4th gen setup questions. . . don't be stingy!

[Supercharged111]

As some of you may know, I bought the car with 1200ish# front springs and recently ID'd 325# rear springs. Last month Perry donated some 950# springs to the cause, so I threw them on between qual and race (a buzzer beater at that having never done it before). I immediately noticed that the steering wheel would rotate farther before the tires broke loose, so I figured this was a sign that I took a step in the right direction. The front also has a 30mm bar, Z06 wheels, 1/2" spacer, 2 degrees camber, and 1/8" toe out. It seemed less bad, but I still was plagued with a mid corner push and my lap times just weren't as on par with the leaders as they were at Hallett. I simply couldn't place the car where I wanted to consistently because it just wouldn't respond and I'd miss my apex. Turning in earlier was not the fix, I tried it. I also tried all combinations of spacers and dropping tire pressures to no avail. The car did respond to spacer changes, but it never really took the way I wanted it to. So just last weekend I went out for a practice day. I'd raised the car a bit since HPR in July so the tires weren't tucked into the fenders and I'd replaced the swaybar bolts so they weren't shanked out and I got the endlink bushings properly tight. Camber was verified at 2 degrees and alignment still 1/8" toe out so one less variable there. At first the car seemed awkward, but after a couple sessions I determined I was just driving with sledgehammer inputs. Once I settled down the car was predictable, but still suffered from that mid corner push. I added 3/4" spacers to the front of the car as a last ditch effort and the car was amazing! My lap times only dropped a few tenths, but they were so much more consistent. The car went where I pointed it without being overly loose and just flat worked. I'm pretty sure I could have dropped lap times with another session or 2 of wheel time as the car now tolerates throttle input much sooner. Problem: I'm 1/16" too wide here. I'm sure I could grab some 5/8" spacers but I'll lose some of what I gained. I'll likely grab them anyway, but I want to know if the fact that wider spacers worked so well is an indication of something else that needs changed (springs/sways?). I know I need to drop the rear spring rates. Though the car wasn't super loose, as Ryan mentioned it may be causing me to chase my tail. He also suggested more camber. I've started with 2 sets of full tread RA1 this year and what I've noticed is that the outside tapers quite a bit. The shoulders don't take too bad of a beating, but the tread as a whole tapers and wears more on the outside than the inside. Were I to take tire temps, I think that would definitively tell me what the car wants for camber and air pressure, but I'm not there yet. So for next month's race, my intentions are to bump camber to 2.5 degrees and fit 250# springs out back and run the test and tune the Friday prior to feel out the changes. Am I missing anything huge here or does that setup sound like something that will make the car get around a track and not suck? Maybe do camber first, then the rear springs to see how it takes? Rear springs take all of 5 minutes to swap out now.

[GlennCMC70]

Adding the spacers effectively softened your wheel rate (spring rate). That is a sign your still too stiff. You mid corner push could also be too much camber (or caster - you didn't list it). With higher spring rates (or wheel rates as you need to factor the sway bar too), you need less static camber and less caster as there is less body roll. Less body roll results in less camber loss due to body roll. Running lots of caster just adds to wheel turned camber (thus your mid corner push. If tire pressures were right to begin w/, you likely did see any gain as a result of the change. Lends to you being on the right track. you must run that 32mm bar. The 30 is just too small. That is why some folks liked to run large spring rates - to make up for some of the body roll. A push can be caused by too much or too little camber. My guess is you have too much as the push comes when you are at max wheel input through the corner. Just a guess w/out you providing where it is now.
A soft car is easier to drive. It can also be driven offline (for making a pass) easier than a stiff car. Softer rear rates will help plant to front some during turn-in, but if the F/R balance is off, it will pick up a push through the corner.
I still think 700-800F is the sweet spot. 225-275R would match. Depending on your driving style a 3:1 to a 3.5:1 F/R spring rate ratio is the target. If I had made Hallett, I would have let you drive my car to compare.

Pay more attention to tire temps across the face than wear.

[Fbody383]

Also:
http://www.aicmctexas.com/showthread.php?4309-Red-Shift-Racing-82-Set-Up-Notes (http://www.aicmctexas.com/showthread.php?4309-Red-Shift-Racing-82-Set-Up-Notes)

I think Orange is running 750/225 at the moment... ish. Somewhere in that range. Hallett was the second event ever on 17s and I think we were narrower than the limit given the spacers we had on hand. I think the last alignment was around -2 camber, 4ish caster, and a little toe in with the stock bushings. Never taken tire temps but really probably should.

