Suspension & Tires

[dan0617]

Originally Posted by Bo White

That's more just on one side than factory calls for total. .5* total toe is a ton.

Let me see if I can clarify my basic understanding in 3 different drag setup alignment setups, 3 different scenariaos, all of which are ok, depending on budget and use. Alot of my experience is from my Corvette but it seems to apply perfectly to my experience with this car so far. Please read closely and let me know what you all think:

#1 All out drag, high dollar, not afraid to break parts setup: You set your rear up to be very stiff, very little squat. You want the weight to transfer back but the rear to not squat. For this setup to be right you need many suspension components, coilovers, likely small rims with big tires for more sidewall flex, and not be afraid to replace broken drivetrain components, or upgrade them ahead of time. Right combination of parts and settings is critical, especially to keep it from unloading 30' out. I've seen many launch like a rocket, then begin spinning. Keep that from happening with this setup and you are golden! With this scenario, you would want a small amount (1/32" or 1/16" per wheel maybe?) rear toe, and about 0 camber since there won't be much squat so there won't be a need for much if any positive camber. This scenario will give you the absolute best 0-60 times IMO. This setup is what hooks up on the strip with big clutch dumps, super high stall converters, super low gears, line locks, trans brakes, etc.

#2 Weekend warrior, low budget, want it to hook and aren't afraid to replace a drivetrain part but don't want to replace alot or have it breaking all the time: You want your rear to squat. Not because squatting is easier on parts, but because it starts the process of loading of the rear tires with less than optimal track prep (street racing from a stop), and with less than slicks or bias plys. For this setup just replace cradle bushings for sure, and maybe some other bushings, maybe replace toe rods. Stock 20" wheels with decent streetable drag radials so that you aren't "dead in the water" if you get caught in the rain on the highway. Set psi to 30 so the TPMS light won't be on. Just lower psi down to 20-24 when at dragstrip. With this scenario, you will have rear squat. The more power you make and the harder it hooks, the more rear squat you will have. Because of this, you need more positive camber (0.5 to 1.0), and subsequently more positive toe (1/8" or 0.25 degree per wheel), so that when you are foot to the wood in the launch the tires are flat and pointed straight. Will wear tires quicker than #1, maybe get 5000-7500 miles out of a set of good drag radials. This scenario will give you a very good launch at the track. Should be able to just mat it to the floor but won't be able to do a huge clutch dump or a flash stall on a 4000 stall converter. Won't be as good of a launch at the dragstrip as #1, but will likely give you a better launch (from a stop or from a roll) on the street than #1 because with #1 it takes a fairly violent takeoff to transfer the weight without the rear squatting, and on the street you may not have the traction to start the process. Every car I've raced on a "streetlike condition" I've jumped out ahead of them because they spin but I just squat and go. Now at the track it is a different story, as my car is putting energy into the rear squat theirs is lifting the front and heading down the track, so they jump out a little ahead of me. For the street either drive around a while for heat in the tires or a VERY light burnout. Then just roll the pedal down fairly quickly, the rear squats which helps start and continue weight transfer, and the tires are now flat with the pavement. The larger rear positive toe will also help eliminate the understeer feel during spirited street driving that is normally felt when you go up to super wide, sticky rear tires but keep the stock skinnier tires up front.

#3 Daily driver, low to moderate budget, don't mind upgrading a little but don't want to break parts or wear tires extremely fast: Do as many bushings as you can afford, replace toe rods and anything else you can. Get some soft non drag radial tires. Set rear alignment to same as #1. With this scenario you will not have the traction of #1 or #2 but you will have more traction than stock on the street and at the track, won't wear tires out that fast, likely won't break stuff, and should hook up nice from a roll. Should be able to roll the pedal down when on the track and it stay hooked. On the street, might have trouble getting it to hook in first, some spinning, just don't go into the rev limiter hard then let off or you just killed the run. Try to pedal it to be hooked by the top of 1st so you are golden for 2nd gear, manual or auto. If you put drag radials on it will hook more, squat more and you will be giving up some potential because the tires won't be planted flat. So then you need to go back and choose either #1 or #2 to reach the full potential of the DR's and the setup. #3 is a good setup for non boosted low to moderate rwhp cars, cars with stock converters, etc. Put the boost to it (especially with a top mount) or put in a high stall converter (especially with a centri) and you will quickly see the benefit of going to #2 or #1.

This is my general understanding of IRS setups from Mustangs and Corvettes I've had and experimented ALOT. I set this car up the same and it seems the same principles apply. All comments welcome!

