Braking Instability Pt. 2

[Ponyboy]

Had a club track day on Tuesday of this week and was really looking forward to see how the car responded to the year long installation of mods. Yeah, it has been a full year (almost to the day) since I've had my car on the track. Anyway, it was eyeopening to saw the least. I experienced exactly what Edo described here:

Braking Instability

Wow, kinda scarey. I'm using SO-3's and Cobalt VR pads up front and they'd immediately lock up. Don't remember what I'm using in back though it's one of Cobalt's more aggressive pads. Specifically, under braking the car would immediately lock up and then pull to one side or the other. Even under more progressive brake application the car would feel vague and disjointed under braking. Really scarey feeling. In T10, normally I'd brake about the 1 1/2 area and that day I had to brake around the 3 in order to keep it under control. Here's some vid:

Hallett vid

Here are the possible gremlins; too aggressive pads, not sticky enough tires, alignment off, steering or bushing issue, corner balance off, ABS needs bleeding, etc. Anyone else come up with another idea? Need them - don't want to go thru that again.

Thanks!

 

[Andrie Hartanto]

Shawn,

that is the same thing I experienced when I had only front brakes upgrade! That's why, I keep telling people that have brake upgrade to do the rear too. Brake balance is critical!

A lot of people that said only front brake upgrades needed and good are either not driving their car hard enough or simply not good enough drivers to notice this kind of behaviour.

I also can't believe some brake vendors also recommend to go with softer compound in the rear using stock NSX brakes. The stock NSX brakes is well balance and should have identical compound front to rear.

Are you going to NSXPO?

 

[Ponyboy]

No NSXPO for me this year. This is my busy time for business travel.

The whole reason why I bought the Stoptechs was b/c it didn't require rear calipers and rotors. I figured I never had any problem with the rears so if Stoptech could balance out the bias according to stock I shouldn't have any issues. That was the theory.

But the problem may be something else. I won't know until I figure it out and eliminate the variables.

I "eyeballed" the corner balance the night before. I hope that it corrected will solve the issue. Hard braking previously had no indication of wander or vagueness.

 

[docjohn]

Sounds like your abs was'nt working.The brakes were overpowering your tire grip,so if you could'nt threshhold break and the abs is no worky=lockup.Andrie,I take issue with your bold statement about all front only upgrades being unballanced,come ride with me for a few laps before xpo is over I'll show you how nice the comptech 12.4 brembo kit is!

 

[Andrie Hartanto]

Sounds like your abs was'nt working.The brakes were overpowering your tire grip,so if you could'nt threshhold break and the abs is no worky=lockup.Andrie,I take issue with your bold statement about all front only upgrades being unballanced,come ride with me for a few laps before xpo is over I'll show you how nice the comptech 12.4 brembo kit is!

John,

you got spoiled running with ABS. I got so used on running without ABS. The ABS in the NSX is so old its a joke too. Do you know it is the same unit the Integra run in 92.

That being said, I have confident in the Comptech 12.4" brembo kit. It is small enough, that combined with track tires the weight transfer would be correct and it should work great. I always have confident with Comptech products, they do their homework!

 

[Peter Mills]

I had the same problem with wheel lock up in the braking zone for turn 6 at Watkins Glen. I installed AP racing 13" rotors with four pot caliphers and was on street rubber. Too much brake torque. Chris Willson told me not to worry when I put on track rubber toyo RA1 235/40/17 that situation would correct it's self. He was right it did. I've track the car since in the rain at WGI and very light pedal pressure brings the car to a straight non-lock up stop.

 

[docjohn]

come to think of it I never did track the car with my bigger breaks and street tires.I would agree that putting wider track tires would help with your break lock-up.Andrie your right , My abs barely works if at all.I can lockem up if I want.