Oversized Brake Drums
 

I am working on putting together a set of 1935 Ford mechanical brakes & drums.
There are two different camps when the topic of brake drums comes up.
The warning comes to not use brake drums if turned beyond 12.060 stating it is dangerous. Why?
The folks who have worked on these for years will cite using drums turned well beyond 12.060, none so far can remember a drum failing?

The drums I have turned to 12.100 have about .110 wall thickness.
So is the warning because of drums failing, or overheating, or warping?

Several shoes I have removed have paper like shim material under the lining to compensate for the drum diameter. I have not found thicker woven lining so I have made .030 metal shims to use with woven linings.

Lots more experience here on The Barn than I have.......so do you see any pitfalls with using oversized drums with shimmed linings?
Any one with experience of drums failing?

Thank you!

Re: Oversized Brake Drums
 

Get involved in an accident even if brakes weren't an issue, having drums in excess of the maximum is looking for a lawsuit. JMHO.

Re: Oversized Brake Drums
 

Overheating and brake fade as in no brakes.

Re: Oversized Brake Drums
 

Never have I heard of anyone ever having someone wanting to measure brake drums for being overturned after an accident.

Re: Oversized Brake Drums
 

I’m stuck on the application of a .060 limit to every drum ever made....
How thick are your brake drums after turning?
What is your experience?

Quote from another........
“Most drums are cast with enough thickness to allow 0.090" of wear. In other words, the difference between a drum's diameter when new and its discard diameter is 0.090," but that doesn't mean you can machine a drum right up to the 0.090" limit.

Re: Oversized Brake Drums
 

most machine shops won't turn beyond .060.

Re: Oversized Brake Drums
 

I spent almost 8 years as an investigator for the California Department of Transportation's Legal Division. The last 2 1/2 years as the supervising investigator in charge of all law suit investigations pertaining to vehicle (and other) accidents. It does happen. The California Highway Patrol Multi Disciplinary Accident Investigation Team (MAIT) conducts lengthy accident reviews which focus on all factors that may have contributed to the cause of an accident, including brakes.

Re: Oversized Brake Drums
 

….only because it's ILLEGAL! You kill some baby with that 'old hot rod' and the Momma gets the 'right' attorney involved, they will tear that car apart looking for anomalies, and they'll make the remainder of your life unbearable! DD

Re: Oversized Brake Drums
 

just be careful if youre oversize , you'll need oversize linings to match, dont just buy off the shelf and expect them to work.

Re: Oversized Brake Drums
 

It depends if there was a fatality or major injuries. The police may do it in the case of a fatality or the insurance investigator may do it when there is a law suit.

Re: Oversized Brake Drums
 

That makes it simple. Just don't get involved in a FATAL accident, and just refuse to let anybody file suit against you! DD

Re: Oversized Brake Drums
 

Doesn't even need to be an at fault accident. My son was T boned by a car that ran a stop sign (totalled a fresh restoration of my old 56 Chev pickup) 100% fault of the person who hit him. He was not injured thankfully but even so, the truck was taken to a shop and all 4 brakes were checked and measured. I kept a log of everything done on the truck and that was in the glove box, and everything I claimed I did was checked off as in good condition. If anything was off the insurance company of the person who hit him would not have paid anything and fought it in court. It is what they do, insurance companies have lawyers to do that and the average joe can't compete meaning afford to fight. They (after a year) settled for 30k but they strung it way out on something that was cut and dried, police issued a citation and everything.. It is false economy to use safety issue parts (steering, brakes, tires) that are not legal.

Re: Oversized Brake Drums
 

Some folks worry more that me. My wife was a fatality in a car accident. I followed her car from tow yard to junk yard, to junk yard, to a 'final' junk yard. I can assure anyone, that NO ONE ever came to inspect ANY portion of her car. And, I saw at least two things that I feel were manufacturers defects, that made her accident a fatal one. No one cared. And the insurance company paid promptly. My point being, some of the above posts present possibilities. But, seems to me, very unlikely. New or newer cars, yes, I wouldn't cut corners on drums or rotors. They are mostly inadequate when new, anyway. The shittiest brakes I've ever encountered, have been on modern, near new cars. I live in the mountains, and I've had at least two modern cars where I could warp the rotors on just ONE trip off the hill. But, for our 'old' cars, seems to me there is, and always was, a little extra margin. Obviously, opinion. And, goes without saying, I can predict opposing opinions.

Re: Oversized Brake Drums
 

It seems odd to me that anyone would want to deliberately build a vehicle in violation of the law. This type of stuff is what leads to government inspections to the level of being ridiculous. There are legal limits on how much you can turn a brake drum. If I remember correctly there are drums that can be legally turned beyond .060, but these drums are clearly marked as such.