Yes, Mr. Allford - the Global West bushings are waiting patiently in their little box for installation. Gotta keep up with Ross.

[Suck fumes]

super soft is fast....just sayin.

[Pranav]

I'm running 650F and 200R. I did this because the springs came with the car, I felt like I needed to start my DE and first few races off on a soft spring.

I started off with 30mm front at the 19mm rear that came with the car, then later upsized to 32/19.

Overall I the car always felt just a bit more pushy than I'd like, and had always wanted to up to a stiffer a spring and put a little more bias to the back, but constant engine swaps/issues put it on the back burner each time.

Going up to a stiffer 800F and something stiffer in the rear (keep a few pairs in the 225-275 range to play around) was the plan.

With the way the car behaved on RRs at Hallett, I'm wondering if I should go stiffer?

Alignment is maybe around 2.25* in the front, caster is whatever the max is. Need to get a proper camber reading since my readings weren't trustworthy.

[Suck fumes]

Going stiffer in front will not solve your push. The shock travel is what you need to look at. More than likely your car is to low and you are bottoming out.

[ShadowBolt]

Don't use Hallett as a guide. My car went from loose to very tight between TWS and Hallett. The new surface had my car different than it had ever been.

JJ

[Supercharged111]

So it's not just me, I thought my car pushed less at Hallett judging by my pace relative to the field. I've felt I'm shooting blindly here without the ability to take tire temps, I know they'll tell me what camber the car wants and which end wants more/less spring. The car currently has 2 degrees of camber and an unknown amount of caster. 2 of the bolts are hogged out to the max and pushed out as far as they'll go and I just used the other 2 to set camber only. I know some people like higher spring rates than others and I figured a heavy spring with a lighter bar ought to get me close to where I want to be. The 30mm bar has about 100# less rate than the 32mm bar (according to Strano's site) and attaches real close to the bottom of the shock, so wheel rate should be similar to a spring change right? So does that mimic an 850# spring up front but with better brake dive resistance? I'm not against going lighter yet to see if I like it, but I'd hate to bail on this spring/bar setup if it can be made to work, or at least work better. Let's also not forget the shocks will probably start making the car act funny too when they get that far out of their range. I don't even know how to identify when a shock is holding me up. So nobody's running more than 2 degrees camber? If not, I can cross that off my list of things to try. First and foremost then is to get a lighter rear spring and 5/8" front spacers.

[GlennCMC70]

I run about 2.2.

[AllZWay]

Glenn's information is about dead on to my own as is Dave's.

There maybe be faster setups for a certain track, but for an overall decent setup follow these guidelines and the car will work pretty well.

[Fbody383]

super soft is fast....just sayin. Aaron, did you guys see much spring rate difference going RA1 to RR?

I don't think I get the hard transitions from "good" to "bad" like hitting the bumpstops or bottoming shocks. Of course that could literally be my inability to recognize it.


I don't even know how to identify when a shock is holding me up. +1

[Suck fumes]

We don't change springs during the season. I find one combo I like and setup the car around it. We didn't change anything going from ra1 to RR. Shocks are huge! You can tell when they bottom out when you enter the turn and the car gets fully loaded on one side. If it starts to push right as you start to turn and steadily gets worse as you accelerate then your on the bumps. If it starts to step out on the rear under the same scenario then the rear is bottoming out. Now for me it's a feel thing. I can drive a car and know exactly what it needs by how it behaves but that's just seat time that you need to get to understand that. You need to go to a test day and purposefully change things to see what they feel like to really know what works.

[Supercharged111]

I don't mean when a shock bottoms out, I mean when it's too stiff or too soft. I know they're most active during corner entry/exit, but am not yet smart enough to know when to blame a shock for an undesirable behavior vs springs/sways. I am still curious about stiff spring/soft bar vs soft spring/hard bar. I've googled the matter and there seems to be no definitive answer. So if a bar is rated 100# less than another, do I subtract 100# from the spring rate or 50#? Or is it way more complicated than that? Since the sway and shock mount so close, I figure it's fair to consider their effects about equal with respect to wheel rate. My mindset is that softer = more grip too, but I really do want to see what the 950 setup drives like properly balanced before going softer yet in case it does end up working with the 30mm bar. At what point should I worry about my shocks being out of their usable range? Another part of my reluctance to go softer. Then again, if the combined wheel rates of the springs plus sways comes out similar then maybe it's not that big of a deal? I also want to measure my pickup points and calculate wheel rates with different spacers. I that'll help me wrap my head around that matter too.

