Still got brake issues on my 48 p15

[MattWalker]

So here is the story so far-

My car was just not stopping period so, I did new hoses, new wheel cylinders, new shoes, rebuilt master, flushed the brake lines, adjusted the major and minor adjusters(using the feel method from the tech page), took it out for drive yesterday.... And the pedal is still going low. It does stop the car but it goes nearly to the floor and I can pump it back up with a few strokes to about half way. It never goes all the way to the floor though, about an inch or so of the floor. This makes me think its air but I bled the brakes 3 times. Am I doing it wrong? I'm just getting a friend to pump up some pressure on the pedal by pumping it a few times and then I attach a tube and crack the bleed valves til I don't see bubbles....do I need to put alot of fluid through it to make sure all the bubbles are gone? Do I need to get a pressure bleeder? Any help would be appreciated.

[yourpc48]

I had a really hard time getting the air out of mine. Try the pressure bleeder. I made my own yesterday.

Pics are here http://www430.pair.com/p15d24/mopar_forum/showthread.php?p=289313#post289313

[busycoupe]

Check the major and minor adjustments again. These brakes do not take up extra slack the way more modern Bendix brakes do, the shoes need to be very close to the drums, but not dragging. The correct procedure is to have the radius of the shoes ground to match the diameter of the drums. I must admit, I did not do this and my brakes seem to work well. - Again, check the shoe adjustments.

Dave

[Guest P15-D24]

You need to bleed again, go around twice. Start with the wheel cylinder farthest from the master, then work you way back to the closest. If the pedal still won't hold after you pump it you have a leak. Pressure bleeder is good way to find leaks.

[Frank M.]

Remove a rear wheel and make sure the push rods dont have any slack between the cylinder piston and the shoe. a lot of manufacturers have different

pistons in their cylinders and dont furnish the right length push rod with the kit. I found

5 different length push rods availiable at the parts store. If you used the old

ones--that could be your prob. I had a issue with this a while back, and wound up saying a lot of naughty words till I found the problem. Frank M.

[MattWalker]

Assuming I find the push rods are too short, is there a good place to get longer push rods or specify what size I need? I know for a fact that there are a few different size push rods across the four wheels cuz I noticed this when I was reassembling them. I didn't think much of it til I just read your post.

But the more you adjust the shoes out in general, couldn't you end up needing to change the push rods length? In other words, do you need to change the push rods as the brakes wear?

[Guest P15-D24]

Assuming I find the push rods are too short, is there a good place to get longer push rods or specify what size I need? I know for a fact that there are a few different size push rods across the four wheels cuz I noticed this when I was reassembling them. I didn't think much of it til I just read your post.

But the more you adjust the shoes out in general, couldn't you end up needing to change the push rods length? In other words, do you need to change the push rods as the brakes wear?

The fact the pedal comes up when you pump means you are in the ball park with shoe adjustment. You can't adjust shoes if you have air in the system. The fault diagnosis is easy, pump the pedal and it come up, then release. If it goes backdown on the next pump, you have air in the system. If you pump the pedal and the height of the pedal always returns to the same height and is low, you need to adjust the shoes.

[ptwothree]

then there's the push rod adjustment at the master cyl. If it's too short, you'll get a low pedal no matter what. Too long, and the brakes won't release.

Adjust it till it just barely touches the backside of the piston; that should get in the park.........

[plyroadking]

Are you sure that you have the correct piston in the master cylinder? They made two different lengths and I always seem to get the rebuild kit that has the wrong piston in it.

[Jerry Roberts]

As mentioned earlier , if you have a fluid leak you won't have brakes . All it takes is a very slight leak so don't look for a big puddle , just a small wet spot . Lots of good suggestions .

[MattWalker]

Thanks for all the suggestions guys. I will try to see if I can figure this out.

If not, is there anybody in the Atlanta area that knows these cars well? There must be an antique car mechanic?

[falconvan]

Matt, for what its worth I decided that the main problem with my 1949 brakes is that the technology is 60+ years old. Even with everything working and adjusted right I'm not very happy with them. I'm going to live with them for this summer but some kind of upgrade is definitely in the works.

[martybose]

Matt, for what its worth I decided that the main problem with my 1949 brakes is that the technology is 60+ years old. Even with everything working and adjusted right I'm not very happy with them. I'm going to live with them for this summer but some kind of upgrade is definitely in the works.

I had the original brakes all freshened up and adjusted using the right tools by someone who knew what they were doing, and was still scaring myself, because I was used to the braking power of a modern car. Last summer I upgraded to front disk brakes, and it is much better.

