Proportioning valve question

[BIGBLU 72]

Im swapping to disc breaks in my 68 but i am keeping my manual brakes. i know that i need a prop valve and i have one on a truck that is a parts truck so would it be ok to use this one or should i buy a new one? will a master cyl off a 75 truck bolt up to my 68?

[oldblue1968chevy]

you will need a disc drum prop valve(assuming you keep your drums in the back still)

keep an eye on the parts board or buy a new one. A car disc drum works also. Summit/board vendors/speedway/ece/cpp etc will have one!

[BIGBLU 72]

would you think it safe to use the 40 year old one chilling on my parts truck??

[Stocker]

Disc brakes take more pressure to operate, which is why most are power -- you probably know that already, just a heads up since you are staying manual. It may take a lot more leg to whoa the truck down with manual discs.

Having said that, my old '65 Corvette had 4-wheel manual discs and seemed just fine to me!

[BIGBLU 72]

thanks for the heads up! got plenty of leg (600lb squat max) im just hoping that the truck will stop reliably when i get this all set up lol

[Sammy]

Most won't recommend not using power front disk. But I have seen it done and drove a few setups that way. And once they are free of air they work fine. They will not put you through the windshield as with power brakes but you will see minor improvement over the front drums brakes. Personally compromising on a few bucks on brakes /steering is never worth the safety sense you get in return.

[Tx Firefighter]

Plenty of these trucks came with disc brakes and non power assist. They stop exactly as well as trucks with power assist, just more leg pressure needed. The hydraulics are the same. Safety is the same. Driver convenience is the only area that's not equivalent.

Assuming your parts trucks prop valve has been kept sealed up and not had lines loose and water getting into it you should be quite able to use it on your truck. Further, yes the master cylinder will bolt to your firewall. The bolt patterns are the same
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[cdowns]

i'd use the old prop valve as they rarly have problems but i whould spend a bit of money and get a new master cylinder

[Roadmarks]

I just put power brakes on a '71 that came from the factory as a standard, no power disc/drum set-up. The 1975 master/ booster will work fine, but you'll have to make some kind of brackets to mount it. I used the original NON-POWER proportioning valve that came in my truck and it works just fine! Basically, in our trucks, there only 2 different valves, disc and non-disc. They don't care where the pressure comes from!

It's an easy swap and a huge improvement in drivability. You'll love it!

[BIGBLU 72]

hey guys thanks for all the info! just got the spindles broke loose today and ball joints and New MC are on their way!

[flashed]

I think I still have my prop valve from my disc/drum truck .I upgraded to power disc ,you can have it if you want it ,just pay shipping.

[BIGBLU 72]

if you can find it ill give ya some money for it! figure out shipping to 41102 is and ill paypal what you need out of it to ya!

[flashed]

Let me look in my shop to make sure its still there .Ill let you know .

[flashed]

I just got back in from my shop .The prop. valve is still attached to the master cylinder and lines are intact .Would you want the whole set up and just pay shipping .I dont need it in my way in my shop and you can use it if you want it .It worked fine on my 72 as I just bought a complete master cylinder w/booster and prop valve .Let me know and I can get it to you .PM your name and address and tell me if you want it all or just part and I can get it on its way and you can send postage after you receive it .
John

[Roadmarks]

For what it's worth, although they look a bit different, the ones from 1973 to 1987 work exactly the same. They mount on the front cross member. They are front disc / rear drum when they come off the pickup. The cars all had them, too, and they are probably the same, but I have never tried those.

best wishes

[flashed]

Tx Firefighter ,good to see you again .I always enjoy your posts ,someone said you were mostly on the 65 area of the board .I havent been there yet.

[flashed]

BIGBLU72 ,The master cylinder and prop. valve are on their way to you .I put them in the mail this morning and should arrive to you sometime on Monday. I will PM you the tracking number and I left a card with my address in the box .You can re pay the postage at your convenience after the packsge arrives .I hope it is what you need and its one less part in my shop in my way.