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Taylormade

Brake Drums

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The brake drums on my 32 DL have been sitting for over 40 years. I took one of the front drums down to the local auto shop. I wanted to know if there was enough meat left to turn them. Nothing looks scored and the rust pitting doesn't seem too bad. They looked at them and said they looked a little thin, but would need to know the factory specs as to how much they can be turned before they reach the point of no return. I checked the owners manual, the only "shop manual" available, but they list no information. Anyone have the specs or a source where I can find the information? If they are too thin, is there any way to save them? I seriously doubt I can find any in better shape. Is it possible to have an "inner band" installed, like a cylinder liner, or am I over-thinking the problem? Any help would be appreciated - especially from someone with 4 NOS drums still wrapped in the original factory packaging.:D

These are drums for wire wheels.

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Take them to a shop that is not so picky.

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ditto! Find someone who knows who Ted Mack was.

If he knows who Major Bowes was, you better stand behind him while he turns the drums in case he falls!

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Maybe the humor is going right over my head - as it often does. Obviously Ted Mack/Major Bowes refers to amateur hour. Me, or find an amateur that will turn my possibly dangerous drums? This car will be a driver, and I don't intend for me or my wife to be injured half-assing the brake system. No offense, just looking for some help here.

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Brake drums from this era can be resprayed with metal,either mild steel or cast iron can be applied to a mild steel drum then machined to size

If the drums run reasonably true then they are usually serviceable. most drums cant be turned down as there enough metal to do so

hope this is slightly helpful

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Sorry Taylormade.

What I meant was you should find an older mechanic who is more familiar with old drums. Someone who remembers Ted Mack would have to be about sixty years old.

Major Bowes went off the air in 1947. If they remember him, they would have to be around 86 years old. I meant that would be too old to be working in a repair garage.

Again, sorry for the confusion. I was not disrespecting you in any way. I wouldn't do that.

Dwight

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I would get a few measurements of similar era drums and compare that with what you have.

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Try feeling the drums for a wear ridge. If the drums look O.K. the best course of action is to fit them and road test the car.

It of course it depends on whether the car is likely to be used on any long descents as brake fade can show itself with thin drums overheating.

You should find the front drums will show more signs of wear than the rears. I would say a drum is in need of skimming (if new replacements are not available) when it is worn up to 0.005" . Any more than this then it will need to be metal sprayed and turned down. For this you will need the correct original measurement.

Sometimes drums are found to be oval - this manifests itself in brake judder. Contrary to popular belief, drums in this condition will not have worn oval but may have been knocked out of true through rough handling or distorted through the use of heat treatment. Again 0.005 is the max.

Of course, another wear indicator is when the drum has "bell mouthed" and has worn more towards the outer edge than the area adjacent to the hub - this is a sign of worn anchor pins, holes or bushes.

Should you wish, you can get an accurate picture with a measuring gauge which can be purchased quite cheaply but to check for thickness you will need the correct manufacturers figure. For ovality or scoring; if you are in possession of a lathe then mount the drum on the face plate (or use a modified hub with good bearings mounted in the chuck) and check the set up with a dial gauge. Heat crazing (or hairline cracks) are quite often found and so long as they are not deep, skimming will deal with them. Don't take off more than 0.002". If more than this is needed to true up then the drums are probably too far gone and will need metal spraying or replacing.

Ray.

Edited by R.White (see edit history)

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I use a place in Rochester New York. Rochester Clutch and Brake. They have trued out of round drums for me in the past. I am not sure if they do spray welding, but they do have a great deal of info on the original manufacturer specs. As a side note, they are great with clutches. They can rebuild and original clutch disk if all you have left is the splined collar. Great guys to work with, good turnaround. If nothing else, a good resource to ask questions.

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No problem, Dwight, I just got up on the wrong side of the bed, I guess. It's hard to determine if these drums have been turned beyond their usable limit and I can't find any information that would help me to determine this. Is it the remaining thickness of the hub wall or the inside diameter of the drum that makes the difference? I'll post some photos when I get home tonight - they may help.

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I am interested in this too as my '33 Plymouth drums could use some attention.

I don't think there is any marking on the drums for the maximum they can be turned. I've heard 0.100" from some sources but there are some 1940s training material from Chrysler that implied 0.060" to me. And if your shoes are not arced to the diameter of the drum it will not be possible to get a good adjustment. In the old days you could apparently get thicker lining than standard to work with the 0.060" oversize drums. Arcing standard thickness lining to match a 0.100" oversize drum will result in a pretty thin shoe.

Brake drums from this era can be resprayed with metal,either mild steel or cast iron can be applied to a mild steel drum then machined to size

If the drums run reasonably true then they are usually serviceable. most drums cant be turned down as there enough metal to do so

hope this is slightly helpful

I've heard this. I don't know about the '32 Dodge, but for the '33 Plymouth the drums are Centrifuse design: A steel drum with a cast iron liner. Since metal spray has similar characteristics to cast iron, it seems like this would be a reasonable repair. But have been unable to find anyone in the US that would do it for me.

