need help getting through a corner

[idontknow]

Hi, I'm new to this area and have a question I hope someone can answer.

I went to an autox yesterday and this autoX one was HARD to get through. Lots of powersliding, decreasing turns and a RADUISED slolum. this is the 270 corner that noone can figure out.



The drawing doesn't show things very well. the entrance cone is about 2 ft wider than the car while the exit cone is about 10 feet wider. The cones increase in raduis as they og around. The exit is just wide enough to slide the car through sideways. Believe me, I know!

Any ideas on how to get the rear wheels to let loose and the fronts to grab and not let go?

We're going again today so any advise would be great. Hopefully in another 6+ runs I'll have it mastered.

[ttweed]

Without knowing what comes before and after this element on the course, there is no way to answer the question perfectly, but I would say as a stand-alone turn, this would be a perfect example of "slow in, fast out." I would trail brake into it to get the car to rotate and give the front tires some bite to make the initial turn-in, hug the inside as much as possible to diminish distance traveled, and then I would get on the throttle to slow the rotation and plant the rear when I had turned the car enough that I could see my way clear to the exit.

YMMV,

TT

[Zeke]

They have things like that in autox? A turn where you actually drive over your own path? That's just plain stupid to me. No wonder I don't do autox.

Any corner near and beyond a 180 would be tough. I guess you have to sit there and skid pad the thing until it finally opens up to let you out. A freakin' merry-go-round. If anything will work, what Tom said.

Looks like a figure 8 demolition derby design. I promise you, if I showed up and the course was laid out like that, I'd leave. No where in the real world does there exist such a thing except the traffic circle here in Long Beach which is so notorious people come here to study what not to do. I'm serious.

[ted]

Zeke,
I'm not a big fan of this concept either. I don't really see where this exercise is relative to performance driving. That concept looks like it would wear tires faster than it is exciting.

The safety issue is not the cross over as a feature like this near the start then becomes the starters gauge. When the first car has exited the circle the 2nd car can be released. No chance of two cars in circle at the same time.

The danger in track layout is that if this were a larger circle at higher speeds then it makes it difficult to anticipate where a car may leave the track, you would have to design a lot of runoff room 360 degrees around the circle.

As for the quick line I agree with TT.

edit. It looks like a good work out for the corner worker cone retriever too.

[Cosi1]

idontknow,

To expand slightly on Tom's excellent observations and advice, one's approach to handling this type of turn depends upon four things:
1. The length of the straight prior to the turn
2. Length of the straight following the turn
3. Speed potential (radius(i)) of the turn itself, and
4. Amount of power (acceleration) available from your car.

In terms of elapsed time, frequently what is around this turn is far more crucial than the turn itself!

If the turn you describe is very tight (say 25-30 mph for autocrossing), then you must concentrate on sustaining speed on the straights before and after this corner.

If the straight leading up to this turn is longer, follow Tom's advice of extreme trail braking, extending the "straight" as far as possible into the turn. One would almost treat it as a 90 degree turn, followed by a 180 degree turn, with no straightaway in between. You are sacrificing speed in the second half of the turn. This is a good technique for a car with lots of torque.

If the straight following this turn is longer, it is critical to extend that "straight" as much as possible by accelerating as early in the corner as possible, aided by the increasing radius you describe. One would almost treat it as a 180 degree turn, followed by a 90 degree turn, with no straightaway in between. One is sacrificing speed in the first half of the turn. More important to an underpowered car.

However, if the turn you describe is a sweeper (say 35-50 mph for autocrossing), approached by a slower section, and leading to another turn or slow section, you must concentrate on sustaining speed through this corner. Here the double apex works best, but hugging the inside radius will lose too much. Treat it as a 90 degree turn, followed by a 180 degree turn, with no straightaway in between. (Your slowest pinch-point wil be approx 90 degrees into the turn.) You are sacrificing speed before and after for maximum speed in the corner.

Good luck with the second set of runs!

Ed LoPresti
RacePro Engineering
New York

[John Rogers]

I have seen SCCA auto-x courses with turns like that and they can drive you nuts. That is why the SCCA drivers always win TTOD at the Porsche Parades since they have to deal with stuff like this! I'd find a very experienced Honda CRX driver or other short car driver and get them to help you. A 911 is good for this turn, a 914 terrible as it is longer and more balanced. You want the rear wheels to get loose so higher tire pressures than normal in the rear, lower in the front. Of course the trade is these settings can ruin the rest of the course so you have to be sure this part is worth the sacrifice. Good luck.

[idontknow]

Okay, we all had it figured out by run 4. Trick was ( for me) to charge in as hard a vehically possible, and threshold brake entering the turn. Cut the wheel to the left once the front corner has past the cone, rear end swings around, begin countersteer. Jump on throttle and the car magically swings around the center cone and you exit FAST!

I believe this was the 180 then 90 as suggested. Thanks to all whom helped. I cut 5 seconds off my time at the slight expense of lumpy tires.

I can handle anything now, or so I believe!