Dave what bars do you run? Didn't see that in your first reply.

[Trublu]

Listen to your butt. Record what it says. Think about what it said. Think some more. Make a single change. Repeat.

[Suck fumes]

You put a 950 spring in any car and you might as well remove the shock cause it will do nothing haha. Might as well be racing a train that doesn't flex at all and will be so unstable and twitchy you will get eaten alive in the turns. Like I said a thousand times before but only one person has listened.....softer is faster! You just have to be smooth! You'll be surprised how much longer tires last and how consistent your tires will be too cause the suspension actually moves and works instead of putting all the pressure on the tires and Sliding them.

[mach1]

You put a 950 spring in any car and you might as well remove the shock cause it will do nothing haha. Might as well be racing a train that doesn't flex at all and will be so unstable and twitchy you will get eaten alive in the turns. Like I said a thousand times before but only one person has listened.....softer is faster! You just have to be smooth! You'll be surprised how much longer tires last and how consistent your tires will be too cause the suspension actually moves and works instead of putting all the pressure on the tires and Sliding them.

Depends on the motion ratio, on a mustang 950 isn't bad, wheel rate is ~1/4 of that

[Suck fumes]

Like I said only one person has listened to me and he is a lot faster now. Y'all can choose what you want.

[Supercharged111]

Aaron don't forget 950 is noticeably soft compared to what I had. I went from a 1200 down to a 950, a 250# drop is significant. I don't think it's the end all, IMO I need to go too soft before finding what I really like. I think the biggest shocker is that it doesn't oversteer like crazy with 325 out back.

[GlennCMC70]

Aaron don't forget 950 is noticeably soft compared to what I had. I went from a 1200 down to a 950, a 250# drop is significant. I don't think it's the end all, IMO I need to go too soft before finding what I really like. I think the biggest shocker is that it doesn't oversteer like crazy with 325 out back.

Remember where I said above that the 4th gens like a 3 to 3.5:1 front/rear spring ratio? Well w/ the 950/325's you are at a 2.9:1 ratio. Right on track. Combined w/ soft bars, you may be close. I ran 850's and 275 for a year or so. Car was OK, but not consistent from track to track. Biggest issue was standing starts. I would just get killed due to rear tire spin. No weight transfer. Softer springs allow the weight to shift. You need this to happen.
The F/R rate ratio is a guide as some guys like a lose car and some can't drive one that way. Lose is fast, but is hell on rear tires. makes the front work very well though as they can do more stopping and less of the turning. Remember, brakes and throttle are for turning too.

I agree w/ Aaron to a point. You can go too soft. Since roll rate stiffness is limited by the sway bars, you must add some spring rate to compensate for that. If softer was better no matter what, we all would be running OEM spring rates. Trust me, I've run 5 years on a 550/175 rate set-up w/ 315's on all 4 corners w/ a previous 4th gen. My CMC car is way faster w/ 200 less HP.

Set-up is a puzzle. The pieces of the puzzle are springs, sway bars, camber, caster. Mess w/ one and all need adjusting.
One way to tell is all the puzzle pieces are fitting well is to look at tire temps across the face as well as air pressures of the tires front to rear. If your F/R pressures are different by more than 5lbs, you need a set-up change. If your tire temps across the face of the tire are off by more and 10 degree steps (ex: outside220, middle205, inside220 = too low air pressure) you need a set-up change.
You should be using the tires equally across the face. This gives you even tire temps (10 degree total spread should be the goal). My tire pressures are normally 2 or so different at most from front to rear. I may even have a difference of 1 or 2 from left to right.

#1 -Know why your making a change, #2 - predict what that change will give you. #3- If you get something different, question #1. #4 - If you get what you expected, was it more or less than what you need. #5 - Go back to #1.

So you have the rate ratio range (3 to 3.5:1) as a guide. Are you in that zone?
How are your tire temps across the face?
How are your air pressures from tire to tire?
Is the car faster now than before?


Also, never use tire wear as a guide to set-up. I need to flip my tire between each event to get full life out of them.

[Suck fumes]

After I sell my CMC car this yr I'll reveal some numbers on my car but until then I have to remain quiet haha.

