New front disc brakes, front end rebuild, steering rebuild for the '38 Plymouth

[deathbound]

Are you running the stock master cylinder with your disc brakes? How is that possible?

Not completely finished yet, but yes, I will be using the stock m/c. Why do you ask, can you tell me why this may not work?

[OldDad67]

Disc brakes require more fluid from the master cylinder do to the size of the pistons in the calipers. Do you think you'll have enough for safe braking? Just a question, since I've never seen disc brakes and rear drum brakes operating from just a single master cylinder. Not trying to be a smart a-- just don't want to see anyone hurt.

[deathbound]

Disc brakes require more fluid from the master cylinder do to the size of the pistons in the calipers. Do you think you'll have enough for safe braking? Just a question, since I've never seen disc brakes and rear drum brakes operating from just a single master cylinder. Not trying to be a smart a-- just don't want to see anyone hurt.

Didn't take it as you being a smart ***, just curious. The instructions said the stock m/c will work & I will check, double check, triple check, etc on short/slow around the neighborhood trips til I'm completely satisfied EVERYTHING is working as it should. If I feel uncomfortable about anything, I will then convert to a dual reservoir m/c or add a remote reservoir. Thanks for the input & concern.

EDIT:Just read my post & it automatically substituted *** for a$$, except I used ss's instead of $$'s. Must be filtered?

Edited November 25, 2011 by deathbound

[yourpc48]

I dont have one BUT... Another advantage to the dual is that if the front or rear brakes went out, you still have a little bit of brakes on the set that didnt fail. Im thinking of switching mine. (Not right away since Im all stock brakes still.)

[Niel Hoback]

It seems to me that disc calpers actually use less fluid for application since the pads are already against the rotors and only need pressure applied not very much movement at all, where drum brake shoes need to be moved from their adjusting cams out to the drum surface.

Initially, on assembly the whole system may hold more fluid, but only a very small amount actually moves through it as pressure is applied.

This post is IMHO, only.

There are others on this forum using OE masters with good success.

[Plymouthy Adams]

Disc travel on the average is but a few thousandts of an inch in reality if properly working...however..you still need a lot of fluid displacment due to the actual physical size of the caliper piston compared to the smaller drum cylinder..I have never done a CC for CC check but will think you will find them close in perspective..

[deathbound]

It seems to me that disc calpers actually use less fluid for application since the pads are already against the rotors and only need pressure applied not very much movement at all, where drum brake shoes need to be moved from their adjusting cams out to the drum surface.

Initially, on assembly the whole system may hold more fluid, but only a very small amount actually moves through it as pressure is applied.

This post is IMHO, only.

There are others on this forum using OE masters with good success.

Exactly what I was thinking, once the system is full & pressurized, it's just a matter of compressing what's in the lines. If more fluid is needed-as long as the m/c is full-the piston won't require more than the m/c's capacity.

I do see the point if the front or rear fails using a single vs. dual reservoir m/c.

If anybody using a stock m/c with front disc/rear drum wants to chime in, please do.

[Don Coatney]

I ran a stock master cylinder for many miles with front discs and rear drums on my P-15. When my master cylinder failed I switched to a dual master cylinder. For a "how to" on my dual master cylinder install follow this link.

http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=22469

[Robert Horne]

I have been using the Dual Master Cylinder, drums front, drums rear, all summer, and the brakes have been very good. Here in Virginia, roads are up and down, so the brakes get a good test very often.

[Big_John]

Exactly what I was thinking, once the system is full & pressurized, it's just a matter of compressing what's in the lines. If more fluid is needed-as long as the m/c is full-the piston won't require more than the m/c's capacity.

I do see the point if the front or rear fails using a single vs. dual reservoir m/c.

If anybody using a stock m/c with front disc/rear drum wants to chime in, please do.

As I understand it, the larger capacity of a "disc brake" master cylinder is for two reasons. The main reason is as the pad wears, the piston moves outward and more fluid is needed. While the piston in a drum brake system moves too, it doesn't displace near as much fluid. If you ever have a pad come off the backing (I have) you will move the piston out a lot in a hurry. You want to have a large enough reservoir to allow for the brakes to still work should that happen.

The other reason is because there is more fluid needed for the entire system, a leak in one caliper can drain the master pretty fast.

I know there are a lot of people that have had successful results using a small reservoir master cylinder but this is the way I would do it.

[OldDad67]

As I understand it, the larger capacity of a "disc brake" master cylinder is for two reasons. The main reason is as the pad wears, the piston moves outward and more fluid is needed. While the piston in a drum brake system moves too, it doesn't displace near as much fluid. If you ever have a pad come off the backing (I have) you will move the piston out a lot in a hurry. You want to have a large enough reservoir to allow for the brakes to still work should that happen.

The other reason is because there is more fluid needed for the entire system, a leak in one caliper can drain the master pretty fast.

I know there are a lot of people that have had successful results using a small reservoir master cylinder but this is the way I would do it.

With the different braking between disc's and drum are you using a proportioning valve along with a residual valve to balance out the system with your single master cylinder?

[deathbound]

As I understand it, the larger capacity of a "disc brake" master cylinder is for two reasons. The main reason is as the pad wears, the piston moves outward and more fluid is needed. While the piston in a drum brake system moves too, it doesn't displace near as much fluid. If you ever have a pad come off the backing (I have) you will move the piston out a lot in a hurry. You want to have a large enough reservoir to allow for the brakes to still work should that happen.

The other reason is because there is more fluid needed for the entire system, a leak in one caliper can drain the master pretty fast.

I know there are a lot of people that have had successful results using a small reservoir master cylinder but this is the way I would do it.