Re: Oversized Brake Drums
 

California, that just explained it. 🙂

Re: Oversized Brake Drums
 

Doing shoddy work that can be called out after an accident will also give our hobby a black eye. It might also lead to targeted regulations.

Re: Oversized Brake Drums
 

Sometimes it feels good to live in Sweden. No problems with lawsuits :-)
Just wondering where does the 0,60 figure come from?
Is it something Ford said.
Or is it just a safe number that all cars have to use?

Don't know much about drums, but disc's you use the number the manufacturer say.
And its usually "stamped" on the disc.

Re: Oversized Brake Drums
 

If you have an opportunity, take a look at a '40 drum that has been turned past .060. I have some that, according to my drum mic, are .090, .100, one is even .120. These came off old brakes systems.

Even at .090, the metal band is visibly thinner. Why does that matter? A thin drum will heat up much quicker and starts to distort causing brake fade.

My thoughts are, cut corners somewhere else. Brakes are crucial for you and everyone else on the road with you.

Interesting note, the ribs casts into Lincoln and '42-'48 drums are to strengthen the drum outer "band" and to help aid in cooling like at air cooled motor.

Re: Oversized Brake Drums
 

you could have the drums banded.i seen it done on model a drums

Re: Oversized Brake Drums
 

Mr 42,
I could not find the reference and hence asked the same question here. I am not dodging safety just looking for the “why is it”. & what have you done to mitigate the differences. Maybe with 51504bat’s experience with Ca Highway Patrols MAIT team he can provide more info.
I am venturing to guess there are at least a gaggle of early Ford’s with original mechanical brakes and hopefully most have been done safely and stop well. So far no one has offered up any new drums for 32-38 Fords. Agreeing with Tim on drum safety the standard is based on manufactures design and at least with modern drums it is stated for the service person.
Sooooo with out info from Ford/Kelsey Hayes it is fair to ask what is the minimum thickness for a 1935 Ford Drum. At 12.090 the ( “stated maximum” ) drums are about .125 thick.......

So far I have restored the brake assemblies with NOS Ford parts, if you have 2 NOS 1935 drums I’d love to buy them!

Re: Oversized Brake Drums
 

I suspect you'll have a hard time finding any federal or state laws that prohibit drums from being turned to an ID greater than .060" oversize.

Laws will be written to prohibit exceeding the drum/disc manufacturer's recommended minimum thickness, not some arbitrary measurement of .060" or such.

Manufacturer A's drums may only be able to be turned to 12.060", while Manufacturer B's drums may be able to be turned to 12.160".

Re: Oversized Brake Drums
 

Doesn't have much to do with Ford, there are state and federal laws that cover this. This applies to all brake drums (with some exceptions) on all vehicles. Why, because that is the design safety limits. Can you exceed these limits and get the brakes to work? Yep. Just like any safety limit there are designed in margins, the brakes are not going to fail at .061 over. I don't know what the safely margins are on brake drums, but typically safety margins run at least 2x or more. So .120 would work without total failure but would totally defeat the whole purpose of having safety limits.

The thickness of the drum has to do with lots of design elements, one bit one is heat dissipation. A problem with drum brakes is fade. With heavy use the drums heat up enough that they stop functioning correctly. The thinner the drums the quicker that occurs.

There are also issues with the shoes. The more the drum is enlarged over it's design diameter the poorer the match there is the shoe design diameter.

Re: Oversized Brake Drums
 

Seems like we are starting to get wrapped around the axle here with this thread (no pun intended). The bottom line is that there are specifications and limits pertaining to maximum allowable limits for brake drum over sizes. While I'm no expert here is some info regarding brakes which may or may not pertain to your situation.



The Federal Motor Carrier Safety Administration specifies requirements for trucks:
405 Federal Motor Carrier Safety Administration
§ 393.47 Brake actuators, slack adjust-ers, linings/pads and drums/rotors.
(g) Drums and rotors. The thickness of the drums or rotors shall not be less than the limits established by the brake drum or rotor manufacturer.



California (as I'm sure other states as well) has requirements pertaining to vehicle brakes as well:



CALIFORNIA CODE OF REGULATIONS (CCR) SECTIONS 3300 THROUGH 3320]


BUREAU OF AUTOMOTIVE REPAIR BRAKE ADJUSTERS’ HANDBOOK practicable with respect to the wheels on opposite sides of the vehicle.” The adjuster should not certify a vehicle if (1)any drum or rotor exceeds the vehicle or parts manufacturer's service limits, (2)the thickness of the brake lining (friction material) is found to be less than that specified by the manufacturer's service limits, (3) the vehicle fails to stop within the required distance, (4) the parking brake system is found to be inadequate or in operative, or (5) any other condition is found that would make the service braking system unsafe.


