master cylinder

[airbrusher]

hope someone can help me out , i am building a 72 c10 which was a 6 cylinder three speed column shift with manual disc brakes. I have converted it over to a 350- 350 with power discs, herein is my problem when i went to hook up my lines from the proportioning valve to the master cyl the fittings are not right they are basically reversed big hole on the front small hole on back my fittings are just the oppositte. a master from a 73 has the right fittings but wrong plunger depth so no go there. supposedly i have the right master has anyone run into this or have any idea? thank you!!

[john]

Do you possibly have a c-20 master cyl? The lines are reversed between c-10 and c-20 trucks.

[airbrusher]

im not sure will have to check that out obviously its wrong though thank you!

[johnnytuff]

What happens if you go ahead and hook them up the way they will fit?

[airbrusher]

i wondered myself not sure how the pressure or volume would work out i do know that each resivoir is the same size guess i could try and see, anyone ever done that?

[Robznob11]

Im not sure but all the disc masters i have seen have diffrent size resivors. I just bought a 71 c10 cardone master at oriles for 18.00 bucks. thats cheap inshurance. ps the napa rebuilt that runs 42.00 bucks is also cardone go figure

[Robznob11]

here is a pic

[Longhorn Man]

they are stupid cheap, just go get the right one for a 1/2 ton

[michael bustamante]

I think the prop valve is mounted backwards. Mine has the needle push thing facing the front of the truck. Also my mc seems bigger than yours. Mines from a 72
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[airbrusher]

gonna hit up a couple places tomorrow do some research thanks everyone

[Robznob11]

you are correct my edit did not go through that is why i posted the pic. here is what i was going to say. Im running a 75 proportion valve and a 71-72 c10 master . if you look close one line is a 3/16 and one is a 1/4 they both have different ends meaning if you use the oem fittings you cannot possibly put them backwards. Im thinking that what he is discribeing is the set up that i had on my truck witch was manual drum. now i know a 72 has disc but maybee they used the same set up. and you are correct in the fact that my proportion valve is backwards hence the reason my lines cross. I did that because I did not want to rebend the lines that were on the truck to swap it around when it just seemed to fit naturally that way. I wish we could see some pics of his set up and find out if he has a proportion valve or a residual valve because I have never seen a disc master with equal resivors.

[my67c20]

Your prop valve is backwards. Notice the 2 holes at a 45 ish degree angle. The picture is of a C20 set-up.

[Robznob11]

yes i know its backwards . the point is does it really matter if the lines are correct. Im trying to figure out why your lines are oppisite of mine because all of my ends were diffrent sizes meaning one went from point a to point b and one from point c to point d there was no way possible to install the lines incorrect . most ask why my lines are crossed and its because the valve is backwards. I don't understand why yours are crossed if its correct. but im assumeing that its a differance in masters and that you cannot install yours backwards either.

[stich626]

a disc/drum master the disc side holds twice the fluid..
if the they are the same size you have either a drum/drum master or a 4 wheel disc master..
and if the residual valve is in the master you can't use a drum /drum master or reverse the lines on the front/rear ports.. as the disc side doesn't have a residual valve , of course if that valve isn't in the master then no issue.. untill you get to the prop valve that has the lines backwards because it was easier..
good luck

[Robznob11]

stitch im not understanding what your saying or if you are replying to me or someone else. my master has one small and one large resivor it is for a 71 c10 power disc now the lines that connect the master to the valve have ends witch cannot possibly be hooked up incorrect. the 3/16 line ends match and are the same size but a compleatly diffrent size thane the 1/4 lines witch are two diffrent sizes. now you know witch ends go together because the hole in them is either 1/4 or 3/16. and you know where the screw in because they will only screw into one hole that they fit in. so what diffreance doese it make if the proportion valve is turned 180. your rear lines are 1/4 and front 3/16 so again they only screw in one way. its a no brainer. i put the valve 18 so i did not have to rebend the lines from the frame.

[stich626]

Originally Posted by airbrusher

i wondered myself not sure how the pressure or volume would work out i do know that each resivoir is the same size guess i could try and see, anyone ever done that?

to this

[airbrusher]

well guys i am headed to the parts house as we speak will try and figure something out today! will hopefully post something posotive tonight.

[airbrusher]

well john you were 100 percent right turns out the old parts guy gave me one for a c20 the young guy says yep they are reversed so here we are hooked up and ready to bleedem out thanks one and all!!