dzombek

Looking through my aligenment spec's I see something that I don't understand... I have attached an image of the alignment and if you look at the camber upfront it shows 2 numbers. Left is 2.7 and Right is 1.9.

Caster and Toe are setup real nice and have a small variance.

Are the numbers a bit off because the allowance for the driver weight in the car?

Couple weeks to Mid Ohio!!!

David

dzombek

OH, BTW, ignore my bad spelling... Long night last night..

sweanders

An alignment is best done with the weight of the driver in the seat. And with 2.7 resp. 1.9 I hope you got the alignment for free. Perhaps there was a reason for not being able to adjust the camber to more than 1.9 degrees on the right - running like that on the track will kill the outside of the tires and you'll probably wear it down to the tyre wall side text.

RKD in OKC

Are you doing the course clockwise or anti-clockwise?

Personally, I would have wanted them set the same.

dzombek

The shop took into account that I weight ~180 when they did the corner balance. And the tracks that I will be running are Mid-Ohio, Putnam, and VIR(If the accountant(Lori) will allow

Yeah, I would normally want them the same but I thought there might be a reason for the difference.

The car goes back on Sunday so that the Toe can be check as I had to replace the TR-ends. (Oh btw, this is the first time my car cut me and caused me to get a Tetanus shot)

I will ask them when they have the car.

jerome951

Since you're running a mixture of street and track, I think you'd want them equal L:R.

If that weight is with a 185# driver, you're going to drastically understeer and wear the outside shoulder of the right front tire on left-hand turns.

If that was the reading with no weight in the car, ask them what the values were when they had weight in the car. If they're just guessing as to where to set the alignment to account for weight, find another shop unless they're 944 experts.

FWIW, I checked the camber change with me (220#) in/out of the car. Less than 0.2 degrees change, though I'm running heavy front springs. You'd likely see more with stock springs.

dzombek

Thanks Jerome, I talked with the person who did the alignment. The reason for the camber settings being the way they are is that he set the car up for tracks in this area like Mid Ohio, Putnam, and VIR.

Since this car will see the track more than the street, I asked for a good track setup. So the amount of -camber on the left side is to accout for the tracks with more right hand turns than left hand turns.

Man this is a delicate balance between Street and track driving, I think I am now officially listing to the track side... Now I have to tell my wife.

Z

sweanders

I don't understand why you would intentionally want to ruin the cars left turn capabilities. It isn't oval racing we are talking about and the excuse the shop is using sucks because even -2.7 degrees camber is still mild.

dzombek

Good point Sweanders, well taken...

jerome951

Probably to benefit the more-numerous right-hand turns. Keeping the right wheel more perpendicular on right hand turns should benefit cornering ability.

However, most racers I've talked to develop 'staggered' camber settings based on tinkering at the track between runs and gauging it's effect on overall lap times (at the expense of drivability and tire wear). Unless this alignment shop has significant experience in setting up 951s w/ your type of suspension, I'd play it safe and keep them even.

The other issue I see is that they didn't modify the right rear camber much in relation to the front. You're gonna generate a lot more rear grip in left-handers than front grip, which is going to lead to big-time understeer. You are going to hate T1 and T13 (?, fast left-hander exiting Thunder Valley) with that little front right negative camber.

Even on right-hand turns, I think you're going to see some understeer w/ that F:R camber combination.

Chris Prack

Having set up more of these cars than I can tell you, your alignment is less than optimal. You are going to be unhappy. You are going to kill one of the front tires. You have almost a full degree differential in the front. For what? Sweanders is correct, this isn't NASCAR.

You need to get the camber corrected. If your car has a mechanical limitation in the front and they cannot get any more than -1.9 on the right side then you need to match the left to the right or atleast get as close as possible. They should be able to get more caster than that as well.

What tires are you using? What size tires are they? What suspension do you have on the car? What is your experience as a driver? What do you want from the car? Is it mostly track or street?

dzombek

Thanks for all the information on this alignement. It made me do some thinking and reading on a subject that I don't have much technical knolwdge on.

Since I am taking the car back tommorow to have the toe checked, I am going to have the camber set to (some medium) on both wheels upfront and have the rear adjusted to reflect the fronts. Any sugesstions?

Well, the car sees some street when we goto our local PCA events, and about 3 track events a summer. The tire wear I can live with because we only put 1000 miles on it last year.

So with all the input I can say I will feel better and safer with the camber adjusted to a happy medium.

Thanks
"Liven and learn'n"
Z

sweanders

I have R-compounds and a very stiff suspension on my car with the Cup car sway bars and I run -3,4 degrees camber. One of the fastest 951 driver in Sweden runs -4,1 degree camber up front but that is with a track only car.

EDIT: I just dug up his numbers and they are:

Front: toe 0. camber -4,5 (right) -5grader (left) caster unknown
Rear: toe in 2,5mm per side. camber -3,5

See how much camber you can get, maybe 2,8 is a good number for you? I don't have much experience for streetish suspensions..

Chris Prack

I can give you my suggestion on alignment specs but you need to answer the questions posted in my quote. EVERYTHING matters. Throw on top of that the fact that no two drivers are the same. The way I have my car aligned could just drive you into fits and vice versa. There is no "one" spec.

OK. Starting point. R compound tire like a RA-1 or Kuhmo. Front camber -2.8 to -2.5. Get as much caster as you can that keeps it even side to side. 0 toe.

Rear camber -2.2 to -2.0 and go about 1 to 1.5 mm toe in for a total of 2 or 3 respectively.

You can match front and rear camber if you want but the rear does not need as much due to many factors, the least of which are tire size and the fact that they are not suffering camber change like the front.

Street tires I would drop camber front and rear. Running a Hoosier or MPSC I would go more negative and make some toe changes as well.

dzombek

Thanks Chris... On the track I am running RA-1s with the following sizes
(F) 225/50 16 inch
(R) 245/45 16 inch

The suspension has been lowered and has Koni front and Koni rear coil overs. I didn't look at the spring rate.

Not sure how to answer the "driver experience", not good at talking about my self. But I am looking to get a good track setup with street useability for PCA events. Like I mentioned, the car hasn't seen may street miles last year...