L Cubed

Hi Autocrossers and Track Enthusiasts,

I took my new to me 944 S2 out to an autocross this past april and was quite happy with it's performance except for some hairpins. Racing through the slaloms the car felt precise though a little limited in grip due to the stock size (205/55/16 F and 225/50/16 R) BFG G-Force Sport Comp 2. When I was in the hairpins however I felt as though I was using old dead tires up front!! The understeer was quite high and I needed a LOT of steering wheel input to get around the hairpins. I did notice that part of this was due to me being in 2nd gear instead of 1st (~20-25 mph hairpin) . Though the initial turn-in made it feel as though I could have gone faster but if I tried I squealed tires and had to stab the brake to keep it on course. Since words can only describe so much here is a video of my fastest lap...
So my goal here is to find a solid baseline setup as the car is before I start modifying it so that I know what a 944 should feel like and can move in the right direction as I continue to autocross and track it. To help with this I will list the setup as it is now:
Stock with Koni Yellows, M220 LSD, 2983 lbs (3183 with me) 49.2% cross when I'm seated in the car. 968 caster blocks, red poly bushings in front control arm.
Camber: 0* front -1.0* rear
Toe: 10' toe-in front ~15' toe-in rear
My spring plate bushings look like this though:


With all this in mind, I am thinking of setting the front camber to -1.0* and toe to near 0 up front, because I noticed some shoulder wear on the front tires (and this really helped my Jetta). Watching the video above I noticed the rear wheel moves around a lot and I am concerned that may mean my rear spring plate bushings are toast.

Do you guys /gals that race think I am heading in the right direction? Should I be looking into doing other things? Should I not make too many decisions until I run square tires all around? Do I need to replace my spring plate bushings before making a call on my baseline setup?

Thanks a bunch! This forum has been an awesome resource so far and I hope to be able to contribute after I gain more experience with my 944.

mel_t_vin

Heading in the right direction...yes.

When were your tires manufactured?

Understeer is a result of overwhelming the front end of the car [hard tire compound, narrow section width, lack of camber, front dampers/springs/sways too stiff, rear dampers/springs/sways too soft].

Moving to an 8" or 9" square setup, as many folks here have done, will improve your turn-in/cornering noticeably. More camber [-1.0 to -1.5 for a street/autox setup] and less toe-in [0* to slight toe out] will also aid turn-in/cornering.

Does your car have factory M474 dampers? Original? What sways are you running? 25.5mm front and 16mm rear?

L Cubed

The tires are less than two years old, roughly half tread life. I have driven two sets of these tires off my Jetta doing daily driving and autocrossing, so I know they are up to the task. The sway bars are 26.8mm F and 16mm R, the springs and t-bars are stock as far as i know.

The car came with M474, though a previous previous owner replaced the rears with Sachs. About 4 years ago the guy I bought the car from converted the front struts to inserts and 2 years ago the rear shocks were replaced with Koni Yellows.

I would like to get a pair of 16x8 D90 rims to put on the front so I can run 225/50/16 all around until I upgrade to 17x9 rims. At some point I will also add stiffer springs, t-bars and sway bars. Though I don't want to upgrade and then cover up any maintenance or setup problems that will cause me to redo stuff later on because I didn't get a good baseline the first time.

Arominus

Put a little more rear bar in it and see how you do. It will dial out some under steer. The camber will help too

mel_t_vin

Agreed.

L, sounds like you have a handle on things. Tires [2 years old]...check. Front M030 sway...check. Going to a square setup for turn-in/front end grip...check.

As mentioned, experiment with a little more camber, and a little less toe, in front.

When Porsche spec'd the '87+ M030 suspension, they paired the front 27mm sway with a downgraded [from the standard 18mm] 16mm rear sway, probably in an effort to lean toward [less hazardous] understeer. Source an 18mm [non-M030], 19mm [968 M030], or 20mm [944/S M030] rear sway. That, with a more aggressive front alignment, may alleviate most/all of your pre-mature outside shoulder wear.

raleighBahn

The 968 m030 rear sway has three settings (discussed in another active thread), so plenty to play with. The Lindsey variant has five settings. I noticed same thing on my 951s. Have gone from 205 to 225 up front, rear remains 255, waiting on that bar myself. Given that understeer caused by more weight being transferred to outside rear tire than outside front in the apex (causing front to break loose firstj, stiffening up the rear some in conjunction with wider front tire is a good incremental step for both of us. Three settings to play with in the rear and adjustable koni up front that can be loosened, should be able to dial it in.

harveyf

If it were me, I would replace every suspension bushing on the car, front and rear. Go with poly (versus OEM rubber). It will cost you about $500 in parts and replacing the rear bushings will be character building But unless you do this, you really won't be "base lined". I've got some pretty good articles on my website about doing this on both of my cars (orange and silver cars).

