The Stovebolt Site Forums The Shop Area Driveline Disc brakes and dual master cylinder options

I'm thinking of upgrading the brakes on my '51 burb. I understand there are kits to add a dual master cylinder and also maybe a kit to add front disk brakes.

Curious to know who has done this and what is involved. Is it a reversable procedure? Any harm done to the original parts?

Are the results worth it?

Who makes the kits?

And about what does it cost? I would do the work.

Thanks for any replies,

Kurt

Yes, I converted my 50 over to front discs.

Added the dual master cylinder under the floor in place of the original.

you can purchase a kit from CPP http://www.classicperform.com/

or from Ecklers Classic Chevy (where I purchased mine) http://www.ecklerstrucks.com

The kit bolted right up to 1/2 spindles. I feel I can now stop at HWY speeds where as before I didnt want to drive in any traffic.

Yes it is very reversable.

Good luck

You can assemble your own kit if you are able to fabricate the caliper brackets.
I did mine with 78/80 K10 rotors, and 78/80 C10 calipers. I used a 1 inch bore Disc/drum M/C mounted under the floor.
I made plywood templates of the brackets, then had a friend cut them out of 5/8 steel plate.

Thanks for the links. I noted that they are recommending changing from the original ball bearings to tapered roller bearings to the tune of $150. I recently replaced my bearings with the original type.

Is this change to roller bearings necessary, or is this just an opportunaty to sell bearings?

Thanks,

Kurt

Are you considering a power booster?

Some brake kits do not clear stock wheels (calipers hit)
Search the forum for info
You will most likely have to run new brake lines
If you go with a power booster it may interfere with the transmission crossmember


I did add tapered bearings

Great pictures. Very clear. I am not planning to add a power booster.

Are the new brake lines necessay because the old lines are not in the right position to connect to the new MC?

I saw the kits had some warning that the caliper might hit the wheel, but they did not say stock wheel. One kit indicated wheels smaller than 15 inches would not work. I have 16 inch stock wheels. Mayhaps I'll give them a call. Really don't want to change the wheels.

Thanks,

Kurt

Do you currently have a dual MC?
The disc set up uses a prop valve and the line will route to that


...pic...

I remember a thread about 16's I believe it will clear with slight grinding.

Great pictures.

I do not have a dual MC at this point. Everything is stock.
So with the dual MC, does one cylinder control the back wheels and the other the front wheels or what?
Thanks,

Kurt

Yes
the prop valve sets different pressures for the rear drum and front caliper.

Is the prop valve adjustable? If I were to do this conversion in stages, for example, put the dual master cylinder and prop valve onfirst, would this take a different pressure set up for front and rear brakes if the front brakes were still drum brakes?

Thanks.

Kurt

Humm Not sure, I believe the M/C and prop valve are specific to the type of set up its designed for.

I don't think you can run a drum/drum system on one designed for disc/drum.
Maybe someone else can chime in or ask the supplier you decide to go with.

I am curious as to how many who have done this conversion have done it without power as compared to with power. Can you get good braking without power?

I went with the manual master cylinder.
It is a very good improvement from my drum/drum setup.

the power set up is preferred.

I did mine without power assist. It works very well.

Kurt,

you could certainly upgrade your single master to the dual master and keep drums. Some early 70's vehicles still ran that way. The dual MC gives you more security in case 1 brake line blows you dont lose both front or rear brakes. The prop valve is adjustable to adjust front to rear braking.

A front disc/ rear drum set up also requires residual pressure valves (RPV) also.. discs require only 2 PSI while Drums require 10 PSI.

Since you are separating front and rear brake lines, plus adding RPVs you will be running some new lines. Not a bad idea.

I actually purchased my non power MC from Old Dog Street Rods in STL. They had a bracket which bolted to my frame under the cab. I found later it is a Corvette MC and primary/secondary wells are reversed. Not sure why this is a good thing, but works well with Old Blue.

yet one more source for disc brakes is Speedway motors. Their catalog has diagrams which help explain the brake line RPVs and prop valves.

I am running 15 inch Ralley wheels and have good clearance.

Kurt,

All the power booster does is lower the pedal pressure necessary to actuate the system, so in my opinion it is unnecessary, especially since you are familiar with the "feel" of the old brakes. Discs will still require some "leg" to operate but fading will be a thing of the past and you will improve the efficiency of your brakes a bunch. Replumbing your whole system will be a good idea, too. You know as well as I do that 60+ year old lines will have some problems somewhere! it's not expensive, either.

Also, try Pirate Jack's in Asheville for your brake stuff.

later,

Les

Les,

Yes I am planning to use the manual setup. No booster for me.

Oldblue, are you suggesting that the residual pressure valves are needed in addition to the prop valve? Or are these the same thing? Had not noticed the RPV item in the online kits.....just the proportional valve.

Kurt

Kurt,
I found this site from Wildwood that explains it pretty well:

http://www.wilwood.com/MasterCylinders/MasterCylinderValves.aspx

Apparently the RPVs are required when the MC is below the horizontal plane of the calipers and maintain the right fluid pressure (eliminate reverse flow to the reservoir)for correct pedal response.

I had forgotten the specifics, but can remember I needed these for my under cab Master cylinder, Disc/ Drum set up. I also remember all the fun of bending the brake lines. Very Satisfying.

good luck
Tim

Hey Kurt,

You asked earlier about the "Required" bearing change. Disks put a heavy side load on the rotors that drums don't. Plus the load is spread over a larger area with rollers. I would guess that is the reason.

Les

I curious if you had to drill & tap the rotors to mount them to the hub? All the ones I've seen you would have to.

Eric, The rotors mount to the backside of the hub. They are held on by the wheel studs. You will need new longer studs. rotors installed

Wayne, I would have expected the rotors to have slightly oversize holes for clearance to the studs. That would be why they are bolted to the hub where the drum attached. Like this

Thinking a little more. Are the studs pressed into the rotors? If so, then what keeps the hub centered? Seems it would have oversize holes also.

I have looked into this before and needing? to have the rotor drilled and tapped for mounting bolts, makes it about a wash to buy the kit, especially if one does not have cores for the calipers.

I purchased the kit from Perf. online, the lug bolts on mine are longer because the rotors mount behind the stock hub. It is necessary to remove the stock lug bolts from the hub prior to adding the rotors. It was necessary to grind the kingpin retaining pin nut a small amount to keep it from interfering with the rotor mounting bracket, but it was a small amount.

I have a question though, Since I am retaining the stock master cylinder position ( replacing it though) and have not lowered the front of my truck, will I need to install a residual valve? my rotor inlet is on the top of the hydraulic area on the rotors and since I am working with the front end elevated till I get the installation finished I don't have any way of determining if the rotor inlet is actually higher than the master cylinder. Anyone have experience with this??

Thanks, jim

Hello, Did you have any problem with clearance when you put the new double master cylinder in? I bought the CPP MC and there is a flange on my frame where the old single M.C. bolted up. When I attempt to bolt the new one there the pedal linkage is about at least an inch from lining up. Almost seems like the MC should be tucked in closer to the frame and NOT bolted to this flange piece/?? Any Input would be appreciated...Thanks

Hi, When you bolted the MC up to the frame ...was there like a flange that angled out?? My 52 has this and the holes line up with my CPP MC but it throws the MC pedal side to side alignment way off. Wondering if I should cut it out, but it looks factory?????