[Fbody383]

Dave what bars do you run? Didn't see that in your first reply. To be blunt, I'm not sure anymore. I will try and get a caliper on them and let you know. I do know they are one deal slower than Curtis and Ryan at Hallett.

[Supercharged111]

Tire temps continue to haunt me. I even read an article recently that said what you said, it's great feedback that tells you exactly what's going on. I couldn't tell you my tire temps, I don't yet have a probe.

Is the car faster? Hard to say. With the illegal spacers, yes, but when I max out track width legally it may get pushy again. I got my ass handed to me at HPR, so relative to the field no I wasn't faster than before but there were a lot of variables. On my most recent track day, I ran as fast in 95 degree heat as I did in May when it was 75, but the track wasn't being heated by cars last weekend (about 8 turned out total) so how hot was the track really? I had plenty of open laps in May once the field spread out too. I know the car makes less juice in the heat, but on my last run I was able to hit the rev limit every single lap between T3 and T4. I've never done that before, ever. I was also able to hit the limiter in 4th just before the brake marker every single time and I couldn't do that before either. The car gives indications that it's faster, but it isn't putting up the lap times and I was driving the wheels off of it compared to May. I was more consistent and picked up a lot of speed in parts of the track I felt I was lacking in back in May.

#4: I got what I wanted on that spacer change, but it makes me wonder if there isn't more to be had?

On another note, I think I may have artificially stiffened the front when I raised it and the roll center.

[AI#97]

Tire temps continue to haunt me. I even read an article recently that said what you said, it's great feedback that tells you exactly what's going on. I couldn't tell you my tire temps, I don't yet have a probe.

Is the car faster? Hard to say. With the illegal spacers, yes, but when I max out track width legally it may get pushy again. I got my ass handed to me at HPR, so relative to the field no I wasn't faster than before but there were a lot of variables. On my most recent track day, I ran as fast in 95 degree heat as I did in May when it was 75, but the track wasn't being heated by cars last weekend (about 8 turned out total) so how hot was the track really? I had plenty of open laps in May once the field spread out too. I know the car makes less juice in the heat, but on my last run I was able to hit the rev limit every single lap between T3 and T4. I've never done that before, ever. I was also able to hit the limiter in 4th just before the brake marker every single time and I couldn't do that before either. The car gives indications that it's faster, but it isn't putting up the lap times and I was driving the wheels off of it compared to May. I was more consistent and picked up a lot of speed in parts of the track I felt I was lacking in back in May.

#4: I got what I wanted on that spacer change, but it makes me wonder if there isn't more to be had?

On another note, I think I may have artificially stiffened the front when I raised it and the roll center.

Is the car inconsistent or is the driver? Track surface could have been different too?

I also think you are overthinking all of this. Set the rates to something you like. Then buy the right shocks that can help you make finite adjustments at the track to change the setup to the conditions. Beyond that. Get tons of seat time. With that seat time, you will get a better feel for the car and can make small changes as YOU get faster.

Good luck!

[Suck fumes]

Yah you have to get a lot of practice in to understand what you feel under the car. No point in changing a bunch of stuff until you know what you are changing.

[Supercharged111]

What I really know is that, before the spacers, I had an undeniable mid-corner push that was driving me nuts and holding me up. It wasn't a small nuisance, and I'd like to keep it away without relying on illegal spacers. The front simply wouldn't dig enough to make the car work. My goal was to add grip up front and not simply make the rear loose to shift the balance. Most of my laps are usually within a second of each other with a few rogue slow laps here and there. I'm not as consistent as Bryan, but when the car turns to a dump truck 3 laps in it can be tough to be that consistent. I think that's why I was so much more consistent with the spacers because the car finally responded to my inputs. Was it ideal? I doubt it, but it was good enough that seat time would again be beneficial. There for a while, I'd really felt I was hitting a wall and it was frustrating. Up through Hallett, I kept seeing incremental improvements in my driving but at HPR, I didn't see any. It was awful. I think it was just a bad weekend for me, but seeing how there's another race there in October I'd really like to do better then and see that improvement again.

[Suck fumes]

Your situation is a combination of tire pressures set incorrectly and having spacers softens the car which again tells you softer is better assuming the camber is set correctly. When the tires heat up to fast from sliding (which is from being to stiff, or from setting cold pressures to low) then the tires balloon up really fast after you run a few laps and you overcook the grip level.

[Supercharged111]

So would I see a smaller swing in tire pressures by going softer or a slower swing in tire pressures, ending up the same at the end?

