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Vibration at 50 to 60 mph coasting in neutral after rear brake shoes



 
 
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  #1  
Old February 12th 18, 08:22 PM posted to alt.home.repair,rec.autos.tech,ca.driving
ultred ragnusen
external usenet poster
 
Posts: 31
Default Vibration at 50 to 60 mph coasting in neutral after rear brake shoes

Just replaced the rear brake shoes with the result of vibration at 50 to 60
mph which was unrelated to braking or the transmission where I'd like to
learn from your experience what happened.

Balance: http://i.cubeupload.com/nejkmM.jpg
Backoff: http://i.cubeupload.com/k0rDm2.jpg
Adjust: http://i.cubeupload.com/I3FpwG.jpg
Assemble: http://i.cubeupload.com/nQ17UA.jpg
Gray Paste: http://i.cubeupload.com/TkVVqJ.jpg
===========================================
1. Replaced just the brake shoes and tested at 50 to 60 mph where
noticeable vibration occurred that wasn't there before the brake job.

2. This noticeable vibration was unrelated to braking events or to coasting
downhill in neutral and was unrelated to road conditions.

3. All four wheels were previously balanced and originally put back in
their original position after the initial repair as were the drums.

4. All six lug nuts on each wheel were torqued to 84 foot pounds using the
classic star pattern. A thin coating of old (partially congealed)
never-seize was applied to the rear hub to drum mating surface.

5. The main deviation from factory protocol was the common practice of
adjusting the star wheel to the shortest position so that the drums go on
easily and then lifting up on the emergency brake handle about a hundred
times to adjust the parking brake to 7 clicks.

6. After an 18-mile test-drive loop, start to finish, to get to the highway
and then to the first exit and back where half was highway and half were
local roads, both drums "sizzled" a wet fingertip, perhaps the driver side
drum more so than the passenger side drum.

7. The brake shoes had a gray pasty appearance, almost of leaking oil but
no oil leaked on the brake shoes.
===========================================
A. I rotated the tires front to back but they were balanced before so I
don't see how that mattered afterward.

B. I very carefully torqued the six nuts on each wheel to 84 foot pounds,
in a star pattern, with plenty of banging on the wheel assembly to jostle
the seating position, although they were previously torqued to 84 foot
pounds so I don't see how that mattered afterward.

C. I visually inspected the u-joints, wiggling them by hand, but I did not
feel more than about a half millimeter or so of movement, but I don't know
how much they're supposed to move - but they didn't change anyway.

D. I visually inspected the front and rear brakes, where no visual anomaly
was seen, and wiped some of the never seize off, but it was a very thin
layer anyway.

E. The only procedure I did very differently was that I explicitly followed
the factory protocol for adjusting the brake shoes just prior to the drum
replacement which was to mic the drum and mic the shoes and set the star
adjustment to 1/2 mm (20 thousandths of an inch) smaller than the drum
diameter.

F. I also left the parking brake adjustment loose at about 8 or 9 clicks
instead of the 7 clicks (it still held the car on a hill but not as firm as
did the first adjustment if the car was previously moving).
===========================================
The procedure above "solved" the vibration problem.

The job is done but I would like to learn more about changing brake shoes.
Do you have any idea what specifically had caused the vibration?
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  #2  
Old February 12th 18, 09:35 PM posted to alt.home.repair,rec.autos.tech,ca.driving
Clare Snyder
external usenet poster
 
Posts: 69
Default Vibration at 50 to 60 mph coasting in neutral after rear brake shoes

On Mon, 12 Feb 2018 11:22:10 -0800, ultred ragnusen
> wrote:

