flatsixforme

Hey guys. I'm thinking of taking the plunge with some PSS10's and I wanted to get educated on what alignment options I have. I certaintly want to cure as much of the understeer I feel currently, however, seeing as I do mostly street driving I need a good compromise for tire wear.

What are the differences (if any) between the following (and what other options are there)?

- US spec
- Euro spec
- RS spec

A couple more questions:
- do I need to get RS drop links
- do I need to do sways (I have a C4 without M030 option)
- anything else I should replace while I'm in there?

Thanks for the help!

Steve Weiner-Rennsport Systems

Adam,

US & Euro alignment specs are largely the same; RS specs are different due to the car's track usage and mostly add more negative camber.

The need for RS rear droplinks lies with the car's final ride height. If its close to RS ride height, you will need the RS rear droplinks since the rear bar must be positioned above the rear lower toe control links.

The need for different swaybars depends on the driver's wishes/preferences and how the car will be used. One can use ROW M030 bars, ROW Twin-Turbo bars (larger), or the RS adjustable ones (very spendy).

flatsixforme

Thanks much Steve.

So, at ROW height I would not need drop links, correct?

Is it recommended to upgrade the sways from my current 17/19mm stock setup or will I not notice much difference? (I drive aggressively on street and plan on at least a couple DE/track days a year).

Bill Verburg

Steve covered the bases pretty well, just some thoughts,

there is a range of adjustment for everything,

if you get down to RS height you will want to add RS uprights & rear drops so you probably want a height between RoW M030 & RS

You'll want as much caster as you can get,

the more negative camber w/i the spec range the better cornering performance

the less toe down to zero f/r the quicker the car will turn(less straightline stability), most people aren't going to be comfortable on the street w/ near zero toe too close to zero in back results in rear steer, this can be unsettling

InTheAir

Bill, did you mean "camber" instead of caster?

Bill Verburg

caster, the spec is 5*20'+15'-30' and it can be hard to get

front toe spec is +5'+/-5', on a track car it can be near zero
front camber -20'+/-10' RS is -1*27'+/-30', track will run -2* or more

rear toe spec is +10'+/-5'
rear camber spec is -1*10'+/-15', RS is -1*20'+/-10', a tracked car will run -2 * or more

InTheAir

Gotcha.

In my case, which was admittedly ROW/HD (not PSS10s) down to just above RS ride height, I had no problem getting caster to RS specs, but camber was tricky to get close to -2.

Anyway, thanks for the clarification.

Bill Verburg

up around -2* or more negative camber you'll need camber plates, that's another reason why JIC are popular for tracked cars.

flatsixforme

Thanks Bill for the great info. Your second response is why it is important to have a trusted alignment specialist!

Tom W

If you keep it at US ride height, you may not be able to get much camber into it. If you go to ROW or RS ride height, you should be able to get -2° or a little more. While I have PSS9's, the most camber I could get at US ride height was about -0.75°. Getting to RS alignemt spec at a little below ROW height was not a problem. It's worked fine for street use and the track work I did in it before I bought the 964.

flatsixforme

How many miles would you say you lost on tire life due to the more aggressive alignment? I want to set the car up right for handling but at the same time don't want to cut my tire life (rear that is, I don't care about the fronts as much as they last a long time) in half.

black ice

Adam,
I have a 95 C2. The car came with M030 and Bilstein HDs. When I got it the car was pretty low and was running just over 2 degrees negative camber in back. I drive about 25K miles a year in my 993 and was very surprised to find the car eating rear tires for breakfast - no matter what tire in back, I was getting no more than 8K from a set of rears.

I had the car aligned and raised to ROW height. I had hoped for lower but ROW was as low as I could go and still get 1*20' out of the left side, which is stock camber. I've gone about 13K on a pair of Potenza RE750s since then and expect I'll get something over 20K out of them.

Dave

Steve Weiner-Rennsport Systems

Hi Adam,

Alignment is one of those things that requires some compromises,....

Adding more camber does increase grip in the corners but exacts a toll in tire longevity and straight-line behavior. As more camber is used, the car becomes more sensitive to road irregularities tending to wander more, especially under braking.

One is, therefore, forced to make choices about realistic tire life vs ultimate grip in the twisties and road manners. Further, people using R-type tires need additional camber (over street settings) to make those tires worth the effort & investment.

Once you determine what kind of tire life you require, I'd be pleased to offer some specific recommendations about alignment settings for how you will use the car.

maurice97C2S

I've been running RS height & alignment (with PSS9s) for 6 years, and get decent (near standard) tyre life even with occasional track days ..

HTH, cheers, Maurice

jimbo3

FWIW, Mine is set within a couple MM of the top of RS height. Needs no RS drop links or the RS shock tower thingies on the front. I can JUST get a low clearance (4 1/2" minimum) floor jack under the jack points by lifting up on the fender and sliding the jack underneath. Never a clearance problem driving on the relatively good roads here in TX. The MINIMUM rear camber the car could get was a hair more than 1.4 degrees, although the minimum may vary from car to car.

IIRC, Jeff (In The Air) is at RS+5mm, which is about 3mm lower than mine, has about the same story.

I'd say that the range of RS+5 to RS+10 is a pretty good compromise for all-around street use.