexity often just causes more headaches than it's worth. Without a true data acquisition system and a shock dyno, trying to tune shocks is a nightmare and best left to the pros. (2) The corner weighting on my car is already close enough to perfect to not warrant fiddling. (3) I have no intention to fiddle with ride height. (4) $2000-$4500 is a lot of races. I think seat time in the new car will be more valuable to me than Motons.

So, the only options I see for getting a lot of spring without buying coilovers is: (1) Some sort of custom fabbed sleeve similar to a ground control sleeve over the stock shock combined with re-valving the stock shock (they are after all Bilsteins) (2) having a custom spring fabricated. (2) is probably not possible, and would probably be more expensive than it's worth.

Has anyone on here ever tried fabbing their own coilover sleeve?

[racer_d]

Originally Posted by iflyadesk

I'm a bit confused on the tires. Are you saying I should run 245s all round, but keep the 7/8.5 wheel staggering? One of the rules for TTC is you are assessed points for the tire width of the widest tire. So, if I had 205/255s, I'd be charged for having 255s. However, if I ran 245s all around, it'd actually be less points than the previous setup.

I was pretty proud of my 1.5 deg neg camber... I guess it needs much more.

1) I am not sure you can fit a 245 on a 7" rim..

2) Running 245's all around will reduce understeer and make the rear a bit more tossable. I know several folks who ran Carerra Lightweight 18" wheels, I believe 8" (possible 8.5", sorry) wide all around, with 245 hoosiers with great effect.

3) Hoosiers and R comps will wear on the outer edges with less than -2.0 degrees. I think Tirerack has a "care and feeding" section for all the top tires. Seeing neg camber of -2.5-5.0 is really where these tires need to be to maximize potential.

[easyc]

You can pinch 245's on the stock boxster front Rim... BP has a good right up on it over at BRB. I think though that 8.5 all around is the best as you can rotate tires to balance wear out. As far as 245's all around... thats a preference... Im trying 245's all around next month, but right now Im at a staggered setup with 245 F and 275 R... Suspension wise the third option are Ruf Springs... they are made by HR but to Ruf's rates. Honestly though... PSS9's can be had for 1900, and their installation is not much more than it would be for the springs... As far as the front strut brace... thats a touchy subject... BUT money is def better spent on sway bars... The guys who cup race a cayman in Canada have been experimenting with adding a brace on the underside of the engine... and their reports are that it makes a difference...

[iflyadesk]

You guys have been a ton of help. This is what I love most about racing: consistently high quality people ready and willing to help fellow enthusiasts!

My registration hasn't been approved yet at BSR and BRB, but searching their threads have been very educational.

Here's what I'm planning at this point

H&R or GT3 front sway (still can't find a supplier for the modified endlinks--help)
H&R rear sway
H&R or RUF springs (waiting on RUF to confirm that they're significantly stiffer)
Used Schnell camber plates from "Rob in VA" if I can get a hold of him... registration pending...http://boxcar-racing.com/forum/index.php?topic=491.0

...although this writeup from "bodine" has me second guessing the camber plates:

"If you are building or plan to build a BSX car (that's the one with minimum mods, no cage, full interior) please hold off on buying camber plates or adjustable A-arms. I am going to petition the rules committee to remove these as options for the BSX cars. They will of course remain available for the BSR cars.

The reason is this. Pyrometer readings from the most recent POC Streets of Willow Event have shown that enough neg camber can be dialed into these cars for auto X and STS without them. Temps were linear across the tire with inside being higher by 6-30 degrees. This is a reasonable indication that the tire is not being worked excessively on the outer edge. More runs will be necessary to see a wear pattern and I will update you all on this.

We want these cars to be usable as daily drivers so if we can avoid excessive neg camber, we might hope for more than 800 mi to a set of street tires!

The delete of camber plates or A-arms will make this entry class even more affordable.

If you have already made this investment for your BSX car contact me for names of people who need these parts for their BSR cars at a no-loss buy-back.

bb"

I'm going to wait for the article this month from GRM on race tire testing, but I think I'm going to run 245s all around (maybe 245/18s with some new wheels based on some things I've read).

Any additional thoughts before I start swiping my card?

[easyc]

I got my droplinks from Tarett Engineering. They are a work of art and as strong as I will ever need. You can also get them from The Racer's Group, or I believe someone is know selling some custom one over at BRB.
The only other thing is... do only changing out the springs cost you less points than say struts and springs? Reason I ask is that changing out the springs is going to lower your car significantly and your stock OEM struts are not paired for such springs... thus at some point they will give away much sooner... many people will pair their aftermarket springs with Bilstein Sport Struts or ROW struts... Also I still think you should think about the PSS9's, you will be almost spending the same amount on installation for the springs as the coilovers will be... and the difference between the two is night and day.

Lastly have you thought about safety at all? Brey Krause Roll Bar extension is pretty much essential in our cars....

[racer_d]

Double check the safety component needs.. Some tracks/clubs require a BK bar ($350 or so used, $700 new), and/or the hardtop ($800-$1500 used) to be installed, and others still, a roll cage for what are technically "open" cars.