1946 D24 Front Brakes

[Jeff.P_46]

After spending all day trying to adjust the front brakes (Lockheed dual cylinder) on my recently aquired 46 2 door coupe, I'm not sure if I have made any progress. When I first got he car I noticed the front brakes were locking up so I rebuilt the master cylinder (by-pass port was plugged). Someone had put new shoes and rebuilt the front wheel cylinders in the past so I left them alone. I first tried the "drum-on drum-off" method of adjusting the shoes then ended up slotting the anchors which helped. But my problem is when the brakes are applied the brakes lock hard and take awhile for them to release so I have now adjusted them with the residual pressure left in the line which leaves the shoes very slightly dragging after the pedal is released. The master cylinder only really has a one way valve in it so there will always be pressure in the line (at least for awhile) and the pedal is firm but is this correct? Also I noticed the shoes linings are rivited heel to toe with no space left at the toe, is this correct? I'm use to seeing linings that are left "short" to prevent binding. Sorry for being so long winded but for those that have every tried to adjust the Lockheed brakes will understand.

Thanks

[MBF]

I've been through the brake system on my '36 Plymouth a couple of times in the 45 yrs we've owned it. The DOT3 fluid wicks in moisture since it is alcohol based. This is probably the worst thing for a car that sits 99% of the time. I'd recheck the inside of your front cylinders-if they're starting to gum up or corrode in the bore-that will slow up the brake realease process. You also said that your show lining went all the way to the end of the shoe-I wonder if with these type of non self energizing brake (shoes are anchored on bottom end) if that small section of the shoe lining isn't dragging too. I use the brake caliper tool when setting up the brakes on my '36 and my 52 dodge 1 ton and then dial them in with the major and minor adjustments. I also got into the habit of flushing the brake fluid out of these vehicles on an annual basis to slow down the corrosion process. Whatever you do-don't mix the DOT5 and DOT3 fluids together-that will turn all of the internal rubber parts to a black mush. Mike

[Guest Nile Limbaugh]

If your brakes are slow to release it may be due to old rubber lines collapsing internally. Have you replaced these?

[Lou Earle]

A small air bubble in any line will cause that

[bob westphal]

The grabbing sounds like an adjustment problem. Make sure that you have the shoes adjusted properly. Your repair manual goes through several methods. Since I let my shoe aligning tool go with my '51 Windsor, I use the 'drum on' method. It works well. Like Nile said replace your flexible brake lines.

Bob

[Jeff.P_46]

I've been through the brake system on my '36 Plymouth a couple of times in the 45 yrs we've owned it. The DOT3 fluid wicks in moisture since it is alcohol based. This is probably the worst thing for a car that sits 99% of the time. I'd recheck the inside of your front cylinders-if they're starting to gum up or corrode in the bore-that will slow up the brake realease process. You also said that your show lining went all the way to the end of the shoe-I wonder if with these type of non self energizing brake (shoes are anchored on bottom end) if that small section of the shoe lining isn't dragging too. I use the brake caliper tool when setting up the brakes on my '36 and my 52 dodge 1 ton and then dial them in with the major and minor adjustments. I also got into the habit of flushing the brake fluid out of these vehicles on an annual basis to slow down the corrosion process. Whatever you do-don't mix the DOT5 and DOT3 fluids together-that will turn all of the internal rubber parts to a black mush. Mike

The front cylinders might be the problem, I plan on going thru them now and I have flushjed the system. I'm still curious about the length of the lining on the shoe, does anyone out there know if the lining goes the full length on the 46-50ish dual cylinder style front brake assembly? Jeff

[Jeff.P_46]

If your brakes are slow to release it may be due to old rubber lines collapsing internally. Have you replaced these?

I have replaced the rubber lines but still have the lock up problem. I will rebuild/replace the front cylinders next. Jeff

[Jeff.P_46]

A small air bubble in any line will cause that

I have vacuum bleed the brakes several times but If I can find an attachment for a pressure bleeder I will try that. Jeff

[Jeff.P_46]

The grabbing sounds like an adjustment problem. Make sure that you have the shoes adjusted properly. Your repair manual goes through several methods. Since I let my shoe aligning tool go with my '51 Windsor, I use the 'drum on' method. It works well. Like Nile said replace your flexible brake lines.

Bob

I'm down to rebuilding/replacing the front cylinders and pressure bleeding but would like to know about the length of the lining on the shoe. Should it be full length? I don't have a shoe aligning tool but I do have plenty of time to try aligning them (although it would be faster to just cut the front end off and put a clip under it Jeff

[Guest Nile Limbaugh]

Actually the length of the lining material doesn't have anything to do with whether or not the shoes stick. If the diameter of the shoes matches the diameter of the drums you should be fine in that area.

[Jeff.P_46]

The brake linings on my '48 D-24 are full legnth on the front shoes. Rear shoes were not. 1 short, one long.

