Another Autocross Line Question

There should really be cones on the inside of the corner at the crossover. Wheels on the grass=DNF.

racerdave600 wrote: Moreso than lines, I would say braking is THE area where most people can find time. It is the hardest part of autocrossing and the most difficult to master. Especially since most people think they do it correctly. After autocrossing for 10 plus years, I did a Skip Barber class and had an instructor totally change my braking. I still wouldn't say I do it well, but it dropped a large amount time. Lines are difficult in that they can vary between cars. There are a couple of areas I might run a different line, especially around the "D", but until you see the actual course, it's just theory. All in all, it looks pretty good though.

Can you clarify a bit? Are you talking about being more consistent, or about really threshold braking and laying on them much harder than most people think they should or what? I would love to do a Skip Barber class someday.

drdisque wrote: There should really be cones on the inside of the corner at the crossover. Wheels on the grass=DNF.

That's just an idiosyncrasy of the site. It's pretty common to leave it up to the drivers to obey the "no two wheels off at the same time" rule.

mazdeuce wrote: Waaaaait a minute....240SX? Were you at the last SCCA event at the police academy a couple of weeks ago? If you were, I was your rookie chief for the day because the usual one was out of town.

Yep, that was me. Green 240SX.

Excellent. Come find me next time and I'll make sure you get rides/instruction from the fast guys who are most relevant to your car.
It's nice to meet GRM people in person.

The cones pretty much tell you where you have to go. Not much choice.

The going left at the end is because you car is headed that way after going around that last wall. You have to avoid the wall on the right.

c0rbin9 wrote: Dunno, just pick a hypothetical car and discuss the line for that car. I'm not looking for specific concrete details on what to do, more theoretical discussion. FWIW, car is a 1997 Nissan 240SX. Automatic, bone stock, all season tires. The auto transmission probably means taking a wider than usual line on some corners if not downshifting to first.

I don't know much about 240SXs. In my RX-7 it is happiest when pointed in a straight line and accelerating. Accelerating in a corner doesn't happen. So the goal when driving is to make as many straight lines as possible and if you have to dive in and park the car in a corner, it ends up still being faster than taking a "conventional" line.

Oddly enough, my polar-opposite car, a front drive Volvo, can be the same way. Tight corners are best taken in a dive in, turn, and power out methiod, rather than trying to find some mythical "perfect line". It feels wrong but the clock doesn't lie.

I don't really read course maps. I have never driven a map, I've always driven a course. And this is one of my big rants about the way the RallyCross national championships have been done. Every one I have been to, there was a course map laid out days/weeks in advance. That is an autocross mindset and mentality and it does not work on an unimproved surface and it often leads to very dangerous situations. A paved surface is generally consistent, an unimproved surface can have soft spots or holes or lips that don't show up on a map but are plain as day when you are actually on the ground. The course must be designed to take ground conditions into account, if you have to move the course ten feet thsi way or that way, you just DO it instead of saying "well, this is the way we said we were gonna do it, so we have to do it, is it really that bad to have an off camber corner with a big rut in the end?"

So when I go to the RXNC this year (fifth time!) look for the tall guy in the big leather hat bitching about the autocrossers who designed the course again And it will always be that way because there is the autocross mindset that the course is some mythical creation that must be put into the guide booklet that everyone gets, instead of the RallyCross way of designing and setting up a course on the fly.

Anyway, I RallyCrossed long before I ever autocrossed and that is the habit I got: you see the course on the course walk or parade lap, and then you go balls-out on every run, and expect the course to be different every time so there is no real point in theorizing, just drive what you see.

Desmond wrote:

racerdave600 wrote: Moreso than lines, I would say braking is THE area where most people can find time. It is the hardest part of autocrossing and the most difficult to master. Especially since most people think they do it correctly. After autocrossing for 10 plus years, I did a Skip Barber class and had an instructor totally change my braking. I still wouldn't say I do it well, but it dropped a large amount time. Lines are difficult in that they can vary between cars. There are a couple of areas I might run a different line, especially around the "D", but until you see the actual course, it's just theory. All in all, it looks pretty good though.

