VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 Turning Brake Drums?

What is the story on turning 1931 brake drums? Should you do it, is it necessary, and if so what is the minimum thickness you can cut them to? My drums are fairly smooth so I am not sure if it is needed. I have the style of pads that squeek when they get hot and I am tired of it. I am going to change to the Filling Station pads. Does any one have any information on this?

The pressed steel drums used on pre-hydralic brake Chevrolets (and 1936 Standards) can not be turned on a drum lathe as the later cast iron can.They would need to be ground.Also they are so very thin to begin with and I would not suggest doing anything to make them thinner.If it were mine I would usea coarse sand paper or emory cloth to scuff them up a bit....and it common for them to squeal under some conditions.

If you change to the pads provided by the FillingStation I would be interested in the results.I am also having the same problem and though they stop good the noise is in my opinion excessive.My lining is new non asbestos "woven moulded" which seems to have a high metal content(probably brass) and the drums have been lightly "ground".After 3000 miles the drums look as they did before grinding,quite smooth and slightly worn.It is my opinion that the high metal content of the lining is causing the noise.Perhaps someone from the Filling Station or someone who has used their reline service could advise as to the construction of the lining they are using and their satisfaction with it.

The steel drums are usually out of round. I turned mine just to the point of truing them. In any event, I'd resist going more than .030 past standard. There is no turn spec for these drums. I do have some old literature where they refer to turning these old drums. They can be "turned" and not ground by competent machinest on a good drum lathe. I sold brake parts for over 20 years and I watched our guy turn them countless times. Linings have really changed over the years. What I like to use is the "heavy duty open woven" on the front shoes. This is basically your Model "T" type lining, just kevlar with no resin base. Very high friction, great for front where the cables are always going out of adjustment. These use to be a straight asbestos material. Kevlar is an adequate substitute. For the rear I like to use non-hydraulic wire back. This is close to an exact replacement for the OEM material. Known also as a molded lining, the bonding agent today is a fiberglass material, also an adequate replacement for the prior asbestos material used. This lining wears better than the HD open woven in the front, necessary because the rears with the rods are usually more closely adjusted than the front. I guess I'm saying you do more stopping with the rear than the front, just the opposite of modern cars. Brass chips in brake linings or pads are a "wiping agent" there to brake the glaze build up on the drums or rotors to prevent squeal. Mostly, any more zinc chips are used.

The noise is caused by the drums vibrating when the linings grab and release when applied. Your best option is ear plugs! Softer linings may help and harder linings will make stopping distance longer and may help or make the noise worse. Adding springs to the outside of the drums may also help but keeping them in place is a problem.

I know that the brakes on my '31 are working well then they make noise so I am happy to hear them.

Chipper , so is the guy in the car ahead of you happy to hear the noise..! Hearing your brakes being applied is a sooothing sound! The screaming of your passangers isn't quite the same sound!
My passanger rarely screams, but the sound of toe-nails scrapeing the toe boards and that sucking sound of a rapid intake of air accounts for something.

Is it possible that the noise is a result of the drums being to smooth and I should ruff the surface? I have a spray that I put on the shoes and drums and it lasts for a few hundred miles but then the noise comes back. The spray is a metalic material. I may try the sanding of the surface unless someone can tell me why I should not.

After experiencing squealing brakes on my Dad's 1950 1/2 ton Chevrolet truck, I removed the brake drums and scuffed the lining contact surface with 80 grit sandpaper with the scratch marks running across the width of the lining contact surface. The deep scratchs might not "look right", but it stopped the squealing. I did this about 30 years ago and the squealing has not returned.

All brakes do indeed squeal, the trick is get them to squeal out of the range the human ear is able to detect.

All brakes do indeed squeal, the trick is get them to squeal out of the range the human ear is able to detect.

30-32 cars and trucks came with the new style "Huck" brakes. They were used in a lot of GM products. I once helped a guy with a 34 Cadillac get his car to stop. Same brakes as ours, just larger. It had a vaccum booster to help pull on the mechanical rod to stop the vehicle. GM stayed with the "Huck" brake until, I believe, 1951. Then they went to the duo-servo design, as did they other big 3 on most models, when patent rights ran out. The duo-servo had a single star adjuster that made brake adjustments simple. This design, still widely used on drum brakes today, was easily adaptable for a self-adjusting mechanisim. The 30-32 Chevys have a S-cam adjustment to take up for normal wear of the linings and drums. Often overlooked in getting these brakes to function properly is the "centering mechanisim". With new linings and or dressed drums, this centering ajustment must be done before the final S-cam adjustment is made. It probably won't move until take it completely apart, clean out all the rust and lubricate it sparingly with silicone grease. Now your newly lined shoes are centered on your freshly dressed drums. Minimal movement of the foundation brake parts is part of the formula to get stopping power with reduced squeal.

No question about turning drums would be complete without talking about arcing the brake shoes to fit the dressed drum. First you can't arc standard size. A new standard drum and relined shoes should make perfect contact if the lining is installed correctly and the drum is in fact round. The shoes also have to be correct ie not bent or distorted. Arcing would be to restore full contact to standard lining size to a drum turned to less .060. At .060 it becomes single oversize on passenger and light truck drums. In this event, you'd want to get single oversize linings, if available, or a brake shop can put a .030 shim between the shoe and the lining. Done properly, this is an acceptable practice. Any drum turned less than .060 can have the shoe arced to fit. In reality, arcing is becoming a lost art and with lung disease worries, mandated dust recovery equipment too costly for small shops to comply. A standard shoe against any drum turned less than .030 will do just fine and "wear" in if you treat your brakes gently at first. If my car fell in the area between .030 and .060, I'd just treat my brakes extra careful and be aware that there'd be an extended break in period. During this seating in period, shoe contact would be minimal and prone to glazing due excessive heat build-up at point of contact that could lead to excessive squeal through the life of the lining if the problem were not attended to.

