97 olds 88 rear shoes click/clunk
#22
Senior Member
Posts like a Turbo
![Default](https://www.gmforum.com/images/icons/icon1.gif)
The self-adjusting brake mechanism consists of an actuating link, adjuster lever, adjuster lever return spring, override spring and override pivot.
The self-adjusting brake mechanism operates only When the brakes are applied while the car is moving rearward and only when the secondary shoe moves a pre-determined distance toward the brake drum.
As the car moves rearward and the brakes are applied friction between the primary shoe and the drum forces the primary shoe against the anchor pin. Hydraulic pressure in the wheel cylinder forces the upper end of the secondary shoe away from the anchor pin. As the secondary shoe moves away from the anchor pin, the upper end of the adjuster lever is prevented from moving by the actuating link. This causes the adjuster lever to pivot on the secondary shoe forcing the adjuster lever against the adjusting screw sprocket. If the brake linings are worn enough to allow the secondary shoe to move the pre-determined distance, the adjuster lever will turn the adjusting screw sprocket one or two teeth, depending on lining. wear. If the secondary shoe does not move the pre-determined distance, movement of the adjuster lever will not be great enough to rotate the adjusting screw sprocket.
When the brakes are released, the adjusting lever return spring will move the adjuster lever into the adjusting position on the sprocket.
An override feature is built into the self-adjusting brake which allows the secondary shoe to be applied in reverse in the event the adjusting screw becomes "frozen" preventing the self-adjuster from operating.
When the car is moving forward and the brakes are applied, the upper end of the secondary shoe is forced against the anchor pin due to the selfenergizing action of the brakes, and the selfadjuster does not operate.
I borrowed this from another site as apparently I'm afflicted with "CRS"
2004 Bonne SLE
1971 Chevelle SS
The following users liked this post:
Mike (02-02-2014)
#23
Retired
![](https://www.gmforum.com/images/ranks/veteran_army.png)
![Default](https://www.gmforum.com/images/icons/icon1.gif)
CRS? What'* that?
__________________
Retired Administrator
Retired Administrator
#25
Retired
![](https://www.gmforum.com/images/ranks/veteran_army.png)
![Default](https://www.gmforum.com/images/icons/icon1.gif)
Oh, CantRememberShit... Roger.
__________________
Retired Administrator
Retired Administrator
#26
Senior Member
True Car Nut
![Default](https://www.gmforum.com/images/icons/icon1.gif)
Re: How do drum brakes self-adjust?
The self-adjusting brake mechanism consists of an actuating link, adjuster lever, adjuster lever return spring, override spring and override pivot.
The self-adjusting brake mechanism operates only When the brakes are applied while the car is moving rearward and only when the secondary shoe moves a pre-determined distance toward the brake drum.
As the car moves rearward and the brakes are applied friction between the primary shoe and the drum forces the primary shoe against the anchor pin. Hydraulic pressure in the wheel cylinder forces the upper end of the secondary shoe away from the anchor pin. As the secondary shoe moves away from the anchor pin, the upper end of the adjuster lever is prevented from moving by the actuating link. This causes the adjuster lever to pivot on the secondary shoe forcing the adjuster lever against the adjusting screw sprocket. If the brake linings are worn enough to allow the secondary shoe to move the pre-determined distance, the adjuster lever will turn the adjusting screw sprocket one or two teeth, depending on lining. wear. If the secondary shoe does not move the pre-determined distance, movement of the adjuster lever will not be great enough to rotate the adjusting screw sprocket.
When the brakes are released, the adjusting lever return spring will move the adjuster lever into the adjusting position on the sprocket.
An override feature is built into the self-adjusting brake which allows the secondary shoe to be applied in reverse in the event the adjusting screw becomes "frozen" preventing the self-adjuster from operating.
When the car is moving forward and the brakes are applied, the upper end of the secondary shoe is forced against the anchor pin due to the selfenergizing action of the brakes, and the selfadjuster does not operate.
I borrowed this from another site as apparently I'm afflicted with "CRS"
2004 Bonne SLE
1971 Chevelle SS
The self-adjusting brake mechanism consists of an actuating link, adjuster lever, adjuster lever return spring, override spring and override pivot.
The self-adjusting brake mechanism operates only When the brakes are applied while the car is moving rearward and only when the secondary shoe moves a pre-determined distance toward the brake drum.
As the car moves rearward and the brakes are applied friction between the primary shoe and the drum forces the primary shoe against the anchor pin. Hydraulic pressure in the wheel cylinder forces the upper end of the secondary shoe away from the anchor pin. As the secondary shoe moves away from the anchor pin, the upper end of the adjuster lever is prevented from moving by the actuating link. This causes the adjuster lever to pivot on the secondary shoe forcing the adjuster lever against the adjusting screw sprocket. If the brake linings are worn enough to allow the secondary shoe to move the pre-determined distance, the adjuster lever will turn the adjusting screw sprocket one or two teeth, depending on lining. wear. If the secondary shoe does not move the pre-determined distance, movement of the adjuster lever will not be great enough to rotate the adjusting screw sprocket.
When the brakes are released, the adjusting lever return spring will move the adjuster lever into the adjusting position on the sprocket.
An override feature is built into the self-adjusting brake which allows the secondary shoe to be applied in reverse in the event the adjusting screw becomes "frozen" preventing the self-adjuster from operating.
When the car is moving forward and the brakes are applied, the upper end of the secondary shoe is forced against the anchor pin due to the selfenergizing action of the brakes, and the selfadjuster does not operate.
I borrowed this from another site as apparently I'm afflicted with "CRS"
2004 Bonne SLE
1971 Chevelle SS
I just double checked in the FSM for my car, and it confirms the brakes self adjust with application, and no motion is necessary.
#29
Senior Member
Posts like a Turbo
Thread Starter
![Default](https://www.gmforum.com/images/icons/icon1.gif)
this guy above is a bit goofy.... but gives you the idea.... only thing I did not do is lube the backing plate... must be the issue why I get the clunks/clicks
Thread
Thread Starter
Forum
Replies
Last Post
killer_cr80r
Bonneville GXP/ Northstar Powered Cars
23
04-11-2004 01:38 PM
Drifter420
Everything Electrical & Electronic
2
04-01-2004 07:32 PM