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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.Quote:
Originally Posted by Rob Liebbe
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.
Careful - the winter break in Texas NASA is only a couple of months long, it goes by fast.
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.
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.
It's only expensive up front...Quote:
Originally Posted by Supercharged111
Well, getting there right? They make it look easy to keep hanging out there.
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.
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.Quote:
Originally Posted by Pranav
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).
Since as long as I can remember I ran 700/225 (subject to edit) springs.Quote:
Originally Posted by Pranav
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...)
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?
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!
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.
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?Quote:
Originally Posted by Supercharged111
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.Quote:
Originally Posted by Fbody383
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?
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.
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/a...psnkqfqwkw.jpg
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.Quote:
Originally Posted by 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.
Try the Corvette forum. The road racing guys run all rears and have little interest in the fronts.
Both, the RR's are wider than the RA1's, they are "cheater" 275'sQuote:
Originally Posted by Supercharged111
Cheater parts are the best.Quote:
Originally Posted by mach1