Can you clarify a bit? Are you talking about being more consistent, or about really threshold braking and laying on them much harder than most people think they should or what? I would love to do a Skip Barber class someday.

Most people start off braking harder as they get closer to the corner and then ease up as they go through, but you need to get on the brakes very hard initially and then ease up from there. This is a bit oversimplified, but that was the way it was explained to me. It is also easy to over slow the car before turn in this way, but it teaches you to leave the braking until the last possible moment. You need be either on the brakes, or on the throttle. I wish I was as good the Skip guy in relaying it. But your initial braking should as hard as it ever gets, with a trailing brake from there.

Learning your braking points is part of this too, and the most difficult thing to learn. From those I've ridden with, and from what I had done too, the tendency is to get off the gas a fraction of a second before you hit the brakes, start the braking, and then get on them harder until you judge where you need to be. This is a big time waster. On the brakes really hard, no locking, easing off, then on the throttle. It also helps set the front of the car at turn in.

Not sure I'm explaining this very well, but hopefully it gets the point across. I do remember the instructor saying this was probably his biggest issue with people that had autocrossed or done track days before, and one of the most difficult habits to break.

In reply to racerdave600:

A big part of this theory deals with the fact that braking is doing two things. 1. Slowing the car. 2. Transferring weight to the front of the car. Keeping weight on the front of the car as you turn in dramatically helps grip. Anyone who has tried to autocross a 911 has dealt with this. If you can't get weight transferred to the front of the car, you can't turn.
Left foot braking is really good for keeping weight on the front of the car even as you start to apply power. When I drive my 911 at the police academy I'll gradually feed in brake on that big sweeper as the front of the car starts to wash out. I do the same thing when rallycrossing all the time. Car won't turn? Keep on the throttle, stab the brake to weight the front, get the car turning, feed in throttle. It's a dance. It's fun.

Knurled wrote: I don't know much about 240SXs. In my RX-7 it is happiest when pointed in a straight line and accelerating.

What kind of RX-7 do you have? If all goes according to plan I will be picking up a very clean S4 RX-7 Sport next week.

mazdeuce said: Excellent. Come find me next time and I'll make sure you get rides/instruction from the fast guys who are most relevant to your car. It's nice to meet GRM people in person.

See you there! I've gotten instruction before and always found it helpful. Of course now I'm pushing the boundary of novice status, this being my 8th event.

Interesting braking discussion going on. I find I was braking too late.

c0rbin9 wrote:

Knurled wrote: I don't know much about 240SXs. In my RX-7 it is happiest when pointed in a straight line and accelerating.

What kind of RX-7 do you have? If all goes according to plan I will be picking up a very clean S4 RX-7 Sport next week.

mazdeuce said: Excellent. Come find me next time and I'll make sure you get rides/instruction from the fast guys who are most relevant to your car. It's nice to meet GRM people in person.

See you there! I've gotten instruction before and always found it helpful. Of course now I'm pushing the boundary of novice status, this being my 8th event. Interesting braking discussion going on. I find I was braking too late.

It's a series 3, although the rear suspension is something I designed that actually PUTS power down, the front suspension is mostly series 4 and the rest Subaru GC/GD, and the drivetrain is egregious and excessive. IME series 4s make okay drift cars because they can't put any power down, the right pedal makes the car slide instead of go forward.

Braking is my weak point. I know this. I know it deep down, I know it intellectually, I know it consciously. I only have too modes: lift like a weenie or brake way too late. I have a helmet mounted GoPro that records all of the failure. It's good because I can see how much my driving sucks. It's bad because I see how I did poorly and then overdo the correction the next time.

I figure more power and grip should cure that

https://www.youtube.com/watch?v=WRFKaRxkV7E

35.2s fastest run. FTD was around 28s. Definitely room for improvement! The car feels predictable in corners but the stock 150k suspension is very wallowy. I have to assume all the old bushings, strut mounts, springs, etc. aren't doing me any favors.

Not to gloat but from my earlier post...

JohnRW1621 wrote: This looks like a very short course. I'll bet lap times of 30-35 seconds.