Matt Harwood

1956 Windsor, mushy brakes

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We've tried everything to get the brakes on Melanie's wagon to firm up. It stops OK, but pulled to the right pretty badly. So we adjusted the shoes to reduce that, and now it stops pretty straight. However, the pedal goes down an alarming amount before anything starts to happen. We pulled the brakes apart again last week and found a bad front wheel cylinder, so we replaced that and bled the system. The pedal STILL goes almost to the floor before it grabs. Plenty of stopping power, brakes will lock up, but the pedal is just too low.

 

Any other ideas? Should we try adjusting the shoes even closer to the drums? I think we've got them pretty good because you can just barely hear them touching when you rotate the wheel by hand. Could it be the power brake booster? It wasn't always like this, it used to have good pedal. I'm afraid we screwed something up when we did the rear end rebuild a few weeks ago. Is the master cylinder linkage adjustable?


Your thoughts are much appreciated!

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Posted (edited)

These brakes are wonderful when they work right. The downside is you don't get to take any shortcuts.

 

If they have an e-brake function (I doubt it), back it off. The shoes should match the curve of the drums VERY closely. A small feeler gauge should go in at the end (look in the manual for the spec). If there is a bunch of gap, the shoes need to be arc ground. This isn't really optional unless you like mush.

 

With the shoes back on the car, the shoes need to be adjusted so they fit the drums right (more specs in the manual). The shoes adjust both up and down, and in and out. This is done with a special tool that attaches to the hub or spindle, and has a rod that lays on the face of the shoe, and adjusts to the actual drum diameter. You run it around the shoes, checking with a feeler gauge as you go. The tool is impossible to find. Plan on making one out of random stuff laying around the shop or hardware store.

 

Obviously there can't be any leaks, I gather you have taken care of that.

 

I don't know about the brake booster. Generally speaking now (instead of specifically to Lockheed brakes, so I'm not sure this applies to you), there MAY be an adjustment on the pushrod coming out of the booster. If you look down in the master cylinder, and push the pedal SLOWLY (or it will squirt you in the eye), there is a big hole and a tiny hole. Any motion before the cup inside the cylinder completely covers the tiny hole is lost motion at the pedal.

 

A booster of the type used on more modern cars generally has threads on the pushrod, or a tip that pulls out with some shim washers under it. In theory you can adjust it until you can see the seal, then back off until you just can't, plus a little more, so you are sure the seal is not resting on the hole. If you get this too tight, then due to flex, thermal expansion, and so on, there may come a day that the brakes wont release and there you sit. If in doubt, use the specs in the book instead of my way.

 

1 hour ago, Matt Harwood said:

I think we've got them pretty good because you can just barely hear them touching when you rotate the wheel by hand.

 

That isn't even a start with these brakes, unless they are already working perfectly and you are just taking up a tiny bit of slack.

 

1 hour ago, Matt Harwood said:

I'm afraid we screwed something up when we did the rear end rebuild a few weeks ago. Is the master cylinder linkage adjustable?

 

I'll bet it is the rear brakes then. Did you back any adjusters off to get the drums off? I don't know about the master cylinder linkage (unless it is power, and configurable as I mentioned above). Did you do anything to that linkage when you had the rearend out?

 

If you turned any drums or replaced any shoes you are starting from zero on those wheels. These are a lot of work. Good luck. You wont believe how good they are when you get them right. There is no servo action, so they have a solid "right now" feeling like disc brakes.

Edited by Bloo (see edit history)
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Thanks, guys. We do have a manual but it is surprisingly vague about adjusting the brakes. It says to turn the adjusters (there are two per wheel, one per shoe) until the drum locks up, then back them off until the drum turns freely. Seriously, that's about all it says. I did note there's an adjustment screw between the pedal and the master cylinder, so I may try to adjust that to raise the pedal a bit--it bites and the car stops quite well, the pedal is just really low. 

 

I may also try bleeding them the old-fashioned way rather than using the vacuum bleeder. 

 

I'll also go through the rear brakes again. Dr. Francini did the work and he doesn't usually make mistakes, but it's probably worth a look. I just hate pulling those press-fit drums. Ugh...

 

I think I will have the shoes re-lined next winter and then we'll have to index them. There's enough meat on them now to last a while and I don't want to take it off the road, but eventually we'll need to get that done.

 

Thank you for the tips, I'll do some work tomorrow night and report back.

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Posted (edited)

I had a friend help me put this tool together last weekend. The result of setting the brakes, concentric, properly to the axle is awesome. I played around with brake settings for two years. I could not get it right. Low brake pedal too. Pumping 2x at each stop made did bring the pedal up. 

 

Once I set the shoes up properly, the pedal came up where it should be and feels great. The car stops better. I am so happy to have a tool that allows me to get the brakes properly set up in my 53 Windsor. They are the same Lockheed brakes.

