Does anybody have some good wheel alignment specs for Solo II? I am going to run Hooiser A6's 275/40 & 315/30, will switch to 295/35 when available again.
Everything else is stk for now, will run SS class.
Thank you
Thanks,
I run 710's on my Camaro but I was going to try hoosiers because they make a 295/35 for the frt but Tire Rack was out of stock. Would think that 295's in frt would work better? same height, just wider.
Thanks,
I run 710's on my Camaro but I was going to try hoosiers because they make a 295/35 for the frt but Tire Rack was out of stock. Would think that 295's in frt would work better? same height, just wider.
I tried 295's on my 96 LT4 & it was ok, since I've settled on the 275's (both the LT4 and the z06).
Some run 315's on front on a wider rim (not stock class) & have good results.
The bigger tire is heavier though, unsprung weight & rotating mass & all that.
But the short life is what kills the Hoosier deal for me. If I were a nationals guy & had Hoosier giving me tires I'd run em every weekend.
I run 2.5 neg front 1.5 neg rear w/ 1/8 in front and 1/8 out rear. On v710s 295 front 315 rear. running 32psi front and rear. This makes my car (02 Z) dead neutral. I also have radials for the street. The car is driven on the street regulary and has been on 2 1000+ mile trips. I have no adverse effects on the tires. You will however notice a huge difference on how the car turns in on the track. Try it ya will like it
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I run 2.5 neg front 1.5 neg rear w/ 1/8 in front and 1/8 out rear. On v710s 295 front 315 rear. running 32psi front and rear. This makes my car (02 Z) dead neutral. I also have radials for the street. The car is driven on the street regulary and has been on 2 1000+ mile trips. I have no adverse effects on the tires. You will however notice a huge difference on how the car turns in on the track. Try it ya will like it
Question for ya ... toe IN in front? I usually read toe OUT to help turn iin.
toe OUT in rear? I usually read toe IN so that the toe trends to neutral during acceleration out of turn ...
This is with front camber ~ 1.5 and rear between 1 & 1.5 ...Perhaps it's different when running as much camber as you are
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Question for ya ... toe IN in front? I usually read toe OUT to help turn iin.
toe OUT in rear? I usually read toe IN so that the toe trends to neutral during acceleration out of turn ...
This is with front camber ~ 1.5 and rear between 1 & 1.5 ...Perhaps it's different when running as much camber as you are
Everyone I have talked to (includes SCCA national autox champs) specifies toe OUT front & toe IN rear.
Maybe Gimpy got his in/out mixed up?
All I can get in front is 2.2 neg. That's all she wrote.
I am going to start at camber -2 frt -1 rear, 1/8" toe out frt, 1/8 toe in rear. As much caster as possible, keeping them even.
I have put this question on 3 forums, Autocross US. & Corvette action center and you guys by far have been the most help.
The reason I went with Hoosiers this time is because the hooiser's are .8" lower in dia than the Kumho's comparing 295/40 K & 295/35 H and 315/35 K & 315/30 H, plus the Hoooser's are 1 - 2 lbs lighter. I have used A4's before and liked them with out a big difference in wear but the Hoosiers were alot more money. Now the A6's are closer to the Kumho's in price and they claim they wear longer than the old A4's.
I guess it has alot to do with the rider level (5yrs) or personal taste but at least I will give them a try.
In our part of the country (the boonies) we are lucky to get alot of runs on a weekend. There are two of us driving the car and on Fri aft is Test and Tune we get 10 - 15 runs each, 8 each on Sat and 8 each on Sun. Thats 52 to 62 runs in a weekend. Thats because we have a long way to drive 2-4 hrs and we do this 4-6 times a summer. Then we have our normal one day events too.
That was what I was told by the local guru. So that was how I had it set up. Toe in in the front so when the wt transfers to the outside it helps "swing" the front end of the car. Out in the rear for the same reason. The outside tires (where all the weight is) are basicly trying to "spin" the car around its center axis. Think of 4 wheel steering. Now as you apply power to the rear wheel it goes straight/neutral under accelration, and drives you out of the corner. If you have toe in to begin with and you apply power it will go in further scrubbing the tires and wasting power. I will admit this was given to me as a Road Race/Auto-X set up buy a Road Racer. I know several guys around here that use it. Maybe it is wrong but it made since to me and I know it works WAY better than stock.
