brake max o/size

aussie merc

aussie merc

Well-known member
Part 1 cant seem to find a listing for max o/size on wide five brake drums have heard that .060 was max but others say they will take .120 without problems just dont need to create more problems also cant find any cross reference from factory linings to sae codes [ee,ef,ff. etc] as even the factory fitted two different linings in each wheel moulded to the front [long shoe] and woven to the short/rear shoe i suspect the woven was the softer of the two [and we know henry wouldnt have bought two grades of lining if it wasn't absolutely required] Part 2 any changes required other than new flex hoses when fitting a booster as the system pressure will go from 500psi@ to 1500psi@
 
Just a hunch but I suspect max diameters were introduced after our era of Fords were made as safety mandates became more prevalent. That doesn't mean there isn't a max diameter, but common sense must prevail. I'd be reluctant to use something at .120 over though.
Personally I avoid skimming drums as a matter of habit. I just do it when necessary, and then only the absolute minimum to take out the worst of the high spots.

Common sense.

Mart.
 
Mart said:
Just a hunch but I suspect max diameters were introduced after our era of Fords were made as safety mandates became more prevalent. That doesn't mean there isn't a max diameter, but common sense must prevail. I'd be reluctant to use something at .120 over though.
Personally I avoid skimming drums as a matter of habit. I just do it when necessary, and then only the absolute minimum to take out the worst of the high spots.

Common sense.

Mart.
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I'm with you Mart. At .120" oversize, there isn't much drum remaining. Yes, lots of guys, do lots of things. That in itself doesn't make it correct or smart.
 
I looked through motor vehicle regulations in various states at brake drum sizes, .060 is mentioned as maximum unless the drum is marked differently, with no markings some states revert to manufacturers specifications.
Some states allow a cracked drum if it is banded, other states call it a crime to even offer an over .060 drum for sale.
I had .040 drums for me 36, though that was too large for a proper restoration, searched and found NOS , my rear drums are .025, have been looking to replace them too if I find new ones.

You talk about tripling the brake pressure, the thinner they are the easier they will distort under the pressure,
 
There are likely a few shops that sleeve drums back to size but I wouldn't do that unless a person has unobtanium parts. Sleeving will take procedures to lock them in place so it would not be cheap. There are usually some good ones out there somewhere.
 
G'Day mate,
For what it's worth, I had .120" over drums on my Roadster with mechanical brakes and it never had a solid pedal.Plus as the drums got hotter the pedal got worse. I have been lucky to find four NOS drums for my rebuild.
Regards, Gary
PS, Have a great Christmas and New Year
 
you did not say front or rear drum you can band the drum its no big deal to have machine shop make them. they mike the drum od & make the band a few thousands smaller then you heat it a& drop it on. in the usa its ez to get an other drum. not so in oz
 
Comparing modern brake drums with those from 80 years ago and suggesting modern spec. for Max size is a bit difficult to reason. If I remember correctly modern spec. often do have the Max. size for regrinding at over 0.060 but if the drum is at 0.060 there is allowed one more regrind which can take the drum out to 0.090 Most of the guys doing regrinds take 0.030 off unless asked otherwise.
 
Man, all of the things to play it safe and conservative, I'd certainly hope it would be one's brakes.

Why fool around and push it to the outer most limit? How much is your life, someone else's life or your car worth?
 
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Terry said:
Comparing modern brake drums with those from 80 years ago and suggesting modern spec. for Max size is a bit difficult to reason. If I remember correctly modern spec. often do have the Max. size for regrinding at over 0.060 but if the drum is at 0.060 there is allowed one more regrind which can take the drum out to 0.090 Most of the guys doing regrinds take 0.030 off unless asked otherwise.
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Terry, as you'd mentioned, it is difficult to compare "modern" drums to our old Ford drums.
For many years modern drums have the maximum diameter cast directly upon the drum so there is no mistake / no excuse for exceeding the lawful limit.
Not to mention that a drum produced for one particular vehicle will not necessarily be produced the same for another vehicle.
Then there is modern design to be considered. The vast majority of drums on modern cars are manufactured as light as possible. Cost and weight savings most likely the main reasons. It has been years, perhaps decades that most drums are considered "throwaway" by a knowledgeable repair person. Often enough, no turning possible as they simply don't have enough material to turn and still remain within legal specifications.

I speak from some "authority" on this matter having been ASE certified in brakes for approximately twenty years. Then and now, I would not consider turning a drum past the legal limit. No how, no way.
 
Section 7G: Used brake drums; servicing, sale or grinding; prohibition

Section 7G. No person shall service, install, give away, or sell or offer for sale, for use on a passenger motor vehicle, a used brake drum the interior diameter of which exceeds sixty-thousandths of one inch maximum oversize, nor shall any person turn or grind a used brake drum for use on a passenger vehicle to an interior diameter any greater than sixty-thousandths of one inch maximum oversize. Whoever violates any provision of this section shall be punished by a fine of not more than five hundred dollars. No person shall sell, offer or expose for sale, or have in his possession with intent to sell any brake drum or brake disc designed for use on a motor vehicle, which drum or disc was manufactured after January first, nineteen hundred and seventy-one, whether as original or replacement equipment, unless such drum or disc is permanently and plainly marked to clearly indicate the maximum safe diameter or minimum safe thickness to which it may be worn, ground or turned; provided, that after said date no person shall install on any motor vehicle or trailer any brake drum the inside diameter of which exceeds said maximum safe diameter nor shall any person install any disc brake rotor the thickness of which is less than said minimum safe thickness.
This is Massachusetts law. —- I haven’t seen markings on the new replacement model a drums saying max oversized so technically they aren’t legal in Massachusetts also.
 
Thank you Kurt.
I knew this went back a number of years and thought all the way into the 70's. Still, I tend not to relay on my memory as much as I once had :)
There was a time, for certain into the early 80's, that places sold oversize shoes to circumvent the drum restrictions.
The "better" parts houses would not sell this crap. My guess? They didn't want to get in any possible involvement of an accident stemming from "iffy" brake parts.
I also recall a time when a guy could get cheaper disc pads than what had been factory installed. At least in Wisconsin, that stopped decades ago.
Same reasoning. Engineered safety.
 
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