[Suck fumes]

Well you definitely do NOT want to start your tires to low. Anything in the 20psi range is WAY to low and they will heat up faster cause they are flexing to much. Without seeing your car and measuring everything it's hard to tell you what needs to be changed. But I do know for a fact that the 4-5 lap dump truck handling comes from either overdriving or over flexing your tires early on. Start with a higher cold pressure then work with camber and toe. All while being smooth with the gas haha. Running a softer setup will make your car more consistent cause you won't be putting as much stress on the tire itself. The suspension will take more of the abuse instead.

[Supercharged111]

Yeah, I'm always a sledgehammer the first couple sessions. Takes a bit to quell the excitement and get back to work on the little things. I'm starting with 27 cold on the front outer tire which gets me about 36 hot, no nitrogen yet. The 4-5 lap dumptruck effect is what caused me to go down cold in the first place. I didn't think I'd hit the wall this quickly, I really do need to get a handle on tire temps to smartly move forward here. Every time you harp on softer suspension, it reminds me of when I fixed the broken swaybar on the wife's car. Without it, it rolled like crazy. Once I fitted a 1 piece swaybar, roll was decreased but the car wouldn't tolerate much steering input before it understeered like crazy. Kind of like when I swapped the 950s in at the track, first yank of the steering wheel and I could tell it tolerated more input before breaking loose.

[Suck fumes]

Having the car roll is what you want. Granted there is a fine line but you want the weight to roll onto the wheels cause the weight is what gives you grip. Without roll you have little weight pushing down on the tire hence the eventual push.

[Supercharged111]

If I were to guess, I'd say too much roll is when you exceed the usable range of the suspension and can't maintain even tire temps across the face?

[Suck fumes]

Bingo! Have to try various rates though to know what is too soft. Have to have someone take temps right when you come into the pits to get accurate readings.

[Supercharged111]

I think I have a grasp on this, just haven't had a real logical way to get there in my mind. I've read my ass off on suspension so when somebody talks, I'll understand. It's just a little intimidating to put it to work for yourself.

I just measure my scrub. I ran a string across the 2 ball joints all the way to the floor. Then I put a straight edge against my brake rotor where the wheel mates with it. The distance between those 2 points on the ground was 2". Subtract 54mm (the offset of a Z06 wheel) and I have -4mm scrub. I'm going to measure again, but right now it looks like all of my scrub comes from spacers. I wonder if sliding the lower control arms back in some and using wider bolt on spacers up front wouldn't change it for the better?

EDIT: I just calculated wheel rate, strictly with respect to springs. I'm not entirely sure how to treat the sway bar as both wheels share it. A 950# spring has an effective rate of 489# with a 1/2" spacer and 482# with a 3/4" spacer so IMO that change in the car's behavior was in no way attributed to the effective change in spring rate. Now it may still want softer springs to be better than it was, but it seems that's only part of the story.

[Suck fumes]

Work on springs and bars first. Spacers aren't a consistent fix

[Supercharged111]

Yeah, spacers are all I had though so my goal is really to extrapolate what the spacer change actually did to make an informed decision on my next move. I snuck an edit in up there too.

[GlennCMC70]

Like I said above - The sway bars are fixed variable for the most part since 4th gens only have 2 real options for front and rear. Most all guys I know run the biggest you can. Then make the car work w/ spring changes.
Use the smaller bars to tune the balance from track to track or from old tires vs new tires.

Keep in mind.....
Big spring rates, small bars. Small spring rates, big bars. Caster is a fine tuning tool here.
Stiff set-up, less camber. Soft set-up, more camber. Again, caster is a fine tuning tool here.

Caster give you the camber you need in the corner, but don't want to run under straight line braking.

Lots of camber, less caster. Little camber, lots of caster.



Something I always tell myself and when it was told to me the light bulb started to come on.......
The end of the car w/ the least amount of grip will let go first.
If the car pushes, the rear has more grip. If it overstears, the front has more grip. Don't confuse that w/ one end or the other at max possible grip, but the grip level relative to one end vs the other.

For 4th gens, it is far easier to make at the track changes on the rear of the car.
Gotta find the balance for everything together. They all play off one another.

[Supercharged111]

Yeah, haven't forgotten a thing anyone's said. I just have to wonder though, just because everyone's doing something 1 way does that mean it's the best way? There is more than 1 way to skin a cat. I know I can reduce rear grip to balance the car, but then in my mind I'd just have both ends sucking. I'd really prefer to increase grip up front. I'm currently looking at how much money I have to see if I can't slice off some for a tire pyrometer with probe. This far into a season is usually pretty thin for me.