 

 

Brake Tool.jpg

Edited by keithb7 (see edit history)
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Spent a few more hours playing with it and trying to adjust the shoes. They were way out of adjustment so I followed the instructions in the book but the pedal still goes to the floor. Looked under the dash and saw that the linkage and seal were wet so I'm guessing the master is shot. I'll replace that and try again.

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Posted (edited)

You know I realize that this is Blasphemy but I did my 52 without a gauge  and have no issues with the brakes. Good pedal, No problems with pulling and pretty reasonable stopping power.  I. just kept playing with it until I was happy.  I am sure an Ammco gauge would have been faster and better but Hen's teeth... 

Edited by plymouthcranbrook (see edit history)

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It's not blasphemy, and theres no theoretical reason it couldn't work, it's just that the odds are bad. I'm glad it worked out for you.

 

A long time ago I screwed around with 55 DeSoto for about a month thinking I could do that. I was a gas station monkey in those days, and it did at least provide a few weeks of entertainment for a gray-haired coworker who had told me what needed to happen before I even had the drums off. It's not a performance I am looking to repeat. :lol:

 

The difference is astounding when you finally get it right.

 

 

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 You could get lucky and get the brake settings close without a tool.  It can be done. You may spend lots of time trying also. Then still have limited results.  Brakes are very important.  It makes sense to take the right steps to do things right, with confidence. You’ll appreciate it when that 5,000 lb wagon is overtaken by gravity on a steep hill.  

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4 minutes ago, keithb7 said:

 You could get lucky and get the brake settings close without a tool.  It can be done. You may spend lots of time trying also. Then still have limited results.  Brakes are very important.  It makes sense to take the right steps to do things right, with confidence. You’ll appreciate it when that 5,000 lb wagon is overtaken by gravity on a steep hill.  

 

Agreed, I want to do it right. I'm prepared to take all the advice offered here, just need to get the brakes healthy again. If the pedal goes to the floor, all the adjusting in the world probably won't fix that so something else is amiss. We'll start with a new master cylinder and bleed the system again. Then I'll figure out how to set the shoes up properly with a tool. I'm sort of thinking that if I'm tearing it all apart, I may as well buy new shoes and put those on before we go through all the trouble of setting things up. We're planning on going to the Chrysler national meet in Detroit in August, so hopefully  I'll have it ready by then. Melanie wanted to take it to a show on Sunday, but with the brakes being like this, I'm not going to let her drive it.

 

Any thoughts on either of the tools up there being the one we need for setting it up? 

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16 minutes ago, Matt Harwood said:

 

Agreed, I want to do it right. I'm prepared to take all the advice offered here, just need to get the brakes healthy again. If the pedal goes to the floor, all the adjusting in the world probably won't fix that so something else is amiss. We'll start with a new master cylinder and bleed the system again. Then I'll figure out how to set the shoes up properly with a tool. I'm sort of thinking that if I'm tearing it all apart, I may as well buy new shoes and put those on before we go through all the trouble of setting things up. We're planning on going to the Chrysler national meet in Detroit in August, so hopefully  I'll have it ready by then. Melanie wanted to take it to a show on Sunday, but with the brakes being like this, I'm not going to let her drive it.

 

Any thoughts on either of the tools up there being the one we need for setting it up? 

 

It's the Ammco 1750 but that one shown is not complete.  

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This nice one was posted the other day by @keithb7:

BrakeTool_keithb7.thumb.jpg.805390e19e3d49616203409214046e70.jpg

This is my one:

BrakeAdjustingContraption.thumb.jpg.4fe808c212e25f9426983d83ed16b694.jpg

 

To use these, put the drum on and adjust one shoe at the top (beside the cylinder) to just touch the drum. That is your reference. Remove the drum, fit the tool and set the tool to that reference on the shoe. Then adjust the shoes top and bottom, using a feeler gauge of thickness the book says, under your reference setting.

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The drum calipers shown above could be used to measure the inside drum diameter. That would tell you if the drums are still within spec. They are of little help in setting up the brakes properly. 

 

Simply put, the trick is to set the curved shoes, equal distance at all points, to the very centre of the axle. This is 99% impossible to set accurately without some help from some sort of tool, or other creative idea.  When the round brake shoes are set just right they make full contact with the drum. All points. This is so vital to proper brake operation. Think about the total contact area of all brakes shoes on the car. Its not much. These shoes have to stop these big heavy cars, full of passengars and luggage, on a down hill slope at a good speed. Every little bit of shoe area that is not contacting the drum properly has a big effect on reducing brake power. 

 

The amco tool as shown above, is pretty well useless. Important required pieces are missing. Hen’s teeth was mentioned earlier with good reason. You can see why some of us are reverting to home built tools. 

