Track Alignment

Mn23

Hey guys, I’ve searched through the board and seems everyone is running less than -3 degrees camber up front and -2 rear for track. My alignment shop however recommended -3.7 front and -3.0 rear on my car. Is this too much even for a track only no DD Z?

My setup as follows:
KW competition 20k f 18k r
SPL all arms
275/35/18 RE71R square

Thanks

Zewerr

-3.7 is too much for for 275 RE's I had -3.7 after my first autocross alignment with 285 RE's and the inside of the tires were getting much hotter than the outside. I adjusted them to -3.1 for the following weekend and the temp across the tread was much more uniform. I settled for about -2.0 for the rear which seems to keep temps on the back pretty even. I am curious how my car will collect OPR, which may alter my preference. Also, I'm running about 6.2ish degrees of caster which will also make a difference.

Mn23

Thanks, so checking tire temps across the tire is the key. Should the outside be hotter? I was trying some used 305 slicks all around and the front were close with the inside being a tad bit hotter (~3 degrees celsius). But the rears were about 10 degrees (Celsius) hotter on the inside. Plus the rear were sliding out every corner exits, don’t know if the tires are done or my rear dampening is too stiff...(front Hotchkis, LSD and rear sway disconnected)

Thinking of going back to RE71R now.

AlWakRa

Do you have true coilover setup at the back?

The front camber looks good for slicks, I would prefer less at the rear. As for extreme summer tires, I got luck with around -2.7 front camber and -2.0 rear, 0 or a hair toe out front with stock rear toe in value, and around +6 caster.

About rear sliding, maybe too much rear toe in.

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Rusty

You want the tire temps even across the tire if possible. I would use this to set your alignment to. But if you run on a different track. The alignment might need changed to suit.

Slick can run a little more camber, but not much. Dial in your caster to +7, more if you can get away with it.

The Z has a weird camber curve built into it's rear suspension. The more it squats. The more camber it has. It's not linear. My 2 cents. Anything more then -2 camber is a waste unless you tire temps are even across.

Also, you can play around with tire pressure too.

Get a big 3 ring binder and keep track of all the changes you make. Keep notes on everything.

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Mn23

I have divorced setup in the rear, will lessen the camber in the rear to around -2 first.

Thanks Rusty, I’m currently at +6 caster, is there any cons for going +7?

Rusty

No.

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AlWakRa

So the rears aren't that hard, it may even be on the soft side, as most divorced setups focused on track have an equal or stiffer rear spring rates compared to fronts. I would suspect camber + toe in. I used to have a lot of toe in rear, around 0.9 total toe in, and the rears were sketchy and love to slide even with semi-slicks, getting it down to stock toe in value made it very sticky even with street tires.

Second guess would be very low rear height which mess the rear geometry.

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Rusty

People don't realize this when they lower the rear. The rear camber curve is not linear.

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Mn23

Yes I am planning to raise the height a bit as it is quite low. My spring rates are quite stiff at 20k front and 18k rear. Should I set the rears height a bit higher than the fronts?

My rear slicks were somehow sliding a lot at the last track day, I thought the tires were done. My rear toe is at 0.07

2011 Nismo#91

This is what I use, if it were a dedicated track car I would be in the -3 something range and lower ride height. I still are destroying the outer edges of my tires on the track.

Hotrodz

I run wide tires 315 square -3.3 front and -2.0 rear all with a tad toe. Caster is 6. If you are not doing tire temp in the hot pit after the tire is up to temp then forget about it. Play with your tire pressures. It is the easiest and most consistent way to adjust to conditions for those of us that don't have team of folks to help us and is still a what the big teams do. Once they have temps were they want them they play with tire pressure to dial it in.

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AlWakRa

I wish only camber curve, even toe adjustment range change with your camber value, less camber means higher toe in range to play with, due to its multi-link suspension design.

Your toe looks alright, suspension stiffness wouldn't have any issue, I run 21kg front and 7kg rear truetype (don't know the exact equivalent for divorced but should be in the range of 14-18kg) and it tends to understeer with equal height, I need to get my rear higher to get more balanced setup.

Maybe your assumption is right, old tires, as slicks performance depends a lot on heat cycles and storage. With re71r, you should be good with the alignment mentioned before.

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Hotrodz

I think coilover setting are dependent on the manufacture and their setup strategy. I run Fortune Auto true type rear 12k and front 14k. I am lowered about an inch an may go lower another .5 or .75. I find it hard trying to get it dialed in. I get better turn in down low and it seem I get more oversteer at higher ride heights. I also have a big wing and a front splitter that extends about 6" from the front bumper. All of those things impact how the car will handle as well.

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OptionZero

how the **** is a 315 front on a 18x11 +16 not destroying your fender under compression?

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