mazda/feed

THINKING ABOUT GOING THE THE M2 BIG BRAKE SYSTEM WAS WONDERING IF ANYONE KNOWS IF I CAN TAKE OUT THE ABS SYSTEM AND WOULD OR DO I NEED IT

turbovr6

you don't NEED ABS in any car, it's just a safety thing. You can rip the abs out of any car and just run regular brakes.
If you wanted to take the ABS out of your car you would have to re run some of the break lines and add a proportioning valve also. It can be done, but I'm not sure why you want to. If you don't like your ABS then pull the fuse.

Import Convert

If I was building a pure drag car then I would remove it but there is no reason to take it out for anything else. I'd reccomend leaving it in.

Zoomspeed

yeah, unless its a pure drag car leave it in. W/o abs you won't be able to hold the brakes all the way down and steer the car at the same time. Very useful for dodging stupid drivers.

jumprdude

Of course you can! Its called "threshold braking".

I recommend people learn it. Having said that, I also recommend people leaving the ABS in unless they know what they're doing.

mazda/feed

OK kool thanks for the replys, i just thought that by puting in a big break system it wouldnt be needed, but now i know. thanks

maxcooper

ABS can help you get maximum braking when the bias is off (like after adding a big brake kit) because you can just push the pedal until both axles start to lock. Without ABS, you can only push until one axle starts to lock unless you want flat spots and spins.

SCC regularly praises ABS for shortening stopping distances, and says that you can't beat it with your own modulation (based on the results of their testing). Cars with ABS usually have shorter stopping distances in other tests I have seen, too. ABS is illegal for many racing classes, but I would guess that you would see it on the top cars if it wasn't. That said, I usually try to threshold brake anyway - ABS freaks me out a bit when it activates.

-Max

Gene

iTrader: (1)

Since you are talking about an M2 kit I assume this is for a 3rd gen. Keep it, the 3rd gen system is supposed to be very good. If it were a 2nd gen we were discussing, I'd say rip the sucker out because it's a piece of crap and leaks everywhere.

Btw: using the ABS system for proportioning isn't such a good idea, it's really best to properly proportion the braking system so the ABS only has to act when you REALLY get into the pedal (or drive on a reduced traction surface)

maxcooper

Agreed, but raise your hand if your car is properly proportioned. (I don't see any hands in the air).

-Max

Gene

iTrader: (1)

right... you need a proportioning valve! though a dual master cyl and a bias bar is really the way to go...

maxcooper

The stock system has a proportioning valve, but of course it is tuned for the stock front brakes. I'm going to try to make up some of the difference with high-friction rear pads and rear brakes from the RS model (which has a larger rotor diameter).

I was thinking that maybe the reason ABS does better in tests (even with competent drivers) is that it nullifies sub-optimal bias. Lots of things change brake bias (including how much gas is in the tank), so perhaps the ABS allows you to acheive near-optimal braking from both axles, where a non-ABS system will always be a little off due to the specific conditions that are present during a test. Just a thought.

-Max

ajmacdon

Yep, Max hit the nail on the head. ABS outperforms non-ABS systems because it can use the rear brakes more agressively. I believe the 3rd gen system is new enough to even increse rear bias if it knows the car is going straight (based on wheel speeds) further reducing stopping distace without sacrificing stability.

Alex

easy p-cheesy

I know that people with 2nd gen MR2s install a switch to turn it on and off. might be a good idea for certain situations.

Eric Michel

I have had the AP kit for a couple of years now and I have to tell you, the bias is so far off that the ABS cannot fully compensate for it. On the street you won't notice it but on the track, it feels as if the rear is not doing anything and the ABS kicks in a lot sooner, it's much harder to modulate. I tried using a more aggressive pads in the rear, didn't help much. I finally put a proportioning valve in and MAN WHAT A DIFFERENCE. Trust me on this one, unless you are going to put something bigger in the rear (I don't really think that is neccessary) you need a proportioning vave with these kits. I used Rob's site as a reference but I found a much easier way to install the valve, you do not need to cut and flare any lines. I just disconnected the line going to the ABS unit and carfully bent it over and connected it to the valve. I then bought an 12" line with fittings and bent it to connect the other end of the valve to the ABS. It was easy and came out really well, I will post some pics later.

maxcooper

Thanks for the feeback, Eric. Putting a proportioning valve on the front brakes has always scared me a bit, but I am glad you have shared your positive experience with that change.

