mark kibort

Any good drivers out there that are proficient in using racing ABS, or standard ABS? Has anyone seen lap time differences most all things being equal, or is it just a matter of consistancy, predictability, and confidence.
I posted this on the Cup car list, as they seem to have the highest performing ABS system. My race car from 1986, seems to have a very slow scanning ABS that is good as a safety net, but with full pedal depression, the car feels like it is on ice and has 2x the stopping distance, where a skilled foot should be able beat its performance.
You often hear that some racing series allow and then remove ABS from some of the competitors cars to help even out the rules. When that happens, it doesnt seem like it sets them back much as far as raw lap time.

Thoughts?

mk

Veloce Raptor

BMW Motorsports makes a superb racing ABS that is awesome. Takes a lot longer (i.e., much closer to true threshhold) to engage, and then engages much more sparingly. Similar ot he Cup car version, but IMO much better (Porsche probably has something similar on the RSR, I don't know).

Street car ABS--even modern ones--are designed partly by lawyers, and thus tend to be intrusive and very discouraging to solid laptimes.

All that said, my M3 started as a street car, and I try my best not to get into ABS at all, because it beats the **** out of the brakes. Hell, SRF's dont even have ABS!






Professional Racing and Driving Coach

bobt993

When Larry and I worked with Cervelli on heavy trailing, we were taught to use the ABS as the car approaches the apex. The advantage being the outside loaded wheel worked more efficiently and inside was avoiding lockup. You can over engage the ABS for multiple wheel lockup, but having a single wheel reach lockup is really the best use of ABS. Patrick Long commented on this about how to drive a 911 and his description was yes to ABS, but you should only feel it in the steering (fast, max braking) not the pedal ( too much, slow).

Veloce Raptor

That is an excellent distinction.







Professional Racing and Driving Coach

mark kibort

I havent had a try at my e36 street ABS as its not working any more, (when it was, it felt like it was pretty good) but the abs on the 928 is really nothing more than a safety net. If you feel it start to engage, you better modulate. if you press hard and let it do its thing, the car takes off down the apex like you are on ice.

I imagine the scan, or dwell times of the racing ABS in porsches or BMW motorsports is probably as good as it gets. I often wonder if the abs effect can help destroy components if used too much. It would seem to be controlling a huge amount of force on the rotors!

Thanks for the comments.

mk

SG_M3

Depends if the car is setup for a braking system without abs. My car's abs current doesn't work and its awful. I've driven cars without abs, but with braking systems setup for it and it is a night and day difference. A dual MC car with bias adjustment and no abs is not hard to adapt to. My car with a very forward bias non adjustable stock braking system designed for abs, is awful. There is no feedback, and the MC is so big, it takes huge pedal movements to unlock the wheel once it has locked up under braking. There is no feedback through the pedal.

So, you can't just compare a modern street car with and without abs. If the car was designed with abs in the braking system, keep it. If you are starting from scratch, i'd build a system without abs but with the proper components to allow the use of maximum braking ability.

Veloce Raptor

Like a World Challenge car....







Professional Racing and Driving Coach

Geoffrey

At the Club level, a Racing ABS system is a benefit to almost every driver, and I think Chris Cervelli would agree. Street ABS, particularly the older 3 channel systems can be detriment to lap times because, as mentioned, they are slow reacting, designed to work with street tires in slippery conditions, not slick tires on grippy pavement, and, although, the rear wheels have separate speed inputs, if one locks, BOTH rears are pulsed which reduces traction. An average club racer can probably drive better with a 3 channel ABS system turned off, particularly on a bumpy track. I agree in general with Patrick and Chris's observation, however that advice is really only good for an ABS system that utilizes 4 channels, not 3 channels.

The Racing 4 channel systems in the 993 Cup/RSR and the 996 Cup work great (I think the 993 system is better). It is much less intrusive and pulses at a faster rate. I don't intentionally get into the ABS in my car, however, when really pushing it and trailbraking, it will generally pulse the inside wheels just after turn-in, and it will activate on bumpy sections of the track. I like it and prefer a Racing ABS system to no ABS system.

I've installed the 996 Cup system into BMW M3 cars with dual master cylinders and it really helped the lap times and the confidence in the braking. So, you should be able to install a Racing system into your car without much difficulty and you have multiple options including 996 Cup, Bosch M4 ABS, and the BMW unit Scott is referring to.

As far as the wear on the components, I think Racing is hard on the components and an ABS system doesn't add much in terms of shortening the longevity of calipers and rotors.

Larry Herman

I found that braking with my RSA (3 channel ABS) was pretty much the same as with my non-ABS Carrera, except that I was braking to impending ABS activation instead of impending tire lockup. Never flat-spotted a tire with the RSA though.

924RACR

Hey, man - no lawyers in this office!! Gotta call ya out on that one...

Blame it on the OEMs, they decide just how important racetrack performance is. Corvettes have excellent ABS for the racetrack - with stock suspensions and such.

Geoffrey's got it right.

SG_M3

Is it possible to add any of these with a single master cylinder?

Geoffrey

I would think so. For instance, the 964 and 993 cars have the same size master cylinder front and rear, so although they have independant circuits, the pressure is identical (I've measured it with MoTeC DAQ on my 993 system). You can simply tie it into the front and rear circuits of the ABS pump. I haven't done it, but wouldn't be afraid to try it.

Tom W

I went the other direction and completely removed the stock (3-channel) ABS from my car. Once I learned to drive without it (2 events or so) my lap times were as good or better. I have a dual master cylinder now and can adjust the bias to what I want/need for the track I'm driving (although once dialed in, adjustments are infrequent).

SG_M3

interesting, i'll look into it. You'd think the difference in dynamics(rear engine vs front) could be a slight programming issue.

Geoffrey

Ive installed the 996 Cup Racing system inot e30 M3 race cars and they have worked extremely well. I'm not saying it is ideal, but I am also not good enough to find the flaws.