[GlennCMC70]

Your right, more than one way to get there. But the range of "getting there" is not unlimited.

The car will not work w/ 900lb roll rate sway bars and 100lb springs. Get my point?

I like to use Nick Steel as an example. 2006 Nats. I ended up behind him in the Champ race. We had a great battle for most of the race. I was only slightly faster than him, but only after 10-15 minutes of racing. At the start, he was faster. He was known for running 1200lb rates on the front. I noticed as I got closer, he was making more and more mistakes. I finally figured out his tires were going away. This was a 45 minute Champ race. I sat back and just stayed on his ass showing my nose any chance I got. He ended up driving off at T1 at Mid O.
So like Aaron said, stiff still may be fast, but for how long? Is stiff for you? Your style will dictate if that works. Stiff will also not work well off line. Not many passes take place w/ the overtaking car on line.

If you do some testing on non-race weekends, see if someone will allow you to use the springs they have to test with.

[Supercharged111]

Well you confirm what I've experienced with the car. I also found an old video of someone beating him at Sonoma. Off like a rocket at the start, then a few laps in he gets passed and is never heard from again.

How hard is it to change driving style? I have to believe that my style is currently developed around how the car acts. I know I tend to cheat corners at times with an early initiation/late apex simply because the car won't tolerate a sudden, large input to bomb down toward the apex so that's the only way to force it down to the apex. It's subtle, but because my trajectory is slightly off at the apex I feel I've been sacrificing mid corner speed. I saw it work against me at Hallett T1. There's that dip right where you need to turn in. When I tried to turn in from that dip, the car snapped loose and I'd miss the apex so I cheated the corner and lost a bit of speed. As I chased Dave Francis, I watched his car wallow through, hook, and turn up the hill nailing both curbs along the way. He carried more speed through T1 and that's likely part of why he was able to pass me back in the bus stop 1/2 lap after I passed him.

[Rob Liebbe]

Supercharged111 - remember that Mustangs and Camaros are different animals. While the generalizations may cover both vehicles, the details are vehicle specific.

[AI#97]

Supercharged111 - remember that Mustangs and Camaros are different animals. While the generalizations may cover both vehicles, the details are vehicle specific.

You speak the troof! With both cars in our garage, I can tell you what works for one, doesn't work for the other AT ALL sometimes. General rules apply however, they are truly apples and oranges when it comes to setups.

[Supercharged111]

I know my front rates are similar to what works for a couple of people who can outrun me, so I think I can work with what I have, but I also believe I should try going too soft down the road to make sure it's not something that's going to work for me. I don't want to reinvent the wheel before my next race, I have the winter for that, but I can try a couple of subtle things between now and then.

[Rob Liebbe]

Careful - the winter break in Texas NASA is only a couple of months long, it goes by fast.

[Supercharged111]

I brought in the right side rear a arm bolt in an attempt to narrow the car. I also found that 2 degrees is as good as it gets for camber for me. Since my gauge lacks resolution, I'd call it more like 1.9. The car got wider. WTF. My guess is the BJ is ahead of the center point with respect to the front inner joint if that makes sense, so to narrow the car I must move the rears out. Mind blown.

[Supercharged111]

Mind blown further today. Track width extracted via slightly more camber gave similar positive effects as just slapping bigger spacers on, 'cept today I was legal (practice). I was full of shit in my last post, the BJ was not in front of the inner LCA mount bolt. I must have just gotten more camber with sheer rage for as hard as those bastards fought me. Some 1/16" Blaine fab spacers ought to bring me within 1/16" of max width. The handoff from brakes to entry was hairy when I tried riding the edge today (or was I really getting down to the nitty gritty?) so I really think that dropping the rear spring rate will make the car easier to drive. So would a softer rear pad compound seeing how the bias valve is fully backed off already. :roll: Stupid expensive race cars.

[Fbody383]

Stupid expensive race cars. It's only expensive up front...

[Supercharged111]

Well, getting there right? They make it look easy to keep hanging out there.