>Just replaced the rear brake shoes with the result of vibration at 50 to 60
>mph which was unrelated to braking or the transmission where I'd like to
>learn from your experience what happened.
>
>Balance: http://i.cubeupload.com/nejkmM.jpg
>Backoff: http://i.cubeupload.com/k0rDm2.jpg
>Adjust: http://i.cubeupload.com/I3FpwG.jpg
>Assemble: http://i.cubeupload.com/nQ17UA.jpg
>Gray Paste: http://i.cubeupload.com/TkVVqJ.jpg
>===========================================
>1. Replaced just the brake shoes and tested at 50 to 60 mph where
>noticeable vibration occurred that wasn't there before the brake job.
>
>2. This noticeable vibration was unrelated to braking events or to coasting
>downhill in neutral and was unrelated to road conditions.
>
>3. All four wheels were previously balanced and originally put back in
>their original position after the initial repair as were the drums.
>
>4. All six lug nuts on each wheel were torqued to 84 foot pounds using the
>classic star pattern. A thin coating of old (partially congealed)
>never-seize was applied to the rear hub to drum mating surface.
>
>5. The main deviation from factory protocol was the common practice of
>adjusting the star wheel to the shortest position so that the drums go on
>easily and then lifting up on the emergency brake handle about a hundred
>times to adjust the parking brake to 7 clicks.
>
>6. After an 18-mile test-drive loop, start to finish, to get to the highway
>and then to the first exit and back where half was highway and half were
>local roads, both drums "sizzled" a wet fingertip, perhaps the driver side
>drum more so than the passenger side drum.
>
>7. The brake shoes had a gray pasty appearance, almost of leaking oil but
>no oil leaked on the brake shoes.
>===========================================
>A. I rotated the tires front to back but they were balanced before so I
>don't see how that mattered afterward.
>
>B. I very carefully torqued the six nuts on each wheel to 84 foot pounds,
>in a star pattern, with plenty of banging on the wheel assembly to jostle
>the seating position, although they were previously torqued to 84 foot
>pounds so I don't see how that mattered afterward.
>
>C. I visually inspected the u-joints, wiggling them by hand, but I did not
>feel more than about a half millimeter or so of movement, but I don't know
>how much they're supposed to move - but they didn't change anyway.
>
>D. I visually inspected the front and rear brakes, where no visual anomaly
>was seen, and wiped some of the never seize off, but it was a very thin
>layer anyway.
>
>E. The only procedure I did very differently was that I explicitly followed
>the factory protocol for adjusting the brake shoes just prior to the drum
>replacement which was to mic the drum and mic the shoes and set the star
>adjustment to 1/2 mm (20 thousandths of an inch) smaller than the drum
>diameter.
>
>F. I also left the parking brake adjustment loose at about 8 or 9 clicks
>instead of the 7 clicks (it still held the car on a hill but not as firm as
>did the first adjustment if the car was previously moving).
>===========================================
>The procedure above "solved" the vibration problem.
>
>The job is done but I would like to learn more about changing brake shoes.
>Do you have any idea what specifically had caused the vibration?




Sure sounds like the rear shoes were not adjusted properly and the
emergency brake was partly applied tp position the shoes which were
allowed to "float", spontaniously and intermittently applying
themselves.

When you properly adjusted the brake shoes they were properly
positioned in the drum and did not "float", and therefore did not
apply themselves.

You guys that insist on doing brake work on your cars without having
a clue what you are doing SCARE me.

One of these days something SERIOUS will happen and someone will be
killed, or worse yet, maimed for life.
  #3  
Old February 12th 18, 09:58 PM posted to rec.autos.tech
dsi1[_11_]
external usenet poster
 
Posts: 275
Default Vibration at 50 to 60 mph coasting in neutral after rear brake shoes

On Monday, February 12, 2018 at 9:22:14 AM UTC-10, ultred ragnusen wrote:
> Just replaced the rear brake shoes with the result of vibration at 50 to 60
> mph which was unrelated to braking or the transmission where I'd like to
> learn from your experience what happened.
>
> Balance: http://i.cubeupload.com/nejkmM.jpg
> Backoff: http://i.cubeupload.com/k0rDm2.jpg
> Adjust: http://i.cubeupload.com/I3FpwG.jpg
> Assemble: http://i.cubeupload.com/nQ17UA.jpg
> Gray Paste: http://i.cubeupload.com/TkVVqJ.jpg
> ===========================================
> 1. Replaced just the brake shoes and tested at 50 to 60 mph where
> noticeable vibration occurred that wasn't there before the brake job.
>
> 2. This noticeable vibration was unrelated to braking events or to coasting
> downhill in neutral and was unrelated to road conditions.
>
> 3. All four wheels were previously balanced and originally put back in
> their original position after the initial repair as were the drums.
>
> 4. All six lug nuts on each wheel were torqued to 84 foot pounds using the
> classic star pattern. A thin coating of old (partially congealed)
> never-seize was applied to the rear hub to drum mating surface.
>
> 5. The main deviation from factory protocol was the common practice of
> adjusting the star wheel to the shortest position so that the drums go on
> easily and then lifting up on the emergency brake handle about a hundred
> times to adjust the parking brake to 7 clicks.
>
> 6. After an 18-mile test-drive loop, start to finish, to get to the highway
> and then to the first exit and back where half was highway and half were
> local roads, both drums "sizzled" a wet fingertip, perhaps the driver side
> drum more so than the passenger side drum.
>
> 7. The brake shoes had a gray pasty appearance, almost of leaking oil but
> no oil leaked on the brake shoes.
> ===========================================
> A. I rotated the tires front to back but they were balanced before so I
> don't see how that mattered afterward.
>
> B. I very carefully torqued the six nuts on each wheel to 84 foot pounds,
> in a star pattern, with plenty of banging on the wheel assembly to jostle
> the seating position, although they were previously torqued to 84 foot
> pounds so I don't see how that mattered afterward.
>
> C. I visually inspected the u-joints, wiggling them by hand, but I did not
> feel more than about a half millimeter or so of movement, but I don't know
> how much they're supposed to move - but they didn't change anyway.
>
> D. I visually inspected the front and rear brakes, where no visual anomaly
> was seen, and wiped some of the never seize off, but it was a very thin
> layer anyway.
>
> E. The only procedure I did very differently was that I explicitly followed
> the factory protocol for adjusting the brake shoes just prior to the drum
> replacement which was to mic the drum and mic the shoes and set the star
> adjustment to 1/2 mm (20 thousandths of an inch) smaller than the drum
> diameter.
>
> F. I also left the parking brake adjustment loose at about 8 or 9 clicks
> instead of the 7 clicks (it still held the car on a hill but not as firm as
> did the first adjustment if the car was previously moving).
> ===========================================
> The procedure above "solved" the vibration problem.
>
> The job is done but I would like to learn more about changing brake shoes.
> Do you have any idea what specifically had caused the vibration?


