Manual Disc master cylinder
 

Working on a 1968 C10 with 1972 frame. Stock disc/drum brakes. I've searched the forums and the answers vary. I want to go with manual brakes but can't seem to find a master cyinder for stock manual disc/drum. I can find one for power disc/drum. Does anyone know if there is a stock manual disc drum master cylinder made or do i just use the one for power. I would think the bore would be a bit smaller for manual.

Re: Manual Disc master cylinder
 

I just bought a master for my 71 with original front disc’s. I got it from Napa. They list one # for both power & manual. I rechecked this to be sure. I have not installed it yet. Supposed to have a plug you remove for manual application..:metal:

Re: Manual Disc master cylinder
 

I'd be interested in seeing how that would work. Those master cylinders have different bore diameters IIRC.

Re: Manual Disc master cylinder
 

Only for manual/ manual set up.

By manual/manual do I mean manual brakes and manual shift
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Re: Manual Disc master cylinder
 

Just bought a new M/cyl for a 71/72. My Napa guy says it fits manual or power. He's not a novice rookie/bumpkin.
Now if Napa's listing is correct???
I plan to run manual disc on my 67 and 68

Re: Manual Disc master cylinder
 

I have no idea what manual/manual means. And just because a counter guy says it fits both applications (which it will), it does not always mean a part is "designed" for both applications. There is a difference between a 72 C10 power brake system master cylinder and a non-power brake system master cylinder - and some parts houses carry separate part numbers and list applicability based on power vs. non-power. Believe bore dia is different as mentioned above - and also that the depth of the depression in the back of the piston varies between power (shallow) and non-power (deep). Here is an LMC example:

Re: Manual Disc master cylinder
 

68Gold/white, So what is the Napa part number or manufacturer part number that Napa sold you? Did you also get a stock proportioning valve or other parts for the conversion from them? Please let us know how it works out. I would be interested in that conversion someday.

Re: Manual Disc master cylinder
 

From what I've read on this forum, the master cylinders for our trucks are either 7/8", 1", or 1-1/8" bore. The 7/8" is for manual brakes and the 1-1/8" is for power brakes. It looks like the 1" bore can be used for either.

Re: Manual Disc master cylinder
 

I just looked up the napa m/c. They only list the 1 1/8 bore. Have yet to see a bore size of 7/8 unless it's for drum maybe. The only one for 1 inch is for aftermarket M/C from what i can tell so far. Could it be that they used to make and now they just don't.

Re: Manual Disc master cylinder
 

I was referring to manual drum/ drum , front and rear..sorry ? They call for a different master.

Re: Manual Disc master cylinder
 

Ah, duh, I got it now - thanks for clarifying, wasn't thinking front/back.
Curious if the plug you mentioned was in the back of the piston facing the firewall - if so, then that really does sound dual purpose (i.e. would support the short intermediate pushrod used with a booster, or, removed, the long pushrod for the non-power setup).

Re: Manual Disc master cylinder
 

CPP is the only one I've seen with a removable plug.

Original type MC have deep hole for manual and shallow hole for vacuum power boost.

Bore diameter is a different issue. 1 1/8" bore without power assist may require a considerable amount of foot pressure.

Re: Manual Disc master cylinder
 

Go to Napa ask for a New brake master for a 75 C10 (less expensive than 71-72 and same dimensions. Put it up to a booster or not if you want manual brakes. To my knowledge there’s no difference between power and manual brake masters.
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Re: Manual Disc master cylinder
 

Look at an 84 c10 manual brakes master cylinder
Aluminum body plastic reservoir

Re: Manual Disc master cylinder
 

This

Re: Manual Disc master cylinder
 

I will try to remember to get that number when I go home for lunch. THe hole in the end of the M/C piston on mine IS the deep hole. It would have to be to retain the brake pedal rod

I don't believe the 73-up master cylinders have the deep hole in them. THat particular master cylinder was used for years and years on cars and pickups!!!
The Wagner part number for it is (or was, I have not sold auto parts since 1998) F101254 for the new cylinder or R101254 for the re-man. I don't use re-man master cylinders, any more, EVER...

Re: Manual Disc master cylinder
 

Napa part number M2062. Bore appears to be 1-1/4" hole in piston is about 2 inches deep. No plug to convert to shallow piston, only plugs for bench bleeding...

Re: Manual Disc master cylinder
 

Judging from the reply's there is no one master cylinder for manual disk brakes for a 72 c10. I just don't want to have excess pedal pressure to get it to stop. Maybe I need to rethink the manual brakes.

Re: Manual Disc master cylinder
 

I'm not going to install my m/cyl for a while. Have read many here that liked it.

