Datsun Roadster Forum-311s.org

Hello
I was looking for the brake drum wear limit, but didn’t see it. What are drums supposed to be new and what is their wear limit?
Thx
Linda

228.6 was the new dimension per the factory shop manual. I did not see a wear spec.

How are you supposed to know when drum is worn out? Must be a spec somewhere. I thought I saw it but can not find it now.
Linda

:Even 3/16 in of cast iron contact surface would be ok
As very lite vehicle and no power bakes

The numbers you need are frequently stamped onto a rotor or drum. Not on our cars, though, and the last time I took a pair of roadster drums to O’Reillys for minor resurfacing they called and told me they couldn’t do the work b/c they couldn’t locate the specs. Only after I assured them that the vehicle would be driven “off road only” would they then do the work. Good luck!

“… in this case, if the truth won’t set you free, then lie.” Mr. McCoy, Bonfire of the Vanities

Jon

I’d be afraid take the drums to Oreillys even with the specs.... But odd that the info is not readily available
Funny quote. Some people are saying the Prez likes that book...

Linda

Linda wrote: Sat Aug 08, 2020 12:08 pm Funny quote. Some people are saying the Prez likes that book...

Linda

This is YOUR thread, "Our Fair Lady" of Fairladys, but please be careful with that can o' worms!

Jon

LoL. Duly noted.

Linda

From a post on this topic in 2009

"The "green" 310 manual has some seriously poor grammar, but from what I can make out, the drum diameter is 228.6mm with an allowable limit of 0.80mm X 2. So I take that to mean 230.2mm is the max inside diameter.
Jeremy

1964 Datsun 1500 SPL310
now sporting a '67 R-16 and 5-speed"

Jeremy,

Your diligent sleuthing reminded me to consult my seldom-used Chilton’s, which shows the same 9.0 inch (228.6mm) drum inner diameter for SPL/SRL311, PL510, and HLS30 (240Z).

In all the above cases, “… drums should not be machined more than 0.04 inches beyond their original inside diameter.” (pages 218-20)
So, 9.04 inches or 229.62mm is the max according to Chilton’s.

Jon

Very good work, thx all..
9.04” would be good to note in the Wiki.
I wonder how much they take off when they turn the drums?
Linda

How much they take off depends on the surface of the drum. If someone has run shoes down to the metal, the gouges/tracks in the drum could be considerable. If the shoes are installed properly, and replaced before there is significant wear, there may be very little material needed to be removed.