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Discussion Starter #1
i'm working on a 70' chevelle malbu putting in front disks. the cars still striped down but slowly putting every thing back in. anyway after i started to plumb the lines when i relize i cant find my distribution block.
its the one that sets off the warning light and is a splitter for the front line. i went to two local auto part stores and they both sent me to the dealer. it turns out that chevy only keeps its searchable records to 76' but if i have the part number i may be able to get it. so i need some help, if any body knows the part number or if you know where to get a new one please let me know.
 

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brake combo valve

in chevy high performance magazine there are parts places that stock strictly chevy parts, even antiques. hope that helps. ive found alot of stuff for my rides in there
 

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Does it absolutely have to be the original part for the car?

When I went to disc brakes on the front of my 55, I used the proportioning valve off of an S10 that had a front disc/rear drum setup. It has the connection for the low brake fluid sensor and all that jazz. I picked it up for $10 at the local junk yard.
 

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it doesent have to be original but i'd rather it be new. id dint even think about getting it off something newer. what year was the s10 it didnt have anything else like propostioning valve or somthing to increase pressure on a broken line. thanks for the help but i might need a 4 drum set up beacuse i've got a new proportioning valve i want to use. thanks again
 

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All the proportioning valve does is keep your rear from getting as much braking force as the front. The idea being that in an emergency braking situation, if they were both getting the same amount of force from the hydraulic fluid the rears would tend to lock up sooner than the fronts because enough of the weight is being transferred to the front wheels. It sounds to me that you're describing something totally different - I took a picture of mine just in case.

Pictured is a 1972 Chevelle master cylinder for a disc/drum car. The brass piece is the proportioning valve and it has a connector on top that to me seemed to be a low fluid/pressure sensor of some kind. I believe it came off an 88 S10...but I'm not terribly sure, its been several years and it was just the first one I ran across in the junkyard while I was looking for one. Might help you out as 55-57 Chevy's use 68 - 72 Chevelle components to convert to disc brakes on the cheap.



btw - the line that comes out the back goes to the rear drums, the line that comes out of the bottom goes down to the driver's side frame rail. There I have a T block that connects to the brake lines that are ran to the left and right calipers. I can take more pictures of that if you need them.
 

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Discussion Starter #6
thanks a lot that really helps out. i know that you want to proportion the pressure to have less on the drums becuse they require less pressure to start working but my problem is that i have an addition propostining valve with a pressure gage that i want to use instead of a stock one. the one i bought is very easily adjusted. so if i use a didtributin block that has one could i set it wide open and then just use my vavle to adjust the pressure. thanks again. i really like the yellow and red u put on there. the only thing you need is to get that altinator chromed or painted. looks real good.
 

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That alternator isn't even hooked up. It was laying on the shelf and I need an adjustable pulley so I could belt up the water pump. I haven't decided what color to go with for one yet though.

Anyhow - I think I see your trouble and may have a solution to try. I don't want to jump to conclusions though, can you send me a link to where I can buy a valve like what you have? I want to see what it is exactly and know for certain what you're dealing with.
 

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Discussion Starter #8
heres the link for the valve http://www.stainlesssteelbrakes.com/products/detail/1010/?make=Chevrolet&model=Chevelle&year=

when i bought my kit through pst it came with this valve. i guess i could be able to do with out it but i like the idea of being able to adjust it on how i'm dirvving that day just by turning the knob.
i'm putting a picture of the box and the valve up. its kind of hard to see but the valve itself has a "in" on one side and "out "on the other. the gauge is is on a spitter on the "out" side. the knob sticks out the narrow side. you turn it to the right to increase the pressure and left to deacrease.
i hope this gives you what your looking for. thanks for the help again
 

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If I were in your position, here is what I would do.

I would hook the brake system up w/o the proportioning valve in it at first. The disc brake conversion should already have you set as far as splitting the front and rear brake circuits and the s10 proportioning valve will help make sure your rear brakes don't lock up on you. This would get you rolling. Then I would see which pair of tires lock up first.

My suspicion is that the fronts would lock up first. The aftermarket proportioning valve would go on which ever circuit was locking up first. I'd use it to dial out pressure from whichever set was locking up so that the front or rear locks up 'just' before the rear or front does. This is somewhat a personal preference. Factory automobiles are engineered to lock the fronts first because its statistically safer for the occupants if the car slides head on into whatever it is they were going to hit. Some people like the rears locking up just before because then you still maintain the ability to steer. This is obviously more dangerous if you were to mishandle the car as you might just end up turning it sideways and only have a door to keep whatever it was you were going to hit from ending up in the driver's seat. Given all this, I doubt I would use it at all.

Honestly, I'm not sure what real world application your proportioning valve would have other than selling it to someone else so you can get more stuff for your car. The valve isn't meant to be adjusted based on how you're driving that day. I'm pretty sure its meant to just dial in the car's braking ability and if you use it, more than likely you are going to have to purchase some sort of a check valve. The thing about disc and drum brakes is this - discs use a valve to keep about 2 lbs of pressure on the brakes at all times. This is so that you don't have to push the pedal as far to begin acheiving some braking effort. Drums use about 10 lbs of residual pressure. This is to accomplish the same end but drums use return springs and whatnot so there is a little more to over come than discs.

Did your disc brake upgrade kit come with a disc/drum mastercylinder?


edit - wp something or other posted this in another thread in this forum, I think it would be a good thing to look over.

http://www.oldsmobility.com/discbrakes.htm
 

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Discussion Starter #12
that site just what i was looking for really good stuff. as for the question, the kit i bought was for swaping a 4 drum car to front disks. it came with a new master cyilinder and power booster and all the stuff to put the disks on the front. i was suppose to reuse all the other parts and lines. i supposes if the car was brand new i would have had no problem, just connect everything and i'm done. but since it has been a daily driver up here in the north east i could see reusing anything. so i have to get some parts and piece it back together. the simplest thing to do is get a front disc rear drum block thats in good shape. if i have problems i may have to get the 4 drum block and and my valve to adjust it as needed. i guess i'll play it trial and error just like most stuff so far. thanks for the help it really gave me somthing to work with.
 
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