Okay...I understand, but the welts give just as much joy without the eventual downer of breaking with autothority.

Suspension
I started with turboS suspension which meant it came with the rebound adjustable Koni Yellows. I replaced my suspension because the rear torsion bars were worn out and bottoming on acceleration. I did a LOT of research, most everyone was recommending what Schumi did. The only ones that recommended different was Andial. Andial were the guys that setup the suspension on THE FACTORY 917 race cars. They felt the 944 cup car suspension was too stiff. That is the 400 front springs, coil over helpers, bilstiens, and M030 swaybars. Instead Andial recommended the setup below. I was impressed because Andial had the parts for the cup car setup, but still recommended the softer more adjustable welt bars and springs even though they did not have any of the parts.

Front springs - 180 to 410 progressive from Porsche Motorsports USA, I think Lindsey Racing has some copies the've had made.
Rear Torsion Bars - 30 or 31mm the biggest you can get. It is equivalent to progressive 400lb coils in front.
Front Weltmeister sway bar with adjustable drop links.
Rear Weltmeister adj sway bar.
Weltmeister Adjustable sway bars are way better than the M030 bars that have holes. They have a sliding sleeve that gives you much more precise adjustment. Recent tried to help someone with M030 bars from Lindsey Racing with 5 adjustment holes and needed between two to get a good balance.
Shocks Koni Yellow with rebound adjustment. Fronts should also have ride height adjustment.

Lower the car 1 in with adj spring perch in front and by indexing rear torsion bars. Mine was low enough that I had to drive it up on 2x4s to get my floor jack under the side of the car. Lowering also gets you more negative camber adjustment in the front without going to camber plates. Too low and you will damage the oil pan on the street.

CORNER BALANCE the car! Took 2 full seconds off my 70 second autocross lap times with only 1/16 adjustment on one corner.

Front and rear camber -2.0
Toe and castor to factory spec or tires will wear unevenly.

Adjust swaybars so car breaks loose both front and rear at same time slowly accelerating around a 75 to 100ft radius skid pad. Then increase stiffness of both until that break loose point starts happening at lower speeds then loosen the just a little. This skid pad balancing of the the swaybars once the tires and alignment is done is critical to achieving the fastest corner speed. 75 to 100 ft radius skid pad is an average corner. When set right adding power the car will slide all four tires out to a bigger radius, lifting the throttle and the nose will tuck in and turn sharper but the rear still stays under control and doesn't simple oversteer.

Adjust the rear rebound as soft as it will go so the rear will lift on braking and the car will start rotating on turn-in. You lift off the brakes as you are turning in. This makes up a LOT of the older suspension design not being as quick on turn-in as the newer cars. To catch the rotation, just get back on the throttle to maintain speed through the apex.

Adjust the front rebound so the car stays balanced as you apply throttle in a turn. Too soft, the front will lift and the car will push. Too firm and the front will stay planted but the rear tires will spin to easily.

I beat many a 944 Turbo with cup car setups.

My 928GTS is a 50/50 front engine rear transmission just like the 951. I set it up the same way as I did my 951. A bit softer than the track guys recommend and balanced sleeve adjustable sway bars, and it has koni red externally rebound adjustable shocks. The only real differences are the way the power comes on with the V8 versus the 4cyl turbo (front rebound adjustment) AND lowering a 928 screws up the suspension geometry offsetting any advantage gained by lowering the CG.

It is really fast around the autocross and track often setting FTD but still rides very well on the street.

I mostly agree with Richard's analysis.

There are a few ways to go about setting up a 944, but a rule of thumb is that you need to go a soft as possible whilst keeping the tires happy. This means camber gain in roll, mainly in the rear. a correctly rated and balanced FARB and RARB is where the secret lies IMO.

You need to maintain a correct total lateral load transfer distribution when making the changes (typically 5-10% forwards of the weight distributions, which on these cars is 50-50). This is what people flub up most of the time.

The other big thing that is mistaken is people throw on 4-500 lb springs and run with dampers that are not valved for that ride frequency. This will reduce transmissibility and result in very unoptimal tire force variation- ie the tire will not be following the track under upsetting loads as effectively.

Longitudinal weight transfer on these cars is your friend. The rear needs to be soft enoguh to dive out of corners under hard acceleration, shifting weight to the rear axle and providing more traction. However, lateral weight transfer is your enemy as without an LSD you will just spin up the inside rear. This is where proper RARB sizing comes in, and why I recommend a stiff yet adjustable arb. Use the RARB tuning to tune out that inside wheel spin.