[Supercharged111]

I feel like I should give some feedback on some recent changes I made. So initially the car had 1200/325 springs and a 30F/small rear bar. I've left the bars as is, hoping to run a big spring/small bar combo because in my mind it just sounds better. I ran the car like this at Hallett. A month later, I tried some 950# fronts. Though I could feel what I perceived as an improvement through the wheel (tolerated more input), the car really wasn't working that well. I was still under max front width too. When I slapped wider spacers on, the car took off. At first, I thought this was because of the lowered wheel rate. Well I ran some calculations, and it was off by about 8#, so definitely not the cause. Next thought was scrub radius, but that was also squashed. Lastly, I realized that a wider car transfers less weight. So we're back to springs, but now for the right reason. Lighter springs transfer less weight. At this point, I'm still sitting on a 950/325 combo that is still prone to understeer even with the alignment tweaks I'd made (which go the car to legal max width). I ordered some 275# rear springs as I suspected I was just too far outside of what everyone else was running to make the car function. I (and others who guided me) was right. The car still had a mid corner understeer, but now I could get on the throttle and the car would rotate. Not drift, but just rotate and hook and go. It was a very progressive feeling, unlike how it's ever acted before. That was practice, after that I snagged some 900# fronts off of Bryan, threw them on, and started to feel the car out again. Relative to the field, I was the fastest I've ever been. Hell, relative to myself I was the fastest I've ever been. I beat my Z06 lap times by 5 full seconds! I still plan to grab some 250# springs to bounce back and forth with, but I feel I can concentrate a little less on the car now and a little more on me.

[Pranav]

Reading through this thread and others, I feel like I may be doing a number of things wrong:

Tire pressures: running mid-high 20s starting. This too low?

Spring rates: Went up to 750F/250R from 600F/200R last summer, no spacers in the back. Car feels stable and doesnt seem to push, but I think it's harder to drive offline now. Running 32F/19R bars.

Front camber: I know it's too high, can't get an accurate reading but suspect it is above 2.6*

My pyrometer readings are showing a 20-25*F delta between the inside (hotter) and outside (cooler) of the front tires, so I will take the car to an alignment shop and back off the camber accurately.

What should I aim for front camber/caster/toe when it's on the rack? -2.2 camber, max caster, 0 toe?

What should my starting pressures be?

Hoping to get to TWS this Friday to try out other variables (rear spring rate, rear spacers, tire pressures).

[mach1]

Reading through this thread and others, I feel like I may be doing a number of things wrong:

Tire pressures: running mid-high 20s starting. This too low?

Spring rates: Went up to 750F/250R from 600F/200R last summer, no spacers in the back. Car feels stable and doesnt seem to push, but I think it's harder to drive offline now. Running 32F/19R bars.

Front camber: I know it's too high, can't get an accurate reading but suspect it is above 2.6*

My pyrometer readings are showing a 20-25*F delta between the inside (hotter) and outside (cooler) of the front tires, so I will take the car to an alignment shop and back off the camber accurately.

What should I aim for front camber/caster/toe when it's on the rack? -2.2 camber, max caster, 0 toe?

What should my starting pressures be?

Hoping to get to TWS this Friday to try out other variables (rear spring rate, rear spacers, tire pressures).

My starting pressures are 27F 23R fyi. I will change this depending on outside temps, those are for ~70f.
I like to see 5-10 deg delta between inside-middle-outside which could be up to 20deg total between inside and out. Do you have a tire temp logbook? If so, post some recent entries from it and I will give you my two cents.
Alignment specs sound pretty good, based on the temp delta you posted I think 2.2 to 2.5 (will depend on the track) for camber. I like to run a little toe out in the front if needed (helps turn in).

[Fbody383]

Tire pressures: running mid-high 20s starting. This too low?

Spring rates: Went up to 750F/250R Running 32F/19R bars.

Front camber: I know it's too high, can't get an accurate reading but suspect it is above 2.6*

What should I aim for front camber/caster/toe when it's on the rack? -2.2 camber, max caster, 0 toe?

What should my starting pressures be?
Since as long as I can remember I ran 700/225 (subject to edit) springs.

Made spring change for TWS DOWN to 600/175 (car was too low without the factory spring spacers in the rear), I think 32/21 bars on the car, first time out on RRs and 29 front / 28 rear, about 2.ish camber / 4ish caster. If I measured it I would go for 1/8"-ish toe in since I still have the factory control arm bushings.

Koni singles, rear full FIRM, fronts several sweeps from firm but I think I'm going go up for Hallett test day.

Tyler took temps once for me and shook his head since they seemed to have the right relative spread.