Not sure how well it shows on this pic. a little slow getting a pic posted. I have a new camera with a photo program. This pic from my old file was too large to post. The new camera program said I did not have permission to modify or save photos. Had to use a different program, and that was a challenge as i am computer challenged.

Yep, that is what mine look like too. Thanks for the photo and response. Jeff

[Guest P15-D24]

Go to the main site, WIP page, Brake article and review the process for correctly setting up your brake shoe adjustment.

[De Soto Frank]

Make sure that the piston in the MC is able to return ALL THE WAY to it's internal stop...

To test for this, pump-up the brakes so that they "lock", then crack anyone of the hydraulic fittings slightly... if fluid squirts out for a moment, then the brakes "magically" release(make sure the handbrake is set and/or the wheels are chocked first!), then something is preventing the MC piston from returning all the way, which allows fluid to return to the reservoir via the tiny "relief port" ( this is the 1/32" to 1/16" hole in the bottom of the reservoir, nearest the end where the brake lines bolt-on). Frequently this hole is restricted or blocked due to rust, or is not being cleared by the piston due to incorrect pedal push-rod adjustment.

If your brakes were binding due to insufficient clearance/adjustment, they should release if you reverse the direction of the car...

[RobertKB]

There should be two small holes in your master cylinder. Make sure both of them are unplugged. It sounds exactly like the problem I had with my car some time ago. I cleaned both small holes and everything was fine.

[John Mulders]

Guess this is where Don would post the pic with the mastercylinder and the two holes. Reading the situation I was thinking that that may be the reason.

Don has the perfect picture for that!

John

[Don Coatney]

Guess this is where Don would post the pic with the mastercylinder and the two holes. Reading the situation I was thinking that that may be the reason.

Don has the perfect picture for that!

John

[Jeff.P_46]

Make sure that the piston in the MC is able to return ALL THE WAY to it's internal stop...

To test for this, pump-up the brakes so that they "lock", then crack anyone of the hydraulic fittings slightly... if fluid squirts out for a moment, then the brakes "magically" release(make sure the handbrake is set and/or the wheels are chocked first!), then something is preventing the MC piston from returning all the way, which allows fluid to return to the reservoir via the tiny "relief port" ( this is the 1/32" to 1/16" hole in the bottom of the reservoir, nearest the end where the brake lines bolt-on). Frequently this hole is restricted or blocked due to rust, or is not being cleared by the piston due to incorrect pedal push-rod adjustment.

If your brakes were binding due to insufficient clearance/adjustment, they should release if you reverse the direction of the car...

Hi Frank,

The by-pass hole was plugged initially when I got the car so I figured that was causing the lock-up problem so I rebuilt it. When I work the pedal the excess fluid squirts out the hole. I assume this is because the lines are full since the brakes are essentially locked. I also can see the main piston working back and forth so it is not sticking. This leads me to believe that the problem has to do with the wheel cylinders not releasing. I have ordered new ones from Andy Bernbaum (in stock and shipped out today, $21.50 ea, best price I have found yet and great service, I would highly recommend www.oldmoparts.com). I will post after I have changed them to see if this has fixed the problem.

[Don Coatney]

Jeff P;

I hope the replacement wheel cylinders you purchased are new and not new old stock. If they are new old stock I recommend you purchase new rubber parts and install them prior to installing the wheel cylinders on your car. Rubber parts age while sitting on the shelf and will have a short life once placed into service. I have never purchased anything from Andy B but I have read a lot of mixed reviews on his parts and service. hope your purchase goes well.

Are your brake shoe return springs in good shape? The pressure these springs apply to the wheel cylinders is what returns the fluid to the master cylinder through the small port pictured above.

Although there is a well written procedure for adjusting the brake shoes without the Ammco tool it is my belief that the tool is required. Pictured below is a set of shoes in service for a short time after an adjustment without the tool was completed. I suggest you use a Sharpie and make several marks across your shoes. Drive for a few miles then remove the drums and see if the shoes are wearing evenly. If they are not then the adjustment is not done correctly.

Another option is a conversion to front disc brakes. I have done so on my car at a cost of about the same as a complete replacement of stock components plus the cost of the Ammco tool. Benefit is no adjustment required and replacement pads are available at any bubble pack auto parts house.

[De Soto Frank]

Okay...

Double check the pedal/pushrod clearnance just to be sure that's okay... should be about 1/4" of "float" before the rod contacts the piston.

Some fluid will squirt-up through both holes, until the piston cup moves past them. This is normal, and the "squirting" should stop after about 1/4" of piston travel (not "pedal travel").

Any idea how long ago previous owner rebuild those wheel cyls ?

Do the brakes lock-up only when the vehicle is in motion, or when it's standing-still too ?

If it happens all the time, moving or no, I would suspect a problem with the hydraulics; if it happens only when the car is moving ( and the brakes release when you move the car in the opposite direction), that would suggest clearance issues with the drum ( usually too much toe clearance).

