z32 brakes and MC discussion...

[crzycav86]

On a local forum, we were discussing 300zx brakes and master cylinder sizing relating to brake bias. One member used a program and made a nice visual representation from it...... Here's what he concluded:

Also.. took a few minutes to do some calculations on you guys' brake bias assumptions based on which master cylinder you're using...



For this chart, I assumed the cars in question were an S14 and a Z32, which is where the brake specs came from- rotor and pad sizes, master cylinder size and split point for pressures, caliper piston sizes, etc...

I also assumed front wheels would lock at 2600ft-lb of brake torque, which is 1000psi hydraulic pressure with stock front calipers... These are just ballpark assumptions, but are close enough for theoretical work..

As you can see, the stock rears with with Z32 fronts are a BAD idea.

Otherwise, the stock brakes and stock MC have the most front bias, with the full Z32 setup at the most rear-biased.For initial braking, the 1.5% difference in bias is no big deal...At the limit of brakingbefore your front wheels lock up, there is still only about 4.5% difference.

The part that is going to thow people off is when you're braking at about 50% going into a corner. At that point, you're 10% farther to the rear using the Z brakes than you are using the stock S14 brakes.

for you drifters, this is good- you can tap the brakes to get the back end loose easier, then power through it to maintain the slide. for most road course people, this is bad because you DON'T want the back end to come around on you when trail braking. Of course, that can be overridden to a point by keeping your foot in the gas and breathing on the brakes with your left foot.

So take it as you may, but there's the numbers.I didn't take into account anything about pedal feel or pedal travel here. personal preferences will vary on those issues, but the 240 MC running Z32 brakes will be more spongy.

I just thought this was really interesting. What are your thoughts?

[Dirtylou]

Interesting.

[jacob360]

The stock brakes are perfectly fine with some quality pads, rotors and fluid.

[Bronze MFP]

yeah, that graph is interesting. I have z32 front and rear brakes, but the stock 240MC, like the graph shows, it's pretty well balanced. I personally dont think the pedal feels spongy, and every time i've had to emergency brake, I never felt out of control. Lockup is predictable and controlable. I've never driven any other setups, but the z32 front and stock rear seemed very unbalanced to me, and after driving with my stock MC, i can't justify swapping in a z32 MC. Now I have the graph to prove it too

edit: i'm also running 225 tires all around, so that might prevent lockup a little bit

[Nismo_Freak]

Nice to have graphical representation of what I've been saying all along.

Still not convinced that the Z32 fronts will automatically cause greater rear brake lock-up with the stock rears vs. Z32 rears. Simply because it's a relation between torque bias that is shown, not actual threashold of the rears. Simple logic would dictate the Z32 rears would induce rear lock-up faster, but greater stability before this point.

[kclo4]

Grr, I wish I could figure out what to do about this problem. I have an S14 MC with Z32 fronts and S14 rears and it's pissing me off. Front lockup is too easy and it make it hard to get the car to rotate while trail braking at auto-x and such.

Is there a way to totally remove the internal proportioning valve in the master cylinder so that I can easily use an adjustable external prop valve?

I was planning on ordering a Z32 MC soon to get some of my peddle feel back, but I wan't to make the whole setup better without buying Z32 rears.

[McRussellPants]

I don't know about lockup.

I have S13 Master and Zs all around but I still lock the fronts before the rear. That could be due to the fact of the *** pads in the rear.

I think its mainly for car feel.

people can jerk themselfs off all day about how the front does the majority of the braking so you only need the fronts. But anyone I've talked to that actually does more with their car than slam the brakes after rice manuvers says stock rear and Z32 fronts plow hard with any sort of corner added.

which is kinda obvious when you think about it.

Edit: That may or may not be relevant or sensical. but Im going on 2hrs of sleep.

[kclo4]

It's supposed to lock the fronts first no matter what, it's just way to easy with only Z32 fronts.Everybody wants to put Z32 fronts on to be cool but really only a small % of them actually need them. I track my car often and hard so it was a no brainer after the fade I experienced with stockers.

One of the fastest S14 drivers I have seen around the net runs stock rear brakes with really aggresive pads and big brembo's up front. He placed second at the redline time attack in cali so he is doing something right.

I really want to be able to adjust things with a proportioning valve though instead of screwing with different pad compounds.

[sr20-thoj]

very interesting.. I was planning on getting bigger brakes for my sr 240 too.. but now that i think about it.. i might not need them after all.. maybe stock will be fine as of now.... its not like im gonna go crazy and speed/drift 24/7...

[colies97~240sx]

This has been discussed many times before, even with the same graphs and article you posted. I have 300zx brakes up front and s14 brakes in the rear and I have never locked up my fronts. Even when slamming on the breaks in the rain. If you are really worried about it upgrade to the 300zx mc, but it works perfectly fine with the s14 mc.

here are some past threadshttp://forums.nicoclub.com/zerothread?id=10443http://forums.nicoclub.com/zerothread?id=60563http://forums.nicoclub.com/zerothread?id=63778http://forums.nicoclub.com/zerothread?id=104438http://forums.nicoclub.com/zerothread?id=106283http://forums.nicoclub.com/zerothread?id=112150http://forums.nicoclub.com/zerothread?id=144954http://forums.nicoclub.com/zerothread?id=147976
Modified by colies97~240sx at 6:01 PM 3/15/2006

[steaminhotryce]

Interesting thread. Can I ask more Stock 240MC/Z front/S14 rear equipped owners to input their experiences with this set up? Does it match up to the graph?