I thought the car was a little more raceable, i.e. R4 I was able to go inside the 34 between 1 and 2, but maybe reminded me of the Toyota truck in the sense that you just had to get it all loaded up, but it was entirely predictable. (I know, I shouldn't have changed tires and springs at the same time...)

[Supercharged111]

On my gauge, my starting pressures are generally 27+/- psi. I have the small rear bar and 275s out back, I had trouble with it at PPIR being loose despite it working well at Pueblo last year. Brian let me run his last year RRs and they were a full second faster there than my last year RA1s. I think I want some 250s and then use a bigger bar out back for the pushy tracks. I also need to get a template for recording tire temps, what do you guys use?

[Pranav]

Threw it on the alignment rack, driver's side had 2.3*, passenger 3.3* camber

Man was I off.

In the end I'm now at 2.2* camber, 4.9* caster, 0* toe.

Let's see how it plays out tomorrow!

[Supercharged111]

You done your corners yet? I'm on that now like a fat chic at a buffet. Too bad the rear spacers are in the trailer and I'm a few too many beers in to go grab them. I figured an adjustment at 1 wheel would show at the opposite corner. Not so much. My averages are good, but l/r disparity blows. Going to tweak for greater consistency tomorrow. Mr. Francis are you reading? I've got a borderline deghettofied, halfway sorted out car this time around! The driver? Don't put much stock in him.

[Fbody383]

Mr. Francis are you reading? I've got a borderline deghettofied, halfway sorted out car this time around! The driver? Don't put much stock in him.I always figured I was on borrowed time... Good think I race better than I qualify. What kind of beer is it you said you like?

[Supercharged111]

I always figured I was on borrowed time... Good think I race better than I qualify. What kind of beer is it you said you like?

I just signed up, forgot to put something in sponsor block to taunt you. I'm the same though in that I tend to qualify shitty then once I've got something to chase I'm on it. . . until I finally do pass then I don't know what to do next. I'm a total beer slut. I'll likely have an IPA, a lager, and something red or brown in the cooler. Colorado will do that to you, can't swing a dead cat without hitting a mircobrewery. About to go reattack my corners now. It's weird to read about this, talk about this, then I finally do it and the scales are responding. I'm hoping the car responds too, but I kinda suspect I won't really notice anything. Whether it turns better left or right can often be more attributed to the camber, speed, sharpness, etc of a curve. I think.

[Supercharged111]

So while a 1/8" shift in the shock collar up front provided about a 70# shift, a 3/32" spacer out back did absolutely nothing. Cranking the front up helps to make the ride height more even from left to right, and jacking the rear will only increase the disparity in ride height from left to right. Conversely, the changes that improve ride height disparity adversely affect the l/r weight splits. Diagonals are pretty damn close now though, so the averages of the 2 are close. I imagine it would be ideal to have the l/r split be even which would imply that the diagonals would be perfect, but the changes required for that would leave me with a real odd stance. Does this mean that the tub is noticeably tweaked? Do I need to get this thing on a frame rack?

[Supercharged111]

Couple notes: that first adjustment was a fluke. I reverted to even collar heights and the weight didn't change. Second note was that I did this with sways connected, so I get to do it all over again.

[Supercharged111]

Figured I'd plug this in here. Not the difference in width. The RA1s are on SS wheels and the RRs are on Z06 wheels. Is the difference in width due to the rims or are the RRs actually wider too?

http://i198.photobucket.com/albums/aa70/supercharged111/Camaro/2016%20Tires_zpsnkqfqwkw.jpg (http://s198.photobucket.com/user/supercharged111/media/Camaro/2016%20Tires_zpsnkqfqwkw.jpg.html)

[Pranav]

9.5 vs 9" between those two wheels.

[Supercharged111]

9.5 vs 9" between those two wheels.

Yeah, is that what's affecting my footprint here? I was shocked at the difference when I put them up side by side. The pic doesn't do it justice.

[Pranav]

Yeah they will push the sidewalls out some, that's what you're seeing.

Currently running 3 of SS wheels. Always am keeping an eye out for z06 fronts.

[Supercharged111]

Try the Corvette forum. The road racing guys run all rears and have little interest in the fronts.

[mach1]

Is the difference in width due to the rims or are the RRs actually wider too?



Both, the RR's are wider than the RA1's, they are "cheater" 275's

[Supercharged111]

Both, the RR's are wider than the RA1's, they are "cheater" 275's

Cheater parts are the best.