71 (?) cheyenne brake master cylinder in '64...keep or change?

[GMC Jester]

So when I got my 64, there was, too my best assessment a 71 (?) cheyenne brake master cylinder. I am assuming the booster is a matching booster, and in better condition than the booster.
I was planning on treating the boosters' rust, and but just replacing the bmc.

My question is this: Is this advisable? I have 4 way drums and do not want to go back to the original single. I've done all the reasearch I can, here and google, but not sure if there is something differnt or better I should put in its place.

Follow up: Fenco bmc from autozone? Napa? bang/bucks...

[Captainfab]

If that master cylinder is in fact from a '71 or newer truck, it is for a disc/drum brake system. It is possible it may work for your drum/drum brake system, but it is not correct. If you want power 4 wheel drum brakes, you need either a booster and master cylinder for a '67-'70 truck, or you can add a power drum/drum master to your current booster. The '67-'70 truck power master cylinder has a deep bore in the back of the piston. This design requires a long intermediate pushrod. The typical '71 and up master cylinder has a shallow bore in the back of the piston, which uses a shorter intermediate pushrod. You will probably want to separate your master and booster to see what you currently have, and go from there. If you can post a pic of the master cylinder, we may be able to help you identify it.

[GMC Jester]

[Captainfab]

That is definitely a disc/drum master cylinder. It doesn't look like what I am used to seeing on the '71-'72 trucks either. Also that metering block below and beside the master, looks to be what is used on the '67-'70 trucks drum/drum brake system.

[GMC Jester]

So. What's the best option for me? I assume I still need to see what the booster is from before I commit to a bmc? Would a new bmc and booster be my overall best bet?
Posted via Mobile Device

[lolife99]

Originally Posted by GMC Jester

So. What's the best option for me? I assume I still need to see what the booster is from before I commit to a bmc? Would a new bmc and booster be my overall best bet?
Posted via Mobile Device

You need something like this,...
http://www.performanceonline.com/196...E-BOOSTER-KIT/

[GMC Jester]

Originally Posted by lolife99

You need something like this,...
http://www.performanceonline.com/196...E-BOOSTER-KIT/

Yikes. thats a little pricey. Any place to source it cheaper, or a rebuild or something? I like the dual cylinder though. I've read those are more reliable/safer than the old singles.

[markreed]

You should not need a new booster, or prop valve. All the pressure would be the same for front and back. I guess I don't see you need for wanting a dual MC. Either way, I would think if you traded in that MC for a re-man, then just run your brake lines straight to the MC.


New MC shouldnt be for then 30-40 bucks with the trade-in...

[Captainfab]

There are a few options. Probably the simplest would be to change your current master cylinder for a remanufactured one by A1 Cardone #10-1363. First you will need to verify that the master you have now has the shallow bore in the back of the piston. It will bolt up to your booster and the distribution block and lines should connect as well. Another option would be to change to a complete '67-'70 booster and master cylinder assembly. One of my booster brackets would help adapt it to your firewall.

Originally Posted by GMC Jester

So. What's the best option for me? I assume I still need to see what the booster is from before I commit to a bmc? Would a new bmc and booster be my overall best bet?
Posted via Mobile Device

[GMC Jester]

Originally Posted by Captainfab

There are a few options. Probably the simplest would be to change your current master cylinder for a remanufactured one by A1 Cardone #10-1363. First you will need to verify that the master you have now has the shallow bore in the back of the piston. It will bolt up to your booster and the distribution block and lines should connect as well. Another option would be to change to a complete '67-'70 booster and master cylinder assembly. One of my booster brackets would help adapt it to your firewall.

I appreciate the help. I've seen your brackets. They're really nice. From what I've read they do the trick. I think when I do an eventual frame-off with front disk brakes, the 67-70 will be my route. For now I'm just trying to get it on the road.

