Keep ABS or not?

[petawawarace]

I’m on the fence about this and thought some opinions (especially with FWD experience) may help. 

Our car has power brakes, abs and electric power steering. The wiring on the car is pretty terrible and complicated. There’s and ECU, ABS module and a BCM all communicating via Can-bus. I really want to simplify things to avoid issues and clean up the engine bay. I can easily get/make a standalone harness for the engine that would greatly reduce the mess. I can also convert the power steering to a standalone setup very easily. I can’t do that with ABS. 

I would also like to get rid of some weight. The brake booster, abs pump, factory pedal assembly etc is all very heavy. 
Ideally I would convert to a set of hanging pedals with a good balance bar and get rid of the booster and abs. But I’m concerned that our braking may be hurt. 

How do you guys find manual brakes? Hard on the leg after 2hrs? 

Other than in the rain, is there much advantage to a street based ABS? Ours works pretty well and is fairly modern (2007) but I feel we could get by fine without it?

Thoughts?

[MR2 Biohazard]

What car?

[ABR-Glen]

KEEP!

[turbogrill]

The NC Miata has a similar setup, it's all a CANBUS based mess. The ABS module is also doing brake bias, so when the ABS module has issues your car will brake terrible. A blown fuse, low voltage battery, disconnected sensor and 100 other things can disable the ABS making life difficult. So the ABS becomes a reliability issue.
 

 

I am keeping my ABS since some of my drivers would just flat spot the tires. If I had drivers that where used to non-ABS I would remove it.

But sure, it's nice to be lazy in the rain and just stomp the pedal. Not sure if it makes me faster.

[petawawarace]

6 minutes ago, MR2 Biohazard said:

What car?

2007 Chevy Cobalt

[gavro]

For a reason that remains unclear, our ABS was not working last race.

 

Getting it working again is my top priority before the next race.

 

I 100% recommend keeping it.

[MR2 Biohazard]

9 minutes ago, petawawarace said:

2007 Chevy Cobalt

I would almost always say yes, but some cars ABS is really bad. On the MR2 it does not work well. On more modern cars it usually can help. Though you should look up if ICE mode happens often or if it takes steering input and traction inputs into consideration. Some might use the ABS to slow down wheel spin and have issues.

 

Now on a FWD drive I wonder if having the rear wheels lock up a little bit before the fronts will matter that much with all the weight to the front?

[Team Infiniti]

30 minutes ago, petawawarace said:

Ours works pretty well and is fairly modern

So I see this and wonder why folks rip it out!

 

Infiniti is over boosted and has mediocre feedback, but in 11 years have had 2, yes only 2 flatspotted tires in 11 years (spun on the high banks @ 100+ mph) It has failed 2 times on race day, one was self induced, the other was a bad relay fixed in minutes.

 

Can it be better? Yup,  Is it going to make a difference in any race outcome? It could, a bit fatigued, mid day greasy rear tires  just 3 days ago @ PBIR it kept reminding me with a little buzz in the pedal.. OR 130mph braking too late @ Charlotte when the guy 6 feet in front of you bombs the brakes for infield 1 earlier then you, the distance between bumpers never changes as it does its thing to control your adrenalized brake application, unlike in a panic lock without abs.

 

 

 

 

 

[Black Magic]

13 minutes ago, MR2 Biohazard said:

Now on a FWD drive I wonder if having the rear wheels lock up a little bit before the fronts will matter that much with all the weight to the front?

 

FWD cars at some tracks create impressive polygon shapes with the rear wheels, if your ABS can stop this it is worth it. Happens from trail braking into a corner as the inside rear lifts. Gets even worst if the track banks away from you, think turn 1 at NJMP lightning. You have to run soo much front brake bias to stop it (or work on stopping before you turn) that it seems like the rears are doing nothing 

 

Somewhere between octagon an dodecagon on the inside rear you decide it is time for new tires and new drivers....

