jstyer

I'm pretty new to the 993 world, but have spent a fair bit of time autocrossing front wheel drive "Hot Hatch" type cars... I always seemed to have my best results combating their inherent understeer by breaking a little earlier, and a little more gradually. Holding on to a touch of trail braking into the corner, shooting for a late apex, and trying to nail a fast exit speed by getting on the throttle early.

I saw so many new drivers try and play the hero and brake super late into a lower speed corner, only to push wide and fight understeer at every turn...

Just my 2 cents. Probably worth what you payed for it.


ETA: Bill posted while I was writing mine... I pretty much just repeated his last line.

e9stibi

Trail braking is a very valuable technique to help rotating the car. I would also add left foot braking to transfer weight to the front.

nile13

Ken, I've spent a little bit of time autocrossing old TVRs and a few other oddballs. Where the desired end result is achieved by kind of loosely pointing the nose in approximately right direction and mashing the right pedal. I also drove a few early to mid-80s 911s where steering precision was clearly not a priority. Plus a reeeealy long rack (or is it steering box in those?) in an autocross setting equals the need to drive the car with your right foot.

I think old SWB 991 are kind of like that too?

bruce7

Here is something you might find an interesting read. This is presentation by
Steve Lyman on suspension tuning and development:
http://www.sae.org/students/presenta...ve%20Lyman.pdf

Some shortcuts: pg 32 Starting Out, pg 36 Breaking Down the Course,
and pg 41 Corner Exit.

Good stuff, covers a lot of what others have said.

-bruce

vincer77

Great video. Seen it before and still love it. I really like Seinfeld's comment about the "density of thought." It really does give our cars a distinctive feel. How it is so simple, yet so full. It has everything I really need.

Now what the video has to do with understeer...

race911

While I'll imagine a "current thinking" vintage racer SWB 911 might actually be entertaining out on track, what we were dealing with in 12-15 year old (!) POS 911s was a whole 'nother dimension. I honestly don't know how I didn't crash my '68 backwards, given I was 18 and had a grand total of two years driving a Scirocco. (I did damage the car, but it was a front fender impact with a hillside on a dirt road running a not-quite-sanctioned stage rally.)

I was quite shocked when I was able to get seat time in a '69S, set up almost identically to my '68. Was then that I made the commitment to go full-tilt IROC clone.

Quadcammer

well, i'll say this. I get my braking done early, and its not really a corner entry issue. Even when trail braking to get the car rotated, upon getting on the gas on corner exit (pound on is really just a loose term I threw out, I'm not ham fisted with my inputs), steering inputs seem a bit useless.

nile13

It simply means that you are getting on the gas too early, too much or both. Thus upsetting the balance of the car and not letting it accelerate.

The idea of a turn is simple. You can not gain time there. You can loose more time or less time. How much time you loose in a corner itself is also not very irrelevant. What is relevant is how you come out of it and how soon and fully you an apply power in a straight line after the corner.

The bottom line is that if you are understeering on exit, provide less input and provide it later.

SchnellAuto

sorry posted the wrong video about understeer..here is the one i wanted to post..



Lemon

Ed Hughes

That will create the exact opposite effect. Raising pressure, to some level, will increase traction/grip. Lowering will reduce.

EckFe1

Quadcammer,
I do a lot of mountain driving and get understeer mostly when
- road surface temp is low
- driving up hill and tight corners
- near empty tank
I don't have AWD but at the point of understeer your front diff has nothing to grab onto anyways so I think I can contribute to a point.
The only thing that helps is the correct approach to the turn. So I keep evaluating every turn or group of turns separately and adjust the driving style accordingly. There's a fine line between understeer and when the rear end starts to come around. It's fun to try this out at a driving center and under controlled situations.
Even our old cars can perform brilliantly when driven right, compared to much better cars with inexperienced or hesitant drivers.
Keep having fun driving your turbo. I wish I had that engine in my cab.
Ed

Quadcammer

thanks for the input fellas.

I will say that the rear of the car is rock solid. Even doing some limits testing (closed course), you have to do something really stupid to get the rear to come around. Even full lift around turns won't do it. You really have to get on the brakes hard mid turn to get the rear to come around.

race911

Not if you've got a car that's even halfway competently set up. (And yes that includes 100% factory stock where the intended set up IS understeer, then more understeer.)