<VV> rubber brake adjust hole plugs

[corvairduval at cox.net]

OK, I see you mountain dwellers (ggg) can melt the plugs.

But, I still take issue that GM DID intend to allow you to punch out those
knockouts so that you could unadjust the self adjusters to allow you to
remove a drum if:

1. The shoes were too tight.

2. The shoes were now sitting in a groove (grooves) in the drum.

I stand by this as the procedure is in all the GM shop manuals from the mid
60s! There is even the diagram on how to bend a wire to pull on the self
adjuster lever to unlock it so you can loosen the adjustment.

The rubber plugs came in brake hardware kits.


I've been a proponent of not turning drums and rotors just to do it (no
large grooves) for many years.

I have been vindicated, as GM released a bulletin about ten years ago to
stop turning rotors at every pad change. This is due to so many noise
complaints from improper finishes resulting from the turing operation.

If the surface is smooth (round, parrallel, etc), turning it will not help
anything. Just don't do it. If it is smooth as glass, run a DA over it
(random orbital sander). The DA would only apply to Corvairs with disc
brake conversions...

Frank DuVal

Original Message:
-----------------
From: Bill & Chris Strickland lechevrier at q.com


> I don't think they melt,

I "know" that they can and do, occasionally, not typically -- yes there 
were metal hole covers, originally for the backing plates, a sort of 
spring steel clip that was probably prone to rusting away,  for you east 
side folks.  Could be that they even pre-date the rubber ones.  They fit 
the self adjuster slots in the drum face rather nicely, after the 
knockout has been "removed".  Afaik, GM never intended for the knockouts 
to be removed, and did not offer a part specifically to fill this hole.  
For y'all's info, I did many, many drum brake jobs during the 70's for 
$19.95 / axle, riveting new linings onto the shoes, arcing them to fit 
the newly turned drums and always rebuilding the cylinders, occasionally 
replacing some cylinders at extra charge.

Oregon City, where I live and have worked, has about a 500 foot 
elevation change along the main road through town, not counting nearby 
hills and mountains -- it was hard on brakes (still is).

Not only do the rubber plugs melt, but under 'truly adverse" conditions 
(mechanical or operator malfunction, generally), the rubber piston seals 
in drum brakes can be melted (long after the brake fluid has boiled away).

These days, it is best to avoid turning drums and / or rotors on 
collector cars, unless you have new replacements already in hand.

Bill Strickland


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