Z31 BMC to S13, bolt on?

[DJ-of-E]

I'm actually quite confuse on the z31 BMC and the differences. I tried out the 17/16 with z32 brake booster setup and did not like the "lack of" pedal travel from the system.

I want to try 15/16 with manual booster on the S13. While I was looking up Z31 BMC, I noticed there's a 4th hole in which I do not know what it is.

On another Zilvia thread, it shows a NABCO z31 bmc with 3 openings.




However, I went to several shops and they all have "TOKICO" z31 BMC. I immediately noticed a difference.



Between the 2nd front and rear opening, there's another hole in which the stores plugged it up with something rubber. I checked the z31 FSM, but it only references the 3 flange brake lines.

Can someone explained to me what's the function of this 4th hole and is it okay to leave it alone?

[codyace]

You want the split fronts....get a power booster and call it a day too.

[DJ-of-E]

Originally Posted by codyace

You want the split fronts....get a power booster and call it a day too.

What do you mean by "you want the split fronts"?

[sleepyS14se]

he is saying you want to have the front brakes split. One line front the master cylinder per each front wheel. Atleast that's what i got from it.

[jr_ss]

Yes, each front wheel has a separate port and one port for the rears.

[wowitsaboy]

splitting lines? weird, the replacement I got from autozone was a direct bolt-on, and it was like 30 bucks (after returning my stocker as the core). don't have the part# on hand but I remember I asked for the 88 300zx BMC.

[DJ-of-E]

Ok. So I asked this question a few days ago in a Z31 forums and they stated it is just a weep hole. It is normally plugged up with a plastic cover, but can be exposed as well. They stated if too much pressure builds up in the master cylinder, it would leak out fluid to prevent from damaging the internals of the cylinder.

Apparently The first pospicture the BMC is from 86 and older Z31 models.

Sorry about the second picture, I grabed it from another forum, it does have split fronts but the flash made it look like it has none.

[codyace]

By splitting the fronts, I mean to make sure the FL and FR lines are on seperate ports (in their correct spot) on the MC, and that the rear is the single line to the back (which is then split back there).

My fault on not being good with the description.

[sleepyS14se]

it's ok we kind of deciphered it. LOL