The key here is the manufacturer's specifications or limits. Seems clear to me, if your brake drums exceed manufacturer's you are pushing your luck and endangering others.

Re: Oversized Brake Drums
 

In Illinois back in early 1980's, two folks were killed when a persons brakes failed and they were run over.
The person driving was eventually jailed. It was quite the sensation back then making a lot of the national news outlets.
It also changed a lot of ways of doing business.
No more oversize brake shoes were sold and no more "lesser quality" aka "economy" shoes / pads were sold to those trying to go "cheap". Only pads / shoes manufactured to the minimum required by the car maker were to be sold after that debacle.

So, now you have heard...

Re: Oversized Brake Drums
 

All this has me wondering. Is it possible that some unenlightened judge and jury might find someone driving a car with mechanical brakes liable for using outdated technology? In this litigenous society with super aggressive lawyers I wouldn't be surprised.

Re: Oversized Brake Drums
 

whether restoring from the ground up, or just trying to put an old car back on the road, i'm sure all of us are going to at least check, and go thru the brakes. but, when i look at all the badly worn drums in my stash, it seems they didnt much care. they just put new shoes in and out the door it went. most of what i have are .100 and bigger

Re: Oversized Brake Drums
 

So true. I have a few that are so badly grooved, there must not have been any lining material left and the rivets there doing the stopping.

I was just thinking to myself the other day, why in the world am I holding on to these things?

Re: Oversized Brake Drums
 

I just bought a complete rear axle for my '92 f350 dually from a wrecking yard. The linings were worn off long ago and the bare shoes were getting REALLY thin. Thankfully, I had just done a complete brake job with new drums on the axle that I was replacing. Who drives around like that in a loaded flatbed????? In other words, this type of hackery is still being commited today.

Re: Oversized Brake Drums
 

I have read on the HAMB or here that there is a company that will reline any drum back to new diameter. They were expensive but it might be with looking into.

John

Re: Oversized Brake Drums
 

This is the one. Also in a thread here on the "Barn"...

https://www.jgrelining.com/

Re: Oversized Brake Drums
 

Brakes can fail for many reasons, even driver ignorance. One big no no that people have done is compression fittings on brake lines. A parts store did not want to sell me some compression fittings and a piece of brake line until I explained I was fixing my transmission lines.

Re: Oversized Brake Drums
 

Pay attention to what V8 and others have advised. Don't cheat on your brakes.
Today's lawyers will hire "old car restoration" specialists who will do an "automotive autopsy", find faulty parts and even recreate a visual of the accident.

Re: Oversized Brake Drums
 

In the same light, might that same ignorant judge.....scratch that....."unenlightened" judge also find your 'old-timey' drum brakes on the front of your '51 as qualifying for "outdated" also, in view of the fact that his wife's Mercedes and virtually all modern cars (that he has seen at the Country Club) have anti-skid & disc brakes, at least in the front? DD

Re: Oversized Brake Drums
 

Maybe, but drum brakes are still currently used on some models; mechanical brakes are not.

AND, if you are right, we are lost because we don't have ABS.

Re: Oversized Brake Drums
 

This is really good info that I really appreciate. I've just chatted with Don, the owner, and now I'm on the hunt for 35 drums with less regard for their size. Thank you.

Re: Oversized Brake Drums
 

I bought my Ford pickup 27 years ago. It has disc/drum brakes.
Will there come a day when my insurance company can simply decide, "your truck's too old for us to insure any longer" as a daily driver even if all components function as new?

Re: Oversized Brake Drums
 

Let us hope not. They've enough control as it is.

Re: Oversized Brake Drums
 

'35 drums were one year only in the US. So good ones measuring less than 12.060" diameter, in the area where brake linings contact the drums, are difficult to find. Having/owning a number of '35 vehicles, I hold on to every good one I get my hands on. If the time ever came when I couldn't find good original '35 drums, I would not hesitate to use good original '40-'48 drums, along with ring spacers that properly support '35 wire wheels.
The 12.060 dia. limit was probably dictated to all licensed brake repair shops by law.

Re: Oversized Brake Drums
 

Maybe Change the spindles to later and use the repoped 40 drums ,

Re: Oversized Brake Drums
 

over sizing brake drums has been a subject of great debate ever since they where invented as a licenced mechanic i use manufacturers spec as to max oversize and it stands up in court every time these days with 18 wheelers it costs more to oversize than to replace with new ones as for our oldies parts no longer grow wild so im an advocate of rebuilding drums with metal spray or sadly up gradeing to modern types lets face it i would rather stop in time than have a drum shatter and be a filler for a pine box