Paul902

I'm going in for an alignment on Thursday. I wanted to run the numbers I am thinking of, and get your feedback.

Car is C4S with M030 and Bilstein HDs. Current height is RS+15mm, ie 139mm front and 122mm rear at the measurement points. I have stock uprights and tie rods and stock bushings all around. I typically run Michelin PS2 tires. My usage is 75% street and 25% DE. I would like to balance tire longevity and performance. Currently my front tire wear is even across the tread, but I have corded the outside rears with still 4/32 to 5/32 left on the inside. This is the reason I am going for an alignment, I need to be kinder to those outside rear edges. I am planning to lower the car to 129mm front and 112mm rear, ie RS+5mm.

Current Alignment:
Front:
Camber L -1*00' R -0*57'
Caster L 4*23' R 4*12'
Toe L 0*03' L 0*03'
Cross camber -0*03'
Cross caster 0*12'
Total Toe 0*07'

Rear
Camber L -1*27' R -1*25'
Toe L 0*12' L 0*12'
Cross camber -0*02'
Total Toe 0*24'

Planned Alignment:
Front:
Camber L -1*30' R -1*30'
Caster L 5*20' R 5*20' or max acheivable even on both sides.
Toe L 0*03' L 0*03'

Rear
Camber L -2*00' R -2*00'
Toe L 0*12' L 0*12'

Essentially, I am thinking more front camber for turn-in, front caster per the manual, and more rear camber to save the rear tires. So, what's the verdict?

Paul902

Bump... anyone with experience here. Going for the alignment tomorrow!

Bill Verburg

looks good to me, I'd just go to 0 front toe and maybe a tad more front neg camber, but what you propose should be fine

Mike J

You want more camber in the rear to save the tires? That will help the handling, but 2 degrees will affect tire wear and do the opposite.

FranzBlamRacing

paul902,

Franz took a look at your desired specs and he said that they look like they'll help you reach your goal(s). If you wind up running more time on the track, you may want to go to 2 degrees of camber up front.

Paul902

Hi guys,

thanks for answering the call...really appreciate it!

Mike, yes, right now I am chewing up the rear outside edges at the track much faster than the inside edge, so more negative should help that.

Dwane

Andrew at WeTune?
Dwane

Paul902

Yep. 8am.

jdistefa

More cowbell.

Paul902

Uh... Front cowbell or rear cowbell?

Paul902

Uh...more front or rear cowbell? Mind if I call you !ruce?

flatsixforme

What tire pressure are you running at the track in the rear? You might want to increase tire pressure if you want to protect the very outer edge wear on the tire...2-4lbs can make a big difference in rollover. More negative rear camber can also help this so it's a balance. Downside to increasing rear pressure is you are reducing your traction (contact patch) in the rear so if you have a balanced car it might be a bit oversteery for your liking.

For reference, I run -2 up front and -2 in the rear for camber. I am likely going to go to -2.2-3 in the rear at my next alignment to alleviate the same problem you are having; however, I am about 80% track and 20% street and never need new tires due to inside wear. Also, consider buying tires that you can swap side to side after 6-8k miles...I did this on my street tires and got at least 3k more miles than I would have...well worth the $30 in mounting/balancing.

911CabSteve

Definetely think about the -2 degree on the rears for a mostly street car.. I run -2 rear and corded a set of rears on the inside (do a 993 forum search on "tire failure" and you'll see my pics) when I still had decent tread on the outside. My experience could have been catastrophic if I had not pulled off the freeway to meet my wife (and heard air hissing out)!

I run -2 rear and do the side to side switch of rears after 6-8k miles as Adam describes... This helps prevent premature inside cording when running negative camber and does give you ~2-3k more miles than you would normally get... Definetely well worth the $30 in mounting/balancing.

Fly911

On a C4S you should go for the maximum camber you can get, to get rid of the understeer these cars inherently have. I have managed to get -2.2deg. without camber plates. You will experience more tire wear, but the rears will wear out faster anyway. And since you should change all four tires at a time anyway, it won't help you to save the fronts.

Paul902

Steve, Fly, Adam, yes I'll need to watch the inside rears and consider a tire I can flip. I am currently running PS2s at 39 psi hot. There is so much inside tread left it hurts!

In the end I went with -1.8. front with -0*01' toe (just toed out a touch) and -2.0 rear with KT at 2.5 units. It seems a bit more darty on the street but corners better. I haven't gone hard yet in part because I lowered the car another 10mm and was caught out that the rear M030 end links would not work so I drove home with the rear sway bar in the front...trunk.

Thanks all for the advice and opinions!