TmillerC5

My ABS is out for now. Don't ask as I think it is a wiring issue for the wheel speed sensor. Past 5mph the ABS & traction control lights come on.
Anyway I have a HPDE at Road America in June and just wanted any tips on relearning HIGH speed braking without the saving grace of ABS. Should I brake earlier and lighter into the HIGH speed corners like 1, 5, and 12.
Not the track I wanted to try to learn this threshold braking at but that's the brakes. lol

Any pointers would be great.
Thanks

froggy47

You seem to have time, fix it.

This is sort of like, "My brake pads are thin, are they ok for one more track day"

If you flat spot an expensive tire, you will be out more than a sensor repair.

Plus you are a danger to others, trying to adapt to new braking style either on street or track.

Not to sound harsh, but that's my 2 cents.

mgarfias

If you're on an 01+ fix it. The car has too much brake in the back and relies on the ABS to keep the back end from having too much. I had an issue with the TCS/ABS module appearing to be "dead". Replaced it, worked for a bit, died again. Turns out it was the PS pump spewing fluid on the module and getting oil in the connector. Fixed the pump, hosed out the connector with contact cleaner and its been good since. Sometimes the problems are non-obvious (and not electrical).

TmillerC5

Thanks for the info guys. Car is a 97 so ABS modules are non existent and I don't think that's the problem. Code C1222 RF wheel speed sensor. The wiring issue will have to be trace all the way back from the front WSS to the brake module.
So no help on the threshold braking technique?

Aardwolf

On my older year I removed the ABS and have been using it that way a few years. I do occasionally get into lock up and the tires thump for a short ways but I have yet to catastrophically flat spot a tire like you hear about here.

For HPDE on a dry track I wouldn't think you would be into the ABS so there shouldn't be any difference. No if it rains start braking earlier and get a feel for what is going on.

To me going into turn one at Road America with ABS when it hit it felt like the car accelerated or started to skate. Without ABS there when the tire(s) lock I don't feel much less braking.

SouthernSon

I suppose trail braking is out unless you want to flat spot inside rear. Brake really well as long as front wheels are equally loaded and might want to stick some less aggressive pads on rear and adjust your driving as needed. Otherwise, put on some worn out tires that you don't mind trashing. Seriously, without ABS, your threshold braking just changed dramatically.

Falcon

Is it too late to get a refund on the track weekend?

One time during a race, my ABS went out with about 3 or 4 laps left. I was going into a turn at about 120 and hit the brake pedal hard at my normal braking mark. Holy Chit! The *** end went up in smoke and started coming around. I knew I had a problem so I eased off the brake pedal just a bit, steered into the slide and almost hit the tire barrier, but was able to miss anything and could keep going. I had a slippery feeling in my britches until I got back in the trailer after the race. It was a true Code Brown moment.

My main competitor was right on my *** and he saw my problem. He just rode back there chuckling, knowing I was EZ Pickings. I couldn't hold him off and he came around me as we entered another turn after a long straight.

There's no way I'd knowingly enter a race without ABS and not some method of adjusting the bias off the rear. There's nothing good that can come from it. It's like trying to play in the Final Four with a cast on your leg.

2MCHPWR

with what he said.

http://forums.corvetteforum.com/auto...d-braking.html

ZedO6

Even on the least intensive braking circuit we run here in SoCal, I'm into the ABS at least 2 times a lap. I couldn't imagine running at full tilt without it. At minimum, I'd want a cockpit adjustable rear brake bias.

I could see coming into RA T5 at 140+, off camber braking zone and having to deal with rear brake lock up. Just fix it.

Timz06

You guys are killing me.

I have run my 2002 z06 quite often with ABS issues.

When ABS is not working obviously you have to be gentle on the brake s not lock up the tires. (Ok common sense.)

I don't have any issue under DE conditions running without ABS, you can run decent laps, obviously not pushing the limit on braking.


For racing, I feel it is essential to have ABS, or you will crash into someone. There is a big difference if trying to make a pass under braking or just staying on someone's bumper.

