Conservative Track/Street Alignment

[DJazidca]

I am in the process of setting my car up to run 4-6 track events per year. I will be running my spare set of Goodyear F1 SCs on the track for at least the first few events, and my car is fairly stock but lowered about an inch on the stock bolts. I'm not looking to light the world on fire at the track, so I need a recommendation for a conservative alignment that can be used on the street as well. I've read just about every post I can about alignment, but I'm still not sure how I should set it up. I would also like to know the ideal PSI to run in the F1 SCs at the track. At my last event I wore out the inside of the front tires (although that may have been an alignment issue as well-resolved when the tires were replaced). Thanks for your help.

[wtknght1]

http://forums.corvetteforum.com/show...70&forum_id=23

Well if you plan on driving it on the street too, then you're looking for a compromise...which is tough in this game. You won't get the best performance/wear either on the street or on track. However, you can get some good results with some mild numbers.

Somewhere around -1.5 on the front and about -.75 on back is a good start for a 'hybrid' car. You'll have to adjust from there. Set the toe out just a touch in front and in about the same amount in back and adjust from there.

Put the car back to the stock ride height...or take it to the pros and let them adjust the height and corner weights. If you lowered the car without scaling it too, you have now really screwed up the suspension on that car...bottomed out the shocks, etc.
Talk to the guys at Phoenix Performance!!!!!!!!!!!!
__________________
www.tracktapes.com
Chris W. Ingle
White 2001 Z06 - SCCA T1 National Racer #7
2005, 2003 Southeast Division T1 National Champion
Instructor: TracQuest, Car Guys, etc.

[DJWorm]

There is no such thing as a compromise alignment between track & street.

I recommend having the suspension technician set up the car and mark the alignment settings on the adjusters for both a street and track setting. This way you can switch back & forth at the track in 20 minutes.

Use dedicated race wheels (CCW, Kodiak or Circle Wheels) and either DOT slicks or R slicks (Khumo or Hoosier DOT's) or (Hoosier or GY R's).

Lowering on the stock bolts is OK if the course is smoooth...otherwise shorter shaft shocks will be necessary such as Penske DA's. If you lower further using longer aftermarket bolts you will definetly need the shorter shocks and possible a Baer Tracker Kit. Lowering is advantangeous as it lowers the CG & Roll Center but the suspension as to be adjusted to realign the toe rods and a wider track (wider tires & offset) needs to be used to pull the scrub radius back to ZERO.

As Chris said you can lower too far if these precations & solutions are not used.

For wheels & tire sizes for the track I recommend:

305/30x18 on 10.5x18 with +0.25" offset FRONT
315/35x17 on 11x17 with +0.25" offset REAR

[Olitho]

I have two things to add to what WTKNGHT and DJWORM have posted.

First, I want to clarify that WTKNGHT is probably suggesting that the rear wheels be "toe'd in" and not out. I am not sure everyone would read it that way so I wanted to point that out. I will accept reprimands from WTKNGHT if I am wrong in making this point.

Second, Circle Racing has been partially sold. The metal wheel division was sold off and that is what I think you get when you go to the old website. I got a postcard from them yesterday about the change in ownership. I don't remember the new name for the aluminum racing wheel group, the one you would want, so I will need to look that up when I get back to my office tomorrow. I will post the new name then for those who are interested.

[kmagvette]

This thread addresses the next issue I want to hunt down. I will be running 315x17 on all four corners this year. I figured that I would badly beat the outside shoulders if I didn't go to a track/street compromise along the lines of what Chris suggested. I'm certainly not running at track record paces, but I do alright compared to the rest of the DE crowd at Watkins Glen.

To DJ's point about makring the adjusters. Obviously you think this is practical. How do you accurately mark the adjusters so you get exactly to one setting or the other? How far can you be off without materially screwing things up (in terms of a turn of a nut).

Pushing this thread a bit further... if one were to go down the "adjust for use" path, what alignment setting would be suggested for road course use? My suspension is stock and at the stock height where I would like to leave it - NY roads suck.

I WILL be taking my car to Phoenix to get it set up, but I will probably wait until the end of this year or early next year to do it - starting out from scratch is real expensive

[DJazidca]

Okay, I just chcked my current alignment specs. I am basically running -1.0 camber all the way around (+/- 0.1).

