bavarian06

I had an amazing time during this weekends DE event. I'm so glad PCA offers this type of venue to advance a drivers skill.

While I was at the event, I was hoping for suspension setup tips from fellow 993 drivers but amazingly there wasn't any, asides a stock C4s.

Basically my questions are, what spring rates are owners using and what are their suspension setting (bound and rebound if their CO has that feature)?

Additionally, I was letting out pressure from my tires and wanted to know PSI settings. I'm running streets tires for now (Hankook Evo V12 - the instructors were amazed at the level of grip my car provided on street tires), 245/35/18 and 285/30/18. What PSI setting should I set before the first session and what levels should I lower it after the session. Thx!

Bill Verburg

It's going to depend on how deep your pockets are and your goals.

let's assume a dual use car
shocks -lots of choices best Moton, JRZ, AST also most expensive, I use JIC but they don't seem to be durable enough for my use ~22 track days a year, I suspect other street oriented shocks will be similarly weak.

springs most use a dual spring setup but a single spring would be better for track use, I'd say 450/675 f/r # at a minimum but you can go much higher w/ the right shocks(Motons) i know guys that run 600/800 w/ their Moton equipped dual use cars.

bushes - for dual use i'd changed every bush to a sport rubber harness except the rear toe links which need to be mono-ball, that's 7 bushes per side, 4 front 3 rear. also use solid rear side mounts and Tarret or Rennline rear mono-ball toe links w/ locks and booties.

you already have a good size tire, but an 8.5" vs 8" front helps a lot w/ turn in

If the car has been lowered(it should be) then 993RS front wheel carriers and GT2 mono-ball tie rods are wanted

The above is not going to be cheap

bavarian06

thx for the informative reply bill.

this is a single purpose car (it has been too heavily modified from the previous owner where it's no longer street-able).

currently it has moton double adjustable with 950 front and 1150 rears. we (instructor and i) found the car to be skipping around on uneven surfaces a little too much. the car was originally matched up with Hoosier R6 slicks which gave it a different characteristic than it current has. as much as i would like to go to full time slicks, i have no means to transport the car to events w/o driving it there (hence the street tires).

as for the rest of the suspension components, i have to give the PO a lot of credit. no expenses were spared (thankfully its cheaper to buy a track car than build your own). it has full monoball in the rear suspension and i recently put in chris walrod bushings for the front. it has the GT2 wheel carriers, tie rods, trg sways, camber plates, the full 9 yards.

what are your bound/rebound settings? i think the pressure in the separate reservoir is set too high.

i understand a lot of these settings are due to personal preference, but i would want a general baseline and work from there, refining it to the way i would want it.

thankfully the car doesnt push or oversteer, very neutral and surprisingly decent grip for the tire compound i'm using. i just want to remove the nervous chatter when going over bumps.

race911

Work with someone who knows these cars. $1K in that direction is probably worth $5K mods. Alas, internet chatter is pretty much worth what you pay for......... (Though I'll say nearly all of our opinions are valid, they're based on our specifics.)

One thing I can say without reservation is that I can't imagine not using at least an R compound tire on a car so heavily modified.

I also suggest looking beyond PCA for events, and more toward open test days with professional coaching to achieve specific goals. And data. In today's world, it's all about gathering and properly analyzing data...............

bavarian06

a wise recommendation. i was hoping i could play around with it myself first, then finalize it with a race shop. how do i look up open test days in my area?

any feedback about tire pressure in my first post?

race911

I suppose it depends on where you are in relation to the car's capability? Where were you? Is the car builder local to you? Funny how it's not that odd to run into guys who have 993 experience, but have moved on since the community has pretty much moved to the water cooleds. At least on the West Coast. But what YOU may end up with fiddling around could be 45-150 degrees off in the end.

You can check track websites, or you just have to be plugged in with the community I guess.

I've not run an non-R compound tire on the track since the '80s. I'd stay home or go play golf if street tires were the only option I had.

Larry Herman

Preferring a stiff car, I feel that your spring rates are perfectly acceptable (though a little on the soft side for my tastes). Do you have Moton Club sports (7 clicks) or Moton Motorsport shocks (15 clicks)?

As far as "what are your settings?" there is no one answer. Adjustable shocks are that way because along with the spring and swaybar rates, and tire stiffness etc, the track will affect your settings...for that track. I presume that you might have discovered this already. Find someone in your region who really understands suspension adjustment and have them help you, because as a learning student, you do not have the experience to feel exactly what the car is doing and what it needs.

Your skipping problem could be too much compression and cannister pressure causing you to lose grip when you hit bumps, or it could be too much rebound causing you to lose grip after you hit the bumps and your suspension cannot recover. This is where experience and feel come in.

That being said, if it were my car and I was starting from scratch, I would set the front compression & rebound to 3 (6 clicks in the Motorsport) and the rear C & R to 4 (7 in the Motorsport). I would set the front cannister pressure to 140 and the rear to 180. Then I would start testing. Oh, and keep a log book to record everything that you do and feel. It will help down the road.

d15b7

hi. Larry is an excellent resource for suspension setup and tuning, and his partner Bob races a 993, so I think you've found some useful help!