I will start a thread, asking that question!!!

Re: Manual Disc master cylinder
 

I would love to see a thread about conversion of front manual drum brakes to front manual disc brakes using as many as possible car parts store parts or original equipment traded parts from 71-72+. I am interested in stock height, and love the feel of manual brakes.

Re: Manual Disc master cylinder
 

Yes, there is. LMC # 34-4018 is specifically for a stock 71-72 C10 non-power, disk/drum setup. The link is provided in post #7 (the blue underlined text) $59.95

While I'm not a massive fan of LMC, they don't manufacture master cylinders, they just sell them like anyone else does - and the fact that they list power, and non-power master cylinders for a 72 C10 under different part numbers means they at least understand there is difference - which puts them light years ahead of the other suppliers. I've always trusted Napa too, but original 72 C10s had different MCs for power and non-power applications, so if there is a seller out there that realizes this, I'd have a warmer fuzzy going with their part # for a non-power setup than rolling the dice on one about which a parts guy just said "they're all the same" when they are not - for several reasons outlined above. I've had much better luck with LMC than CPP for brake parts, believe it or not. I too would prefer to purchase one at a local dealer like a Napa, but if you (now) know that there are two separate MCs for two different applications - I'd personally prefer to go with the vendor that understands the system.

Having said all that - if you don't want excess pedal pressure, it sounds like you actually want power brakes. You can easily buy a booster at any parts store and source the stock bracket/links/etc from the parts board here from someone parting a truck, or go with member CaptainFab's custom booster bracket that will tuck everything closer to the firewall. 5th picture down in this thread

Re: Manual Disc master cylinder
 

I bought my power brake bracket/link for my 72 Truck from Classicmuscle.

Re: Manual Disc master cylinder
 

Do they have the same depth pushrod hole as the 67-70 manual brake master cylinder? Will anything need to be done in the cab?

Re: Manual Disc master cylinder
 

Well said! There's a lot of confusion about the difference between power and manual brake master cylinders, and it persists. I do have power brakes on my truck, but am aware of what happens to pedal pressure when the system fails. Our Astrovan had a fuel pump fail, so the hydra-boost of course wasn't working when the engine quit. My wife was driving it and managed to get off the freeway and get it stopped without a crash. I can stand on the pedal in the truck in case of booster failure, but there is no way that my wife could do it and make it stop well. As a result, she has no interest in driving it while pulling our travel trailer.

Re: Manual Disc master cylinder
 

I'm going through this now on the ramp truck. The master cylinder I bought was for a 72 C 10 with disc brakes & drums. It was said it was for any Chevy truck for that year. Manual are power, c-10, c-20, c-30.

I'm not home right now but the guy doing the swap says it has a bigger opening than the booster. I will be going home tomorrow and Friday will be taking the parts back and see if we can figure them out, I may look at the 1975 master and see if it looks right.

I can say this though, when I bought the ramp truck it had manual drums all around no power. I bought a power booster for a 71 factory disc to drum truck and installed it with the drum to drum master I had. It works fine, But I did have to swap the push rod out for a shorter one. :chevy:

Re: Manual Disc master cylinder
 

Boy this is confusing ?

Re: Manual Disc master cylinder
 

Whoever told you that was wrong twice. Manual and Power are different MCs as has been discussed above, but an equally important difference exists between C10 vs C20/30. In other words, a 71-72 C10 mc is not the same as a 71-72 C20/30 mc. They are biased and plumbed differently. Front reservoir on a C10 mc is for the front disks, whereas the front reservoir of a C20/30 mc is for the rear drums (note the smaller 3/16" lines are always for disks and larger 1/4" lines are always for drums). 1st pic is C10, 2nd pic is C20 (same as C30). The distribution block is the same - i.e. front is front, rear is rear. To go from a 68 C30 drum system to a 72 C20/30 disk/drum arrangement, you'd technically need a 71-72 C20/30 mc (manual or power, your choice - but note that by 72, power brakes became mandatory on C20 and above), a C10-30 distrib block, and would need to replumb lines appropriately from the mc to the block (front res to rear of block/rear res to front of block) and then replace the remainder of the existing front drum system's 1/4" lines with 3/16" lines for the 71-72 disks. Not everyone does a line reduction in the front, and the system still works of course - but if you want it to stop exactly like a 71-72 C20/30, the front lines should technically be 3/16".

