4 replies to this topic

[dunejunkie]

Hey guys, I just got my d16z6 swapped round nose on the road. I will be upgrading the brakes from the current 7.5 inch setup to the 4 pot metro turbo brake kit from minispares. I am running the willwood pedal box kit from minitech. I believe the master cylinders are the same bore size for front and rear. The rear slave cylinders are 3/4" bore. Do I need some sort of brake proportioning valve? Or is the balance bar on the pedal box acceptable? I believe the original proportioning valve is still mounted on the rear subframe. Some people have said to bin that and throw in a standard T-connection. Would like to hear you guy's opinions.

 

[Sprocket]

The whole purpose of the balance bar dual master cylinder set up is to allow a wide range of adjustability in brake balance from front to rear. You would normally fit a slightly smaller master cylinder for the rear since very little braking effort is done on the rear wheels, this will keep the balance bar more central. The proportioning valve on the rear subframe should indeed be removed, but for simplicity of pipework, you can remove the innards and just use the valve body as the tee.

 

To complicate things further you can also reduce braking effort at the rear wheels by using a smaller wheel cylinder. I'd suggest the 1/2" bore wheel cylinders and maybe a 5/8" master cylinder to try and keep the balance bar more central while maintaining a decent front/ rear brake balance.

[tiger99]

That is not quite correct. You fit a LARGER master cylinder to get less pressure in the rear line. If the rear cylinders are in good condition, regardless of size, keep them, and adjust with the balance bar until the fronts lock slightly before the rears. If I was replacing them I would indeed use the smallest, but no point in wasting money.

 

Replace the old limiter valve with a T piece.

[Sprocket]

After you pointing it out, I agree that I made a mistake in my statement that the smaller master cylinder should on the rear. You are correct in that the smaller Master cylinder should be on the front. I stand by my statement however that two different size master cylinders should be used in an effort to reduce induced angle on the balance bar.

[Shooter63]

The answers given are sort of correct, you do indeed use the larger to the rear to get lower pressure, but the sizing of the cylinders is for straight line braking, the bias is to allow you to fine tune the system when braking into a corner etc hence the use of an adjustment knob to allow changes on the move, no doubt we have seen the drivers in F1 moving the lever/ knob during a lap. 99% of us without the real skills required to use one properly just use the bias to sort the wheel locking out.

Shooter