Disc brake/master cylinder/booster ????

[Ryan99]

First time poster here. I’m new to the hobby and I’m working on my first project so I definitely don’t have the wealth of knowledge that a lot of you have. I’ve got a few questions regarding the disc brake upgrade that I haven’t seen specific answers to. I’ve searched the database and gotten to the point that I think I’m going in circles so I figured it was time to post my questions. Apologies if these have been addressed before.

My truck is a 1965. It appears to have factory a factory brake booster and master cylinder. I’d like to upgrade the front to disc brakes (5 lug) while keeping the rear brakes as drums for now, but with the option to upgrade to disc in the back in the future. Here are my questions:

1. I understand that I’ll need a new master cylinder for whatever I want to do. But can I use the same master cylinder for a disc/drum setup that I would later use for a disc/disc setup? Is the only difference that I would need a proportioning valve while running disc/drums?

2. Is my factory brake booster acceptable and adequate to use or would I need a newer brake booster? What would be the disadvantage of keeping the original brake booster, assuming it is in good working order?

3. What master cylinder could I use for a disc/drum or disc/disc conversion that would mate up to my factory booster? If there is none, what are my alternative options?

I tend to ask a million questions so I tried to hold off on this post until I’d researched this as much as possible and thoroughly confused myself. I appreciate any input.

[Captainfab]

Originally Posted by Ryan99

First time poster here. I’m new to the hobby and I’m working on my first project so I definitely don’t have the wealth of knowledge that a lot of you have. I’ve got a few questions regarding the disc brake upgrade that I haven’t seen specific answers to. I’ve searched the database and gotten to the point that I think I’m going in circles so I figured it was time to post my questions. Apologies if these have been addressed before.

My truck is a 1965. It appears to have factory a factory brake booster and master cylinder. I’d like to upgrade the front to disc brakes (5 lug) while keeping the rear brakes as drums for now, but with the option to upgrade to disc in the back in the future. Here are my questions:

1. I understand that I’ll need a new master cylinder for whatever I want to do. But can I use the same master cylinder for a disc/drum setup that I would later use for a disc/disc setup? Is the only difference that I would need a proportioning valve while running disc/drums?

Welcome to the forum

Some guys get away with using the same master for disc/disc as they do for disc/drum. However, I recommend using the correct master for your type of system. ie: use a disc/drum master for a disc/drum system and use a disc/disc master for a disc/disc system. The proportioning valve should be the same for the type of system also. Sometimes an adjustable valve is necessary to fine tune the braking bias. Wilwood makes a nice proportioning valve that is adjustable, and is a one piece unit.

Originally Posted by Ryan99

2. Is my factory brake booster acceptable and adequate to use or would I need a newer brake booster? What would be the disadvantage of keeping the original brake booster, assuming it is in good working order?

Yes your original booster should work just fine assuming it is in good condition.

Originally Posted by Ryan99

3. What master cylinder could I use for a disc/drum or disc/disc conversion that would mate up to my factory booster? If there is none, what are my alternative options?

You should use a master cylinder that closely matches the front brake components you are using. If you are using calipers that are typically used on say a '77 C10, then use a master for that year, or at least something close. The same for the prop valve. These master cylinders will bolt up to yout original booster, but the pushrod between the booster and the master will need to be shortened to the correct length. I'm not sure if a pushrod from the same year booster as the master, would work in the early booster, as I have not done so. I typically work with newer boosters.

Originally Posted by Ryan99

I tend to ask a million questions so I tried to hold off on this post until I’d researched this as much as possible and thoroughly confused myself. I appreciate any input.

[LostMy65]

I've been searching the forums and still haven't found the answer.
What adapter do I need to install a summit adjustable proportioning valve?
The rear line is 1/4" but the fittings included with the summit adjustable valve say the are 1/8-27 NPT.

[LostMy65]

I did find this:
http://www.thirdgen.org/propvalve

Maybe I need a 1/4 to 3/16 fitting reducer.

I also found this post in another forum:

All of the adjustable prop valves I've ever seen are 1/8" NPT (pipe) thread inlet/outlet. I can't remember what size Inverted Flare Fitting is typically used on 3/16" vs. 1/4" brake line, but I THINK it's 7/16-24 IFF for the 3/16" and 3/8-24 IFF for the 1/4" (?)

If this is the case then it sounds like the prop valve you have came with the 7/16-24 IFF to 1/8" NPT adaptors and you just need to replace them with 3/8-24 IFF to 1/8" NPT adaptors. Alternatively, you could fit 7/16-24 IFF flare nuts to the 1/4" line instead...

http://www.speedwaymotors.com/Straig...ters,6463.html

Or maybe I'm just missing something here

[ABX131]

I am a newbie to this site and I just got through doing this. I bought a 63' truck which was converted to a 4x4 using a 75 Chevy as a donor vehicle, which meant disk front, rear drums. The MC and booster needed to be replaced. The booster in the truck was bolted driectly to the firewall and all brackets removed. I did not care for this set up and hunted for a new MC & booster that would work. There is a guys on this site who sells custom made booster brackets for your truck, use it or fab your own using his photos. I found the MC and Booster from a 68' vette worked just fine (from Autozone for $120) The reason I liked it was because the back of the booster has 4 threaded studs and the connection to the control arm is a threaded post, not a preattached arm, like on some. We just fabed a coupler and attached the connecting rod already in my truck. Took my first drive yesterday and all was well.

[jocko]

That guy is the one and only Captain Fab, a few posts above. http://67-72chevytrucks.com/vboard/s...d.php?t=347484

[ABX131]

I am so new I have not learned anyone's names yet...did not mean to offend anyone.

[jocko]

NO! Pls don't misunderstand, you didn't offend anyone at all(!) - I was just providing his link - I'm sure the Capt appreciates you mentioning his products! I appreciate your posting!!

Btw - when you said you used a 68 vette master cyl, was that for a disk/drum setup or 4 whl disk? I thought 68 vettes had 4 whl disk (or was that just JL8's??)

Thanks! Jocko

[ABX131]

Was told it would work for my needs..drove it yesterday with no issues.

[jocko]

got it! I'm assuming you retained the disk/drum setup you had on the 75 and just added the vette mc, is that correct?

[ABX131]

Yes, the vette booster and matching MC...my last booster had the internally attached connecting rod and the previous owner cut and welded to it..The heat transfer through the rod into the booster more that likely destroyed it as it ruptured internally. That is why I like the Vette booster because it has a threaded post on the back of the booster to connect to with the pedal linkage.