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Old 05-15-2020, 11:05 AM   #6
nikwho
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Join Date: Apr 2010
Location: Flagstaff, AZ
Posts: 974
Re: What master cylinder and proportioning valve for disc/disc

Quote:
Originally Posted by joedoh View Post
you shouldnt need a proportioning valve for a disc/disc, usually the proportioning valve is needed on a disc/drum setup because the disc needs far and away more pressure to clamp than drums (why power boosted brakes became a thing around the time discs did). if a prop valve wasnt installed it would lock the rear brakes before the fronts even started clamping.

so a disc/disc setup properly balanced (in rotor size etc, not pressures) can use a regular master cylinder. if you really upsized the rears ( a waste of money, in my cruddy opinion, front brakes do the work in 99% of driving) or are experiencing lockup, then you may need a prop valve.

98-03 chevy blazers were around the same weight as a half ton fullsize truck, and had 11" front rotors with dual piston calipers and small rear discs with single piston calipers, so that master cylinder would probably work. but get the fittings from a salvage yard and install them on your lines, they are weird sizes. by the way, the blazer has no proportioning valve from the factory.

thats just my suggestions, others will have more.
Thank you! That all makes sense. I'm curious about master cylinder bore diameter. Seems as though I have read that smaller MC bore diameters give more pressure. So, I would imagine that a larger MC bore diameter would give more feel?

I guess that I will omit the disc/drum proportioning valve, but leave the Wilwood adjustable valve in place to fine tune it. Makes me wonder why they sell disc/disc proportioning valves, though! There must be a purpose!?

I just want to get it figured out, so I buy the correct parts.

Nik C.
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