Unmount your rear tires and inspect the mounting surfaces carefully. Then remount them and road test. If you still have vibrations, take the car to a shop to have the tires balanced.
  #4  
Old February 12th 18, 11:22 PM posted to alt.home.repair,rec.autos.tech,ca.driving
Paul in Houston TX[_2_]
external usenet poster
 
Posts: 153
Default Vibration at 50 to 60 mph coasting in neutral after rear brakeshoes

ultred ragnusen wrote:
> Just replaced the rear brake shoes with the result of vibration at 50 to 60
> mph which was unrelated to braking or the transmission where I'd like to
> learn from your experience what happened.


Out of round drums and shoes were too tight.
Or, shoes were too tight and grabbing.
  #5  
Old February 13th 18, 05:27 AM posted to alt.home.repair,rec.autos.tech,ca.driving
Clare Snyder
external usenet poster
 
Posts: 69
Default Vibration at 50 to 60 mph coasting in neutral after rear brake shoes

On Mon, 12 Feb 2018 16:22:38 -0600, Paul in Houston TX
> wrote:

>ultred ragnusen wrote:
>> Just replaced the rear brake shoes with the result of vibration at 50 to 60
>> mph which was unrelated to braking or the transmission where I'd like to
>> learn from your experience what happened.

>
>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
  #6  
Old February 13th 18, 06:18 AM posted to alt.home.repair,rec.autos.tech,ca.driving
Paul in Houston TX[_2_]
external usenet poster
 
Posts: 153
Default Vibration at 50 to 60 mph coasting in neutral after rear brakeshoes

Clare Snyder wrote:
> On Mon, 12 Feb 2018 16:22:38 -0600, Paul in Houston TX
> > wrote:
>
>> ultred ragnusen wrote:
>>> Just replaced the rear brake shoes with the result of vibration at 50 to 60
>>> mph which was unrelated to braking or the transmission where I'd like to
>>> learn from your experience what happened.

>>
>> 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


Ah! Immediately understood. Thanks for the insight.

  #7  
Old February 13th 18, 06:33 AM posted to alt.home.repair,rec.autos.tech,ca.driving
ultred ragnusen
external usenet poster
 
Posts: 31
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?
  #8  
Old February 13th 18, 06:51 AM posted to alt.home.repair,rec.autos.tech,ca.driving
Clare Snyder
external usenet poster
 
Posts: 69
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?
  #9  
Old February 13th 18, 07:12 AM posted to alt.home.repair,rec.autos.tech,ca.driving
ultred ragnusen
external usenet poster
 
Posts: 31
Default Vibration at 50 to 60 mph coasting in neutral after rear brake shoes

Clare Snyder > wrote:

> 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.


That must be it.

Once the leading shoe touched the drum, the trailing shoe must have been
forced to follow, causing the grabbing.

It must have been happening all the time, but only noticeable at speed.

Thanks for explaining.

My big mistake was in thinking the parking brake adjusted the "final"
position of the shoes.
  #10  
Old February 13th 18, 06:05 PM posted to alt.home.repair,rec.autos.tech,ca.driving
Clare Snyder
external usenet poster
 
Posts: 69
Default Vibration at 50 to 60 mph coasting in neutral after rear brake shoes

On Mon, 12 Feb 2018 22:12:43 -0800, ultred ragnusen
> wrote:

>Clare Snyder > wrote:
>
>> 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.

>
>That must be it.
>
>Once the leading shoe touched the drum, the trailing shoe must have been
>forced to follow, causing the grabbing.
>
>It must have been happening all the time, but only noticeable at speed.
>
>Thanks for explaining.
>
>My big mistake was in thinking the parking brake adjusted the "final"
>position of the shoes.

On some it does - but then you need to manually adjust the handbrake
(e-brake) linkage AFTER the shoes have adjusted - and this
meansbacking off the e-brake adjustment first.

Youstill have not said what vehicle this is - and sincethere areSO
MANY differentsetups for brakes, this is important information.
 




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