 

The master cylinder that is leaking brake fluid is also a concern. Yes, either reseal it or buy a new one. I resealed mine and re-used it. It works well but I see a little brake fluid trapped in the rod dust boot.  So a little brake fluid is coming out where it should not. It’s not dripping or getting worse. Pretty sure I have worn cylinder walls. A new one is in my future some day. In the mean time I keep a very close eye on my brake system. I pull the floor cover and inspect the Master Cylinder fluid level monthly. I look for wheel leaks regularly too. Any opportunity to pull the drums and check the wheel cylinders, I’m in there. Probably 3-4 times each cruising season. (April to Oct). 

 

You can’t be too careful when running the stock single cylinder master. 

 

 

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I wouldn't change the shoes unless theres something wrong, mainly because you would have to arc grind them, and that probably means sending them out somewhere.

 

I'm not surprised the master cylinder failed. That often happens when the pedal goes low for any reason, as the seal may get dragged across some rust it wouldn't normally contact. I try to avoid doing that, but more often than not it still happens.

 

I had to make a tool to fix that DeSoto I mentioned earlier. It was years before the Internet. In those days you just had to ask all the people you know in the business. I couldn't locate one so I threw something together to get the job done.

 

It is amazing how badly eaten up a master cylinder can be, and still seal up and work fine for years with a light honing and some new rubber. These days I would probably just get it sleeved if it is pitted.

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One used to be able to buy oversized cups for use in honed cylinders.

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Don't hone them enough to require that! Honing too much is just asking for a leak. You can't really fix the pits anyway, they're too deep. Just knock down the rust and crud that sticks up higher than the bore diameter. Forget the low spots other than to clean all the crud out .

 

The worst rust damage will be in areas the seal does not normally travel. If you had a bad bore, watch closely for leaks, then go back and look again after driving a couple of days. If it doesn't hold, you need a sleeve.

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Posted (edited)

This 1956 Windsor does NOT have Lockheed double anchor brakes (1946-1955 Mopar cars) requiring the Ammco 1750 or Miller MT 19 special shoe adjusting tools.

It has "Total Contact" brakes.. the shoes self center in the drum..they float in the shoe support plate so to speak.

The shoe curvature needs to match the drum curvature .  This.......... fitting the shoes to each size of drum if they are new shoes or they do not accurately fit the drums.

There are two 7/16" hex cam bolts on each wheel backing plate  that are turned the same direction as the forward wheel motion.. tire needs to be off the ground to spin it then turn each adjusting cam as mentioned till the wheel locks up... back off just till the wheel spins.

I wouldn't waste my time honing cylinders that most likely will leak in a year onto the linings or into the booster ...I'd sleeve them..do it right.

 

JC 300 Brakes gas tank sender copy (28).JPG

 

JC 300 Brakes gas tank sender copy (16).JPG

Edited by c49er (see edit history)

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Our car has the dual wheel cylinders on the front brakes. We already replaced one that we thought was bad, but perhaps the others are gone, too. I did the adjustment as C49er suggests and got the pedal to come up a bit, but it's still almost all the way to the floor, so the master cylinder is probably toast. We're going to replace everything as long as we're at it--master cylinder, wheel cylinders, and brake shoes. We'll have to fit the shoes to the drum and I'm sure I can figure out a way to do that without one of the grinders. Something is wrong beyond adjustment given the soft pedal. We'll have a new master and wheel cylinders in a few weeks and go from there. I'll keep you posted, guys. Thanks for the feedback so far!

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If you want U.S.A. made wheel cylinders and ++ Asbestos ++ Brake Shoes --- I believe you are aware that I have them.....

Those eliminate the first 90 problems you will have by going an alternate route,............

 

Always best to simply call me -- Craig -- 516 - 485 - 1935.....

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Modern hard brake linings do not work properly on these old drum brake systems IMO. I buy NOS linings for all my old MoPars now off Ebay.

As mentioned old stock asbestos or equivalent lining material makes the old drum brakes operate and function well as they did when new.

Safe, high, firm pedal and the ability to easily lock em up if you wanted... not that you would want to for safe quick stops though!

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When I did my 52 I replaced everything.  Lines were already replaced but I did all the cylinders and the master just in case.  Purchased them from a guy in Penn. and they work great.

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Posted (edited)

That guy in Penn. Was undoubtedly me.... I am there for Chryslers @ Carlisle, Spring & Fall Carlisle, Hershey,  Macungie for Das Awkscht Fecht and Wheels of Time, and Allentown.

(I am actually from Long Island, New York -- but am also born in Pennsylvania, which is why I am friendly!!!!!)

Good to know everything is beautiful.....

    Yours, Craig....

Edited by mobileparts (see edit history)

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