Also make sure that when you have the alignment done you are setting in the drivers seat. If that is not an option at least sand bags equlivlant to your weight. It does make a difference.
Last edited by Gimpy : 07-24-2007 at 11:50 PM.
Reason: better explanation
Under hard acceleration the rear wheels Toe OUT as the rear squats. Thus you want to start with static Toe IN and the wheels will tend to become more neutral as the car squats...this aids acceleration.
Under hard cornering the inside rear (unloaded) wheel Toes IN and the (loaded) outside wheel Toes OUT. This allows the rears to "follow" the fronts better in a turn. Thus you want to start with a static Toe IN in the rear.
For high speed road course the Front Toe needs to be neutral.
For AutoX the front Toe needs to be slightly OUT to aid Turn IN
Here are my recommendations:
Objectives:
- Reduce factory understeer AMAP and get car as neutral as possible.
- Better, later and shorter Braking
- More front grip
- Better Turn IN
- Better Steering Response
- Better Steering Modulation
- Better Rear grip and Acceleration
- Better handling
- Increase corner entry speed, mid-corner speed and higher corner exit speed.
Retain some power oversteer.
ORDER: Lower AMAP, Corner weigh, Corner weight, set Ride Height and Rake (1/2" - 3/4"), Get F/R weight ratio as close to 50/50 as Possible (=< 2%).
MOST IMPORTANT SPEC: Cross Corner Weight % Difference as close to 50/50as possible (=< 1%). Set Camber, then Caster, then Toe.
AutoX Alignment:
FRONT:
Camber = -2.4*
Caster = As much positive as possible without sacrificing Camber
Toe = Toe OUT, 1/16" - 1/8" Each, !/4" Total Toe OUT Max.
REAR:
Camber = -1.5*
Toe = Toe IN, 1.8" - 1/4" Each, 1/2" Total Toe IN Max.
The alignment specs are only a starting point and should be adjusted after proper tire inflation pressures air selected and the tires are "read" using a probe type Pyrometer.
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You'll love the Hoosiers. I ran Kumhos and got 115 runs, great tires and great wear. The Hoosiers are a shade quicker and I have 80 runs on my current set, with probably another 15-20 runs left. I run on both asphalt and concrete sites. The new Hoosiers appear to wear much better than the old ones. YMMV. Good luck and have fun!!
Under hard acceleration the rear wheels Toe OUT as the rear squats. Thus you want to start with static Toe IN and the wheels will tend to become more neutral as the car squats...this aids acceleration.
Under hard cornering the inside rear (unloaded) wheel Toes IN and the (loaded) outside wheel Toes OUT. This allows the rears to "follow" the fronts better in a turn. Thus you want to start with a static Toe IN in the rear.
For high speed road course the Front Toe needs to be neutral.
For AutoX the front Toe needs to be slightly OUT to aid Turn IN
Here are my recommendations:
Objectives:
- Reduce factory understeer AMAP and get car as neutral as possible.
- Better, later and shorter Braking
- More front grip
- Better Turn IN
- Better Steering Response
- Better Steering Modulation
- Better Rear grip and Acceleration
- Better handling
- Increase corner entry speed, mid-corner speed and higher corner exit speed.
Retain some power oversteer.
ORDER: Lower AMAP, Corner weigh, Corner weight, set Ride Height and Rake (1/2" - 3/4"), Get F/R weight ratio as close to 50/50 as Possible (=< 2%).
MOST IMPORTANT SPEC: Cross Corner Weight % Difference as close to 50/50as possible (=< 1%). Set Camber, then Caster, then Toe.
AutoX Alignment:
FRONT:
Camber = -2.4*
Caster = As much positive as possible without sacrificing Camber
Toe = Toe OUT, 1/16" - 1/8" Each, !/4" Total Toe OUT Max.
REAR:
Camber = -1.5*
Toe = Toe IN, 1.8" - 1/4" Each, 1/2" Total Toe IN Max.
The alignment specs are only a starting point and should be adjusted after proper tire inflation pressures air selected and the tires are "read" using a probe type Pyrometer.
Combine this alignment with Hoosiers and you will really be surprised how you can make the car dance. The Z06 is amazingly agile for a car of its weight.
