17/16 MC swap on a S14 w/ manual transmission?

[BryanGrigsby]

Should I put a z32 17/16 MC on to the brake booster for my S14? I have a manual transmission and have heard that the booster is different than the one with the automatic transmission, causing the booster setup with the z32 MC mated to the booster on the manual transmission to be too stiff. I have the 17/16 MC and was thinking I was going to just throw it on untile I heard this. I only have the front calipers and was going to leave the rear stock. How stiff is it? Is it worth picking up a booster from a automatic since I have the Z32 MC already or should I skip the MC install?

[cdlong]

i'm more concerned with the different setup of the hardlines and the connection on the bottom. i'm not sure what it is but i haven't really looked.

i doubt the booster will make a difference. but i'm just talking out of my ***.

[onosqv]

i'm more concerned with the different setup of the hardlines and the connection on the bottom. i'm not sure what it is but i haven't really looked.

i doubt the booster will make a difference. but i'm just talking out of my ***.

You *** talker... hahaha

w/ the 17/16 mc in the front, you will still have brake imbalance, however, a little less than before since it has a higher break up point (sends more to the rear longer).

It will definitely make it feel stiffer - if you feel the current setup is too soft - that stiffness is sort of adjustable via the bolt/screw in the brake booster, but basically you have to bleed the brakes each adjustment: making the bolt "tight"/i.e. turn in, makes it softer.

Also, another reason to upgrade is that the normal mc will send much more pressure to the front brakes than the 17/16 mc will. However, keep in mind this mc was designed for the front & rear, not just the front & stock rear.

Anyway, I've only done this on my s13, so I'm not sure what you have to do on the s14. It's definitely stiff, but not omg it's ****in stiff, stiff. You get used to it after a week.

[BryanGrigsby]

Did you swap the brakes all the way around or just swap out the front? I also wonder if that means that rear brakes(stock) will be coming on stonger than the front with the z32 calipers. Will I lock up the rear before the front?

[BryanGrigsby]

I also wonder if there is a MC size that has a proportioning that lends its self to better operation with stock rear.

[BryanGrigsby]

I found this at fresh alloy, but I dont really understand how it will affect the characteristics of the brakes;

If you had searched for "brake bias" in the Basic forum, you would have found this juicy little tidbit of information:

Quote:--------------------------------------------------------------------------------

The way OE proportioning valves work is that the front and rear line pressures go up by the same amount until the pressure reaches the so-called "split point". At this point, the rear pressure increases at a lower rate than the front pressure (with the proportionality factor given by the reducing ratio).

Now the reducing ratio for the Z32 and 240sx MC's are the same (0.4), so the only difference is the split point. The Z32's split point is lower than the 240sx, so above the split point, the Z32's rear line pressure will always be lower than that of the 240sx.

Asad

--------------------------------------------------------------------------------

I'll give you a numerical example.

Up to the split point (say it's 500 psi), the line pressure to the front and rear brakes is the same. Above 500 psi, the additional pressure above 500 psi is multiplied by the reduction ratio, and added to 500 psi, and that's what's sent to the rear.

So if you have 500 psi of line pressure, fronts get 500 psi, rears get 500 psi.

If you have 700 psi of line pressure, fronts get 700 psi, rears get 500 + (700-500) * 0.4 = 580 psi.

If you have 1000 psi of line pressure, the fronts get 1000 psi, the rears get 500 + (1000-500) * 0.4 = 700 psi.

Because the Z32 master cylinder has a lower split point, that means that it starts sending less pressure to the rear brakes at a lower pressure -- hence, it has less rear brake bias.

All this posted by Asad.

So a lower rear bias will effect the stock 240 calipers ....how?

[onosqv]

This is from the billions of threads I read when I was doing my upgrade, so it may not be all that accurate (it's from what I remember).

First things first:

stock m/c thinks there is 4 pistons total (1 each corner). Will send pressure to front caliper (say left) @ XXX pressure, however, that is XXX pressure for EACH piston -> will lead to alot of front bias.

z32 m/c knows to send less pressure since there are 4 pistons on each front as opposed to 1.

This is from what I remember.

The correct pressure to the front for the z32 should give more rear bias (since it's lowering front bias). This will reduce the chance of locking the front wheels... I think.

You can try the 15/16 m/c -> not as crazy, but better than stock.

Again, this is from what I remember, so please chime in if I am wrong (or right).