brake proportioning block

[280z4me2]

Going to use 280zx rear calipers and master cylinder in my s30. I've searched and found some saying the zx came with a brake proportioning block and some say the master cylinder proportions it itself and some say you need a proportioning valve. Which one is it?

[duragg]

I think it may depend on what's up front.

If stock you might just want to try and run it see how it goes.

Easy to add later if needed.

 

I deleted my proportion valve due to bias issues from oversize front brakes.

[280z4me2]

Going to run stock brakes up front and zx disk in rear. Zx m/c with s30 booster.

[Nigel]

There is no proportioning valve integrated into the ZX master cylinder, if that's what your asking. The ZX's have a separate proportioning vavle just like the earlier Z's. Depending on the year of your Z (you don't specify), the proportioning valve that came with your car is either at the rear of the car above the differential (~'70 to '72 Z's), or on the left side of the firewall ('73 on).

 

With the ZX rear brakes, you may have too much brake pressure going to the rear brakes, leading to the rear wheels locking up before the fronts = BAD. In that case, the stock proportioning valve needs to be replaced with an adjustable one allowing you to "turn down" the rear brake pressure.

 

FYI, if your Z has the stock proportioning valve on the firewall, and someone tells you just to "gut" it, don't listen to them! This will tie the front and rear brake lines together.

 

Nigel