Autocross Brake Help!

[kassed33]

I just started doing some autocross. I have a 95 240sx, Sr swap with 360whp, good tires(Michelin PS2), and 300zx calipers with Hawk pads and brembo drilled slotted rotors, Non ABS. Now my problem is there not enough, i'm locking up the front brakes when hard braking, and just sliding and not being able to make some turns when coming in with some good speed. So first question is will swaping the MC to a 300zx one give me improved braking to make a difference? I know it will give me better pedal feel but i dont care so much about that i'm looking for performance. Second if i end up going with a bigger front brake kit like 6 or 8 piston can the stock MC handle that much more over the stock 2 piston? And finally any suggestions on improving my set up for the track and welcome, but keep in mind i do also drive the car on the street, not every day i have an EVO for that but i do take it out when its nice. Thanks

[jspeedm]

first off, if your brakes are locking up, they are doing their job. your tires are loosing traction. get stickier tires or learn how and when to brake with what you have.

[OptionZero]

get rid of the drilled and slotted rotors

[HYPNOTIK]

get rid of the drilled and slotted rotors

Since that's obviously the issue at hand.

I'd try swapping out the BMC, I had the same issue when I went to the Z32 setup. I changed out the MC with a R33 and there was a pretty big difference. If you still have an issue after that then get a proportioning valve, summit sells them for like $40. Even if you fix the brakes issue get some stickier tires, tons of better options out there for auto x. I'm using Star Specs and love them.

[g6civcx]

What class do you run in?

For autocross, smaller brakes are actually prefer to save weight since you don't run long enough to heat up the pads.

I recommend putting back your stock brakes. Do new blank discs and a good set of pads that don't require a lot of heat and you're good to go.

[rains14]

get rid of the drilled and slotted rotors +1 put your cash into pad and mc not into drilled rotors

[kassed33]

Ok so I guess I should say that I can't be sure if the brakes are locking up or the tires are loseing grip only that I stand on the brakes ans I slide. Also why so sure its the rotors I'm not using a race compound pad so too much heat is not my friend and its a 1.1 mile course. And going back to stock brakes makes no sense if what I have isn't working well enough. But pretty much want to know if bigger MC will make big difference in braking.

[g6civcx]

You put a lot more info into the question that wasn't originally there.

You will be bumped severely in class due to your engine mods. So the brake mods will be a moot point.

Since you're new at autocross, I'll break it down for you.

1.1 miles sound like a long distance, but it actually isn't.

Your brakes, even if using aggressive street compounds, require a lot of heat to work properly. It will take about 3-5 continuous laps on that 1.1 course to properly heat up an aggressive street compound. Maybe even more if you're on race compound since you don't get enough speed to generate braking heat.

I recommend stock brakes for autocross simply because they weigh less. All the big brakes look nice and they do help with fading on medium to long tracks, but on short autocross tracks you're better off with smaller brakes to save unsprung weight.


Learn to drive your car. If you smash the brakes, of course the car will slide.

Do what you want. Good luck and don't kill anyone.

[kassed33]

the autocross i'm doing isn't a competition type. It is timed but not a sancshoned "Race" per say. It is more classified as "test an tune" or a "school" with the company running it simply for insurance reasons, its a very grass roots event, only 20-30 cars so i'm not worried about classification, because there is none. I'm just doing it cause i love to drive, and want the car and myself to perform the the best of the abilities. And besides that i trashed my stock calipers when i upgraded them and i'm not gonna spend money to go backward.

[g6civcx]

I said it many times before. I'll say it again here for your benefits.

Brembo does NOT mass-manufacture crossdrilled and slotted brake discs.

That means that one of the following happened:

1) what you have is either done with someone with a drill press punching out a blank disc, or

2) you got Brembo to do a custom batch order for you.


How likely is #2 in your opinion? If you do not know, contact Brembo and ask them.


The problem is with the drills and slots. The edge has to be treated at the factory. Otherwise severe problems with cracking and heat damage will occur.

Also, the purpose of these is to reduce heat and vent gas released from extreme pad wear. Since modern brake pads don't degas and you don't generate enough brake heat any way, these aren't issues.

The material removed from the disc leave less material on the disc. Braking efficiency is reduced.

You'll be surprised by what a good pair of blank Brembo discs and good Hawk HPS pads will do compared with bigger brakes.


I have no more recommendations for you at this point. Good luck.

[bkfill]

do you have stock rear brakes?

I have 300ZX Front + Stock S14 Rear Brakes

i had the same problem, very sensitive braking, light pedal would lock the front if i held it,

go buy a 1988 300zx (Z31) non-turbo brake master cylinder, it has the highest split point, i went with a rebuilt one at autozone

if you seach my name u'll find a brake thread about it with pictures and answers to witch lines go where

[kassed33]

Yes I do have the stock rear calipers on it but not stock pads or rotors. I actually do have the matching set of rear 300zx tt calipers but just never got around to installing them do to the whole ebrake hassel thing. And correction you are right the rotors and just cross drilled not slotted.

[jspeedm]

if the rear brakes are locking up, the mc will help with that. if the front brakes are locking, the only only thing the mc will change is pedal feel. brake earlier and lighter.