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I have a number of brake drums from 51-54 Chevys (5.809). I would like to learn the condition of these drums to determine if or how many times they have been "cut". I cannot find any reference or data to help me ascertain their serviceability. I am sure the the drums are considered "serviceable" by measuring the inside diameter and comparing that to a chart of acceptable measurements. Can anyone point me toward the source for this information? I would appreciate your assistance.
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All I can find says 11" diameter but it doesn't specify ID or OD. The manual says a max of .060 when turning but doesn't say what factory was. Someone will probably be along with the info you need.
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1938 HB Business Coupe
1953 210 Sedan
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Check page 5-18 of the ‘49-‘53 w/‘54 supplement shop manual. The limit is .060”.
The 1954 Chevy specifications state the the brakes are 11”.
Last edited by Rusty 37 Master; 10/15/23 10:09 PM. Reason: More info
Rusty
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Shade Tree Mechanic
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Tiny & Rusty,
I concur with your observations that within the 49-53 manual, on page 5-19, the chart indicates that the BRAKE size is 11 inches, however, that would seem to be an ambiguous bit of information. Is that measurement indicative of the nominal brake shoe dimension, or could it be the inside diameter of the brake drum? I would think that when dealing with a maximum of sixty thousandths of an inch allowance for resurfacing of the wheel, it would be imperative to be certain of the starting point.
Thank you both for chiming in on this.
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If the nominal diameter is 11" that will be the factory diameter and the safe oversize will be 11.060". If you are game you could machine them slightly more but I dont recommend it.
Tony
1938 1/2 ton Hope to drive it before I retire
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Tony, all the spec says is the brake drum diameter is 11" but it doesn't specify whether it's ID or OD. Midi, if it was me I'd measure the OD of the drums in my possession. If more than 11" the spec would obviously be referring to the ID and we have the answer. The max safe ID would be 11.060. If the OD diameter is exactly 11" we still don't have the answer. https://chevy.oldcarmanualproject.com/chevyresto/52028.html
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11" is the ID of drum !!!!
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Gentlemen,
It would seem that the consensus of opinion is coalescing at 11" being the factory ID of a newly manufactured brake drum, and that the maximum serviceable ID would be 11.060". I'll go with that.
Thank you all for your input.
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Any drum turned more than .030" is almost uesless today because over sized brake linings are no longer available.
The mentioned drums also fit 1955-1958 models and 1/2 ton trucks.
Gene Schneider
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Gene,
I have not been aware that "oversized" brake shoes were ever offered? Perhaps you can elaborate on them, and tell us what the parameters might have been for employing them?
My concern, regarding the inside diameter for brake drums, is that by cutting the drum braking surface one reduces the cross sectional thickness of the drum. I have been told that if the drum were cut too thin as a result of over-doing the cutting operation, the drum would overheat, causing the braking action to fade, warp the drum, and cause the brakes to shutter on stopping. I suspect the spring found around the circumference of the drums was intended to assist in dissipating the heat from braking. Perhaps you can enlighten us on the purpose for those springs as well?
As always, I for one, appreciate your thoughts.
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Gene,
I have not been aware that "oversized" brake shoes were ever offered? Perhaps you can elaborate on them, and tell us what the parameters might have been for employing them? Fifth paragraph left side: https://chevy.oldcarmanualproject.com/shop/1949_53/05brakes/5_18.HTM
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