Question re: my diy brake job from this weekend.

[comquat1]

Ok, I did my brake this weekend by putting new rotors and pads on all four corners of the NSX. I'm scheduled to have a bleed of the system as well as an ABS checkup/bleed? as well this Friday so maybe this might answer some of my questions. Anyways, I bedded in the pads as best I could from the instructions I got on here and from Cobalt Friction (FYI I got G3000 rotors all around, GT Sport pads on the front and Axis Ultimates on the rear). Today was the first day I could go out and really hammer on the brakes and I noticed a few things I wonder if I should be concerned about.

First off, I noticed alot of shudder happening when I hit the brakes hard at 80mph til I got down to 50-60mph, I think it kinda went away once they got nice and hot though. Or at least I didn't notice this towards the end of my ride.

Second, when the brakes were cold (or at least not hot) the ABS would come on a cause some studdering as I braked hard but once everything was hot I didn't notice the ABS come on at all. One thing I thought weird was after a couple of initial hard stops I heard the ABS pump go. I didn't think it was too big a deal, but halfway through my drive I heard it kick on again as I was braking rather quickly up to a four way stop sign but it cut off a whole lot quicker than it normally does, like something stopped it on purpose. After that, I noticed no ABS overriding happening.

Finally, this setup grabs really well, so well to the point that my front tires will chirp a bit if I really hit the brakes. They'll only chirp once or twice but I'd be lying if I said it didn't concern me a bit by the herky jerkyness of the situation. Also my tires are SO-3's.

So is this normal for a new pad and rotor set up until you get them broken in? I'm going to Gingerman on Sept. 13th and really really want to make sure I've got this thing up to snuff. I followed the DIY procedures done by DanO so I can't imagine I did anything I wasn't supposed to do. Also this was my first foray into doing a "major" job like this on a car I own myself, so I just want to make sure I I'm experiencing normal stuff or if they really are oddities.
Thanks in advance, any feedback would be great.

 

[nsxtasy]

Everything other than the shudder is totally normal.

The shudder could mean that the bedding wasn't successful... in which case you might try doing the bedding procedure again.

The ABS probably comes on when the brakes were cold because the tires were cold too.

The "grabbiness" of the brakes is because you're getting good grip from the brakes and the tires. Practice modulating the pedal pressure and you should find that you can do so in a way that prevents the herky-jerkiness you mention.

 

[comquat1]

Ok, I just went out again after letting the car set for a bit. No shuddering at all this time, however the ABS did kick in again and cause some studdering as normal once again making the tires chirp a bit. Should the chirping go away once the tires warm up (such as what will happen on the track)? I hope so, I don't want studdering flying into a corner at whatever speed you're supposed to enter at.

 

[nsxtasy]

the ABS did kick in again and cause some studdering as normal once again making the tires chirp a bit. Should the chirping go away once the tires warm up (such as what will happen on the track)?

The objective in track driving is "threshold braking", meaning that you modulate the pedal pressure so that the brakes are on the threshold of locking up, but not actually locking up (so ABS does not engage). You will need to practice this technique in order to prevent ABS from activating.

Some track schools, like BMW CCA, have threshold braking exercises in the novice run groups specifically to teach this technique.

 

[comquat1]

Well, we'll see how I do on Monday!

 

[apapada]

The ABS probably comes on when the brakes were cold because the tires were cold too.

I do not exactly agree about this explanation above... You'd be right if he was using some R compound, but not with street tires (even high performance). Street tires actually work better when operating under normal driving temperature (i.e. "cold" in reference to tire temperature on the track). The warmer they get, the "greasier" they feel...

 

[nsxtasy]

I do not exactly agree about this explanation above... You'd be right if he was using some R compound, but not with street tires (even high performance). Street tires actually work better when operating under normal driving temperature (i.e. "cold" in reference to tire temperature on the track). The warmer they get, the "greasier" they feel...

But if you read his post carefully, you'll see that he's not talking about driving on the track. He has only driven them on the street so far. So "cold" and "hot" in his posts are references to street driving, not track driving. Hope that makes sense.

 

[apapada]

But if you read his post carefully, you'll see that he's not talking about driving on the track. He has only driven them on the street so far. So "cold" and "hot" in his posts are references to street driving, not track driving. Hope that makes sense.

you are right, but even in this case (street driving), street high performance tires (like the S03s) are designed to operate over a broad band of temperatures which is more or less centered on the conditions they will most likely be most used in. Summer tires usually have a narrower band than all-season tires, and racing tires even more narrower band than summer tires. The loss in band width is made up in grip potential. I consider S03s to be summer ultra high performance tires which should be ok as long as it s not cold climate (<10C) or too hot (>95C). I believe our friend's tires should be somewhere in the middle of these temperatures unless I missed something else...

 

[comquat1]

I really don't mind the chirping because I do not go around all day slamming on my brakes to the point of abs activation, I just want to know if that would be normal considering my brake rotor/pad set up.

 

[Steve]

Sounds like you are just somping the fool out of the brakes. If you are on the track doing this you will be making your 1st mistake. You can nail the brakes aggresively without stomping them. Smooth = FAST!