I think I am going to try to avoid a front proportioning valve if I can. Higher friction rear pads, bigger rear rotors, maybe remove or swap out the stock rear proportioning valve for an adjustable one are all things I'd like to try first. Perhaps my perception of proportioning valves being ill-behaved or failing is unfounded, but I'd like to avoid it if I can.

I'd like to see your pics. I can host them if you'd rather not upload them one at a time in messages.

-Max

Eric Michel

I have also heard some people say they did not like the idea of a proportioning valve but I don't remember the reasons why? A lot of people use them and I have not heard of any specific problems yet? every race shop sells them, most race cars have them and they seem to work? Here are the pics, with this method if you decide you don't like it you can easily switch back to the original setup.

FYI

I purchased my AP kit from KVR, I later found out they did not purchase the rotors from AP, they used a cheap knock off. I managed to crack these rotors after only 3-4 track days, bought another set $150 each, installed the proportioning valve which helped but those cracked too. After the second set cracked KVR admitted that they were cheap rotors and that I might have better luck with AP rotors, $300 each. After putting the AP rotors on I immediatly noticed the brake feel/modulation improved, oh and I am still using that same rotors today, I put them on over a year ago. I have been toying with the idea of buying a cheap set of rotors and having them cyrotreated? I will need to replace them soon.

Eric Michel

Another view

Eric Michel

one more

Eric Michel

I was kind of wondering no one responded to my ??? I wasn't trying to argue, if there is a potential problem with using these valves I would like to know.

maxcooper

Eric,

I appreciate the info.

My reservation about the proportioning valve is based on my perception that they don't always work very well, and it could mean big problems if it failed in the front brake line. I would also be concerned that it would make the brakes harder to modulate, but your feedback and Rob Robinnette's info makes me think that it works okay.

My brother used on on the rear brakes on his ITB car (a Mustang-style 81 Capri), and he wasn't pleased with its operation. It ended up causing the brakes to not release well, and it eventually leaked and failed. Perhaps he got a defective unit.

-Max

1FooknTiteFD

ABS can be a beautiful thing for people who don't know how to drive very well. However, if you remove it, you can actually decrease your stopping distance if you know your car well enough to the point before the brakes lock up. Also pulling the ABS involves a lot more driving technique. Ultimately it is up to your own discretion on what you decide you like. I pulled my ABS fuse on my FD for over a year and drove it around and noticed an increase in stopping power, however this is not recommended for people who don't know what they are doing as it can be dangerous especially on rainy days.

maxcooper

Fookn,

That has long been the enthusiasts' story when the topic of ABS was raised, and perhaps it was true when ABS systems were more primitive. But, cars with ABS have been stopping shorter for quite some time in magazines, even with competetent test drivers. I don't think the no-ABS-stops-faster-with-good-driver story is true anymore. One possible reason we raised here is that ABS will dynamically adapt your braking force at each end to get maximum braking, where normally you are left with some sub-optimal bias. Bias changes for a lot of reasons, with ABS your car will adapt braking power at each end while you are stepping on the pedal. Plus, I don't think most drivers are as good as they think they are when it comes to most things, including threshold braking. I try to threshold brake on my car at the track, and I rarely get into the ABS, which makes me think I am just not braking hard enough.

Plus, with ABS you won't get any flat spotted tires. That is reason enough for me to keep it around.

-Max

1FooknTiteFD

Hahaha, I have a lot of flat spots on my tires due to no ABS. However true your statements may be on new cars with ABS, I still think that without ABS, the stopping distance of the FD can stil be reduced if even marginally, but I on't argue with you on that one, because ABS is a good thing to have. I disconnected the fuse mainly to practice my braking techniques if anything, and the car is a ot easier to control with the ABS

SleepR1

I'd flat-spot my Hoosiers WITHOUT ABS--NO DOUBT!

LEAVE THE ABS IN--NUFF SAID!

ajmacdon

I believe the ABS in 1993 would be comperable or slightly worse than the best non-ABS stop you could do on a dry track in a straight line with lots of practice. So, take it off if you want on the track (practicing threshold braking is a great reason to try) but you won't lose much in any other situation

I will also say that, subjectively, the ABS from the FD is *very rough* and quite aggressive to make up for the lack of smooth control. At my company we strive for stability first, steerability second and stopping distance last! However, with the newer systems stopping distance ends up better than non assisted anyway. You really can't imagine what could be done if manufacturers could sacrifice stability! (don't imagine, look at the Porche GT-3 endurance cars).

My only concern with a front prop valve is that they take some volume during braking, has anyone noticed a softer pedal with the valve in place?