Alignment after lowering with bigger tires?
 

Okay so I am putting in Tein S-tech springs with my stock shocks. I also just got 245/45/16 on the stock rims. Now once I get these all put on the car I am going to need to get an alignment. Does anyone have suggestions as to any specifics I should ask for? Or just have them set it as close to spec as possible. As much as I love performance handling I would like my tire life to be as good as possible. Any suggestions would be fantastic thanks.

Stock specs will be best for tire life, but will sacrifice a little bit of handling. Nice name :)

If there is a good alligment shop around you. You could have a custom alligment done to what you want to do. My tires wore weird after just going up to 17 inch rims and wider tires.

I also wondered this, b/c I heard that lowering the car changes the suspension geometry, so the alignment specs change. If I'm not worried about tire life, and handling is my primary concern, how do you go about finding the proper alignment specs?

Thanks
~Ramy

the Pettit long track and short track are good starting places...you can tweak from there

http://www.jimagu.com/tinou/pettit_alignment.jpg

Bah. 7racer beat me to it. I've used those specs since i got the car and they've been great. I was running 1.2 neg camber in the front and saw no noticeable irregular wear pattern on my Kumho 712's after 10k miles. I've also been on track and have the car lowered ~1.5" I've been very happy with these settings for a real daily driver car that sees some time on the track.

As you lower the car the suspension gains negative camber. If you want more, fine. If you don't you have to align the car. Regardless I would at least have the alignment checked so you know what it is after the car was lowered. Toe will change slightly too as the chassis is lowered and excessive toe will eat tires much faster than any amount of camber will.

If you run on the street you try what other people use and see if that works for you. The only true way to do it is to race the car so the tire temps come up and then check them with a tire pyrometer. That along with driver feedback will tell you everything the tire is doing. Driving on the street and trying to check temps would be absolutely pointless.

I'm not worried about tire life as my car is setup strictly for the track. The price I pay is that I go through street tires more than twice as fast and that's with driving them easy all the time!

Oh come'on :) You gotta take a quick corner here and there on the street too! You know you do it. I will give you MOST of the time, but not ALL of the time ;)



I also sacrifice tire wear, for on the track handling... but I align my car after every major component change.

I wouldn't call Tein springs a major change but I would second the statement of just putting it on the rack and seeing what it's at. You REALLY want your toe settings to be in spec. VERY important for tire wear.

I was toying with the idea of going to les schwab or another alignment place and getting the car aligned and a camber kit put on. I noticed that I am going through my tires faster than I should be and the wear pattern is 65% on the inside of the tire.
Is the camber kit (ie"lowering kit") wishful thinking or does this actually exist?

camber kit? FDs have real suspensions, not Macphereson struts. All suspension parameters are completely adjustable from the factory.

Take your car to a performance or racing shop for the alignment. They know how to handle low cars and will typically do a much more thorough and accurate job than a Joe-Blow alignment place.

The Pettit Long Track settings work great for street use -- at least in the 16" wheel column. I think their 17 and 18" settings do not have enough camber at the rear.

Nope. I run so often on race rubber at the track there isn't even a temptation to go around corners quickly on the street; it would do nothing but disappoint me ;)

Once you spend time on the track you realize that even if you were willing to break every written law on the street you still couldn't get this car past 7/10ths at best. It's boring to even try :dunno:

YUP!!!

I used to take my FD (with street tires) to Nelson Ledges racetrack. It was fun the first few times, but after a while I couldn't enjoy it just driving 9/10, since I have the car in my avatar that I race in SCCA Nationals. Because of that, I quit running the FD at the track, because I didn't want to wreck it driving 10/10 (the only way I seem to have any fun).

I guess you only race on the street when you are pulling your trailer :D

I don't consider anything in a straight line to be racing :p:

I have to post new pics of the trailer. You guys are going to love it...

:rofl:

Terrorize any more NSX's lately, Damon...;)

Thanks guys for all the input :) Definitely useful!

Rynberg, I'm sure it varies w/ personal preference etc, but how much camber do you think is enough for 18" wheels?

Thanks
~Ramy

A lot of variance based on suspension setup and personal preference, but I think the rear camber should be pretty close the front camber in value (a little less negative). If you are running -1 deg front camber, I would not run less than -0.5 deg at the rear. I don't know why Pettit's specs are like that for taller wheels -- they produce more oversteer than their 16" settings, that's for sure.

My guess is that the reduced sidewall of taller wheels forces the tread to lose contact with the surface at (relatively) extreme negative camber. For the 16" wheels you have ~112.5mm (4.5") of sidewall between the wheel and the tread that allows for some distortion and squirm, whereas for 18" wheels you only have ~3.5"...about 25% less give in the sidewall. So it seems to make sense that the values are different to allow for this change to keep the tread in the same position relative to the surface.

But i see what you mean. They do cut it in half, which seems a bit drastic. Of course not only is the sidewall smaller, but it's probably quite a bit stiffer as well...so perhaps between the two it equates to about a 50% change in dynamic characteristic.

I'm running -1.3 all around right now with stock wheels. That's a change from -1.0 in the rear and we'll see how i like it on the track here in a few weeks.

Yes, a lower profile tire requires less camber. However, the Pettit settings change the RATIO of front-to-rear camber, not just the values of camber. The Pettit settings at the 17 and 18" sizes will balance the car towards oversteer. I suspect they recommend the settings that way because many people running 17 and 18" wheels run a staggered setup with wider tires at the rear.

So would you keep the ratio close if you're running similar (or close to) size tires all around? Otherwise, go w/ the Pettit settings? Or either way, you'd keep the camber in the front and rear close... say -9 front and -7 rear?

I personally NEVER have an understeer or lack of turn-in response on the track with my staggered width setup. IMO, the rear camber should be close to the front settings. With equal width front-rear tires, I would run the same camber front-rear or very close.

That's what I found worked best for me. I tried for quite a while running less in the rear but the car certainly hooks up best for me with equal amounts front and rear.

My front camber is maxed at -2 for the stock ride height and that is what the rear is currently at as well.

Do some research on the alignment shops in you area. I had a heck of a time finding someone to use my settings, I ended up doing the alignment myself. I found that some shops will only set the car to the “specified range” that’s in there machines data base. Les Schwab’s machine shows a range of -0.7 to +0.8 camber in the front and -2.0 to -0.5 in the rear, that’s twice the range allowed by the FSM. When I tried to explain that to the “tech” he said, “sir, if the green light comes on the computer screen then it’s fine”. I took the car to a shop recommended by a circle track racer, but there machine was so out of calibration I ended up with a 0.4 degree difference in camber between the two front wheels ( and consequently a difference in caster).

I ran the 110m high hurdles in college at Arizona State. I believe that to be a race ;)

You are right about track driving taking the thrill out of driving fast on the street, I was also on race rubber 20 weekends a year, however hitting an occational 90 degree apex on the street at 7/10 and hearing the classic rotary hum as you accelerate away stretching its legs a bit, is still entertaining.

A car shouldn't HAVE to be driven to 10/10 to be enjoyed...the mark of a truely great car, in my opinion, is that it can be enjoyed at every level.

does anyone have the details for Pettit Long Track settings ?
i seem to just ask my tire tuner guy to put it -1 for the fronts and -1.2 for the rears...