Given those specs and the following facts, should I even mess with the alignment right now?

1. No budget
2. Limited tools
3. Car probably lowered incorrectly (I didn't do it)
4. Must drive at least two hours to every event

I could be convinced to take DJWorm's suggestion and adjust the alignment myself at the track if it is reasonably easy with limited tools, no lift, etc., but I assume I would need to have the suspension set up professionally before that would be worthwhile.

[wtknght1]

Generally speaking, the rear should be toed in...and the front out. Correct.

For track use, if you have a basically stock vette, run the max neg camber you can get up front and about -1 to -1.5 in the back. I run about -3 front and -1.5 in back give or take a little bit. If you're just street driving it, then you might take a look at -1 up front and -.5 in back. Use something in between for a 'compromise' setting.

Having a 'hybrid' car is tough...you won't get max performance either on the street or track, but it'll still do really well. Don't get too wrapped around the axle about the settings right now though. You'll drive yourself nuts. Take it to the pros, put a decent setting on there and gets lots and lots of seat time. After an event or two and you have a chance to really see what the car is doing and examine tire wear, then start to make some small adjustments. Seat time and learning car control should be your priority.

[DJWorm]

There are some basic tools you need for the track.
1. Lite-weight Aluminum Race Jack from Sears or Harbor Freiight
2. 4 jack stands
3. Cordless Impact Wrench. I recommend Milwaukee's new 28 volt system
4. Torque wrench for lug nuts (Sears has a nice one)
5. Brake Bleed Catch Bottle from Pegasus or Mallett
6. Basic Tool set including English & Metric open end & box end wrenches (combo's are OK) & English & Metric Socket set (6 sided is better)
7. 0-60 Air pressure Gauge (Longacre)
8. Aluminum Air Tank (Behrents
9. Instal Brake Speedbleeders

Optional Track Suspension Tools:
1. ART SMART Camber gauge
2. ART Laser Toe plates

I can easily jack the car, set it on stands, remove street tires & wheels, bleed brakes, set track suspension settings, install race tires & wheels, check tire inflation, remove from stands in 20-30 minutes.

You can easily mark the cam adjusters with a punch. The Toe adjusters Max limit can be marked with tape and I know the amount of change per rotation of the adjuster nut for my car and I record where it is currently set in a note book.

Alignment Settings:

Assumes car has been properly
- corner weighed,
- corner weighted,
- ride height set with
- 1/2" to 3/4" Rake.
- as close to 50/50 F/R weight ratio as possible
- proper Cross Corner Weight % Difference as close to 50/50 as possible (THIS IS THE MOST IMPORTANT SETTING)

AutoX:
Front:
Camber: -2.4*
Caster: As much positive wo sacrificing Camber. Equal with NO Caster Lead.
Toe: 1/16" to 1/8" Toe OUT each, 1/4" Toe OUT Total MAX.
Rear:
Camber: -1.5*
Toe: 1/8" to 1/4" Toe IN each, 1/2" Toe IN Total MAX.

High Speed Track:
Front:
Camber -1.8* to -2.0*
Caster: As much + as possible wo sacrificing Camber. Equal with NO Caster Lead
Toe: 0.0", Neutral
Rear:
Camber -1.3 to -1.5
Toe: 1.8" Toe IN each, 1/4" Toe IN Total Max.

Agressive street:
Front:
Camber: -1.5*
Caster: as Much positive as possible wo sacrificing Camber (Just leave at track setting with NO Right Caster Lead)**
Toe: 0.0", Neutral
Rear:
Camber: -1.3*
Toe: 1/16" to 1/8" Toe IN each, 1/4" Toe IN Total Max.

** This will cause the car to pull sliightly right on high crowned back country 2 lane roads but should be tolerable for city streets and Interstates

Another option for Camber is to eliminate the cam adjusters altogether and install Hardbars keyed camber plates. These lock a specific Camber setting in place which can be changed by installing a different sized key. These are positive and will NOT wander like the OEM cams.

