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Squealing brakes are usually not caused by
Brake Linings, per se, but by either lack of lubrication between the brake shoes
and the backing plate, poor return or hold-down springs, or unmatched
drum-to-brake shoe contour.
When the drums were turned, it is important to be
sure that the last cut is very slow, giving a very fine, smooth surface.
If not, the shoes may follow the thread of the cutting tool, and actually lift
off the backing plate and begin vibrating, causing squealing. As a side
note, the cutting tool bit should not be ground to a sharp point, but be rounded
at the tip so the thread is cut more smoothly. Then, either arc the lining
to the arc of the drums, or at least be sure that the drums are the same inside
diameter within .050". This way, when the shoes contact the drums, they
will express the same surface area at the given pressure, and apply equally,
reducing any chance of pulling to any side, and reducing the chances of
squealing .
If the springs are not new, the must be check for
proper tension. The hold-down springs should fit accurately, and be compressed
almost to the point of touching the coils, but not quite. The Return
Springs can be tested by dropping the onto a concrete surface. The shop floor
will usually do, unless it is covered by tile, or a softer surfacing
agent. When dropped to a concrete floor, the springs should not bounce
excessively, nor should they give any "ringing" sound. Return springs
should be very tight, with no gaps between any coils. If the are gaps, or
if the springs are weak, they will ring with a "twang" when dropped, and must be
replaced. I used to replace the spring kit on any customer's brake job if
the age was unknown, or if they had survived more than one earlier brake
job.
I would also always dab a small amount of lubricant
to the backing plate and center pin. Back in the day, it was common to use
white lube, but the are much better, higher temperature and longer lasting lubes
available today. I often see different lubricants on the parts shelves
when I am shopping for various items.
I think that with this attention to detail, you are
likely to eliminate any squealing.
Mike Higgins
1955 Belvedere Sport Coupe
----- Original Message -----
Sent: Saturday, November 21, 2009 9:45
AM
Subject: [FWDLK] Brake Linings that don't
squeal?
Hi Folks ?
When I replaced the front brake drums on my ?57 Dodge
Custom Royal, the best used drums we could find came from a ?62 Chrysler
Windsor, so we used those instead. Everything works great, but the
linings squeal like a stuck pig ? a LOUD stuck pig ? whenever they get even
mildly warm. Definitely not the way I want to draw
attention!
Anyone got advice on where to find quality SILENT brake
linings? The measurements are 2.5 X 11.
Thanks!
John Williams
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