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.Originally Posted by Rob Liebbe
Ah, fugg it.
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.
Rob Liebbe - Texas Region
Camaro, Mustang, doesn't matter to me, I'll race it.
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...
#39 CMC Camaro
Orange is Fast!
CMC-NT01 FTW!
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).
Last edited by Pranav; 05-18-2015 at 11:48 AM.
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).
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