I do have a longacre 4 corner scale set and tire temp gauge and I have used them to cross weight my CP 68 Camaro with adjustable coil over shocks you just raise or lower the appropriate corner to transferr weight and I could get it within 1% from side to side but I am not familar with how to do that on a 04 Corvette. In stk classes I don't think I can move weight around like moving the battery to the rear. Is there an easy way to adjust the load at the corners?
1. For AutoX you should corner weigh, corner weight, Check the Cross Corner weight % Difference and align the car
- After all mods possible have been done
- after lowering
- with the driver or an equilivant driver weight in the drivers seat
- 1/8 tank of gas, 1/4 max load
-Initially with both the front and rear swaybars disconnected
- and if using adjustable shocks; with the Bump setting set on the next to last SOFT setting and just after the car was driven or 'bounced".
- Align & set ride height with the race wheels and tires on the car
- remove all unnecessary weight from the car, this includes:
- empty the windshield washer tank
- run a minimum level in the coolant overflow tank and run a 70/30 water coolant ratio
- with 1 qt additional oil added for C5 Z06's
- remove everything from the glove box and center console
- remove the floor mats
- remove the tire inflation kit
- remove the OEM Ti exhaust and install a Corsa "Z Series" Titanium Race Exhaust WITHOUT the optional mufflers
- remove the plastic coil covers.
2. When installing allowable mods such as a hand held Fire Extinguisher or Fire Suppression System mount them on the RIGHT side of the car as LOW and as far REARWARD as practicle.
- when installing a 6 point drivers restraint belt such as "clip-in" Hardbar or Brey Krause mounts, install the right side passenger mounts as well but remove passenger belts for AutoX competition.
3. Attatch the sway bars and recheck the Cross Corner Weight % Difference
- Minimally adjust the ride height at each corner to bring the CCW%D as close to 50/50 and within 1%. Should be like 50.5%F/49.5%R
The F/R ratio should be within 2%, say 51.2%F/48.8%R max.
- If you have installed an allowable front sway bar you should have also installed adjustable sway bar end links. These initially should be installed at their shortest adjustment. If you need more rear corner weight to bring the F/R ratio and the CCW%D into spec then you can minimally lengthen each front end link. This effectively preloads the bar and shifts weight to the rear. BE SURE TO INITIALLY ADJUST BOTH SIDES EQUALLY.
4. You could also install a higher rate or higher recurved front spring or a low rate or lower recurved rear spring but this would be disallowed and cheating in SS. It also shows the limitations of the transverse spring .....you can not independantly change a corner's spring rate.
As you can see there are some very limited things you can do in SS to lighten the car and shift weight around.
After all the static weight is shifted as much as possible the left front will still be the heviest corner and the right rear the lightest.
Unfortunetly on the Z06 the only other way in SS to adjust corner weights is by tweaking the ride heights and or adjusting the front sway bar end links if you have installed them.
NOTE: as from the factory the Z06 is pretty close to a 50/50 F/R ratio and a 50/50 CCW%D as possible...but it is possible to get it dead on with a little tweaking.
ABOVE ALL, THE CROSS CORNER WEIGHT % DIFFERENCE IS THE MOST IMPORTANT SPEC.
The advantage of a coil over system is that you CAN adjust individual corner weight INDEPENDANT of Static Ride Height. By simply adjusting the spring collar thus adjusting the ride height on a coil over spring perch you are essentially doing the same thing as you are on an OEM Z06 when you adjust ride height using the spring perch bolts. You are taking the easy way out and in effect defeating the advantage.
The proper way to adjust corner weights in a coil over system is to:
1. Set the Static Ride Height and Rake
2. Corner Weigh the car
3. Corner Weight the car by physically moveing things around to effect the corner weight(s), CCW%D
4. Change each individual corner spring as to appropriate Spring RATE to match each individual Corner Weight*
* NOTE: EACH car is different and actually each corner is different...that is why I do not recommend the purchase of a generic coil over system and especially one built on non-adjustable shocks. You are using someone elses spring setting(s) , which while being close, may not be right for your car ...AND as each coil spring should be tailored to each individual corner; each shock needs to be adjusted to each individual spring (rate) to properly dampen the spring harmonics. Non revalvable shocks can not do this and non adjustablke shocks can't do it properly.
Each coil spring needs to be tuned to the individual corner and each shock needs to be tuned to each individual spring at least in Compression and Rebound (each individually). Shock selection is another topic.
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