 

I think it depends on if this will create ice mode, or if the car can handle one rear wheel speed going to zero without flipping out. 

Edited September 22, 2021 by Black Magic

[petawawarace]

Yeah the flat spotting rears is a very real concern. We had some rear bearing issues and I converted to front bearings in the back. Tried without abs and it has locking up the rear inside tire at one corner and picked up some significant flatspots.  Fixed that and the abs does prevent it.

 

The Ice node does concern me.  Under really heavy braking it does kick in and affects the braking ability.  It does recover very quickly, but you do lose some braking space.  I have increased the front compression dampning and this helps quite a bit.

 

So I believe that I could keep the ABS, but get rid of the power brakes and go to an aftermarket pedal assembly.  Any opinions on getting rid of the power brakes?

[Hurljohn]

Keep ABS!  Remember we race in ALL conditions!

 

Keep build simple until you get some laps on it.  Manual brakes done right should be a nice improvement in braking performance as you always have a consistent pedal (especially for left foot brakers) and you can truly bias the brakes versus work around the OEM biasing.  Tilton only recommends some very pricey brake masters with ABS, something about seal "nibble" from pressure oscillation or fluid hammer. 

 

 

[MMiskoe]

I would vote to remove it. 

 

Two street cars have had it kick on at 20mph and let me go cruising through an intersection that I needed to stop for.

 

Racecar that had the pump disabled but not removed had a brake pedal that was impossibly touchy.  That day ended with the car backed into a guardrail. 

 

Several cars I have seen go off the track and the comment was that the ABS went came on when there was some wheel hop.

 

 

Biggest reason is that it makes cars unpredictable during a spin.  Novices get taught "in a spin, two feet in".  It is the best thing you can do for your fellow drivers and not collect someone as the car slows down and then shoots off in an unpredictable direction as the tires regain grip.  The ABS's job is to keep the wheels rolling, so it is pretty hard to keep it from hooking up and making a sudden change of direction as the car does pirouettes.  (doing pirouettes is not a bad thing, destroying someones car in the process is a bad thing).  This alone would be enough for me to not want it in the car.

 

 

[Rodger Coan-Burningham]

Take it out. Well, wait a minute…

 

[mcoppola]

^^^Someone has a real feel for threshold braking....

[Grant]

I've done extensive brake distance testing with ABS vs. none. I run ABS. The big problem without ABS is left-right bias. Without it you can only brake as hard as your weakest tire, which is almost always opposite the driver's weight. In some cars I found the fastest way to stop is actually with a locked-up right rear tire, simply because this results in more braking being done by the other wheels.

 

2 hours ago, turbogrill said:

The NC Miata has a similar setup, it's all a CANBUS based mess. The ABS module is also doing brake bias, so when the ABS module has issues your car will brake terrible. A blown fuse, low voltage battery, disconnected sensor and 100 other things can disable the ABS making life difficult. So the ABS becomes a reliability issue.

There's one CAN bus connecting the ECU to the ABS module (and to the stock dash, if you have that), and as far as I know it's not required for ABS operation. The protocol is fairly simple, and we use it to log individual wheel speeds. The result is more data and less wiring than you'd find in a non-CAN system.

[Hurljohn]

7 minutes ago, mcoppola said:

^^^Someone has a real feel for threshold braking....

and you let him drive your car...

[turbogrill]

2 hours ago, Team Infiniti said:

unlike in a panic lock without abs.

 

 

 

 

 

Have you tried screaming at the brakes? With ABS I push the pedal very very hard in panic mode. Amazed that I haven't pushed my feet thru the floor yet, flintstone style.

[Team Infiniti]

1 minute ago, turbogrill said:

Have you tried screaming at the brakes? With ABS I push the pedal very very hard in panic mode. Amazed that I haven't pushed my feet thru the floor yet, flintstone style.

Screaming? No, but have gritted my teeth while trying to bend or break the pedal/push rod/master, apparently pushing harder does a little something.

