SCCA CAM-C Thread

[NightmareMoon]

New driver running 305/30/19 RT-660’s all around with plenty of negative camber. What range of front and rear hot pressures are people finding that work best? I found some info buried but a fellow driver this weekend had some pressures that were a lot higher than I’ve seen here.

The good news is they aren't super sensitive to pressures AFAICT. The bad news is that at any pressures they're slower than Yokes

Try 33F/32R plus or minus 1psi, should get you in the ballpark.

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[NightmareMoon]

do you even hit 60mph in autocross?

Yes.

They totally do look like street cars, don't they ?

Looks great, much nicer than big ass bare aluminum one. How much AoA adjustment is there ? How'd you set yours ?

Mine looks like this, here without the second element yet (since they didn't send me necessary bolts with it).

Haha, yeah, its definitely no street car anymore.

FWIW, my wing builder (Zebulon) recommended to start with this specific wing slightly nose-up on the main element, because that's where this one is most optimal for downforce/efficiency ratio.

2nd element is set at max angle for autox, and min angle for track. Fancy-pants endplates (seperately adjustable for angle) leading edges should be perpendicular to the airflow.

IF I feel like its not doing its part to generating enough downforce back there at speed, I'll pitch it down more. I'll also do some testing at some point to find out at what angles the airflow detatches. This wing stuff is all new to me, so I'm going to enjoy figuring it out.

I haven't run it yet, except to drive it home, so no idea where the balance is at until this weekend's local event.

It surprises me (a little) that the 9 lives only bolts down with 2 bolts on each side (granted most wings are only connected at 4 points at the wing connection anyway). I went a little overkill with 8x 6mm bolts per upright. There's only 4 bolts holding the trunk on the car, so I may have over done it a little. Lateral stability is rock solid tho, this one is not going anywhere.

 

[WItoTX]

New driver running 305/30/19 RT-660’s all around with plenty of negative camber. What range of front and rear hot pressures are people finding that work best? I found some info buried but a fellow driver this weekend had some pressures that were a lot higher than I’ve seen here.

FWIW, I run falkens 29 front, 25-27 rear (on a 19x11.5 rim).

If you are on factory wheels, that 305 falken up front is going to make turn in less sharp. I had that set up with factory rims, and it was unpleasant to say the least.

 

[WItoTX]

It surprises me (a little) that the 9 lives only bolts down with 2 bolts on each side (granted most wings are only connected at 4 points at the wing connection anyway). I went a little overkill with 8x 6mm bolts per upright. There's only 4 bolts holding the trunk on the car, so I may have over done it a little. Lateral stability is rock solid tho, this one is not going anywhere.

Somewhat related to connection strength, two months ago we had a local event where a relatively new guy in a GT350 clipped the guy wire of a power pole with his spoiler. The spoiler stayed connected to the trunk, trunk latch stayed connected, and ripped the decklid off the car from the hinges.

If someone would have told me the spoiler was that well adhered to the car, I woulda called BS until I saw that.

 

[kz]

If someone would have told me the spoiler was that well adhered to the car, I woulda called BS until I saw that.

How did he do that - that just caught that wire the spoiler and nothing else ? Spoiler is bolted to the trunk with 3 (at least) bolts and has shitton of adhesive that is painful to remove.

As for wing mounting - aero forces - as long as the wing is generating downforce and not a lift, should be unloading those mounting bolts (I asumme we're talking uprights to the trunk) - only manouver/ G loads would create some tension / shear - but since uprights are flanged and unless you jump the car, some of this load would be transferred by the flange of the upright to trunk skin (bottom line - don't think you need a whole lot there).

Btw - main element angle on the pic is ~18 degrees.

 

[WItoTX]

How did he do that - that just caught that wire the spoiler and nothing else ? Spoiler is bolted to the trunk with 3 (at least) bolts and has shitton of adhesive that is painful to remove.

The guy wire was less than tight. He clipped the wire first with his mirror, dented above his drivers window, then I think with the slack in the wire, it was able to clip the bit of the spoiler that hangs over the quarter panel.

I was kind of stunned to see it myself, the whole situation was several things that had to happen just right for the wire to hook in that little gap.

In the drivers defense, I believe he was a novice, and he didn't panic when he started the slide that sent him towards the power pole and wire. He got the car straight and tried to hit the gap between the two. A foot either direction, and far more damage would have been done.

 

[kz]

In the drivers defense, I believe he was a novice, and he didn't panic when he started the slide that sent him towards the power pole and wire. He got the car straight and tried to hit the gap between the two. A foot either direction, and far more damage would have been done.

Stinks either way - to end up with car damage at autocross. We've had some decent share of damaged and even totalled cars here, but still.

 

[NightmareMoon]

We see car damage about 1 in 10,000 runs. Unfortunately thats like once a year for both of the local clubs. Lately its been a bit higher rate too. One recent incident involved a national level camc car (not me!)

We’ve even seen car on car (you have to really get lost and commit to being off course at high speed to pull that off).

then there are the D-prepared Miatas, which just cant stay mechanically working. Mechanicals are not included in my 1/10,000 stats, except when it results in throttle stuck open and the car jumps a tree stump into the adjacent lot. Luckily they’re light so you can push em off course pretty quickly.

