Brake Shoe Specs

[paul25g]

Does anyone know the wear limit for the 175 brake shoes?  The original Technical Handbook refers to the Service Standards Manual but I've never seen that document.  Thanks!

Paul

[BS Mechanic]

I'm not sure there were ever any numbers published, maybe someone else knows of a source?

From a practical side, as the brakes wear you will be able to adjust at the actuators until you run out of adjustment.  If you are a cheap college student, you will then take the brake operating arm off and index it one spline to get some more travel.  You will then shortly discover that the brakes have now worn so far that the cams inside are nearing 90 degrees, and if you press down hard, the cam will lock and the brakes won't let go!  (ask how I know this)

So a reasonable approach is that when you start to run out of adjustment, it's time to replace the shoes.  They will typically go to the end of the adjustment range with plenty of shoe material left, so you won't damage your drums.

[paul25g]

That may be the better question, has anyone ever seen the Service Standards Manual that is mentioned in the original Technical Handbook?  Thanks!

Paul

[reed]

paul25g
If the shoes have been there a long time just replace them you can get them from Richard.
I don't think that they are that expensive.
Thanks.
Steve.

[BS Mechanic]

Paul,

I haven't found anything anywhere regarding the "Service Standards Manual" refered to in the 175 service handbook.  Hopefully someone may have a copy and could post it?  That is if it actually ever existed.  May have been planned but never carried out.

I did at least find similar information for the 350's brakes, which are similar to the 175, under section 14, Tolerances and Fits:
                                         standard                                         Permissible Limit
5. Brake lining thickness         4.5mm (0.1772 inches)                      2 mm (0.079 inches)
6. Brake shoes thickness        179.6–179.9mm (7.07–7.08 inches)      177mm (6.97 inches)
7. Brake drum inside diameter  180–180.2mm (7.09~7.095mm)           181mm(7.13 inches)

Interestingly, the 350's manual doesn't even mention the brakes in the text, nothing at all!

In general, the Bridgestone service manuals were pretty brief, and skip lightly over many areas without going into the detail I'd like.  Oh well, they're the best we've got, and a million thanks to those who digitized them and made them available on this site!!!!!

[paul25g]

Thanks for the help guys....my shoes look pretty good actually, just got curious about that service standards manual.  Hopefully one will show up someday, would probably have some great info in it!

Thanks again!

Paul