The only thing i have to add is that you should consider purchasing a 'road worthy' set of R compound tires; your car really is set up for a sticky tire -- by road worthy, i mean Michi Pilot Sport Cups, or Toyo RA-1, or Yoko A048, something like that with some tread, and with a 'street tire' like carcass. not a Hoosier, or a Kook 214, or a BFG R1. that way, you could safely drive to and from the track, but could also enjoy the kind of grip that you need at the track in such a prepped car.

all that being said, last weekend i was at the track with a student in a stock 2009 Carerra S, with oem tires, and it gripped quite well for street tires; we played with the tire pressures most of the first day, and found for that car (heavier than yours, and on different street tires) that it 'liked' hot pressures of 40f and 44r the best. if you intend to stick with the street tires, you should experiment with the hot pressures (and the suspension, perhaps with the help of someone like Larry), til the car feels 'happy' and is suiting your driving style.

hope that helps somewhat!

sincerely,
Todd
ReidSpeed

Veloce Raptor

I agree 100% with Ken's post above. Those spring rates & shocks are simply expecting the higher grip levels of an R compond or a full slick, and are totally overwhelming street tires. IMO it will be relatively difficult for you to adjust your Motons to get the car to work much better on streets with those spring rates. Like Larry, I prefer a stiff set up....with the proper tires. I'll bet your car would be magical (after you get some help with set up) if you ran better tires. As Todd said, even RA-1's would be a world of difference, AND they are streetable.

bavarian06

Thanks for all the suggestions and advice, I truly appreciate it. I had originally intended to buy a dedicated set of rims+tires for the track and would transport it to the track in my other car (a mini caravan, hence why I bought ordinary street tires with a high thread #).

Since then, I have changed my mind since most events are generally 80-160miles away from home. So in retrospect, I wished I have gone with a set of RA-1 or A048 to serve double duties.

They are Moton Motorsports, I had set it at for 4/15 (from soft). I'm not sure what's the nitrogen pressure in the cannister but I'll get it set at the baseline of 140/180 like you suggested. We speculate that the rebound levels are too great, causing the nervous hopping. The TRG f/r sways were set at the softest levels (I don't know how thick they are).

So the 950/1150 with 150lb tenders are good? Car weighs 2820lbs w/ a half a tank of gas (I was thinking it was too stiff at my level - considering doing a 650/950 setup).

I had set the psi at 35 before the first session. It rose to 43ish after the session and I dropped it back to 31/33psi.

Larry Herman

Yes, for an experienced driver. At your level, unless you are the next phenom, you need a car with a larger window of grip, and one that reacts more slowly so that you can master it. Once that happens, then you can change the car to make it faster, even though it makes it harder to drive at the limit. Dropping back to 650/850 or even 500/700 would not be a bad thing if your budget can handle it.

Check out these 2 articles that I wrote:

Modifying-your-suspension-how-does-it-change-your-car

Modifying-your-suspension-part-2

bavarian06

Thanks for the articles Larry. You're spot on as what's happening right now. The street tires are definitely providing a larger space of forgiveness or slip angle as you have illustrated. In this past weekend’s track, there was a long sweeping left hander before the front straight. According to two instructors that were with me, they said I was already at the grip limits of the tires (constantly providing steering inputs to prevent the rear from stepping out, making sure not to lift). As how accurate they are in saying this, no one really knows cause I didn’t want to explore the edge going +80mph, getting ready to grab 4th.

There were two sections where the car would fly over the bumps of the road, literally propelling us out of our seats. I was always white fisted going through these sections, ready to correct the steering wheel if the wheels came back down differently then how they left the ground; from you excerpt: “The racecar has only ¾ of an inch compression on its outside spring, so it loses ALL grip momentarily. Imagine going from generating 1.2~1.5 G’s of side loading to zero for an instant? It will take a fast and large correction of the steering wheel to keep the car balanced and on course. This is what makes it so much harder to drive. It really requires an innate sense of exactly what the car is going to do, along with the experience to make the right corrections to be able to drive this car at its limit.” We were experimenting if I was better off lifting, semi throttle, or go flat out (I didn’t have the ***** so I would occasionally have to lift from a semi throttle input) going through these sections.

So my question, if I was to swap out my street tires to a RA-1, would this:

1) improve
2) worsen
3) stay roughly the same

the car’s handling characteristics over these two sections? The springs aren't expensive but the labor associated in getting swapped out, car realigned, then corner balanced again IS. I rather opt for new tires depending on what your reply is.

race911

Why so coy about not saying where you were, even if you don't want to disclose lap times? (I already asked initially.) I'm the one guy here who has extensive experience at every West Coast track (save Fontana, and I guess you could say Chuckwalla since it's so new; but you can include Riverside............). Even if I don't know a specific, I've got ex-or-current IRL, USTCC, Grand Am, MX-5 Cup not to mention numerous SCCA/NASA Regional and National champs on our local mailing list to get specific answers to questions. And believe me, I bug them.

bavarian06

LOL sorry race911, I must have missed that part. It was at the Pomona Fairplex (2 mile road course), CA with the grand prix/sgv chapter. The session was not timed, are DE events timed? The car builder is out of state.

race911

Well you've truly got me now. I've never run there! I THINK I could have with POC way back when.

For the record, the faux RS has 600/800 and I don't see any reason to deviate. I'm weird in my preference for a soft-ish car. Most recent evidence was the Spec Miata that held about 8 track records. All set up on the bump stops. I couldn't get within 3-4 seconds when I first bought the car. Put a "generic" ride height on it and I easily got 2+ back.