 

[RobZ71LM7]

FWIW, I run falkens 29 front, 25-27 rear (on a 19x11.5 rim).

If you are on factory wheels, that 305 falken up front is going to make turn in less sharp. I had that set up with factory rims, and it was unpleasant to say the least.

I’m using Falken 305’s with SVE 19x11’s at all four corners. I appreciate the input from everyone. I haven’t autocrossed since 2007 and I’ve got a lot to re-learn after just 3 events this year. Two events were in mid 40’s-50 degrees so the tires were slick as hell. The one event in the 60’s they felt great. I’ve the fronts anywhere from 31-34 and rears 28-33 playing around with them. The car has -3 camber up front and -2 camber in the rear. A more experienced guy with a 1LE was running 37 up front on his. Right now I want as few variables as possible to worry about. It is pretty cool seeing the number of V8 Camaro and Mustangs out there now. When I did it years ago in an F-body it was like pulling teeth to get fellow owners to come out and play.

 

[TeeLew]

do you even hit 60mph in autocross?

In CA, it's maybe 70.

My approach would be to run all the rear downforce you can. Will it be unbalanced? Yes, but what you lose in balance as the car goes faster, you can pretty much make up with aggression and loading the front more deliberately with your feet. Braking will be awesome. Long, fast sweepers will be an exercise in managing front grip, but it'll be easier to do. BALANCED downforce is certainly the goal so add all the front you can, but it's much more important on a road course than in a parking lot. In a parking lot, it's kind of a deal of you take anything you can get.

 

[TeeLew]

I am going to use all the AoA I paid for ! Seriously though, I have little clue what to set it to, especially with little to none front aero currently. Second element is on, it has some of its own adjustment, I've set it horizontal as I could. This thing seems to work though once the car has speed, especially in transitions. Also, these are smallest endplates they sell.

This is from Sunday, ambient temperature 45F.

Looks great and I bet it's performing well. If I were you, I'd go to home depot and get 1/2" x 1/2" aluminum angle and tape (gaffer or heli tape is preferred) it as a gurney flap on the trailing edge of the upper element. It'll make good chunk more downforce at every angle and allow you to keep the underside flow attached at much higher angles. You can run it like a barn door if it's faster at that point. Peel it off when you're driving home for less drag. I promise it won't come off with the possible of exception of a wall and deceleration syndrome.

You should also heli-tape the leading edge of both elements to protect them from being sand-blasted to death.

 

[TeeLew]

We see car damage about 1 in 10,000 runs.

I saw a new guy spin in an S2000 a couple years ago. He just had a lazy, slow-hand loop spin, but he never went to the brake. He rolled 50 feet backward (that's always good for the engine) and right into a concrete freeway barrier. Such a cool little car to shorten up and to do it in a parking lot really sucked to watch. I'm glad it's rare.

 

[kz]

Looks great and I bet it's performing well. If I were you, I'd go to home depot and get 1/2" x 1/2" aluminum angle and tape (gaffer or heli tape is preferred) it as a gurney flap on the trailing edge of the upper element. It'll make good chunk more downforce at every angle and allow you to keep the underside flow attached at much higher angles. You can run it like a barn door if it's faster at that point. Peel it off when you're driving home for less drag. I promise it won't come off with the possible of exception of a wall and deceleration syndrome.

You should also heli-tape the leading edge of both elements to protect them from being sand-blasted to death.

My simplistic reasoning was that it worst case I have something resembling spoiler and even stock engine on street tire is more than enough to handle drag.

It did seem to make substantial difference (I had zero expectations - but it on and see what happens), no really high speed sweepers but went into the slalom at 60 mph and rear just stuck - it felt to have abundance grip.

I hate to use local event results because they're absolutely meaningless (I placed xx out of xxx on pax, yay !!) but I raw timed entire cam s except one car and outpaxed every single CAM car and we have a whole bunch of frequent UMI KOTM invitees (lol - but they're very competent drivers) here with a way more money in their cars that I would ever think of spending (also CAM T pax didn't really change while ours and CAM S went up substantially) - so bottom line is that it must not be that bad.

I do have gurney flap for the main element since it has slot for it - but there are two little spacers for second element sitting in it. May technically cut in into three pieces and put in anyway.
Plan is to have the wing wrapped in vinyl

 

[kz]

I saw a new guy spin in an S2000 a couple years ago. He just had a lazy, slow-hand loop spin, but he never went to the brake. He rolled 50 feet backward (that's always good for the engine) and right into a concrete freeway barrier. Such a cool little car to shorten up and to do it in a parking lot really sucked to watch. I'm glad it's rare.

Some of it is course design (but also site limitations - can't design a course to exclude every possibility) - we've had brand new C7GS go into the paddock (on dry) - ended up t-boning itself on a parked Suburban and luckily no one was in the way.

 

[kz]

That's my left front strut to knuckle joint.... Upper bolt had a nut half way down the thread (completely loose - it's tightened on the pic), bottom one (out of focus) had no nut at all.

I looked this evening at all front joints because of slight rattle over the bumps at low speed last weekend. This also makes for somewhat variable camber (struts were slotted for FS back in the day and bolts are non-splined service ones) and therefore toe....

Really should have been better about making sure car is mechanically sound before the season but was lazy and stupid.

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