This is a good thread. On another note, I watched a EP Scirocco run while I was turn marshalling at the auto x and he was totally stiff. Musta had huge bars front and rear. On one occasion his rear end was hopping so bad that both tires came off the ground and he lost control of the car wiping out several cones. I didn't have the opportunity to ask what set up he had exactly but it seemed as though the rear end was way too stiff.
I am under the understanding that to improve traction at one end, you must increase roll resistance at the other end. i.e. to get more at the front, stiffer bar in the rear. This comes at a price of loosing traction at the end the stiffer bar is on. i.e. Hoppity Hop scirocco. On a FWD drive car like the VW it is very difficult to come up with a good formula for consistent weight transfer without sacraficing grip in the front or totally wiping out the rear end. For me I believe that a mildly increased front bar coupled with a fat rear bar would be best for handling that remains somewhat neutral. The front bar keeps the front inside tire on the ground while the outside is "digging in" and the rear bar hopefully keeps the inside front tire on track while maintaining rear outside tire tracking. Spring rates are important but I don't think they play as much in a roll resistance scenario vs. the wheel rate of the bars. Like John said, it is amazing how a VW handles with such suck ass suspension geometry. It doesn't make sense sometimes. Everything I know came from rear wheel drive cars so I could be off track, I dunno. Need to experiment more. Rich Blake Message: 8 From: "John Caldwell" <[email protected]> To: "Denis Palmans" <[email protected]>, "A2-16v" <[email protected]> Subject: Re: [A2-16v] Suspension Report Auto X Date: Tue, 20 Aug 2002 17:15:52 -0700 A larger front sway bar does NOT help keep both tires on the ground. it increases roll resistance, causing the camber gain on the outside tire to lessen. How does it do this? by transferring weight OFF of the inside front tire. If the two are coupled together and you push the outside front tire up, the inside front tire is going to be pushed up as well... removing weight from it. With a big front bar the car will roll and damn near lift the inside front tire off the ground... if it is unweighted that much, you will just spin the tires coming out of any corner, and your exit speeds will suck ass. If you're going to examine the handling dynamics of a volkswagen, you have to look at a few factors. Why do they pick up the inside rear tire? Because the outside front tire pitches down horribly in a corner. It's like a chair with a short leg... if you lean forward on that short leg, the back opposite one is gonna go up in the air. That's how you can end up with a car that is on 3 wheels and yet the front two tires STILL don't have as much traction as ONE in the rear. The outside front tire is pushed so hard that it is positively cambered, you're driving on the sidewall, and understeering like mad. >From there, you gotta figure out what your goals are and determine which direction you want to go. Direction 1: maximum cornering grip, while still keeping the horrible push the car has. Keep the car as flat as possible without it skating or pogo-ing across the track. Keep the front bar or get a slightly larger one, and run huge spring rates in the front. Keep roll in check, and the tires will stay flat on the ground. The rear suspension is not even worth considering except to say that you need spring rates high enough to match the ones in the front. Direction 2: a "neutral" handling car, that exhibits better dynamics. Use humongous springs or a huge bar in the rear to cause weight to transfer sooner there than in the front, so it will break loose at the same time the front does, or even sooner. It's not "more" weight transfer, because you're already getting 100% weight transfer when the inside rear tire is 8" off the ground. It's just happening soon enough that the outside front tire gets stuffed into the ground. Personally, I am going for 1, with a bit of 2 thrown in. Get the most grip possible from the front end, and then remove some grip from the rear to get it to rotate. My current setup consists of stock bars with 500lb/in springs in the front and 300lb/in in the rear. The car still pushes, and I'd almost say it pushes worse with the bigger springs even though it seems to stay a bit flatter. It's been so long since I've driven my car I can't comment too much, though. After reading any book on suspension design, it's pretty shocking that a VW handles as well as it does with how shitty the suspension geometry is. If only VW would switch to double wishbone in the front and a better trailing arm design in the rear. Oh wait, I guess I could just go buy a honda... ----- Original Message ----- From: "Denis Palmans" <[email protected]> To: "A2-16v" <[email protected]> Sent: Tuesday, August 20, 2002 1:33 PM Subject: Re: [A2-16v] Suspension Report Auto X > I think I disagree on this. Not adding any swaybars to the front is just as > pointless as only adding a huge rear sway bar. The swaybars connect the > suspension on both sides of the car, allowing for roll resistance. A larger > front swaybar would help to keep both front tires in contact with the > ground, which should allow for more grip in order to turn faster and harder. > Adding a huge bar to the back and leaving the front alone seems like it is > not what you would want to do. It would change the car from understeer to > slight oversteer, which while it would defiantly be fun would also be more > unpredictable and probably not as fast and consistent. > I agree with adding on a rear bar, but to not add a front bar, or > disconnecting the front bar does not seem like a good idea to me. Adding a > front bar, and then dialing in a rear bar from there to provide the best > feel seems like it should be how to go. Just because the car understeers or > doesn't 'feel' as fast doesn't mean it really is slower. > It would almost be like running much higher rate springs on the rear than on > the front of the car. > > Any suspension experts in here? > > -Denis