Marty

[Harold M]

I have decided the reason the brakes are hard to bleed is because of one front wheel cyl, being at the bottom and it is hard to push the air down. I made a suction bleeder, got a small air tank of a truck, hooked it to the suctionside of a small air compressor used quarter inch clear tubing to the bleeders. Keep the lid of the master cly and suck it thru

[greg g]

If after all your ministrations, you still need help, look for a commercial vehicle brake shop in your area. The fellows I used here 11 years ago, work on everything from trucks to elevators. They are used to dealing with systems old and new. Check them out, I have done nothing to mine in 12K miles but add a bit of fluid.

[desoto1939]

I have decided the reason the brakes are hard to bleed is because of one front wheel cyl, being at the bottom and it is hard to push the air down. I made a suction bleeder, got a small air tank of a truck, hooked it to the suctionside of a small air compressor used quarter inch clear tubing to the bleeders. Keep the lid of the master cly and suck it thru

Instead of going to all this fabricatin puchase one of the handheld mity mite brake bleeder kits. This is a vacuum hand pump that draws the fluid from the MC to each brake cylinder as you create the vaccum. They cost about 25-30 dollars and can be purchased at any local auto supply chain. Also good for checking on other vacumm leaks and for testing the vacuum advance units.

Rich Hartung

Desoto1939@aol.com

[Harold M]

The hand held bleeders are 40.00 at both NAPA and Orielys. I use my air tank suction to change oil in my IO as well as the brakes. It took a quart and a half of fluid which would be a lot of hand pumping.

[homer2105]

This this is making me nuts (more nuts!) I have just done a COMPLETE brake job on a D24. New slaves. rebuilt master, new hard lines, new rubber hoses, new shoes (arched), turned drums. Now the fun part, I didn't bench bleed my master and I'm trying to bleed my brakes. I've been around this sucker at least 4 times and still don't have a pedal. Someone told me to bench bleed the master. Can this be done while it's till in the car? I also noticed I'm getting some little black specks in the fluid that comes out. Should I flush the whole syten with alcohol? I'm using DOT 5 fluid, very expensive!

I also bought a Mighty Vac but haven't used it because friends tell me it isn't worth a pinch of poop. Any help on this? Thanks, I'm ALMOST on the road.

Edited February 26, 2012 by homer2105
forgot something

[Robert Horne]

You can bench bleed the MC still on the car. Just use a couple of small brake lines routed back into the reservoir.

[Don Coatney]

You can bench bleed the MC still on the car. Just use a couple of small brake lines routed back into the reservoir.

Not a stock master cylinder but this is how it is done.

[Robert Horne]

Not a stock master cylinder but this is how it is done.

A photo makes the best instructions....

[homer2105]

I made up something very similar to thus but dumped it into a jar above the MC height, How long do you have keep pumping this stuff thru? Some one told me I should have adusted the shoes first, then someone else says you can't adjust shoes with air in lines. I did google on adjusting shoes and the one that's on this site. One says to adjust anchor bolts first then cam, the other says adjust the cam first then the anchor. When I try to adjust anchor bolt from the back side one way it tightens up to the point of not beong able to turn it, the other way the nut come loose. WTF is with these things? Starting to think they are a real POS.

Edited February 27, 2012 by homer2105
spelling

[homer2105]

Is there a definitive answer to how to go about bleeding and adjusting brakes? Do you bleed first or adjust first. Do you adjust heel then toe or toe then heel. Does the master have to be bled? Once in the car is that still necessary? I don't think the factory manual mentions bench bleeding, I have found all these answers to these questions on the internet...BUT THEY ARE ALL DIFFERENT!

Factory manuals (like Harley manuals) seem to assume you've already done this before and know what you're doing. The pictires taken with 60 year old technology simply put...sucks. Would be nice if they had some exploded diagrams. Do they have a manual like "working on an old Dodge for idiots?"

[austinsailor]

Adjust, then bleed.

Reason #1, you have to have the drums on the bleed, drums off to adjust.

reason #2, worst case, they are so far out of adjustment that a cylinder comes apart while bleeding.

Reason #3, if they are too far out of adjustment, you may never get pedal even if you get all the air out.

I've never bench bled an old master cylinder of the type we use and never had a problem. I think it's more an issue with the new complex ones. I can't imagine why it would be needed with ours.

Oh, and do it in this order:

right rear, left rear, right front, left front. After I've gone all around, I go back and get another little bit again in the same order and usually get a bit more air.

[TodFitch]

Adjust, then bleed.

Reason #1, you have to have the drums on the bleed, drums off to adjust.

reason #2, worst case, they are so far out of adjustment that a cylinder comes apart while bleeding.

Reason #3, if they are too far out of adjustment, you may never get pedal even if you get all the air out.

I've never bench bled an old master cylinder of the type we use and never had a problem. I think it's more an issue with the new complex ones. I can't imagine why it would be needed with ours.

Oh, and do it in this order:

right rear, left rear, right front, left front. After I've gone all around, I go back and get another little bit again in the same order and usually get a bit more air.

+1

This sure matches my experience.