[mountainbiker2]

Put the car back to the stock ride height...or take it to the pros and let them adjust the height and corner weights. If you lowered the car without scaling it too, you have now really screwed up the suspension on that car...bottomed out the shocks, etc.



Every C5 Corvette that runs in ASP or SM2 that is successfull is way lower then the stock bolts. They might have shorter shocks, but it's not really necessary. With 315/35/17 on the front the stock 04 Z06 shocks bottoms just before the fender would hit the tire anyhow. On the rear with 335/35/17 you have about 1/2" max. before the fender hits the tire.

Stock height?

Steve

[DJWorm]

I really don't like speaking for other people, and I am sure he will chime in; but Chris is correct for the componants he is using and the class he is racing.

SCCA T1 Corvettes do best at the standard ride height....because they are using ALL T1 componants ( shocks, springs, sway bars, camber kits, etc.) which actually raise the ride height (in fact they are lowered to OEM ride heights) and lowering further will NOT allow these componants to work to their maximum effectiviness.

The T1 package was engineered to upgrade a C5 for track use and only marginally improves a Z06. The T1 package is used as a limiting package in that "you can do THIS but no more." Also the SCCA T1 tire set up while correct for the rear is also a limiting factor in the front by not allowing a wide enough front rim. This limits the front end grip, turn in and understeer reduction. But it is better than the OEM sizes.

However, SCCA Pro Solo and National Tour ASP & SM2 Corvettes are lowered further than factory recomendations but are using different componants as are SCCA Solo I Time Trial, WC Corvettes and the C5R's & C6R's This drives the CG and Roll Center Lower and makes them handle better and in fact have faster high speed track lap times than T1 Corvettes. They use different componants which are NOT allowed in SCCA T1 to correct for lowering such as:
- VB&P Extreme Springs which have a better recurve, are lighter and are much stiffer which allow less deflection
- Penske/Mallett, JRZ or Moton DA shocks (shortened)
- Penske TA, JRZ or Moton 4 way Coil Overs
- custom billet spindel/hubs
- custom A-Arms
- Baer "Tracker" pin indexed adjustable rod ends
- offsets which correct the Scrub Radius back to Zero
- correct wheels & tires

The 305/30x18 on a 10.5x18 is a much better tire than than a 315/35x17 on a 10x17 in the front. They both have exactly EQUAL tread width (11.4") and overall diameter (25.6").
1. The 10" wide rim is too small for a 315 and limits the shoulder grip where it is most important.
- this reduces front grip
- reduces turn in
- increases understeer
2. The key is in the lower aspect of the 30 side wall which
- reduces flex,
- increases turn in
- allows better braking
- allows shorter & harder braking later into the corner
- provides better steering feel
- allows better steering modulation

So while the T1 package and wheel sizes upgrade the OEM Corvette to tackable status and work best at the OEM ride heights it is not the optimum that can be done. If you are contemplating turning your street car into a T1 racer and are therefore bound by T1 rules then by all means go that route. However you can do better by lowering the car and using the proper componants if necessary such as shorter shaft DA shocks and possibly the Baer tracker kit if necessary at high speeds as a bare minimum.

[mountainbiker2]

DJWorm. Thanks for the clarification. By the way my 315's are on 17x11 rims.

Steve

[DJWorm]

But they are a 35 aspect ratio and have too much flex....excellent for the rears but poor for the front

[Olitho]

Originally Posted by Olitho

Second, Circle Racing has been partially sold. The metal wheel division was sold off and that is what I think you get when you go to the old website. I got a postcard from them yesterday about the change in ownership. I don't remember the new name for the aluminum racing wheel group, the one you would want, so I will need to look that up when I get back to my office tomorrow. I will post the new name then for those who are interested.

I just found the new information for the aluminum racing wheel division of Circle Racing Wheels that has been spun off, pardon the pun. They are now:

Spin Werkes Racing Wheels
16918 Gridley Place
Cerritos, CA 90703

866-528-SPIN
Fax: 562-467-2066
www.spinwerkes.com

[mountainbiker2]

Originally Posted by DJWorm

But they are a 35 aspect ratio and have too much flex....excellent for the rears but poor for the front

True, but that's the only size Kumho V710's come in.

Steve

[DJWorm]

get the new Hoosier A6 or R6