Routine maintenance (checking fluid levels) should alleviate any low fluid conditions from brake pad wear. Also, this isn't a daily driver, a couple thousand miles a year at best, so wear should be minimal. I know a dual reservoir is better, I will see how the stock single m/c works-cautiously at first.

As far as a leak, whether it's a caliper or wheel cylinder depends on the severity-a bad leak in either will drain any reservoir fast. Thanks for your input.

[deathbound]

With the different braking between disc's and drum are you using a proportioning valve along with a residual valve to balance out the system with your single master cylinder?

I will be using 2# residual valves (1 for each line coming out of the distribution block) on the discs, 10# residual valve on the drums. I will see how this set-up works first, then decide if I need a proportioning valve.

[deathbound]

I ran a stock master cylinder for many miles with front discs and rear drums on my P-15. When my master cylinder failed I switched to a dual master cylinder. For a "how to" on my dual master cylinder install follow this link.

http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=22469

Sounds like you had good results with your stock m/c if you ran it so long. If my stock m/c feels inadequate & after I've checked all other possible problems, I will most likely switch to a dual reservoir m/c. Good read on you thread, thanks for that link, though I would've used the search function had you not included it.

EDIT:Just realized I should have multi-quoted my responses.

[OldDad67]

I will be using 2# residual valves (1 for each line coming out of the distribution block) on the discs, 10# residual valve on the drums. I will see how this set-up works first, then decide if I need a proportioning valve.

Keep the info comming as your project progresses. I'm learning something eveyday, guess i'm not too old to learn yet.

[falconvan]

Nice job! Not sure how I missed your thread before but I'm watching now.

[Big_John]

With the different braking between disc's and drum are you using a proportioning valve along with a residual valve to balance out the system with your single master cylinder?

Sorry, I'm talking about using a dual master cylinder.

[deathbound]

Plumbed the residual valves for the front discs (2#) & rear drums(10#). Here are a few pics.

Distribution block with new hard lines & residual valves, also, rebuilt steering box installed.

By dtw62hd at 2011-12-08

2-2# residual valves-1 for each front wheel:

By dtw62hd at 2011-12-08

1-10# residual valve for the rear wheels:

By dtw62hd at 2011-12-08

[Robert Horne]

With the different braking between disc's and drum are you using a proportioning valve along with a residual valve to balance out the system with your single master cylinder?

My 38 has drum front and rear. The brakes seem to have the same amount of pressure. Going down a gravel driveway, the rear tires slide a little appling the brakes. Going down my driveway in reverse, the front tires slide a little appling the brakes. My proportioning valve must be set up with equal pressure. I do not have residual valves, when my cars set for some time, I have to pump the pedal a couple times to get full pressure up, after that I always have full pedal....

[deathbound]

Everything on the front of the car is pretty much done, moving to the rear. Steering feels nice & tight(tight in a good way) with virtually NO play(at least with the front end in the air).

I've searched & read quite a few threads re:removing rear brake drums, now it's my turn. I'm going to remove or should I say "try" to remove my rear brake drums. I had some scrap 1/2" thick steel plate & attempted to make a puller by burning a hole in the center for the center bolt that pushes on the axle & burned 5 holes-1 for each lug hole. I'm using (5) 1/2"x20 grade 8 bolts thru the plate into each lug hole & a 1/2"x20 grade 8 for the center bolt. I snapped the center bolt, so, I switched to a 5/8" center bolt, didn't break, but no luck. I'm going to check the Autozone, O'Reiley's(free rental) & NAPA to see what they have in the way of pullers. I'm thinking they're going to have one like the 1st pic, though I know I need one like the 2nd or 3rd pics.

If there's anybody in the Southern California area that has one to loan, let me know. Thanks

[Robert Horne]

Even with a very heavy duty puller, the drums would not come off my 38.

The axle flange on the 38 is not very thick.

I ground off the rivets on the drums. I installed new linings, rebuilt the

wheel cylinders, and has good brakes now.

[yourpc48]

I too had to get rid of the rivets on mine. 25 years of sitting out in the blackberries without moving let it rust to the axle.

[deathbound]

Even with a very heavy duty puller, the drums would not come off my 38.

The axle flange on the 38 is not very thick.

I ground off the rivets on the drums. I installed new linings, rebuilt the

wheel cylinders, and has good brakes now.

I too had to get rid of the rivets on mine. 25 years of sitting out in the blackberries without moving let it rust to the axle.

Looks like I may be in the same boat. I tried the puller I fabbed first-the center bolt rests on the axle & I tightened the 5 bolts in a star pattern:

By dtw62hd at 2011-12-26

that didn't work, next tried the puller I rented (free) from O'Reilly:

By dtw62hd at 2011-12-26

that's not working either. I still want to locate & try the puller most everybody recommends, where you use a "beater" on the center bolt.

Robert, how did you reattach the drums to the hub? I was thinking the rivet holes could be tapped, but you'd have to have the hub off to bolt it to the drum from inside thru the hub flange....right????

[Robert Horne]

Here is a photo of a 38 rear axle flange. The flange is not very thick.

I did not worry about reattaching my drums on the flange after I did the

brake job. The drums are a little tight when I got the brakes set good, so

they should stay in place when the wheels are on . Brakes have been

good all summer...

[deathbound]

Here is a photo of a 38 rear axle flange. The flange is not very thick.

I did not worry about reattaching my drums on the flange after I did the

brake job. The drums are a little tight when I got the brakes set good, so

they should stay in place when the wheels are on . Brakes have been

good all summer...

A picture is worth a 1000 words....didn't realize the hub was threaded-I thought the drum was threaded & riveted to the hub. I feel a lot better about having to remove the rivets if it comes to that. Is the locating pin part of the drum or act as a 5th rivet & needs to be removed also? Thanks

Edited December 27, 2011 by deathbound