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TR2/3/3A TR3A 10" Drums

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Geo Hahn

Geo Hahn

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Could someone with a TR2/3/3A manual handy tell me what the maximum allowable Inside Diameter is for 10" drums (early TR3A)?

I'm away from home and don't have the Bentley or Haynes with me. The shop won't turn them until I can tell them the legal limit. Should be in the 'brakes' section of either manual.

Thanks!
 
Geo,
Can't find it in the Bentley Workshop Manual, there's nothing on turning the drums in the Brakes or Data sections. I don't have a Haynes but usually they're just a copy of Bentley.

???
 
Hey, Geo, I looked for it, as well, in both Haynes and the Red service manual... can't find it either?!? Good Luck!
 
The early cars were built before there was a government requirement for minimum safe drum thickness. Now days there is a strict safety requirement for the manufacturer to publish a minimum safe drum thickness spec. Such is our modern world.

A guess probably won't do you much good with your particular brake shop, but it should be perfectly safe with no more than .020" metal removal.
D
 
Oops... looks like I was mistaken about this being in the book. Maybe I was thinking of the spec for turning disks or maybe that was also just a dream I had.

Since they began life at 10" and are now 10.004" I think I can take a little off.
 
In 1990, with 80,350 miles on my 10" drums, my neighbor turned mine on his lathe and removed about 0.020" on the diameter. I had a local brake/clutch shop bond new lining material onto the original shoes. Since then, I've driven another 92,000 miles with no problems.
 
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