For mechanical brakes, the softer the linings the better. Your foot and leg just don't generate the force of a hydraulic brake with even power assist being standard today. The OEM style "mechanical brake wireback" actually comes in a roll, I believe 25ft long and in widths from 1" to, the widest I've seen 4". It's a lot of work for a brake shop to install this lining on your shoes. For our cars, the 2" is trimmed to the proper width and cut to length. Then from the center of the shoe out it is clamped in place and each rivet hole is drilled and countersunk, all the while, keeping the lining tight up against the table of the shoe. Then come the rivets. Today, most are brass plated steel, but in the old days, solid brass rivets were used, this saved your drums if the linings got so thin the brass rivets, would rub up against the drum, minimizing the damage. But this too would be to no avail if you kept going until the shoe table tore into the drum. Some specialty stores do still supply solid brass, it's just becoming less common. This roll lining could be fitted to shoes for drums from say 8" upto whatever size. Just to show the difference in hardness between this lining and moulded hydraulic, a pre-moulded hydraulic lining for an 11" shoe would break if you tried to rivet it to a 10 1/2" shoe. I've seen some good brake shop guys heat the linings with a torch and get it to bend enough to get it on, but this is not recommended. It's easy to see why our cars would just keep going if this lining was put on and just glaze over and squeal like crazy.

Thanks slow learner.

The reason for the "wirebacking" is to give the rivet a place to hold the lining to the shoe, the lining being too soft to hold by itself. There is also a "hydraulic type wireback". Whether it is still made or not I don't know. Our shop never bought it or intalled it, we had no use for it. It was the very first type of hydraulic brake lining, made like it cousin, the mechanical style. Installed in the same small garages and, in the early days, kept quite separate. I know it was sold at least until the 80s. Small garages bought the stuff to put on cars and light trucks to continue a service they has "always" provided. It covered all sizes as long you had the right thickness and a width that could be trimmed, the shop could get the job out, with a minimum inventory. Not being a traditional moulded segment, it would bend to cover a wide range of possible drum diameters. For a hydraulic application, it was pretty soft and would wear quickly. But it had good response and squeal was seldom a problem. Exchange shoes was just a better deal all around and today, prevails. I had a few shops that provided this service. What we have to be careful of is that this stuff doesn't end up on our shoes because it is too hard to develop the friction to stop our cars and would be very prone to squealing. If I were to see a piece of this stuff unmounted, the only way I could distiquish it from the "mechanical" variety would by its flexiblity.

Maybe more of the "hydraulic" type wireback got mixed in with the "mechanical" than we think, hence the bad reputation mechanical brakes have. The other type of "mechanical" brake lining is the open woven. This type preceded the moulded and has no "resins" or fillers. In its time, it was just woven asbestos with some brass chips as a glaze breaker. This lining has a higher friction rating even than that of the mechanical wireback. Today they use "kevlar" in place of the asbestos and will use some soft metal as a wiping agent(glaze breaker). On 30-32 Chevys, the front and rear brakes are designed to do a 50/50 share of the stopping. Because the front cables stretch and are flexible, they just don't apply the same amount of pressure to the shoes as the rears do, with the rods. (That is the beauty of hydraulic brakes, the even distribution of pressure to all 4 corners.) Therefore the brakes don't quite perform the way they were originally designed to do. To help bring the some of the original design intent back to our brake systems, I like to use the HD open woven on the front shoes. Because it develops higher friction with less pressure, it allows the front shoes to contibute more, in spite of the flexibilty and stretch inherent with the cables. Also, HD open woven is even less likely than "mechanical wireback" to squeal. The only drawback is that it probably wears twice as fast as the wireback. But for the safety alone it is a worthwhile trade off even before considering that these cars don't really rack up all that many miles anyway. Bill, thanks for the reply. I hope other people are getting something out of these posts. I don't mean to sound like a know-it-all, but this is a subject I know a little about.

Maybe more of the "hydraulic" type wireback got mixed in with the "mechanical" than we think, hence the bad reputation mechanical brakes have. The other type of "mechanical" brake lining is the open woven. This type preceded the moulded and has no "resins" or fillers. In its time, it was just woven asbestos with some brass chips as a glaze breaker. This lining has a higher friction rating even than that of the mechanical wireback. Today they use "kevlar" in place of the asbestos and will use some soft metal as a wiping agent(glaze breaker). On 30-32 Chevys, the front and rear brakes are designed to do a 50/50 share of the stopping. Because the front cables stretch and are flexible, they just don't apply the same amount of pressure to the shoes as the rears do, with the rods. (That is the beauty of hydraulic brakes, the even distribution of pressure to all 4 corners.) Therefore the brakes don't quite perform the way they were originally designed to do. To help bring the some of the original design intent back to our brake systems, I like to use the HD open woven on the front shoes. Because it develops higher friction with less pressure, it allows the front shoes to contibute more, in spite of the flexibilty and stretch inherent with the cables. Also, HD open woven is even less likely than "mechanical wireback" to squeal. The only drawback is that it probably wears twice as fast as the wireback. But for the safety alone it is a worthwhile trade off even before considering that these cars don't really rack up all that many miles anyway. Bill, thanks for the reply. I hope other people are getting something out of these posts. I don't mean to sound like a know-it-all, but this is a subject I know a little about.