Brake drag

[Frango100]

Owning a classic car is quite an adventure and every time something new. (read, new problem). Miraculously the tick in the engine disappeared again and the engine runs nice and quiet.
But today, while cruising in town, the brake pedal suddenly felt very hard and i could feel that the brakes where dragging. Stopped at the side of the road and smoke came from the front left wheel, while the smell of overheated linings entered my nose. After waiting a few minutes with the engine off, the pedal suddenly felt normal again and of i went. While braking now, the car pulls to the right, making me think that the left front brake is not braking (enough).
Any idea what could have caused the sudden hard brake pedal?
Needs adjustment of the master cylinder?

[jopizz]

If the brakes worked fine before then I don't think it's an adjustment issue. If you have the under dash booster a hard pedal could indicate it's starting to go bad or you have a vacuum leak. Anytime one of the brakes starts smoking you need to take it apart and do a visual inspection. I've had brakes get so hot that it melted the inside of the rubber brake hose. That would cause your left front brake to no longer work which could be why it's pulling to the right.

John

[Frango100]

Driving home from work today, i was thinking about what could be the reason for the dragging brake(s) and came up with the following theory: The master cylinder reservoir cap seems to be non original and as far as i remember, there is no air bleed hole of any kind in that cap. Since there was no seal on this cap, some fluid was leaking from under it. Just put a rubber seal on it this week, to prevent the spill. Can it be that, due to thermal expansion of the fluid, and no way for air to go out of the reservoir, that there stays pressure on the fluid, causing the brakes to drag? Could pressure buildup in there also make the brake pedal hard?
I will check the left front brake tomorrow and also check after some driving, if there is air under pressure in the reservoir.
I also felt each wheel cap by hand shortly after the smoking incident, and they all felt warm, but not really hot. So it looks at least that all where braking with more or less the same force.

[byersmtrco]

You might have lost a shoe return spring.
I think I have that going on with my rh/rr
wheel.
Smoke coming from the wheel?
Not good. Plan on the drum having heat spots.
With luck, they'll machine out . . . If not you'll
be buying a drum.

[Frango100]

I had no time to look at it today, will see lateron this week and let you know.

[Frango100]

So today i took the left front wheel/drum of and didn´t see any signs of overheating in the drum, nor the shoes. The only thing not ok was the aft shoe friction material cracked at the outer rivets. No pieces of friction material missing, so don´t think that this has anything to do with the brake drag. Ordered new front brake shoes with glued friction material, which will hopefully come later this week. Before dismantling, i checked the brake function, and it was working fine.
Will have to see after the car is down on the ground, if the brake pedal can get jammed in some way, preventing it from returning to neutral after braking.

[simplyconnected]

Bonded (glued) brake linings are ok. I had only one fail from non-use. The lining rusted off the shoe and wedged itself in the drum on a Chrysler car (not that the brand matters because Chrysler purchased their brakes, like everyone else).

A failing booster produces hard brakes (as John pointed out). Check it out. - Dave

[Frango100]

When trouble shooting on the brake drag and changing the front brake shoes, i found quite some corrosion inside the brake cylinders and a slight leak on both. New cylinders (4) came in last week and i will be changing them soon. Also got a revision kit for the brake master cylinder, which i will change at the same time. Hopefully after this the brake drag will be solved.

[Frango100]

Update: front brake cylinders are changed. The master cylinder is out and now painted, tomorrow I can put the new parts in. I also took the vacuum assist unit out. Seeing the paint on the bellow, it was not removed during the restoration. Wonder how this restoration was done.
Took the whole vacuum assist unit apart and will paint it again. The bellow looks still fine, even though the rust on the metal sides made some imprint into the surface. I red somewhere that if the brake pedal returns slowly, that the problem most probably is a clogged air filter. The filter seems to be a sintered bronze one, so will clean that one out as well.
I will now also tackle the paint damage in the engine compartment, due to the brake fluid leak.
Then changing the rear cylinders and checking the rear brake shoes. How about the rear wheel bearings, can´t they be greased? Seems that they sit on the dry side of the rear axle oil seal.
My radiator is out for repair as well. The radiator guy, who is working with this for 40 years or so, told me that the coolant attacks the solders and will create leaks over time. Is there any other anti corrosion additive available to mix with the water?

[Yadkin]

Brake fluid makes a pretty good paint remover.

The rear wheel bearings are not greased by the rear end fluid. They are outboard of a grease seal and retaining ring, and permanently lubricated for life, theirs not yours. A rebuild kit includes the bearing, the seal and the ring. See the picture of mine rebuilt, along with a new repair bushing here. Hopefully your axles aren't corroded at the seal area like mine was, but if so can be repaired by an expert.

The axle is retained in the carrier by four bolts on the cover plate, then use a slide hammer to pull the half shaft assembly out. The new retainer has to be pressed in. Due to the length of the shaft few shops will have a press long enough, so be sure to make some phone calls with your required dimensions.

[Frango100]

Putting the master cylinder together today. The 1958 service manual shows a bumper ring. This ring was not on the old kit and its also not inside the new revision kit. Seeing the size, is this bumper suppost to go inside the piston and will it rest against the push rod?
I compared the old and the new parts and also see a difference in the depth of the hole inside the piston, where the push rod enters. The previously installed kit was made in Brazil (at least the seals and dust cap, where it is imprinted), but i suppose that the kit from Raybestos, which came from the USA, should have the right size.
I should have paid better attention to how the whole thing was mounted before, because the manual drawing is not that clear. The valve seat is that just a rubber ring? I have left over a thin copper, shim like ring, which i thought was in between the cup and the piston, but the drawing doesn´t show it. Is this one suppost to be there?

[jopizz]

My advice is to only use what came in the latest rebuild kit. There were many revisions over the years as the kits were reengineered and parts were eliminated. I've never seen that bumper in any of the rebuild kits or in any rebuilt master cylinders I've purchased.

John

[simplyconnected]

Are you taking pictures as you disassemble? Pictures are an excellent form of reference because they might show things you didn't notice.

DOT3 brake fluid is glycol-based (like antifreeze). It is water-based and can easily be washed off with plain water. If left on paint long enough, DOT3 will eat through.

If you need to remove a rear axle and don't have a slide hammer, simply use a tire that is loosely held on by two nuts. This allows you to jerk the tire with enough force to dislodge the axle. - Dave