Then I would set it up to stock specs, which will certainly tend toward understeer, and then gradually stiffen the front via larger sway bars.

If you read the tutorial on FarNorthRacing website about suspensions from start to finish, you will be miles ahead in understanding what is going on. It is really one of the best write-ups I have seen.

But please resist the temptation to start throwing go faster parts at it until you get the 20 year old bushings replaced.

One nice thing about handling in low speed corners is that you can go to any deserted parking lot and do a little testing before you get to the autocross course.

Arominus

I ran my S2 in the local SCCA event yesterday, i have some understeer but its getting better as i set things up. Its a fine line between under/over steer though as i am sliding a bit in places. I do need to do the rear suspension rebuild still, the front is done though. The car is on 17x7/17x9 996 wheels with 225/255 RE-11's.

Pardon the naughty word at the end and my horrid driving through the slaloms.

SpeedyC2

I'll echo what Harvey said about replacing all the bushings. I replaced the sway bar bushing with OE rubber, and all the major suspension bushings, front and rear, with Powerflex Street bushings. The resultant improvement in ride and handling was remarkable. An experienced local indy mechanic/race prep shop owner noted my S2 rides better than any 944 he's ever driven.

I have since also made a few other modifications, such as Koni sports, the 3-way adjustable 19 mm rear sway (I'm using the stock front bar), upgrading to 27 mm torsion bars, and lowering the car overall. The ride/handling comprise is, to me, perfect.

That said, replacing the bushings resulted in far and away the biggest improvement to the car.

harveyf

I was hoping Mike would chime in as I have driven his car and think he has a great machine. When Mike says Powerflex street bushings, they are black and the (relatively) softest bushing that Powerflex sells.

L Cubed

Thanks everybody for the help. I learned the hard way on my other car about jumping for the common go-fast parts before understanding the car fully which I am trying to avoid here.

I went to a PCA autocross on sunday to test out my camber and toe change. I had adjusted the camber to about -1.2* and toe out of about 10' total across the front. I also stiffened the Koni Yellows because they were near full soft, this turned out to be step in the wrong direction. During the first few runs the rear end wouldn't stick to the road as I applied throttle. Softening the front rebound fixed the squirreliness on throttle which helped a lot. I heard later from some corner workers that in hard corner entry the inside rear was lifting... to stiff rear rebound.

So i think the plan moving forward will be to go through all the bushings because I noticed some of the front sway bar bushings are beat up as well. Then get a pair of 16x8 D90 wheels to run 225/50/16 extreme performance summer tires all around and see how that works for me.

I will say that this car is a blast to send through high speed chichanes .... even when your setup lets you down ... or all the way around

BikePilot

Nice, sounds like you are on your way to sorting it. Harvey, PowerFlex's website indicates that purple is the softer, "street" bushing while black is the firmer, "race" bushing.

Arominus

Go 245 all around if you can, i think you can get rivals in that size. More tire is better.

L Cubed

That is my end goal, I want to run 17x9 rims all around with either 245/40/17 or 255/40/17 tires. I am thinking of using the Direzza ZII because they are a little more precise and require more precision in input than the rivals, so they should be a better tire to help learn on as they will reward good driving techniques and not reward the bad.

The problem is finding a set of four 17x9 rims that aren't custom and thus expensive, or needing to find two pair of rear wheels from a 911. This is why I was leaning towards another pair of 16x8 and 225 tires for now.

harveyf

You are correct sir. I have not looked at their website in a couple of years but it looks like they've changed things around regarding color versus hardness. Now I'm curious what Mike used, as what I remember hearing was "black" and "softer".

BTW, I discovered I had a bad link on my blog page for the replacement of the rear suspension bushings for the Silver car. I have fixed the link.