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HybridZ

is stock proportioning valve required if im using an adjusta


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Guest Anonymous

Good question. I have a manual proportional valve installed in my cockpit. I noticed ( as I am installing a new master cylinder) that the MC goes to a what looks like a splitter about 5 inches down the line, to the front wheels, then another splitter ( I guess )to the back wheels circuit. Question is why are splitters installed when the MC has two outlets? I guess I need to crawl under and follow all the lines.

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This may vary thru the early Z`s, but you have the M/C to a brake switch to a proportioning valve!

The brake switch is below the M/C.

The pro valve(some on firewall, some in the back of car)

Both lines from M/C run to brake switch-line splits to frt left / rt-from brake switch a line runs to pro valve-to rear left / rt

Try to look at a Nissan manual for your year, it will have a diagram of the brake system.

 

Anybody please add in, I know that there are differences thru the years!

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> No it is not needed and should be removed

> from system!

 

Well... as always the answer isn't that simple. Is the car running rear drums or disks? Have the front calipers and disks been changed from stock? What master cylinder? What year is the brake plumbing (brake light switch and prop valve?)

 

If the car is using rear drums, leave the stock prop valve in AND install the adjustable prop valve. The stock prop valve gets you very close to optimal front/rear balance and the adjustble valve lets you adjust for rear brake shoe wear during a race.

 

If the car has disks all around, then the questions move to:

 

1) the type of master cyliner including piston diameters.

2) the type of calipers and the number and size of the pistons.

 

... but, in most cases when changing to disks all around (and you know how to properly adjust and balance a brake system) you should remove the rear prop valve and add an adjustable prop valve for the rear brakes.

 

Buy the Tilton knob adjustable one and install it in the engine compartment. Use it to get the balance correct. For racing, add the lever adjustable one next to the driver's seat and use it to balance braking for racing conditions.

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FYI... some of the brake light switches under the master cylinder also have a prop valve in them. They work in combination with the second prop valve in the system and should be kept together as a pair.

 

I have not been able to discern a pattern in Nissan's use of the dual prop valve brake plumbing. I do know that some combinations of prop valves are cherished by ITS racers; probably more for superstitious reasons then anything else.

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alright well i have a 72 240 .. i am replacing all the lines and i am trying to figure out how to do it. i crashed the car due to a brake pull to the right i did notice after the car has been sitting that the right rear cylinder leaks enough to make a wet line down the tire. i am replacing front rotors and disks but i havent decided what to use yet nor do i have the funds to do an expensive big brake kit. id like to replace every last part but im very confused as to which approach to take IE: upgrade or stock the car will have a small block chevy a cage and other fun doodads itll be a daily driver with occasional autocrossing and drag runs. id like opinions more then anything. theres almost too many paths. ive spend entire days going through the forum (12hours+) reading and im still baffled thanks for any advice you can offer -pete

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