hi all

at our local track, there is a braking zone which reduces speed from 135-->60 to setup for the next turn.

My general approach when I hit my braking marker is to go full brakes into ABS.. and then trail off as I am approaching my turn in speed and turn in marker.

1) is there any mechanical reason to avoid going into ABS / frequently?

2) is there any technique reason not do do this? Is the above approach sound strategy for a beginner?

If it makes any difference: I'm running stock calipers / rotors, Ferodo DS2500, Star Specs.

thanks for any advice!

 

If you're into the abs you're not in control of the car and it won't slow as quickly either.

 

You want to brake to the point where you are on the threshold between no ABS and ABS (thus why it's called threshold braking). If the ABS is on, you're braking way too hard.

 

I don't know of a mechanical reason to avoid ABS, but from a skill-building standpoint I'd try to stop as quickly and smoothly as you can without activating it. In fact, from a practice standpoint, it'd be better not to have it at all.

As far as how to modulate the brakes on corner entry, that's the sort of topic that's best discussed with your instructor for the day.

 

In addition to what others have stated, you are applying more pressure to the pads than you need as the ABS kicks in. So for 1/2 the braking time, when the pads are working and ABS is not reducing the pressure, you are applying more pressure than what you need. In most cases, more pressure usually translates into more heat and not necessarily more torque. As you know, getting the pads out of their temp range is not a good thing.

So, learn to use only what you need and the max what your car can handle. It will make you a much smoother and better driver.

Good Luck

 

All good advice - using ABS frequently is bad technique and can overheat the brakes - yep.

In addition, when/if you upgrade to a more track-oriented position and/or track alignment with this technique, you will have a very unstable and unpredictable car to handle.

I used to break pretty hard on the stock + Swift Springs setup, and with a much stiffer suspension for 2008, the same level of braking resulted in a very unstable car during hard 120+ mph braking.

It was both eye-opening and butt-puckering the first time out! The same result can be said of trail-braking.

 

great, thanks all for the info

 

I went to Skip Barber 3 day racing school and to me, at least, the hardest thing to do was Threshold Braking. This was on a Formula car with monobloc 4 piston AP Racing on all 4 wheels. The brake compound was race-only (meaning that you actually have to heat the brake up first before the brake actually works). Oh yeah, no ABS - 2 master cylinders for front/rear and adjust the F/R brake bias by linkages.

Threshold braking is braking right before the wheel locks (and it takes a LOT of practice to learn the muscle memory for EACH setup, tires, pad, rotors, road surface, to do it correctly and precisely at the given surface). The threshold is right before the wheels lock up. You DO NOT pump the pedal to modulate. If you hit it right at that pressure, the brake system will modulate itself. So far, I have not been able to do this on my EVO IX with stock pads - probably too soft of a compound.

If you hit the threshold right, the wheel will act sorta like ABS....it'll lock and turn, lock and turn, lock and turn....you feel a bit of a shattering at the pedal.

Back to your question:

1) No, not that I'm aware of.
2) If you know how to brake, you usually can do better than ABS.

Different brake compounds behave differently in terms of friction coefficient, operating temp range, modulation and feel.

 

The Evo is the first and only car I've driven on the track with ABS, but knowing what it does, none of this makes sense to me. ABS is supposed to hold the brakes at the threshold. You look at data showing the same car stopping with and without ABS(when ABS was new, they used to publish this data everywhere), the car always stops sooner with it. Given this, it would also slow you down sooner, meaning you should be able to brake later if you want to, and in a race, who wouldn't want to brake later? Someone also wrote it overheats your pads..why is that? I have stomped on the brakes in my car, and have always got it slowed down in time, and even a few times when I thought I out-braked myself. I've never locked the brakes either. I used to race a 911 with obviously no ABS, and a proportioning valve (the kind that just pinched off pressure), and would lock 'em up on that thing occasionally. Usually in the first couple laps, but it would happen. I also occasionally drove a 911 GT2 which had the full monty proportioning system, and even it would occasionally lock up a wheel or two, depending on how it was set. With the Evo being AWD, you don't see as much trail-braking as you would with a RWD car, due to you needing to power to the apex, and since the majority of the braking is done in a straight line,
the "threshold" is that much easier to hold, meaning it's easier for the ABS to work as promised. What am I missing here?
TIA

 

ABS doesn't hold the brakes at threshold, ABS is only activated when the brakes have already exceeded that threshold. ABS increases stopping distances over threshold braking, the main reason it was invented is because threshold braking is very difficult to actually use properly. This is a well known fact and I've yet to encounter a racer (both amateur and professional) that states otherwise. Think about how ABS works, it essentially clamps and unclamps the brakes. How can that stop faster than a situation where the brakes are continuously clamped and working?

 

threshold braking performance is very suspeptable to brake bias setting, and in general production cars are VERY front brake biased. With ABS the computer is able to in effect control the brake bias to improve braking performance. Meaning with abs it is possible to get more braking force out of the rear tires with out the fear of the rears fully locking up and causing the car to spin. The result is production cars stop faster(shorter distance) with ABS then they do with out.

Now if you were to adjust the brake bias of a production car closer to the ideal bias setting(think Stoptech brake kit) the car could stop faster then with ABS. But if the tires lock up 1 time (even for a little bit) the advantage is lost.

 

I should also say that I agree with was was said above about not exactly wanting to use abs all the time on the track. There are very few places you should actually need to use 100% brakes on the track and your lap time should be faster if you're not in to the ABS all over the place.

 

again, more great info. thanks again guys

 

I've yet to see results showing faster braking with ABS vs. without ABS.

 

...ABS will never stop as fast as non-abs. Its extremely simple... the abs releases the brakes for a split second, and reapplys them.

If you're at the threshold of braking the tires loose, the pads are in constant contact, and you're slowing down. if the pads aren't against the rotors, you're not slowing down.

ABS is only useful in the evo in extremely wet conditions, when you've gone in too hot. Still isn't gonna slow you down any faster.