Autocross guys often sacrifice peak grip for transient response by making the car too stiff. This is why road racing cars will run softer than a lot of autocross guys do.

It all depends on what you need and the track you're running on. Also be aware that at significant ride rates, compliances come into effect that were once unnoticeable- hence hte need for more solid bushings. The system is a giant system of springs in series- and if there are compliances allowing for very soft links in the system, your response with a high ride frequency will be very hard to predict.

I'm going the 240lb ground control route... Got the sports on the rear... just need to finish building the fronts... and get new bars...

Richard we will have to a suspension tune day when I get this done....

My new invicta kicks ass!

Just ran to town on the 250. It does 85 quite nicely. :D

With both my 88 S and 89 951s the setup mentioned did NOT include solid bushings. Originals worked great and made the setup a little more forgiving to driver input. Most everyone I knew that put on solid bushings and drove the car any amount on the street took them right back off.
Both my cars were very predictable with the stock rubber bushings and there was enough feedback I could feel the 1/16 on corner of the car was off before corner balancing.

LSD is a given for any type of vehicle you want to put power down, especially in turns. I really like my 928 because it has PSD. It electronically dials in up to 100% lock up as needed.

Just for clarification ARB = sway bar or Anti-Roll Bar.

Each driver's style is different. To me tuning a suspension soft in the rear so you can put more power down exiting corners is slower because you are sacrificing mid corner speed for a slight gain in exit acceleration just as the car straightens out. Corner exit acceleration is limited as much by the ability to maintain turning as it is putting power down. Put to much power or weight on the rear an the car is going to push to far out too soon. By the time the car is going straight again the weight should already be fully transferred to the rear for maximum acceleration.

I tune my springs and ARB for maximum apex speed not corner exit power application. That would be like putting softer springs on the front for better corner entry braking. I use Front Rebound to control longitudinal weight transfer under initial acceleration on corner exit just like I use Rear Rebound to control longitudinal weight transfer on turn-in.

Those that go stiff for transients try to maintain a constant speed instead of smoothly controlling the longitudinal weight transfer for turn-in rotation, apex, and then exit. What Andial told me was that the suspension only needed to be firm enough to keep the suspension travel from bottoming out. That way it was firm enough to keep the car afloat, but soft enough to keep the tires in contact with the pavement when the road surfaces are irregular.

Sidney, We got a Driver Tech coming up in June. Bring jacks and tools to tweak your suspension then.

ok. what the hell is an 'invicta'? and what 250 are you taking into town?

Invicta watch.


My nx250 bike...

Hello, G-man reporting in.

Later than usual, traffic....... ugh...

D...

Invicta... BLING!

http://i282.photobucket.com/albums/k...l/photo-11.jpg

Morning, guys!

I see you got Sasquatch to model it for you... :D:D:D:D

J/K! ;)


(morning Marcus)

I can put it on my leg if you would like.... :p

:eek::eek::eek:

No no, no no, I'm good, thanks anyway! :D

Thats what I thought....

Well gents.... I got the lower balance shaft pulley on right and now more BRRRRRRRRRRRRRRR!

It runs as smooth as ever.... Spent a while playing tetris(packing the car) and getting crap gathered up for my trip. Just need to pack clothes now... :)

Working till noon tomorrow and then I'm off!

Guys, I posted a link to a video in the Breakfast Club- some autocross laps during our testing time at the tire manufacturer's test track. Be sure to watch it, but the link has to stay private. We have competitors that would love to see those track times.

I designed the vehicle's chassis, suspension, body, and drivetrain. A few other people contributed design work on the braking system, corners, engine, etc.

A few things about those laps:

-the car was severely down on horsepower - by about 25%- due to a failing coil-on-plug unit.
-paddle shifting had shot craps, so you see he's using a manual shifter
-the things over the left tire are infrared temperature sensors monitoring tire temperature gradients.
-also mounted low on the front uprights are slip angle sensors, which cost more than anyone here's car..
-this track is significantly narrower than a SCCA autocross course- the widest point is about 13-15 feet and the slaloms are 15 paces or so.
-the tires were old testing tires, not stickers. They were on their 2nd to last stint or so.

The car, on new tires last weekend, ran about 3 seconds quicker than the quickest it did in that video.

Peak G's lateral on those runs was about 2.5G. Longitudinal was around 2. Track was still very dusty.

Will set FTD at any SCCA autocross event it rolls up to, guaranteed.

So that's my day job :)

Great work, Shum!
Your awesomeness is huge...




(more comments posted in BC)

Good morning guys.

Just a quick drive by.

Off work. Time to finish packing. Then I'm on the road. Making a few stops in okc on the way