Proper Drum Brake Adjustment-- Tire On or Off?

[George7941]

Originally Posted By: swalve
If I remember from what I read, there will always be a touch of drag if they are set up right. Something about the geometry of the shoe, drum and the pivot points.


Not true. The auto-adjusters will adjust the shoes to within 3-click-of-the-auto-adjuster away from a slight drag, at least that is the way it has been with every automobile I have ever owned. Twice a year, at seasonal tire change time, I will tighten the adjusters two or three clicks till the shoes almost drag. It minimizes wear on the star wheel and adjustment lever to manually adjust.

Someone had mentioned that auto adjusters rarely work. It is true that they are seized on a lot of cars. If kept clean and lubed they work very well. I have never had a seized adjuster on any vehicle under my care.

 

[mechtech2]

Some cars do not have drum brake automatic adjusters. but most do.
And they will adjust going forward. Either by a stepped wedge or a lever that moves the star adjuster.
I never understood the going in reverse thing. Maybe some hard shock loading causes an extra click of tightness.

 

[George7941]

It is true about the adjuster working when reversing. Look at the drum brakes here
http://auto.howstuffworks.com/auto-parts/brakes/brake-types/drum-brake5.htm
When reversing, the drum will be turning CCW. That causes the secondary shoe to move a lttle CCW (remember, the adjuster is floating), stretching the cable and moving the adjuster lever.

I think it was designed this way, to work in reverse, to minimize wear on the adjuster mechanism.

 

[mechtech2]

That makes sense -the shifting shoe may net more travel in a reverse stop.
But like I said, maybe a bit of extra loading for an extra click.
The automatic star adjusters definitely work when going forward.

 

[Vikas]

Even though a typical drum brake has zillion pieces of levers and springs compared to a disc brake, it is still priced cheaper! Just like the Old Ma Bell charging you extra for Touch Tone service even though it cost Ma Bell *more* when you declined the Touch Tone as it tied up their switching circuits longer.

Obviously, once you accept the golden principle that cost and price have NO relationship, you do not worry about these things.

- Vikas

 

[nthach]

I like to pull apart and lube my star adjusters and the ledge piece when I have to replace shoes. Still, they don't reliably work. I adjust my drums until the rear wheels don't freewheel but turns slowly.

 

[mechtech2]

Star adjusters are problematic .
A lot of Mfrs. use the stepped wedge type - simpler and better.