ABS working properly??

[Nihilation]

Background:
Car is 91, I've installed Dali SS lines, running Project Mu B-Force Street/Track pads, Motul600 fluid and the tires are 215/40/ front, 275/35 rear.

Symptoms:
I've noticed that the front's seem to sensitive to locking up under moderate braking. For example this morning I was slowing from ~60mph down to ~25 in a left turn lane and the fronts locked up and I had to let off the brake, then get back on it again to regain control without sliding straight. When it occurs I don't feel the brake pedal pumping or anything like in newer ABS equipped vehicles... and I've heard that the NSX has a really aggressive ABS system, is this part of it?

Brake pedal also feels pretty mushy after this past track event so I'm going to flush the fluid again shortly. Just a little concerned about the braking...on track it seemed to be OK in most cases, is it possible that I'm just not running enough meat(tire) up front?

 

[nsxtasy]

I've noticed that the front's seem to sensitive to locking up under moderate braking.

You don't mention what kind of tires (make/model) you have. Is it possible that you're using tires that are just not that good? Have you checked their inflation? What about the tread - how much is left?

When it occurs I don't feel the brake pedal pumping or anything like in newer ABS equipped vehicles... and I've heard that the NSX has a really aggressive ABS system, is this part of it?

I don't know what "really aggressive ABS" means. When the ABS is working properly, and when you're using really top-notch tires, properly inflated and in good condition, it rarely activates.

is it possible that I'm just not running enough meat(tire) up front?

The fault isn't the tire sizes. However, tire sizes aren't as important to grip as the type (make/model) of tire. It's possible that the tires you're using just aren't very good.

Here's how to test the ABS. Empty the car of any loose items, take it out in an empty parking lot, get it up to 50 mph, and then slam on the brakes as suddenly and as hard as you can - more suddenly and harder than you think is possible. Really slam on them! Do this a couple times if needed. If the ABS is working, you should feel the pedal pulse, and you should hear the whine of the ABS pump. (I've tried this on an NSX and swore the ABS wasn't working, until I realized that I just wasn't slamming the brakes on hard enough and suddenly enough to get the tires to lock up.)

 

[Nihilation]

You don't mention what kind of tires (make/model) you have. Is it possible that you're using tires that are just not that good? Have you checked their inflation? What about the tread - how much is left?

Azenis RT-615 tires, less than 1k miles on them- 34psi front. Also forgot to mention that I hear what I'm told is the ABS Pump every now and then when I start the car in the mornings. When I bleed the brakes next I'm gonna go to ATE SuperBlue(I've had good luck with that in my BMW's on track), not sure how much I like the Motul600, it's also more expensive.

 

[nsxtasy]

Azenis RT-615 tires, less than 1k miles on them- 34psi front.

Oh - those are very sticky! Which I guess makes it more difficult to get them to lock up.

Also forgot to mention that I hear what I'm told is the ABS Pump every now and then when I start the car in the mornings.

Try what I suggested. It's quite possible your ABS is working fine.

When I bleed the brakes next I'm gonna go to ATE SuperBlue(I've had good luck with that in my BMW's on track), not sure how much I like the Motul600, it's also more expensive.

Motul 600 RBF has much higher boiling points than the ATE (593 degrees dry, 420 wet for the Motul, vs only 536 dry, 392 for the ATE). As for the cost, the difference in cost for a full flush is about $20 - a very small price to pay for additional protection against boiling.

 

[Nihilation]

Motul 600 RBF has much higher boiling points than the ATE (593 degrees dry, 420 wet for the Motul, vs only 536 dry, 392 for the ATE). As for the cost, the difference in cost for a full flush is about $20 - a very small price to pay for additional protection against boiling.

I'll try your suggestion. Have you any experience with the Motul600? After my first track event this past Saturday at Beaverun I noticed that the pedal feel had become pretty spongy feeling- wonder if that's related to the amount of pad I wore off that day, lol. I must say though, the combination of the fluid, ss lines and the Project Mu street/track pads worked great hauling the car down from 135 to 60 lap after lap! The first session out felt like I had warped rotors, then the sessions afterwards felt like the greatest brakes in the world, no warped feeling. Guess maybe that first session re-bed in my pads! Also the paint on my brake calipers started to bubble, and in some spots had turned color from red to brown, haha!

Thanks for your help!

 

[Nihilation]

Did the 50mph test. They definitely locked up and just slid without any pulsation of the brake pedal. ABS = no worky. It's official. I don't have an ABS light or anything on though....weird.

 

[NSXDreamer2]

There's couple "possible" causes for your car's symtoms:

First you are saying that your pedal is mushy, that means at some point of your last track event, you had came to boiling the fluid, I would not surprised that you will see quite a brownish fluid when you do the flushing... A mushy brake pedal will effectively "damping" your right foot force... thus with the good grip from the Azenis, just effectively slow down your car without locking up.

I'm wondering how you were doing your 50mph test? In fact to test the ABS, the best condition will be on wet or even loose dirt road...

The second possible cause is that not only you had broil the brake fluid, you had glazed your pad and rotor (Though unlikely with repeated 135-60 braking), thus again decreasing the brake force and not triggering the ABS.

Also, when you feel and heard your tire's locking up, do you release the pedal or you kept one stepping on it?? My brakes are good enough to lock up any tires momentary audibly which, nsxtasy told me that hearding the tire squeal does not necessary meaning locking up the tires. On dry surface, I'm sure the ABS kicked in but I don't feel the pedal "kicking" force as I was puting mroe than 200 lbs force on the pedal, however, when that happen, I'm pretty sure I would hear the ABS pump everytime. If the ABS is not working, you will not only able to hear tire noise, but white smoke and long skid marks...
When that happens, I would advise you flushing the ABS system and had someone take a look at it.

RE: Motul 600, I swear by this product as it's the best product on the market (in the relistic, cost effective term) I had ever tried.
ATE wasn't too bad, but 1. I don't like the big tin can, 2. The blue tint looks cool but it's pretty hard to tell if you have any contaimnant in it. 3. The blue dye made is very hard to come off when you later decided to use the oridinary color fluid.

Last point regarding your brake system since you obviously track your car, make sure the paint you have on your caliper supposed to withstand high temp. I had tried the 1200 degree spray paint and it too wont' withstand the caliper temp on the track. However I spary painted the caliper only in very very thin coat as I expected it'll come off and I don't want it trapping all the heat within the caliper. The other thing is to see if you had "drag" your brake too long and maybe even investing a set of 2 pieces rotor.

Ever since I used the Stoptech areo rotors, I had never ever burnt any fluid despite I'm using RA1 and my lap time was 5-10 seconds faster than previous year. With all the time and money I spent on bleeding the burnt fluid, the aero rotors almost paid for itself.... yes, it's that amazing.

 

[Nihilation]

I decided to do a hard 50mph brake stand while on my way home from work last week. It was sunny and dry, the front tires locked up almost instantly- I know since I tried to steer while it occured and I kept going straight. There was no ABS noise that I could hear and the brake pedal did not pulsate. Tire smoke was also very noticable by sight and smell.

I'll try flushing the entire brake system. Gonna have to look up how to do the ABS portion...