[Rodger Coan-Burningham]

2 minutes ago, Grant said:

I've done extensive brake distance testing with ABS vs. none. I run ABS. The big problem without ABS is left-right bias. Without it you can only brake as hard as your weakest tire, which is almost always opposite the driver's weight. In some cars I found the fastest way to stop is actually with a locked-up right rear tire, simply because this results in more braking being done by the other wheels.

 

I have also found running with ABS to be faster.  Lost a sensor in the middle of a race and could not get to same lap times.  Even an early 90's technology is good enough for what we do.  I have seen the notion argued before about control in a spin, but to me that's the equivalent of arguing against umbrellas in the rain because the metal handle might attract lightning.

 

3 minutes ago, Hurljohn said:

and you let him drive your car...

 

Hey that wasn't my car, that was the 944 after I had started running the Lexus.  So far in 6 years I haven't had a tire look like that come off the Lexus due to this subject, or even anything close to that.  It was somebody you have met though...

[mcoppola]

21 minutes ago, Rodger Coan-Burningham said:

Hey that wasn't my car, that was the 944 after I had started running the Lexus.  So far in 6 years I haven't had a tire look like that come off the Lexus due to this subject, or even anything close to that.  It was somebody you have met though...

Well, with ABS, that better have not been off the Lexus, or something's drastically wrong. 

(edit:) Our tires were still round when Rodger got done with the car Saturday - Thanks! (No ABS on the dump truck)

[MMiskoe]

35 minutes ago, Rodger Coan-Burningham said:

 

I have also found running with ABS to be faster.  Lost a sensor in the middle of a race and could not get to same lap times.  Even an early 90's technology is good enough for what we do.  I have seen the notion argued before about control in a spin, but to me that's the equivalent of arguing against umbrellas in the rain because the metal handle might attract lightning.

 

 

Sorry, all joking aside, I don't follow your comparison to umbrellas.  But I am curious.  Having had a few cars in my family either damaged or wrecked (one a complete write-off) due to a spinner doing an about face perhaps I am sensitive to it.  I can't say that any of the incidents I've been involved in were ABS induced, but I don't see how it would have helped.

 

 

[Triangle42]

The VW has the ABS removed.  It stops like a champ but I do have a proportioning valve in the car to take away as much of the rear brakes as I can.  As a driver you have to be on your game no to lock up the rears but once you learn how to modulate its fine.  I do trail brake into the corners to help with rotation. This will cause a little white haze for the car following to watch but its not to bad for the normal crew of drivers.  However, a new renter in the car actually driving at speed and pushing the limits will flat spot a rear tire in 2 hours just about every time.  Once that tire gets one small flat spot it will just grow every lap. So hope that it happens far enough into a race not to have to worry about it.  

 

The rain stopping is not that bad but then again I have never been in a race car with abs to compare.  I do know that In the rain we go deeper and stop faster than most cars around us, whom I assume have abs.

[Rodger Coan-Burningham]

28 minutes ago, MMiskoe said:

 

Sorry, all joking aside, I don't follow your comparison to umbrellas.  But I am curious.  Having had a few cars in my family either damaged or wrecked (one a complete write-off) due to a spinner doing an about face perhaps I am sensitive to it.  I can't say that any of the incidents I've been involved in were ABS induced, but I don't see how it would have helped.

 

Meaning there is a practical side of running abs that far outweighs (in my opinion) whatever affects you may have in an uncontrollable situation.  And I agree, abs would do nothing for you in those situations.

Edited September 22, 2021 by Rodger Coan-Burningham

[petawawarace]

Those of you running abs, are you able to use 2 proportioning valves for each rear brake line to adjust balance?  

[Rodger Coan-Burningham]

15 minutes ago, petawawarace said:

Those of you running abs, are you able to use 2 proportioning valves for each rear brake line to adjust balance?  

I run the 3 channel stock system. No changes.