It might be a good idea to just go ahead and replace ALL steel tubing and hydraulic hoses while you 're at it; they may look solid from the outside, but brake systems rust from the inside-out.

These systems can be tricky to set-up and adjust initially, but they can

(and do) work reliably.

Good luck !

[Jeff.P_46]

I hope I didn't speak to soon about Andy Bernbaum, found this site http://www.imperialclub.com/Part/Vendors/Bernbaum.htm were people have written some pretty negative things. Hope my experience will be better. As for the doing the disc brake route I had seriously contemplated that but I had promised my wife I wouldn't take this car apart, luckily she hasn't come out to the shop yet to see that that I have the front end apart, the rear end out and the interior stripped out (serious rust problems in the rockers and floor boards) and I have only had the car for a week:) Jeff

[Jeff.P_46]

Jeff P;

I hope the replacement wheel cylinders you purchased are new and not new old stock. If they are new old stock I recommend you purchase new rubber parts and install them prior to installing the wheel cylinders on your car. Rubber parts age while sitting on the shelf and will have a short life once placed into service. I have never purchased anything from Andy B but I have read a lot of mixed reviews on his parts and service. hope your purchase goes well.

Are your brake shoe return springs in good shape? The pressure these springs apply to the wheel cylinders is what returns the fluid to the master cylinder through the small port pictured above.

Although there is a well written procedure for adjusting the brake shoes without the Ammco tool it is my belief that the tool is required. Pictured below is a set of shoes in service for a short time after an adjustment without the tool was completed. I suggest you use a Sharpie and make several marks across your shoes. Drive for a few miles then remove the drums and see if the shoes are wearing evenly. If they are not then the adjustment is not done correctly.

Another option is a conversion to front disc brakes. I have done so on my car at a cost of about the same as a complete replacement of stock components plus the cost of the Ammco tool. Benefit is no adjustment required and replacement pads are available at any bubble pack auto parts house.

Okay...

Double check the pedal/pushrod clearnance just to be sure that's okay... should be about 1/4" of "float" before the rod contacts the piston.

Some fluid will squirt-up through both holes, until the piston cup moves past them. This is normal, and the "squirting" should stop after about 1/4" of piston travel (not "pedal travel").

Any idea how long ago previous owner rebuild those wheel cyls ?

Do the brakes lock-up only when the vehicle is in motion, or when it's standing-still too ?

If it happens all the time, moving or no, I would suspect a problem with the hydraulics; if it happens only when the car is moving ( and the brakes release when you move the car in the opposite direction), that would suggest clearance issues with the drum ( usually too much toe clearance).

It might be a good idea to just go ahead and replace ALL steel tubing and hydraulic hoses while you 're at it; they may look solid from the outside, but brake systems rust from the inside-out.

These systems can be tricky to set-up and adjust initially, but they can

(and do) work reliably.

Good luck !

Hi Frank,

I did adjust the the pedal clearance to give about 1/4" free play and I can see the piston retract. The car has been sitting for about 7 yrs, the shoes are new with no wear and the rubber boots on the wheel cylinders are dusty but show no grime but just because they were new 7 yrs ago doesn't mean they work like new ones now. I will be tearing it back apart this weekend, not looking forward to readjusting them though. Jeff

[Jeff.P_46]

Jeff P;

I hope the replacement wheel cylinders you purchased are new and not new old stock. If they are new old stock I recommend you purchase new rubber parts and install them prior to installing the wheel cylinders on your car. Rubber parts age while sitting on the shelf and will have a short life once placed into service. I have never purchased anything from Andy B but I have read a lot of mixed reviews on his parts and service. hope your purchase goes well.

Are your brake shoe return springs in good shape? The pressure these springs apply to the wheel cylinders is what returns the fluid to the master cylinder through the small port pictured above.

Although there is a well written procedure for adjusting the brake shoes without the Ammco tool it is my belief that the tool is required. Pictured below is a set of shoes in service for a short time after an adjustment without the tool was completed. I suggest you use a Sharpie and make several marks across your shoes. Drive for a few miles then remove the drums and see if the shoes are wearing evenly. If they are not then the adjustment is not done correctly.

Another option is a conversion to front disc brakes. I have done so on my car at a cost of about the same as a complete replacement of stock components plus the cost of the Ammco tool. Benefit is no adjustment required and replacement pads are available at any bubble pack auto parts house.

Hi Don,

Tell me about your disc conversion. What hub did you use, same spindles etc... Thanks Jeff

[PatS....]

Don, I notice that your steering arm has a bend in it. Did you have that done as part of the kit installation?

I ask because mine is straight, no bend at all and Charlies instructions make no mention of that modification.

Is that just part of the PlyDo kit?

Thanks alot.

Pat

[Plymouthy Adams]

appears to be stock P15 for right hand side...

[Phil Martin]

Had the same problem with my 53 dodge pickup. The return springs were weak and not pulling back the shoes.