View Single Post
  #8  
Old February 13th 18, 06:51 AM posted to alt.home.repair,rec.autos.tech,ca.driving
Clare Snyder
external usenet poster
 
Posts: 72
Default Vibration at 50 to 60 mph coasting in neutral after rear brake shoes

On Mon, 12 Feb 2018 21:33:53 -0800, ultred ragnusen
> wrote:

>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?



If the shoes are not adjusted properly and the hand brake cable pulls
the shoes out to where they belong (giving a decent pedal) the shoes
are not on their anchors (depends on the type of brake) and any
suspension movement CAN tighten the cable, initiating a brake
application. Also, on a "servo" type, or "self energizing" brake, if
the leeding shoe "drifts" and contacts the drum, it "wedges" and
aplies the trailing shoe as well. If it's not on the anchors, it Will
drift.
There MAY have been some low speed action, but the servo action would
not be as strong at lower speeds so it may have been virtually
un-noticeable

What vehicle are we talking about here?
Ads