refresh951

Having a blast getting involved in PCA Autocross and I am now addicted Who here is involved? It is a blast and a great value compared to DE events ($45 vs $450).

I am learning a great deal about my suspension setup. Made some adjustments after the last event this weekend. My car was pretty loose (oversteer) so I have stiffened up the front a bit. I can smoke the tires at will in 2nd gear at about 3/4 throttle so I need a new TB cam to give me a bit more partial throttle control. With some adjustments and a more experienced driver, I think it will really be able to compete. Anyway, really a lot of fun.

Droops83

I mostly run track events/time trials but I do participate in a couple of PCA auto-X events per year if there are any in the area (which is rare). It is a great way to learn your car and fine-tune the suspension.

Despite the well-balanced chassis, the 951 is traditionally at a bit of a disadvantage in tight auto-X courses when compared to some other cars due to the tall gearing and turbo lag, but a good driver and suspension/tire setup can mostly overcome this. Learn how to efficiently downshift into 1st gear!

What kind of tires are you running and is your current suspension setup and alignment like?

Adjustable sway bars are key. Is your rear bar adjustable? If so I would start by loosening the rear bar before tightening the front to combat oversteer; it is always better to add grip to one end than take it away from the other. When the rear bar is tight, the rear wheels will be less independent side to side, which can result in the inside rear wheel trying to lift when coming out of a tight turn. This could be part of your traction problem. If there is no more adjustment in the rear bar, then tighten the front.

Do you have a limited slip diff? This is huge in an auto-X situation, especially with a much modified engine like yours. If not, get one!

Otherwise, have fun. Car setup is important, but driver skill is the most important component. Practice and seat time are key! Get an instructor to ride with you, and ride with an instructor. It will open your eyes!

refresh951

Appreciate the input Chris. Tires are Toyo Proxes R1R's, 225 Front/275 Rear. I have an S2 AOT tranny which has LSD. I think the 95 mm stroke makes this setup pretty different than a typical 951 for Autocross. I have plenty of torque off boost so turbo lag is not an issue.

I am running Koni Sports all around and 28 mm torsion bars and 275 lb springs in the front. Currently running 1.5 negative camber on the front and rear. Stock 86 turbo sway bar in the rear, 30 mm front sway and KLA strut brace. Need to look into a rear adjustable sway. I am sure some of the oversteer is too much power and my driving.

Mark924S

i autocrossed my 951 a couple times, it really depended on the club, one club had alot of turbo car participents and i did well another club was dominated by miatas and didnt do so hot, sounds like you have a decent setup to be competitive. seat time is one of the best mods tho

refresh951

Pretty cool that I have two PCA regions and SCCA. Going to try to hit two events a month.

User 52121

Turn the boost down. All the way down.

Power really won't help much, it's all about balance. I AX a lot (I'm my regions coordinator) and that's reason #1 why I don't want to build a 2.8 (or bigger), I don't need more power, and certainly don't need less traction in 1st and 2nd!

The trick is to be smooth. Keep corner speeds up, brake less and try to carry speed into and through the turns. Try to keep your tires from making noise. It will *feel* slower (until you relearn what "fast" actually feels like) but the time will be faster.

I generally tell beginners that sliding = slow. Try to keep in traction. Once you get better you'll be able to learn how to use a little sliding to your advantage but until then stay in traction. If you dive into a corner and the front stops turning when you add more steering wheel input, go slower next time.

And turn the boost down

lee101315

Im also an AutoX addict, doing 2-3 events a month on average. It takes time, practice, and a lot of trial and error. As for tires, Id go literally as big as possible up front and run 200 treadwear tires with about -3 degrees of camber... 225's really dont cut the mustard on a heavy car like the 951; especially when the huge front wheel wells lend themselves to a 275/285 with the right offset.

+1 on seat time
+1 on being smooth

Brake a little earlier than expected, dont fight the car through the corner, and you'll be able to rocket into the next one. Being hamfisted and forcing the car through a corner will get you a low exit speed.

lee101315

By the way, try running the car without the sway bars connected to see what your baseline handling is. That way you can adjust your sway bars a bit more accurately.

V2Rocket

shawn,
what throttle cam do you have currently?
if you recall from another thread i suggested the stock NA throttle cam as an option for you, it is a very progressive design.

i've got one or two laying around if you want one.

bumflick

Shawn, I used to auto x all the time with my Golf GTI back in Maryland. Loved it - used to get that rear wheel up in the air all the time. I spent a lot on suspension mods, and never touched the motor - that was only 128 hp. LSD, tires and suspension were the focus.

Only had my 951 for a year, and have not done anything yet. May join you at one or two of the local events

kev951

was a pca instructor in Sd. One of the best auto-x tracks around, elevation change, on camber, off camber.. you name it!!

Droops83

Interesting. Your power-on oversteer seems like it must be more power related than from any deficiency in the suspension. If anything, your setup looks like a recipe for massive understeer on paper, given the large front and small rear sway bars and large stagger between the front and rear tires.

Turn down the boost, easy on the throttle out of turns and concentrate on your line and being smooth. Seat time and quality instruction are key.

Then you can start playing with adjustable front and rear sways and alignment settings.

Also, in my opinion there is no reason to run any tire/wheel width setup on a 951 except square. Though I suppose with massive power/torque, big meats out back are nice!

refresh951

Boost is all the way down I plan many other things with the car in addition to AX. I think as I learn the car is going to do quite well.

May have to try that. Thanks!

I am using the stock 951 TB cam. I am making a new custom TB cam. I will post up some pics in a few days. Same principal as the NA.

Come out in September. I have been hangin out with Josh B and Brad at the events. Loads of fun.

I need the wide rear tires, trust me. All about compromise as I do a lot of things with the car including drag racing Not sure how you see a setup for massive understeer. I want a little understeer and that's what I was shooting for. Boost was as far down as possible (about 12.5 psi) but I am working on better throttle control. I think that once I get better throttle control and proper line and brake points it would still oversteer a bit. Been looking at some adjustable rear sways and will be getting one before the next event.

Droops83

Very cool, glad you are having lots of fun with your car. I am a bit jealous of your short gearing and torque, as my bone-stock drivetrain is lacking in both! Your engine build threads have inspired me to do something with my spare engine . . . . some day!

I rebuilt my stock LSD with much better Guard internals a few years ago and that made for a huge improvement in traction out of turns and while braking. This might be worth considering, as pretty much any original 944 LSD is pretty much worn out by now.

As for your suspension setup, it is biased toward understeer on paper (varying driving styles/tracks/conditions and spring rates/alignment settings can change things of course).

A big fat sway bar up front, combined with a skinny car out back will cause the rate of weight transfer to be much quicker in the front than in the rear. This will cause the front end to be responsive, but it will generally lose grip before the rear, thus the bias towards understeer.

Tire stagger like yours will usually result in the front end losing grip first, though it sounds kind of necessary in your case!

Finally, more camber in front would make it much pointier and improve turn-in and front end grip (I'd say go to -2.0-2.5). Of course, like everything else in life this is a compromise as it will accelerate front inner edge tire wear and slightly diminish braking traction. Camber plates might be a good future upgrade.

I recommend two old but great books on performance handling. One is from the early '90s and the other from the early '80s but the fundamentals are all the same:

lee101315

May I suggest getting a pair of 17X9" Cup1 or Cup2 wheels, and having some nice 255 or 275mm wide sticky tires on them? You may just want to keep them in your garage and slap them on the front whenever theres an AutoX. The frankenstein look is fairly common at my local events.