By the way, as of a few years ago the manufacturer of Centrifuse brake drums was still in business. They make drums for the larger over the road trucks nowadays and were unable to assist me in information about refurbishment or replacement of my drums.

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That's an interesting question, Taylormade. Strictly speaking, it's the inside diameter and can be measured with a type of micrometer called a Wingauge. I know that with commercial vehicles, if the drums have been skimmed then oversize brake shoes may be fitted. As far as I know, with cars, if the limit has been reached it's the thickness of the drum which is cause for concern. Brake fade is either when the shoe lining has passed it's maximum operating temperature or when the drum expands beyond the effective reach of the shoes. In the first case the linings may simply be replaced; in the second the drum should be replaced or restored.

Your problem is not knowing the original internal diameter. It may be useful to compare the measurement of the rear drums as they often show only little wear in comparison with the fronts but obviously on a car of this age there can be no guarantees.

Best of luck.

Ray.

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Sorry for a bit of bad news....your drums are for 1932 DL only according to the Master Parts Book.

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Have you tried over at the H.A.M.B. for the drums? You gotta know those guys are not using the originals.

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The H.A.M.B might be a possible source, though most of the cars they work on are pretty much trashed before they get them. I'd have to find an idiot who is about to destroy a nice, original DL with very low miles. They are, unfortunately, out there, so I'll give it a try.

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What else is new? Apparently they decided to reinvent and then scrap all 32 technology that year! ;)

Automobiles were one of the high tech industries of the era. One characteristic of a high tech industry is how rapidly it changes. Seems like there was about as much change every year in the period leading up to perhaps the mid-1930s as there is today in small electronics. Think how obsolete last year's smart phone seems to the folks that are into that type of consumer product. . .

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Taylormade, The fellow at the brake place well may have thought your drums "look" thin. They all do. I know of nobody that can determine if a drum is .002 - .025" run-out by just looking at it. From what you describe in your first posting, your drums sound like they're probably OK. Only a measurement will really tell and I know you are looking for that factory specification. I do wish I could help with that. Many older autos that I've come across from the '30's that were on the road 'till the '50's had paper shims installed under the linings. These shims weren't cut out of junior's math homework with mom's kitchen junk drawer scissors either. They were a perfect cut and punch job, I can only assume they were installed by a brake shop, to take up the slack of worn but usable drums. Many cars also used brake bands on the outer surface of each drum to help fading from heat expansion. Some were steel bands, pressed onto drum, some were large spring bands that I think early Buicks used. Dwight Romberger would know this. He owns a '30. With a good lining and perfect adjustment, possibly with the shim paper, I say try them out on your car. I'll bet they'll be OK.

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I'm not real sure why you want your drums turned. You say the car has set for 40 years, but the drums do not have grooves and aren't rusted real bad. You've already found out they are one year drums and being for wire wheels would also effect the rarity.WHy not drive the car and see if they need turning.I've found warped drums that are turned often warp easier again because they are now thinner.

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I'm not real sure why you want your drums turned. You say the car has set for 40 years, but the drums do not have grooves and aren't rusted real bad. You've already found out they are one year drums and being for wire wheels would also effect the rarity.WHy not drive the car and see if they need turning.I've found warped drums that are turned often warp easier again because they are now thinner.

I agree with this. If they don't show much wear or grooves, they should be o.k.

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I also agree with this. You don't really know you have a problem until it manifests itself. I would also like to suggest that even when/if it is needed, skimming is a short term fix. Any wear will show itself by leaving a ridge; somewhat unlikely in this case I would suggest.

Ray.

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If my 35-year-old memory serves me right (we'll see)...at least the left rear drum has a bit of a ridge.

How much? I never measured.

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Often overlooked are the return springs which can weaken with age or over stretch through incorrect handling. Worn parts elsewhere in the system may also cause the brakes to bind; wearing down the drums before their expected lifespan. This can also make them difficult to remove as I have found on occasion.

Ray.

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I agree. I think you're worrying about nothing. I would just set the brakes up as if the drums were new and drive it. The shoes will remove the rust is a short time. I wouldn't take any material off them. I have several vehicles with original drums from that era and have never found any to need truing. Besides this a 45-50 mph. car and the chances of you needing to slam on the brakes in an emergency are remote. The stick shift tranny will do a lot of the slowing down. You will tend to drive the car with much greater care then you drive your daily driver and keep much more space between you and the car ahead. You'll also find yourself looking for a different path if the traffic gets heavy. Even to pulling off at a McD's in a rainstorm to let it pass. Been there,done that.

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