brake proportioning valve??

[bcj67chevy]

I have a 1970 jimmy with factory disc brakes. Just bought it a month ago and am in dissasembly stage. Noticed the lack of proportioning valve where the brake line splices are. Wasn't sure if since disc brakes weren't standard equipment yet if they did things a bit different for a couple years or not.. I know my 72 blazer has one anyway..

[My3Sons!]

Not that it's much help, but my 71 appears to have one

[bcj67chevy]

So the PO must have removed it then i guess. Anyone know where you can get a cheap new one, or is the junk yard my best bet?

[vidman]

Well it looks like there was one at one time. It looke like the po cut it out and used compression fittings to tie the lines together. Those fittings are very dangerous and not safe to use on braks lines. you should only use flair fittings on brake lines. Just contact one of the forum venders and get yourself a new valve. Brakes are not something to fool around with..

[bcj67chevy]

Yes, compression fitting shouldn't be sold at auto parts stores. The PO also used a couple at the rear drums. I guess ignorance is bless. Thankfully i only drove it a couple miles that way for the test drive.

Hopefully i will start a build thread here in a couple weeks. thankfully not too much rust, but just some in weird places. Can't wait!!

[pound41]

1970 did not come with front disk they were drum. I know you can do some kind of a swap to make it disk keeping the same housing most just swap in a 71/72 or newer front end in. My 1970 came with power brakes but drum in front The PO swapped in a newer front end but left the power drum prop valve. I change it to a 71/72 prop valve and had to do some replumming with adapters to make the power drum lines line up with newr prop valve

[bcj67chevy]

I thought that 1970 was the first year for the disc brake as a option.. Are you sure 1971 was the first year for the optional disc equipment?

[lolife99]

1971 model trucks, blazers and burbs were the first year for disc brakes.
1970 trucks were drum brake.

[pound41]

I have a 1971 blazer and bought my 70 from the other part of the state had some friends look at it so sight unseen. Never thought about drum brakes. When it arrived it had a newer front end but the brakes were really soft so I started researching and found out drum or power drum. I am totally replacing a lot of the floor pan in mine without a garage so it has been slow going and haven't driven in a few years. When I was driving it one way you turned it worked great. The other way my gmc ext cab with 8 ft bed steers tighter. I had my dad an old mechanic look at it and he saw it to. I saw a thread or ariticle about when you change front end you need the arm that goes to the steering box because the bend is different. I haven't been able to find the article but I will revisit that when I get it back on the road

[Dale99]

That valve appears to be the same up to 87 model. The hard bent lines might be different. You could also run an adjustable one if you want.

I have been researching this since mine is bad.

[bcj67chevy]

Are the adjustable prop valves expensive ? Anyone had good or bad luck with them ?
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[Dale99]

Depends on which one you get. Some just put a single one on the rear, and plumb the front strait on like you have.

There is a double, it cost about the same as a reman stock.

I have not done one, just been looking.

[pound41]

If I get a chance I will look I think I only had to but one adapter that went into prop valve and the line into it. If its the drum brake lines still on it the one is a different size fitting

[Dale99]

Bringing this back to the top. I picked up a prop valve from an 82 Chevy pickup this weekend. Fit in place just fine. The only thing I had to do to make it work was plug a hole in the front of it where an 82 runs 5 lines, instead of our 4.

Just an FYI if you go to a pull your own parts yard. It is mounted down under the radiator on the front cross member. Its easiest if the radiator and core support have already been removed.

[bcj67chevy]

Sweet. Thanks for the heads up. I wiil probably just grab one from a junk yard.
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