The Stovebolt Site Forums The Shop Area Engine Shop 46' disc brake conversion

Finished the front and rear sway bars on the 46' over the weekend. Wow, a CCP 47'-55' bar on the front and a 94' Astro van front bar mounted on the rear ;] Made one piece leaf spring plates for the rear and all new bracketry for the bar mounts.

Started to finish up my disc brake install today. Questions on master cylinder and booster mount:

1) Does the master cylinder need to sit level or slanted slightly toward the booster? Almost all power brake systems I see on firewalls, the master is slanted towards the firewall/booster.

2) I am mounting the ABS master/booster under the driver side floor. Do I need residual valves inline? What is the plus or minus diminsion one has to decide? Would adding them hurt, if the master is at or slightly above the level of the caliper? THier presence does not appear to help with lack of proportioning valve. The proportioning valve is on the master.

Thank you and, as always, appreciate your thoughts and input.
Cavebull

Brett,
Congrats on the sway bars. Any pics on the installations?

Rick.........

Rick,
Will have pic's in a couple days... playing camera games, and do miss it. Had to go to the old manual to put the fuel puump back together today after tear down a week ago, clean up, and phospho dip.
Planning to write a tech artical on a couple things, the rear sway bar fab is one of them. Fuel pump rebuild may be one. Working on single lever shocks (painting) and steering column is coming as well. Per Sways, the front is very simular to Joe Hand's on his 37', just moved my bar a couple inches further forward, required the welding in of two tabs to the cross member and the fab of brackets to link the ends of the bar, middle of the u-bolts and centered in the axel (length wise), instead of aft of the axel as Joe's was. Might would add an amendment to Joe's Tech if he is cool with it.
Either way, will put in another post when I get the pictures.
Thanks,
Brett

Measured up the calipers and a roughly placed Master. The measurements off ground for front, rear, and master are 13", 16", and 24", respectively. Should be high enough I would think to not need residual valves.

The master is still slanted but can get it to about 10 to 15 degrees toward the Booster. Is this cool or need more or less? Can also fit it to have access to master's rsivoir via the floor, not under seat.

Finally, any leverage issues with shortening the boosters rod that conects to the brake pedal?
Brett

Brett, you are welcome to add any ideas to the tech tip. Thats what they are for. Glad it worked out for you, with both ends of the truck tied down, you are ready for some autocross racing! Joe

I've done the disc brake conversion on my '42 1/2t. Mounted the booster/ master to the frame ...main issue was not specifically the orientation of the master but the proper alignment of actuating shaft so the brakes operated smoothly.

New question, maybe adressed to Steve...
I have all bracketed, mounted, leveled port to starbard and slightly angled toward the booster. I managed to mount my mess from the front and rear of the booster, to the bellhousing (OE) and tranny crossmember, not the frame. I have not bolted the rear bracket to the tranny crossmember yet... it is a tight fit and vise gripped in place. I figured I would drill and bolt after pedal is connected and can be adjusted a bit, up, down ,left and right, to assist getting smooth pedal opperation. Thanks for the heads up Steve.
NOW, not familiar with boosters, I am assuming the actuating shaft is extended fully when not hooked up, so when the pedal is hooked up and depressed, the pressure should push it inward, correct? Sounds stupid but just making sure. If this is the case I will need to cut about 3 inches off the actuator shaft and rethread it for heim joint. Also, for ideal clearence can I remove about 1/2 to 3/4" of the "collar" extending from the boosters housing itself? It is the "collar" that is covered by the boot, packed with foam, an the actuating shaft extending outward from it. Otherwise, I will have to start choppping on the actuator bracket at the swivel point of the pedal's base tommorrow.
thnaks,
Brett

Brett,
If you write a book on your conversions I will buy it. Hey Pape Swap Meet will be at Tx Motor speedway at the end of this month, you going?

Rick.......

My 47 coupe has front discs with original master cyl under the floor and I was told I needed res. valves #2 & 10 and it's been working for years now. I'd think the 'slant' of the master cyl wouldn't affect the operation as long as it can hold enough fluid, otherwise cars going up and down hill would lose braking.
hope this helps.
Jim

Jim,
good point on the hill thing.... obviously not a concern of mine though. I watch the sun rise nad set in Amarillo every day and I am 2 hours north of DFW!
The 2 and 10 psi are diffent one for disc (ower I assume) and one for shoes, correct? Is the Master cylinder above the callipers and brake cylinders on the coup? Do you think it matters if they are on and not necessarily needed? really just a backflow (check) valve to prevent fluid from siphoning back to the Master Cylinder - the liquid, lower point, seeking own level, that kind of thing, correct?
Brett

Brett, I was advised to use the residual valves because the master cyl was so low vs up on the firewall. So it must be important and can't hurt so I think you'll need to install them.
Yes, one res valve is for the shoes and other for discs I'd have to go look at the car to see which one is which! You could check with a local brake shop for help on this also.

Thanks Jim,
I looked em up on Speedways web site...the 2 is for discs and both can be had for 17 a pop, 14 if I go with purple... how do you etch and paint aluminum?
I think I will put them diectly to the master cylinder and eave some slack in the tubing so I still fit, without cutting, if they need to be removed.
Oh, Jim, actuator rod, fully extended not hooked to pedal?
Brett

Cavebull,

If you master cyl is under the floor and equal or below the disks in the front and rear wheel cyls, recommend residual valves as near the master cyl you can get. I also used a porportion valve between the master cyl and the residual valves. (2 lb residual inline valve controls the front and 10 lb rear) I followed the advice from MP Brakes regarding set up and everything works like new. Check out their web site.