Open Source ABS

Curmudgeon wrote: At some point I betcha AngryCorvair's gonna chime in with a good idea.

no, i am not. every time this subject comes up, i poo-poo it and then people start calling me a curmudgeon.

Leafy wrote: Making a controller that takes in 4 pulsed wheel speed sensors, a variable voltage (for the ABS strength dial on the dash), does some math and comes out with a control schema to a few high amperage low side drivers probably wouldn't be terribly hard. I would spend forever and a day coming up with the control scheme, but I could probably come up with the controller hardware in a month or two.

i do not disagree with your assessment.

See? Told you he was smart.

Curmudgeon wrote: Just as a point of interest, there used to be these things called 'Safety Brakers' way back when. Basically it was like a small reservoir which went in the lines for the end of the car that was prone to lock. Inside there was a moveable piston, a rubber seal and a stupid strong spring. The idea was at low brake pressures the piston stayed put, as brake pressures increased the spring would allow the piston to move thus cutting pressure at the caliper/wheel cylinder. Yeah, it was probably about as safe as it sounds. No, I could never bring myself to try one.

Early 4-wheel disc brake Volvo's from the early 70's have these. Intended to reduce rear wheel lock-up. Not sure how well they work. The ex-g/f's ES could lock up the rear wheels at will.

I'm looking at a service manual that describes how it works (one for each rear wheel). It essentially is set to keep brake pressure at 484 psi.

I'm surprised so many dislike ABS on auto X/Track car. Why would it be banned from F1 down to Showroom Stock categories in so many series if it didn't offer a performance advantage? Having raced Spec Neon and done 100's of autocross and track days in cars with and without ABS I rarely have found it to be wanting in any condition,car or situation and often find it quickly improving lap times and getting up to speed safely and with less drama. There is a comment by Randy Pobst floating around about the virtues of ABS and I know there are others who are respected and very capable who also like ABS.

I had a 99 10AE Miata with ABS and loved the system. It wasn't intrusive and even seemed more track focused then other systems I have experienced as modulation at the limit of ABS engagement was consistent and predictable.

There are some bad systems (early GM for example) of ABS and some that don't work as well at the limit but they offer so many benefits I wonder how many have used a decent system in anger or an emergency to be against the systems.

Exactly. I hear people waiting to see the MX-5 cars getting made into ITS cars and keeping the ABS since they can out brake practically anything and can brake while turning. A well done ABS system is going to brake better than an non-abs car 99.999% of the time, the 0.001% is for that time that you actually threshold brake perfectly for the entire braking zone, which never ever happens.

But I dont even care if its faster, I want to stop destroying $300 tires.

Many people remove ABS when calipers/tires/master cylinders all change, because the systems don't exactly work as designed at that point. I'm sure if there were more tunability (i.e., reflashing) to the OEM ABS controllers, people would probably be holding on to them. Datalogging for ABS activation would be incredibly tedious though, requiring a large area to treat as a skid pad and several accelerometers.

I, personally, will be keeping ABS in my S2000. The 4-channel system in it seems to do very well with any combination of tires and calipers as long as the f-r bias is maintained

sobe_death wrote: Many people remove ABS when calipers/tires/master cylinders all change, because the systems don't exactly work as designed at that point. I'm sure if there were more tunability (i.e., reflashing) to the OEM ABS controllers, people would probably be holding on to them. Datalogging for ABS activation would be incredibly tedious though, requiring a large area to treat as a skid pad and several accelerometers. I, personally, will be keeping ABS in my S2000. The 4-channel system in it seems to do very well with any combination of tires and calipers as long as the f-r bias is maintained

Good post to bring us back on track. The OP is looking for this exact solution. Does it exist or does he have to program something himself?

The only time I've managed to freak out ABS was when I went to staggered tire diameters. It didn't cause a major problem, but the ABS did trigger early. Changing caliper piston sizes doesn't seem to have affected it.

Keith Tanner wrote: The only time I've managed to freak out ABS was when I went to staggered tire diameters. It didn't cause a major problem, but the ABS did trigger early. Changing caliper piston sizes doesn't seem to have affected it.

Theoretically it effects what happens once the abs is engaged.since the volume of fluid it needs to move to get the same effect is different with different caliper volume.

Maybe in theory, but in practice it's been a subtle enough change that I've never noticed.

Leafy wrote:

Keith Tanner wrote: The only time I've managed to freak out ABS was when I went to staggered tire diameters. It didn't cause a major problem, but the ABS did trigger early. Changing caliper piston sizes doesn't seem to have affected it.

Theoretically it effects what happens once the abs is engaged.since the volume of fluid it needs to move to get the same effect is different with different caliper volume.

Angry would know for sure, but it all depends on the feedback loop and how tightly the P&ID is constrained. If it's just looking for a lockup signal from the speed sensor and letting the pedal work the brakes until that happens, it may not matter much.

tuna55 wrote:

sobe_death wrote: Many people remove ABS when calipers/tires/master cylinders all change, because the systems don't exactly work as designed at that point. I'm sure if there were more tunability (i.e., reflashing) to the OEM ABS controllers, people would probably be holding on to them. Datalogging for ABS activation would be incredibly tedious though, requiring a large area to treat as a skid pad and several accelerometers. I, personally, will be keeping ABS in my S2000. The 4-channel system in it seems to do very well with any combination of tires and calipers as long as the f-r bias is maintained

Good post to bring us back on track. The OP is looking for this exact solution. Does it exist or does he have to program something himself?

They exist, but they are not exactly "challenge friendly" on their pricing... Let's just say that one could purchase several Miatas for the price of the Bosch M4 system.

sobe_death wrote:

tuna55 wrote:

sobe_death wrote: Many people remove ABS when calipers/tires/master cylinders all change, because the systems don't exactly work as designed at that point. I'm sure if there were more tunability (i.e., reflashing) to the OEM ABS controllers, people would probably be holding on to them. Datalogging for ABS activation would be incredibly tedious though, requiring a large area to treat as a skid pad and several accelerometers. I, personally, will be keeping ABS in my S2000. The 4-channel system in it seems to do very well with any combination of tires and calipers as long as the f-r bias is maintained

Good post to bring us back on track. The OP is looking for this exact solution. Does it exist or does he have to program something himself?

They exist, but they are not exactly "challenge friendly" on their pricing... Let's just say that one could purchase several Miatas for the price of the Bosch M4 system.

Yeah I'm not dropping 11k on the bosch one. Although that probably wouldnt double my current investment in the car, but I try not to think about that.