[dan0617]

Originally Posted by H-E

For a drag only setup you don't want any camber and very little toe,just enuff to help with wondering at the big end...I run a 64th on my car.With a 25 series 22 inch tire with a tread rating of 300 at 50lbs and a six speed I 60 in the 1.70s....We have helped a ton of people with their rear setups including the 5th gen record holder,GTO record holder and the G8 record holder as well as guys trying to get their first 11,10,9 etc. Alignment is ...HUGE with an IRS car HUGE

H-E, I agree totally with this alignment recommendation for Warhorse's setup. I'd suggest a hair more positive toe but yes, this is my scenario #1 above. Also totally agree that the alignment is huge. I don't think our thinking is all that far apart. I just see a couple different directions to go for different setups and uses. Especially for those of us who want and need max. traction on min. dollars.

For the OP, if you read his mods the very first post, I suggest my scenario #2 alignment and Nitto 555R's or maybe ET Street Radials, unless he is up for major suspension modifications, in which case he would want the same alignment as you suggested for Warhorse.

[H-E]

Originally Posted by dan0617

H-E, I agree totally with this alignment recommendation for Warhorse's setup. I'd suggest a hair more positive toe but yes, this is my scenario #1 above. Also totally agree that the alignment is huge. I don't think our thinking is all that far apart. I just see a couple different directions to go for different setups and uses. Especially for those of us who want and need max. traction on min. dollars.

For the OP, if you read his mods the very first post, I suggest my scenario #2 alignment and Nitto 555R's or maybe ET Street Radials, unless he is up for major suspension modifications, in which case he would want the same alignment as you suggested for Warhorse.

I set up our cars the same way regardless of hp.It doesn't cost anymore to set it up my way versus your way when it comes to alignment .I will say that this is an alignment that we found works best for moving the car forward.If someone is a great driver this may not be the best setup for a road coarse but there again there are a lot of straight axles cars that do quite well at the road coarse.We run ever so slight positive camber in our record holding GTO.hardly measurable but I would never run much if any toe.

[H-E]

Also as of now we have the 60 ft record in a 5gen with a 1.24..

[jessrayo]

Has anyone tried to road race with the flat rear camber alignment specs? My ZL1 already has less camber than what I was used to running but it is a completely different animal. I think when cornering fast with some negative camber in the back it would allow you to roll into the throttle sooner without walking the back out. My car has about twice as much wear on the outside half of the rears from how much weight they take road racing..... I want to run a quarter in the 9's but I also want the car to hold in a fast corner. I'm thinking -2 degrees in the front and stay at the -.5 in the back is the best blend. When I finally run that RPS clutch that doesn't slip then my 60ft times will come down.

[H-E]

Originally Posted by jessrayo

Has anyone tried to road race with the flat rear camber alignment specs? My ZL1 already has less camber than what I was used to running but it is a completely different animal. I think when cornering fast with some negative camber in the back it would allow you to roll into the throttle sooner without walking the back out. My car has about twice as much wear on the outside half of the rears from how much weight they take road racing..... I want to run a quarter in the 9's but I also want the car to hold in a fast corner. I'm thinking -2 degrees in the front and stay at the -.5 in the back is the best blend. When I finally run that RPS clutch that doesn't slip then my 60ft times will come down.

I can't drive good enough to need camber in the rear on a road course lol.Fyi.the RPS clutch does not have a warranty in a new camaro....You must have a Street Slayer. ..

[jessrayo]

Originally Posted by H-E

I can't drive good enough to need camber in the rear on a road course lol.Fyi.the RPS clutch does not have a warranty in a new camaro....You must have a Street Slayer. ..

Well I don't know the details about the clutch but I suspect one of the 2 clutches ADM ordered from you in the last couple of weeks is in my car now. My car is still in the ADM shop prepping for the Texas mile.

[SSlim]

I just have the eibachs suspension wise, but running 315 nitto invos and the hook pretty good. The rears didn't last long though. I have 30k on the fronts and still look good. I had to buy new rears around 20k.

[Bo White]

That's nothing lol, 7000 miles on my 295 Acceleras and I've turned them over about 15 times with little to no haze. I drive mostly interstate and the alignment is great. At least its a cheap tire lol.

[Drottie]

I was running Nitto Invos before (450rwhp) and got 16.5k miles out of them. Just switched to NT05 (non-r) after the Whipple and Cam install (650rwhp). So far they've been doing very well, even when I got caught out in a very heavy rain.

[bikerdan]

What kind of air pressure do you recommend for the street, with occasional stoplite drag?
Running p zero 305's on 10 in rims.