Disc / Drum with adjustable proportioning valve

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Dec 13, 2010 | 10:37 PM

JustBlaze

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Senior User

Joined: Sep 2010

Posts: 241

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From: Upstate NY

Disc / Drum with adjustable proportioning valve

Hey guys,
I'm trying to figure out whether this setup would work or not.

I'm doing a completely new brake setup on my 77' except for the non power master cylinder which I'll try and use for now. Anyways I don't want to re use the old proportioning valve and I can buy an adjustable for the price of a new replacement one.

My question is would it be alright running the brakes like I have shown or would I need something more than just the adjustable proportioning valve.

I've heard people mention stuff like the prop. valve applies the rear brakes first and then brings the front on, etc.... I just wanna know if I can run it like I have in the picture.

Thanks
-Justin

Dec 14, 2010 | 08:55 AM

fmc400

MSEE

Joined: Apr 2004

Posts: 10,386

Likes: 35

From: Austin, TX

The way you've shown it won't work; one of the roles of the proportioning valve is to delay the front brakes relative to the rear brakes as you've heard. With drum brakes, the shoes are held at a set distance from the drum surface; however with disc brakes, the pads ride the rotor at all times. The proportioning valve sends fluid to the rear brakes first so that by the time the calipers actuate, the rear brakes are already there. The way you've shown it, the front and rear brakes will engage at the same time (albeit at different stopping powers) and you won't get any rear braking action.