ervtx

td - I had a feeling those pics would end up here!

Scott - awsome pic... did you used to drive for Joie Chitwood?

himself

Yeah, it did seem like a good spot to re-post those.

-td

Bryan Watts

Definitely! The guys who built our car (www.rrtsuspension.com) spent a lot of time modeling the suspension and coming up with a better solution for making grip up front than the typical BMW solution of lots of front spring and lots of front bar. They certainly didn't reinvent the wheel, as most of the things we've done have been done on BMW's racing in Pro series in the past, but the did take the time to study and understand why and then explain it to me.

On our car: Helper springs, smallish front bar connected to the control arms rather than the struts to further limit it's effective rate, roll center adjustments to the subframe and control arms to limit roll through geometry, and increased track width of 2+ inches over the stock control arms through the use of a tubular front arm.

Thanks to the wider track and improved roll center geometry, we're able to run a relatively soft front spring, which further helps to add additional rebound travel.

As has been mentioned in this thread as well, things you do to the back also affect the front. We run no rear anti-roll bar in order to maximize rear acceleration travel, but rebound damping and other things must be considered to make sure the rear doesn't totally squat coming out of the turn and carry the nose.

For the guys running 1300+ pound spring rates, what kind of dampers are you running? It takes good dampers to control such a heavy spring over such a very small range of movement.

Larry Herman

Moton 3-way motorsport shocks.

Bryan Watts

Ran those in the past but found them to be too stiff for the spring rates we wanted to run, and, at the time, the only option we were given for a revalve was to send them back to Europe. Running Ohlins on our car now.

schvetkaaks

Same here

smlporsche

Todd-

Thanks for allowing those of us who are neophytes in suspension engineering to use your example.

In addition to Bryan's comments (and he obviously knows alot more than me) in looking at pictures of cars that are "set up" two thoughts occur to me when I see a pic like your's.
1. The road just drops off as is the case on the inside of many corners...
2. that the car doesn't have enough rear spring to keep the outside rear corner from squating too much.

As my friend the engineer said all cars flex and as is the case in most cages you don't have your cage welded to the strut housing so there will always be some flex.

I've tracked a Boxster S as well as my 944 SuperCup. When the cars were near stock configuration with R comps on it was relatively easy to get a tire off the ground comming out of Oak Tree @ VIR. Now with a much stiffer rear end I can't get a picture of me lifting a tire there.

Food for thought.

PS - Todd in looking at your signature I would have thought that you would run stiffer springs in the rear as it is a rear weight biased car. I'd be intrested in why you did what you did.

schvetkaaks

It wasn't me, it was the builder of the car. I bought it from the previous owner, who changed to Jetta TDI's, and I think it is because that after much testing, this fairly neutral handling car worked best on the long, smooth tracks they were running in Grand Am. Speedsource Motorsports had 2 Boxsters in Grand Am and came to the exact same setup independently. (see this interview - http://www.motorsport.com/news/artic...39&FS=GRANDCUP - I can't remember where I saw the numbers, but they were the same as mine)

I will probably switch to different springs sometime this year, but I've already poured too many thousands of dollars into fixing the problems with this car this year to spend anything more.

sjanes

Well, my 911 Targa lifts the inside front and I wouldn't put that car in the "minimal chassis flex" category In older 911's at least, I believe it's due to the front roll center being too low.

mark kibort

I like this one of Sofro

Porschemac

Wow, great setup.
Todd...
Your car looks alot like the one featured in Excellence June of 2006.
Is this were you got the idea?

Of course the Shadow is Much more Aggressive, I can't help but think how awesome a whole fleet of Boxster Patrol Cars would look.
Maybe that should be a required SpecBoxster Color scheme. I am surprised we haven't run at the same events yet.
The Shadow has been masquerading as a Patrol car Since 2003!
Check out the website For The Official CHP Boxster.
http://www.chpboxster.com/

MTosi

TRG at LRP

Jarez Mifkin

Wow, the 997 cups must be getting the air because the engine is is the back and the front end is so light.

DanR

or they are just going silly fast!

DanR

here is my effort from WGI last week.