[luvbowties]

I've found that a 1981 c-10 booster from AutoZone, #54-71069, will bolt right up to your firewall. May hafta modify pedal-to-booster rod length, using a "sleeve nut" (about 1.25" long, fine-threaded nut:same diam. as pedal rod) from Lowe's. Then a m-cylinder from A-Zone, #M1494, will mate to booster.
May hafta make a short 'plug' to fill a more-deeply drilled piston in the rear of mc, as CapFab said, depending on whether mc has deeper or shallower hole in rear of its piston--this'll all make more sense once you remove & look at yours.
None of these mods are very technical & can all be done with simple tools--you may need to use a die to thread a rod for modding a pedal-to-booster rod, and a hacksaw and grinder to cut off a bolt to make a free-floating piston-plug: it serves merely as a spacer so booster-rod will push piston in far enough. Like Cap'n said, some mc's have almost flush-with-housing piston ends while others have ~1 inch countersunk hole in rear of mc-piston. Booster cost is 79.99 and mc is 14.99--less than 100 bucks for all-new. **Should you desire really strong power brakes, get a different mc/one for a '67 C-20--the 3/4 ton--& it'll push more juice-per-pump: A-Zone part#M1331; costs 16.99.
Hook up your metering block!!!
The plug can be made easily from an unthreaded section of a proper size, low-grade bolt, hacksawed off and ground round on one end and flat or indented on other end. The pedal-extension can be made from a high-grade bolt, hacking off an unthreaded section along with its threaded end. Join the original pedal-rod, using the sleeved nut to thread onto this hacked section AND onto the end of original pedal rod that you will have threaded with the die.
Good luck & happy/safe stopping.
sam

[GMC Jester]

Captainfab....you wish your mounts were as nice as that....stack..of...washers....


I had been so wrapped up in tearing out the bed of the truck and the interior and old wires I hadnt taken the time to realize that I just need to start at square one. new booster/ different mounts, etc.

[luvbowties]

[QUOTE=markreed;5582662]You should not need a new booster, or prop valve. All the pressure would be the same for front and back. I guess I don't see you need for wanting a dual MC. Either way, I would think if you traded in that MC for a re-man, then just run your brake lines straight to the MC.


I'm guessing he wanted the dual mc for safety purposes; I know I did, and it was among the 1st 3 things I did to mine. Until I bo't it & started driving, that had not really crossed my mind but I soon thought how I'd like having a backup system (the other end of the truck still with brakes) in case a wheel cylinder blew.
Another thing I learned came just from exposure: when 1st changing to dual system, I did it w/out a prop. valve; & every time I applied brakes any way but very softly, the rears would grab & drag. Had to lick that calf over & plumb in a prop valve which cured all that. Never knew it'd make such a difference!
sam

[GMC Jester]

There is a big old Olds 454 in the engine bay. which caused the brake line to need a minor adjustment. I think thats why the PO had to put those washers in place.

I am still working through this one.

[Captainfab]

That booster probably came out of the same Olds the 455 came from. Yeah I'd be for doing something better there for sure.

[Figuarus]

Sorry to bring up history, but I have a question regarding this exact issue.

My single BMC : http://www.partsgeek.com/assets/dimage/full/1000378.jpg
has a leak. I need to fix it, but I'm wondering if it would be advantageous/possible to install a Dual resi BMC from a 67-70 and split the lines while still keeping the front drums?

Would I need a metering valve in order to do this, or would It not matter as the brakes would still be a manual system?

[1963c-10]

Dual mc would definitely be the better route. No metering valve required since its all drum.
And like you mentioned, just split the lines front & rear.

[Figuarus]

Originally Posted by 1963c-10

Dual mc would definitely be the better route. No metering valve required since its all drum.
And like you mentioned, just split the lines front & rear.

Is there any difference in mounting or pedal length?
Posted via Mobile Device

[1963c-10]

Im not sure on that. I'd check the FAQ section or wait and see who else responds.

http://67-72chevytrucks.com/vboard/s...d.php?t=646002

[Figuarus]

thanks 63.

I did do some searching, and this was the closest thread I found. Figured it would be safe to ask here.

[Mike Wessinger]

Originally Posted by Figuarus

Is there any difference in mounting or pedal length?
Posted via Mobile Device

I did the same "upgrade" to my 65 last year. I used an inexpensive off-the-shelf 67 MC. Exact same mounting holes, and no difference on the pedal/rod length.

[Figuarus]

Awesome. thanks much!

Is it better to run a Front/Rear split, or a Driver front/passenger rear - Passenger front, driver rear split?