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Brake Proportioning Valve Location


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Any reason not to install an adjustable brake proportioning valve in the stock location above the differential? This would be for a street car, where I'm thinking that once it is adjusted properly, it won't need to be touched again. Car is getting Z32 calipers on all 4 corners.

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I would want it in the center console, the whole point of having one is for easy adjustability. You can adjust bias with different pad compounds and that's something that might mess you up down the road also if you don't have easy adjustability.  And what are you doing with the car? You may want adjustability if you go from full to empty on the gas tank.

 

When you say stock location above the diff that is just a T fitting.

 

Also be aware of going from drums to discs. The stock splitter valve on a 240z (the one on the firewall) is setup for drums, if you swap it for a 280Z valve it has a delay function (as opposed to a proportioning function).

 

Assuming you are swapping masters because there's a difference there also in the residual pressure valve for the rear.

Edited by Chris Duncan
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If street get knob type. If road racing, get lever type. I never can remember which way to twist the damn knob in the heat of the moment. If racing, you will adjust it based on tire temps and rain, etc. it really does make a difference if you have legit rear brakes. Most OE brakes will be biased toward the fronts from the factory so adjustments aren't that critical. On race track, running too much front bias will cause early wear out of front pads, fade and boiling, and you will go off track going forward right off the end of the turn. Too much rear will put you in the grass sideways. Take your pick! Old Andy's location is awesome! Mark it somehow so you know if your x-girlfriend has messed with it. I put mine a little more out of sight for that reason, but again, I can't ever remember which way to turn it. Will have to put a reminder on dash.

Edited by RebekahsZ
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Well, I guess I'll scrap the idea of putting the adjustable valve in the stock location.

 

Can anybody confirm that the splitter in the engine bay is anything more than a splitter? If it is, might it make more sense to install a combo splitter/adjustable proportioning valve, like this one?http://www.wilwood.com/Images/MasterCylinders/MasterCylinder_Photos-Large/260-11179-lg.jpg I believe I can se the 3/8-24 flare nuts on the stock line,if anybody knows otherwise, please pipe up.

 

Also, I am planning to just install a union where the stock proportioning valve was, right in front of the Tee above the differential. Is there a reason not to do this?

 

And yes, I'll be installing a larger Master Cylinder, and still trying to figure out which booster to use. I need to confirm my research, but I'm thinking a 15/16" or 1" M/C and a booster out of a 79-82 Z.

Edited by JoeK
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  • 2 weeks later...

Went ahead and returned the Wilwood regular proportioning valve. Got the new splitter and proportioning valve combination, will have to reroute the stock lines a little, and re-flare them with different nuts but it doesn't look like it'll be too hard. Went ahead and got a new 1" Wilwood Master Cylinder and Wilwood clutch master, along with a rebuilt booster from a 78 280z, I think it's 8.5 inches.

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There is a prop valve above the diff on cars sold in the US starting in 1972.  On a street car I would put an adjustable prop valve next to the master cylinder in the engine compartment.  That's where it was on my race car but I also ran a balance bar and that adjuster was on the dash.  

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