Re: Manual Disc master cylinder
 

I'm beginning to think nobody knows what they are selling anymore. I can't say much right now because I'm not at the house to look at stuff and know. I will figure it out though that's for sure. I'm putting a 86 whole front end in it to make things even worse!:chevy:

Re: Manual Disc master cylinder
 

I had a heated discussion with the owner of my local NAPA store about this. He didn’t even believe me about 71 model year trucks having disc brakes up front. As far as his books showing only one # for both power and manual, he’s stands firm. He did ask me for the number cast into the master I have presently installed. I looked but can’t find a #. Can anyone provide a number off theirs ?

Re: Manual Disc master cylinder
 

Anyone have the # ?

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I went by and looked at my Ramp truck setup. The master cylinder looks to be for a disc brake system even though it's been on a 4 wheel drum truck. The first 3 pictures are of the booster and master that is on the truck and the push rod.
The last 2 pictures are the O-Reilly part for a C-10,20 and 30 truck for 71-72 disc/Drum master cylinder.
The one in the link is what I ordered today for it. It looks like what is on the truck now. It's a 76 master cylinder for Disc/Drum.
As far as which way the bowls are for the disc/drums it don't mater as long as you hook the lines up to the correct one.
Hope to know later today if it's the right one. It's suppose to be at the store by 2pm.:chevy:




https://www.oreillyauto.com/detail/b...cylinder&pos=3

Re: Manual Disc master cylinder
 

Thanks for sharing the pics Andy. Pic 2 looks like a non-power mc to me and Pic 5 looks like a power mc to me (or maybe Pic 2 just "looks" that way in the pic - question, is it the exact same indent as the piston in pic 5 or is it deeper (which is how it appears to me?)). Reservoir size difference is not necessarily the full reason for how you hook up the lines between the mc and the distib block (but they can be "a" reason since some mcs have uneven bowl sizes, just not necessarily in these trucks) - internal biasing is also a reason. Recall the distrib block is not an adjustable prop valve, so the order and amount of juice applied front/back is managed inside the mc and is not adjustable. If you hook up a C20 mc front bowl to the front brakes, you will be providing the opposite of factory biasing in the mc from what GM designed. In other words, a C20/30 mc uncovers/opens the brake fluid passages differently when the piston is depressed than a C10 mc does.

Or maybe a better question would be - if GM hooked up the C20 mc as depicted above in pic #2 of post 29, why NOT replicate it? Why say it doesn't matter when clearly GM hooked up the lines on a C10 and C20 differently - it wasn't a simple matter of choice for the guy working the assembly line that day? Again, I'm just talking about trying to replicate a stock system. If talking 4-wheel disks and so on, then different story. But believe you are trying to replicate a 72 C30-equivalent system(?)

As for the link to the mc you ordered, I only see C/K-5/10 in the applicability chart, no C20/30 anywhere.

Re: Manual Disc master cylinder
 

Lots of info and i'm still following along, Thanks for all the replies.

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Picture 2 has the booster hooked to it now. The one I sent the link to is for about any vehicle GM built and as far as I know everything past 72 had power brakes for the masses. You had to special order a vehicle after 72 without power brakes.
The computer said it fits all them at the store. They don't show separate part numbers for them.

Oh the master they got this afternoon wasn't right either. It was a shallow one. Maybe the one in the morning will be right.
Just for info I don't care what year it is are what part it is for as long as it works and will stop the truck. As far as the bowls they don't matter if they are front are back. When you push the brakes they both react it only when one side has a problem but they both react the same. I'm not using a normal proportioning valve I bought adjustable one.:chevy:

Re: Manual Disc master cylinder
 

My local Napa owner crossed referenced 29881 to a current Napa # for a non power disc 71/72 cylinder. He ordered one for me. Will get back with the new #.. Jack

Re: Manual Disc master cylinder
 

You are incorrect stating that one master will work properly for both manual and power ! I have confirmed this by my local Chevrolet parts manager. He still remembers this issue from the days these where still available from GM.

Re: Manual Disc master cylinder
 

Went to O-Reillys this morning and here is the master cylinder they finally got me. Part # 11364 looks to be for a long push stud and booster like what I need. Fitment is for a 74 thru 86 with disc brakes and drum. It looks to be just right.:chevy:

Re: Manual Disc master cylinder
 

"long push stud and booster like what I need"
Well I thought the long push rod was for when you were not using a booster. So is that for power brakes or non-power brakes? What is the bore size?

Re: Manual Disc master cylinder
 

I've reached the conclusion after 40 post on this that there is not a master cylinder for manual disc brakes for a 71-72 c10. I"ve checked all the parts houses NAPA, Advance, Auto zone, Oreillys and looked all over the internet including cardone, wagner, raybesto. The only factory stock master cylinder that seems to be available is the one with 1 1/8 bore for both power and manual brakes. Looks like i need to make a decision on that one or aftermarket.