Drum diameter

[Datrock]

Hi, I am trying to find the maximum inner diameter of the rear drums. I only found the NOS dia. of 9.00". I have a few sets of drums and want to find out if they are still safe to use. These are late model alum. finned drums. Does 9.030" sound right? Bill

[Dave]

Bill, the following was posted by Brian Hollands on the roadster mailing list:

You might just be surprised by how bad the roadster brakes can feel if the rear drums are any more than 9.050 in diameter. 9.040 is the wear limit iirc. If you've got spongy brakes, long pedal travel, etc. take a look at the drum diameter before you go spending the big bucks.

I don't know Brian and can't speak to the accuracy of his statement, but it's a good starting place and maybe other folks here on 311s can chime in with their opinion on it. Personally, I plan to pull my rear drums and have them measured against this spec as my brakes are horrible!

[oilleak]

I think I was wrong - the specs say you can turn to a max of 9.040 and the wear limit is 9.055
I had a set that was at the limit and had a guy re-line an old set of shoes with slighty thicker material and have had no problems.

[itsa68]

Our rear drums are the same basic design and are of the same diameter as the 240Z.
The Z drum max wear limit is 9.055, so it would be safe to say the roadsters is the same.

Ray B.

[George H]

To use the 240Z drums I've seen adaptor plates on the main site. What material would be used to make the plates?

[itsa68]

Aluminum 7075-T6