So if you have any driving skill, for DE it is not a problem, for racing you need ABS or a properly proportioned system.

davidfarmer

Like Timz says, you'll be braking earlier and easier. Even a full balance-bar dual-master cylinder setup can't adapt side-to-side variations in track and load, so modern ABS is always better than running without it.

Under flat, straight conditions, you should be able to brake near your normal spots. Any curving or cresting brake zones may require special care.

And remember, once you lock a brake, you have to RELEASE the pedal to get grip back. So you risk either trashing a tire, or trashing the entire car, if you end up locking a tire or two!

redtopz

I would just fix the problem since you have plenty of time and it should be a simple fix (wiring or hub).

Otherwise, if you want to know how to threshold brake with no abs, just go karting. They only have rear brakes and they'll teach you to have a sensitive feel for lockup.

SouthernSon

You do quite well without the ABS. That was fun chasing each other around AMP a little while back. PM me a good email for you. I can't remember which one you use most.

moespeeds

I learned last summer with no ABS, having never turned a wheel on a track. In my opinion, I think guys rely on it way too much. I fixed my ABS late last summer, then lost it again at a track day in Nov. I went out and ran without it, and actually knocked 2 sec off my previous best time. I found I liked trail braking much better with it off. You can run without it, and you can trail brake without it, and you will not catastrophically flat spot tires. I only ever flat spotted one front, and it was completely ragged out, just about to the chords. You just can't stomp on the pedal, you have to set the front end with a gradual, easy push, then brake progressively harder until you reach the threshold. It will become second nature after awhile. My only concern was what David said, without allot of practice it's tough to panic brake without locking them up. I'm currently completely rebuilding my car, and I'm going to install a power switch to the EBCM so I can turn it off and try driving without it. Ultimately I'd like to goto a proportioning valve and racing pedals, no ABS.

Timz06

Yes it was! I am looking for more events at AMP since it is down the street, but haven't seen any.

TmillerC5

Well thanks guys, sounds like it divided on yea or nay to ABS. I have a DRM proportioning valve so I can dial it back some. The wheel hub is fine and works. I will see if I can carve out some time to trace the wiring/short issue but life goes on sometimes and might have to drive easier this trip and dive in to it after the RA event.
So brake earlier and lighter for those that have run without, makes sense.
Thanks

moespeeds

I spoke to DRM about the portioning valve, and their advice to me was not to use it without the ABS working, so I didn't buy it. No harm in trying it out though, let me know. Ask the guys who say don't drive without ABS if they ever really took the time to try it and learn.

On your ABS not working, I had fits with mine and it turned out to be the plugs right at the wheel speed sensors. I just cut out the plugs, and directly wired them with barrel connectors under heat shrink. I then protected the first 8" or so with asphalt loom. There is another plug about 14" down the harness anyway, so no big deal if you gotta get the hub off. Those factory plugs stink and don't seem to hold up very well to all the vibration and flexing. Good luck this weekend and have fun.

Supercharged111

I wouldn't hesitate to track my car without ABS at a DE. If you rely on ABS, that seems like a crutch to me. Of course on the threshold, tires will be chirping, or else you wouldn't be on the threshold. Without ABS, you'd have to modulate more, that's about it. If you're a remotely decent driver, you should be able to feel it out on your first session. How did they do it 20 years ago without ABS?

Olitho

When my ABS goes out I prefer to pull the fuse and completely disable it. What drives me nuts is the erratic behavior is seems to have when not working and with the fuse still in the system.

The big key is to be cautious on brake application (I don't mean to sound condescending) and then be extra cautious on bumps, declining radiuses and any situation where the weigh balance of the car changes suddenly.

With some caution and practice you can make it work, but it is a huge handicap because:
1. You can't beat the braking performance of the Z06 unless you go aftermarket
2. The brake bias on the car is adjusted by the computer so it is really funky without ABS
3. In bumps, humps, declining radiuses, etc. the computer does stuff we can't do as a driver (See point #1)

I agree with others that the risk can be very high on some tracks if you are not cautious and practiced at driving without ABS.