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Old February 13th 18, 06:33 AM posted to alt.home.repair,rec.autos.tech,ca.driving
ultred ragnusen
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Posts: 54
Default Vibration at 50 to 60 mph coasting in neutral after rear brake shoes

Clare Snyder > wrote:

>>Out of round drums and shoes were too tight.
>>Or, shoes were too tight and grabbing.

> No, the shoes were too loose and the cables were too tight


I want to learn so I appreciate the responses, where I realize you can only
know what I thought to tell you, so it's hard to diagnose from afar.

After reflecting on Clare's answer, I think what he suggested is probably
what happened as what he suggested "fits" the picture, although I'd like to
understand better what he meant when he said
"the shoes which were allowed to "float", spontaneously and
intermittently applying themselves."

The evidence does seem to back up what Clare said, in that the drums were
sizzling, and that the vibration was a "grabbing" type and not a
"side-to-side wobble" like most tire shimmys are. So it was a weird
different type of vibration that must have been occurring at slow speeds as
well as fast speeds.

- But why would it only shudder at the fast speed?
=====
I agree that it's very possible that Clare is correct when he said "the
rear shoes were not adjusted properly", because when I used the factory
adjustment procedure of 1/2 mm between the drum and shoes and then
adjusting the parking brake by pulling up on it a few times, the vibration
went away.

- But why didn't the procedure of putting the shoes on loosely and then
adjusting the shoes via the parking brake work?
=====
In the end, what Clare said seems to fit when he said:
"When you properly adjusted the brake shoes they were properly
positioned in the drum and did not "float", and therefore did
not apply themselves."

- This fits that
a. the drums were sizzling before and just warm now
b. the vibration had an odd feel to it (but why only at speed?)
c. original adjust was by pulling the parking brake a hundred times
d. the gray paste on the shoes might have been drum metal flakes
=====
I have to agree that I misunderstood how drum brakes work in that I thought
the parking brake adjustment adjusted the brake shoes themselves, so I
would just like to learn more about what Clare said when he said
"the shoes were too loose and the cables were too tight"

- Was the vibration likely due to the specific combination of loose shoes
and tight parking brake, or just to the fact that the shoes were too loose?
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