No ABS?

[erik325i]

I'm considering removing my ABS on my '89 m3, and was wondering how many other track cars out there are running no ABS.

Here is the brake setup so far:

Brembo GT kit up front (4 piston calipers, 13" rotors)
Stock e30 m3 rear brakes (with the solid guide pins)
Dual 5/8" master cylinder setup with no brake booster (from Mike B.)
Stainless lines all around.

This car will see no street driving, only track. It will have about 340-350hp and weigh about 2200-2300 lbs.

What are your thoughts about deleting the ABS?

-Erik

[DSP74]

Why.....

It's been proven a bunch of times that an ABS computer will outbrake a human. Even a really good driver.

[Sean]

Why.....

It's been proven a bunch of times that an ABS computer will outbrake a human. Even a really good driver.

Not to mention you can threshold brake all day long, but you can still have one rear tire lock up and flat spot for a split second, while the others keep turning.

ABS is good to have to eliminate risk of locking up just one tire. You can still threshold brake with ABS as well.

That's my take on it, know that's not the answer you were lookin for....

[Massive Lee]

ABS is good to have to eliminate risk of locking up just one tire. You can still threshold brake with ABS as well.

There's currently a heated discussion on Bimmerforums (track section) on ABS or no ABS.

I regard of Sean's comment, I'd say he is right. ABS will keep you from flatspotting one wheel, by releasing all four wheels... Which means you are loosing any possibility to brake. Basically, your braking power under ABS is the braking power of the wheel with the least grip.

My suggestion is to keep ABS for street driving where panic stops can occure. For a racecar driven by an experienced piot, you'll go faster without ABS. Other opinions might differ.

In regard of Erik's brake set-up. You will have way too much front bias. You're not the only one with a front-only kit with bias problems. I suggest you ditch the pressure limiting valve to the rear to help gain some of the balance. Ask PaintPro21 on S14.net.

Lee

[Sean]

There's currently a heated discussion on Bimmerforums (track section) on ABS or no ABS.

I regard of Sean's comment, I'd say he is right. ABS will keep you from flatspotting one wheel, by releasing all four wheels... hich means you are loosing any possibility to brake. Basically, your braking power under ABS is the braking power of the wheel with the least grip.

My suggestion is to keep ABS for street driving where panic stops can occure. For a racecar driven by an experienced piot, you'll go faster without ABS. Other opinions might differ.

In regard of Erik's brake set-up. You will have way too much front bias. You're not the only one with a front-only kit with bias problems. I suggest you ditch the pressure limiting valve to the rear to help gain some of the balance. Ask PaintPro21 on S14.net.

Lee

Interesting - for some reason that never dawned on me.

For new cars, it brakes tires individually, doesn't it? So, this wouldn't be an issue?

[joshh]

Some people like to have more control over the brakes. This is something you'll have to try if you really want to know.
I prefer ABS but I feel ABS kicks in a bit too early sometimes.

[Sean]

If i wanted to give it a shot, could I just unplug the ABS computer? Or, is true ABS without having the ABS unit at all (where all the brake lines go in) going to feel noticeably different?

[Hallen]

I regard of Sean's comment, I'd say he is right. ABS will keep you from flatspotting one wheel, by releasing all four wheels... hich means you are loosing any possibility to brake. Basically, your braking power under ABS is the braking power of the wheel with the least grip.

Lee

I always thought ABS would release only the wheel that is locked. It makes absolutely no sense to release all 4 wheels if only one wheel is locked. That would seemingly be dangerous in track conditions and street panic stops.

Picture one completely bald tire on a car with the rest of the tires in good shape and you are driving in heavy rain. You do a panic stop but because the one tire is hydroplaning, your car does not really slow down at all because the ABS is release all the brakes because one wheel is locked. Why would engineers design something like that?

[Scott///M]

I say you go for it.

Just don't throw any of your ABS stuff away. Because once you flat spot a couple of sets of tires and give up a position or 2 because you're getting out braked... you'll want to put it all back.

But the only way to know for sure is to do it.

[PiercedE30]

I would suggest learning to brake without it. That way if you ever find yourself with a bunk ABS system, you will be able to react to it properly.
That said, the makes of MegaSquirt are coming out with a General Purpose Input Output controller in the next 3/4 months. They have definitely talked about using it to control a 4 channel ABS. Once it comes out and they get a few of the software kinks worked out I am definitely putting a 4 channel system in. Plus, it is only going to be about 300-500 dollars.

[Jean]

What's ABS ? :D

[Massive Lee]

ABS is the anti-blocking system. It keeps the wheels for locking up. A locked wheel will have much less stopping power than a wheel at the threshold. Older cars such as e30s had a rather primitive ABS programming (still much better than its US counter part of the days). If one wheel locks, it kicks back on the rake pedal releasing all four wheels.

Personally, I think it is still great for most everyone driving on the street or with only average rack experience. But people who track their car may prefer to regain full control on their brakes. It is possible to remove the relay to disable ABS, or install a switch.

[kommissar]

I regard of Sean's comment, I'd say he is right. ABS will keep you from flatspotting one wheel, by releasing all four wheels... Which means you are loosing any possibility to brake. Basically, your braking power under ABS is the braking power of the wheel with the least grip.

I always thought ABS would release only the wheel that is locked. It makes absolutely no sense to release all 4 wheels if only one wheel is locked. That would seemingly be dangerous in track conditions and street panic stops.

Sorry Massive Lee, but I'm quote sure that Hallen is right. Are you absolutely sure that it will unlock all four wheels? The rear wheels may not brake independent of one another, but the front wheels have separate brake lines and are controlled independently of one another. Look at the ABS unit under the hood, and note the amount of brake lines coming out of it.

The fact that the vibrations from the servos in the ABS unit travel back up through the pedal does not mean that it is affecting all of the wheels.

[gobuffs]

E30 ABS is a very primitive system.

I removed it from my track car as it was easier to remove than to get it working right (or so my thinking was at the time). Kinda wish I would have kept it (at least be able to turn it off and on to see the difference).

I have AP race calipers up front with PFC01s, Tilton pedal box with AP MCs, M coupe rear brakes. Still trying to get the balance adjusted right...

[nando]

Interesting - for some reason that never dawned on me.

For new cars, it brakes tires individually, doesn't it? So, this wouldn't be an issue?

I'm pretty sure it brakes them individually (except the rear) on our cars too - we have a 3 channel ABS system. ABS is to help braking while turning on a slippery surface, not just to prevent lockups in a straight line.