Autocross c4 tire ?
06-08-2009, 05:52 AM
#1
Racer
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Autocross c4 tire ?
I'm thinking about using my C4 with a/t for our local autox instead of the CSP miata I usually drive. My wheel choices are 17" sawblades or 17"/18" C5 magnesium. Are used A6's available?
06-09-2009, 05:05 AM
#3
Racer
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It runs in street prepared, since I have a harness bar. I have let a friend run the car at our local event 3 or 4 times, it's just a postage stamp sized lot, so the C4 isn't that competitive. I'm just trying to keep up my seat time while I'm waiting for a banged-up hand to get better. I worry more about being competitive in my CSP car.
06-09-2009, 12:03 PM
#4
Le Mans Master
FWIW, a harness bar does not put you into SP:
Stock Catagory
13.2.I. Driver restraints as outlined in Section 3.3.1 are allowed. Seats
may not be cut to allow for the installation of alternate seat belts
or harnesses. Passive restraint systems may not be removed. A
horizontal “harness bar” may be used as part of the installation
hardware for allowed driver restraints. It may serve no other
purpose (e.g., structural enhancement).
Stock Catagory
13.2.I. Driver restraints as outlined in Section 3.3.1 are allowed. Seats
may not be cut to allow for the installation of alternate seat belts
or harnesses. Passive restraint systems may not be removed. A
horizontal “harness bar” may be used as part of the installation
hardware for allowed driver restraints. It may serve no other
purpose (e.g., structural enhancement).
06-09-2009, 02:23 PM
#5
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John Berget Racing Tires (jbracingtires.net) might be a good place to start, but 17" A6s seem to be hard to come by used. One of my buddies has been calling him regularly for months now with no luck.
06-10-2009, 05:14 AM
#6
Racer
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My harness bar bolts in at the upper seat belt mounts. I understood it to providestructural rigidity to the chassis. I was told it bumped me out of stock. Is that incorrect?
06-10-2009, 12:13 PM
#7
Le Mans Master
IMHO I would have a hard time seeing a bolt in bar that does not connect to the frame as adding any real structural rigidity, although the vendor may claim it to some extent in their ads.
See if you can get one of your local tech inspectors' opinions before the event.
06-10-2009, 08:25 PM
#8
Burning Brakes
Tech (At SCCA events) does not determine class "legality". If Tech is telling people what cars are legal or illegal, they are out of bounds.
Legality is the responsibility of the fellow competitors. If they don't protest, then it's not going to be an issue.
That said, unless the bar *also* bolts into the chassis somewhere and starts triangulating things, it's not adding any meaningful rigidity to the car.
Now, is there anything else you've done as well? The bar is legal, but if you've gone and cut the air lid you might draw paper...
Legality is the responsibility of the fellow competitors. If they don't protest, then it's not going to be an issue.
That said, unless the bar *also* bolts into the chassis somewhere and starts triangulating things, it's not adding any meaningful rigidity to the car.
Now, is there anything else you've done as well? The bar is legal, but if you've gone and cut the air lid you might draw paper...
06-10-2009, 08:29 PM
#9
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The determination will be made at tech inspection, but the only time I've seen a harness bar bump someone out of stock has been when it's clearly a welded-in rollbar-style hoop vs. a bolt-in harness bar.
IMHO I would have a hard time seeing a bolt in bar that does not connect to the frame as adding any real structural rigidity, although the vendor may claim it to some extent in their ads.
See if you can get one of your local tech inspectors' opinions before the event.
IMHO I would have a hard time seeing a bolt in bar that does not connect to the frame as adding any real structural rigidity, although the vendor may claim it to some extent in their ads.
See if you can get one of your local tech inspectors' opinions before the event.
My bar also attaches in the upper belt mounts.
06-10-2009, 09:03 PM
#10
Burning Brakes
The intent of the rule is to prevent someone from sneaking a chassis brace thru and calling it a harness bar. If it bolts to the belt bounts, and has the minimum necessary extra structure to prevent it from moving out of position, it should be easily defensible as a legit harness bar.
The upper belt mounts really aren't the issue... It's what else it attaches to. Thin gauge tabs that keep the bar from rotating (like the AS&M bar has, that use the targa mounts) aren't going to add any measurable stiffness. Something that has triangulated connections into the frame-rails on the other hand, might not stand up to protest so well
The upper belt mounts really aren't the issue... It's what else it attaches to. Thin gauge tabs that keep the bar from rotating (like the AS&M bar has, that use the targa mounts) aren't going to add any measurable stiffness. Something that has triangulated connections into the frame-rails on the other hand, might not stand up to protest so well
06-10-2009, 11:23 PM
#11
Le Mans Master
The organizing Region may at its discretion provide an advisory
inspection for vehicle classification and legality, in connection with
technical inspection.
Last edited by billla; 06-10-2009 at 11:27 PM.
06-11-2009, 05:26 AM
#12
Racer
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The only mods are Wheel/tire and as&m harness bar. I think I won't have to worry about protests until I actually start beating people, and unfortunately the vette is has a big disadvantage on the home course. We run on a tiny, postage-stamp sized lot, and ftd goes to miata or s2000
06-11-2009, 08:40 AM
#13
Le Mans Master
I share your pain
We had a gate at an SCCA event last year that literally you could not get a 'Vette through without almost stopping....but the little cars were zipping right through it 
06-11-2009, 02:02 PM
#14
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I run BSP. 11 inch wheels all around 315s in the front 335s in the back . . . ran Hoosier A6 the first year . . . but am currently on kummo's (a tad cheaper) but no change in times
