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JSeery · 07-30-2020, 08:12 AM

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.

07-30-2020, 08:12 AM	#22
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	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.