C7 Autocross Alignment
Burning Brakes
Joined: Sep 2011
Posts: 960
Likes: 40
Basically, add negative camber.
Lowering the C7 the 3/4" that the suspension bolts allow will increase negative camber in itself. But the lowered car will have less spring pre-load which the driver style might like or might not like.
Well, the most interesting autocross rules would allow any suspension and any wheel and tire sizes as long as the tire tread stays under the outside fender line.
Weight can be reduced with smaller mufflers, a 21 pound Braille battery, and one-piece forged wheels (most often now called monoblock wheels). And all that if allowed by the rules. Reduce weight by avoiding run-flat tires
.
Lowering the C7 the 3/4" that the suspension bolts allow will increase negative camber in itself. But the lowered car will have less spring pre-load which the driver style might like or might not like.
Well, the most interesting autocross rules would allow any suspension and any wheel and tire sizes as long as the tire tread stays under the outside fender line.
Weight can be reduced with smaller mufflers, a 21 pound Braille battery, and one-piece forged wheels (most often now called monoblock wheels). And all that if allowed by the rules. Reduce weight by avoiding run-flat tires
.
Last edited by B Stead; Aug 10, 2014 at 01:47 AM.
Racer
Joined: Jun 2013
Posts: 311
Likes: 3
From: Poconos PA
The manual does have track alignments. I autox about 3 weekends a month. I use bone stock everything. I have a z51 m7. I should lower the car with the bolts.
B Stead, wouldnt lowering the car create MORE spring pre load? Im confused.
B Stead, wouldnt lowering the car create MORE spring pre load? Im confused.
Burning Brakes
Joined: Sep 2011
Posts: 960
Likes: 40
Spring pre-load doesn't change the spring rate but it does translate the use of the spring to a different force range of the spring.
Here's a motorcycle link where you can read about spring pre-load. Now, sag is a motorcycle issue of the rider weight being a large percentage of the sprung weight. But sag is also explained as increased pre-load raising ride height or decreased pre-load lowering ride height:
http://www.sportrider.com/technicali...eload/?image=0
Then the first graph shows a spring's force range.
The second graph compares a stiffer spring to the first spring.
And the third graph shows the force range of the first spring with pre-load increased as compared to the first graph. And that third graph shows the translation which means that the graphs differ by the same amount at any point. (Translation is the adding or subtracting of a constant.)
.
Here's a motorcycle link where you can read about spring pre-load. Now, sag is a motorcycle issue of the rider weight being a large percentage of the sprung weight. But sag is also explained as increased pre-load raising ride height or decreased pre-load lowering ride height:
http://www.sportrider.com/technicali...eload/?image=0
Then the first graph shows a spring's force range.
The second graph compares a stiffer spring to the first spring.
And the third graph shows the force range of the first spring with pre-load increased as compared to the first graph. And that third graph shows the translation which means that the graphs differ by the same amount at any point. (Translation is the adding or subtracting of a constant.)
.
Last edited by B Stead; Aug 10, 2014 at 10:17 PM.
Thread Starter
Intermediate
Joined: Aug 2014
Posts: 41
Likes: 5
[QUOTE=MRink79553;1587556511]Looking for suggested Autocross Alignment for C7.
Did see the "track" settings in the manual. Was hoping to find something more for autocrossing along with not tearing the tires up as much driving to events.
Thank You
Did see the "track" settings in the manual. Was hoping to find something more for autocrossing along with not tearing the tires up as much driving to events.
Thank You
Racer
Joined: Jun 2013
Posts: 311
Likes: 3
From: Poconos PA
[QUOTE=MRink79553;1587566649]Because I drive 250 miles round trip on a lot of the events I do with NCCC, I leave the alignment stock for your concerns. Chewing up the tires. 250 miles of driving to and from, for maybe 2-5 miles of actual competition driving. Just not worth it for the fraction better. I'm thinking about turning the car down though.
Melting Slicks
Joined: Nov 2005
Posts: 2,074
Likes: 309
Try going to an event and asking for advice. Alignment can make a big difference and if you get really serious, tire wear will be an acceptable penalty, or else you'll buy a truck and a trailer. The numbers in the manual are probably more conservative than the more serious people will arrive at, although I'm still waiting to see my first C7 at an event.
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Thread Starter
Intermediate
Joined: Aug 2014
Posts: 41
Likes: 5
[QUOTE=Baron7700;1587567127]
Because I drive 250 miles round trip on a lot of the events I do with NCCC, I leave the alignment stock for your concerns. Chewing up the tires. 250 miles of driving to and from, for maybe 2-5 miles of actual competition driving. Just not worth it for the fraction better. I'm thinking about turning the car down though.
Well, just went thru my first set of tires on stock alignment. Basically 3,000 miles with approximately 100 runs. Just did my first two NCCC events at Tire Rack and Peru. Each day is like 3 SCCA events, 14 runs a day!!
Guess I'll try the track alignment unless somebody else has some past history with the C7 at autocrossing.
Also just found out that if you get the magnetic ride control pkg on the Z51 it is impossible to completely turn the PTM off...........
Because I drive 250 miles round trip on a lot of the events I do with NCCC, I leave the alignment stock for your concerns. Chewing up the tires. 250 miles of driving to and from, for maybe 2-5 miles of actual competition driving. Just not worth it for the fraction better. I'm thinking about turning the car down though.
Guess I'll try the track alignment unless somebody else has some past history with the C7 at autocrossing.
Also just found out that if you get the magnetic ride control pkg on the Z51 it is impossible to completely turn the PTM off...........
Racer
Joined: Jun 2013
Posts: 311
Likes: 3
From: Poconos PA
[QUOTE=MRink79553;1587614495]
Well, just went thru my first set of tires on stock alignment. Basically 3,000 miles with approximately 100 runs. Just did my first two NCCC events at Tire Rack and Peru. Each day is like 3 SCCA events, 14 runs a day!!
Guess I'll try the track alignment unless somebody else has some past history with the C7 at autocrossing.
Also just found out that if you get the magnetic ride control pkg on the Z51 it is impossible to completely turn the PTM off...........
I have been consistently reading that the ptm is chewing up brakes and tires. I have a z51 with not PTM. It seems like the "better" way to go overall, if you include maintenance of the car. Will it be slower around the track, very possible, but my tires are going to last over 7k.
For my NCCC events in the East Region, we get about 9 sanctioned runs a day. Then if there is time we do fun runs afterwards. I also help my local club run our non sanctioned event, in which I may get up to 20 runs a day! I would say I have EASY over 160, if not 200 autox runs on the car. I also have a 7 session HPDE day at pocono, and 18 passes down the drag strip.
Well, just went thru my first set of tires on stock alignment. Basically 3,000 miles with approximately 100 runs. Just did my first two NCCC events at Tire Rack and Peru. Each day is like 3 SCCA events, 14 runs a day!!
Guess I'll try the track alignment unless somebody else has some past history with the C7 at autocrossing.
Also just found out that if you get the magnetic ride control pkg on the Z51 it is impossible to completely turn the PTM off...........
For my NCCC events in the East Region, we get about 9 sanctioned runs a day. Then if there is time we do fun runs afterwards. I also help my local club run our non sanctioned event, in which I may get up to 20 runs a day! I would say I have EASY over 160, if not 200 autox runs on the car. I also have a 7 session HPDE day at pocono, and 18 passes down the drag strip.