RCR917 suspension set up

Jack · 03-20-08, 11:16 AM

Fran,

I want to build a RCR917K for SCCA and NASA racing in their Super Production and Super Modified classes respectively. (These are basically CanAm classes. "Run What You Brung". There's a guy in Arizona running a Lemans winning 962!) After I read Graham's story from a year ago about how time and money consuming the original suspension was to set up, my heart was broken. I have neither the time, knowledge, support or Money to spend a half season doing nothing but go to Lime Rock and dial in the suspension.

Since the mono tub is a big departure from originality, wouldn't a more user friendly geometry be a better choice? Since all your wonderful cars are mainly for street use, wouldn't this be a better criteria for all your cars?

Jack

Big-Foot · 03-20-08, 01:31 PM

Jack - Having built and campaigned a number of cars in SCCA's SPO class - All I can do is to tell you to read and understand - very carefully - the GSCS for the GT class cars and the GCR. You won't get an SPO Logbook issued if you don't meet every letter of the regs.

-edit- You can go online to SCCA Sports Car Club of America to find the rule-books.

Ron Earp · 03-20-08, 01:40 PM

I second what Randy has said. I am putting together a Lola for SCCA SP classes and the cage design took some work. It meets the specs easily, but a lot of thought went into the design (not my doing, I had my tech inspector and a good cage fabricator do this work). The open nature of the Spider helped out with making the cage easy. The small enclosed nature of the 917 will make it harder, but a cool project!

Jack · 03-20-08, 02:12 PM

Thanks for the input guys. I have read the rules and for every car I'm interested in, those include all of Frans cars and the GTM, the first thing I do is design a roll cage based on those rules and all other safety considerations. The reason I like those classes is you can have your cake (917) and race it too.

Stay in touch guys as you are presently doing it, I still in the planning stage.

Jack

I think I attached two photos or files. We'll see!

Donnie Barnes · 03-24-08, 08:57 PM

I dunno, if you're that worried about the suspension, get a SLC and start from there. I'd guess Fran's suspension on that is better than the near forty year old Porsche design. But if you want to race a 917, race a 917! The truly hard work is done. I'm sure what Fran sells will be in the ballpark. If you want it good fairly fast, well, I'd suggest getting an assortment of springs and find a pro near you to go to a track day and help you sort it. Might not take that long. If you find it's somehow *horrible*, you could certainly get some input from Fran I'm sure on how to get it close.

If it helps, I have the first monocoque 917 on the way and definitely plan to track it. I have access to folks like Brian Smith and Don Knowles to help me set it up (as well as Farnbacher, potentially), and plan to get it pretty good. I won't cage it for actual racing, though. But I'm certain whatever I find would get you in the ballpark, at least.

--Donnie

Jack · 03-24-08, 11:24 PM

Thanks Donnie, I have completely settled on the 917K and it will be great to know someone else with knowledgable people to help is out there. What are your plans for an engine a transaxle?

Jack

Donnie Barnes · 03-24-08, 11:41 PM

Mine is getting a 993 long block that will be built by a professional race shop to be about 375 crank horsepower and VERY streetable. TWM throttlebodies with individual horns will give it a nice look, too. Doing a 930 gearbox with the r&p flipped. Will likely MoTeC control it and use a MoTeC dash, even though it's going to be street legal and titled as a kit car in NC.

I'm not very knowledgable, but I know people that are.

--Donnie

John · 03-24-08, 11:58 PM

I read Graham's story when he posted it as well; and i too was a little surprised at what he said. I know that the time period that the 917 was coming out of was a very revolutionary time for suspension development. In the span of 10 years, they went from fat drivers on skinny tires, to skinny drivers on fat tires. The '60s also saw the first computer aid in the design of a suspension (GT40) to optimize those wide tires.
I would love to know, what is it about the 917 suspension that makes it so hard to set up? I do a lot of time trial type events where I don't have a lot of setup time, I hope their is a few general tunes that I can use. Maybe, one for a tight course, fast course.. etc..