gads after proof reading this 5 times its still goofed up . where it says 'leading and trailing 'rear' brake shoes' delete 'rear' - its getting late
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gads after proof reading this 5 times its still goofed up . where it says 'leading and trailing 'rear' brake shoes' delete 'rear' - its getting late
Hi,
I work as an mechanical engineer and I can help you out. There no such thing as putting the bigger shoe in front or back. It depends on the brake design.
There is a simple trick that always works: Starting at the pivot point of the brakes, imagine the wheel turning when its going foward. following this direction of rotation, the smaller shoe has to be installed on this side of the pivot.
SO, if the brake pivot is on top, the short shoe goes in front. And if the pivot is at the bottom, the bigger shoe goes in front.
(the reason is that a component of the friction force add to the braking force on one side and reduce the braking force on the other side. You have to install the bigger shoe on the side with the bigger force to spread it on a bigger surface. This way you have an even pressure on both shoes witch result in even wear and balanced heat build up)
Well on the more common drum brakes in use today [Bendix] the brake shoes are floating,with pressure applied from a dual piston brake cylinder to the tops of both front and rear shoes. This provides the shoes expansion to the drum[the adjustment screw is on the bottom]. Then force is directed from the leading shoe and then to the trailing shoe causing a wedging [self energizing] action, and therefore more braking effort from the rotational action. In any case use riveted brake lined shoes. I just had a bad example of broken bonded shoe coming off and wedging in a drum and locking up a rear brake.
From my 1955 Buick service manual (which is excellent) --
"The brake assembly at each wheel uses a primary (front) and a secondary (rear) brake shoe of welded steel construction with one-piece molded lining attached by tubular rivets. The primary shoe lining [front] is shorter than the secondary shoe lining [rear] and is of different composition; therefore the two shoes are not interchangeable."
Hello Fatclub.Now you have a answer from Buickmembers to do
it right on the car.Give a second of your mind and tink,peoples
helps over continents.I hope the brakes be perfect.
Stubbe in Sweden:shifter:
Hi, I'd like to get my two cents in as well. For many years, I've worked on the big trucks. (18 Wheelers) To adjust their brakes, tighten the slack adjuster (on a car it's called, a brake adjuster) until the wheel will not turn. Then back off 1/4 to a 1/2 turn. This will give you just enough clearance between the shoes and the drums, so the slack adjuster doesn't have to move too far and go over the 90 degree angle. (a truck techs knowledge of slack adjusters) Now on a passenger car, when I first started replacing brake shoes. Most of them had what was called, "self adjusters". All you had to do is back up and step on the brakes, and if they were out of adjustment. (if they worked at all!) A wedge on a cable would turn the adjuster because the shoes would shift due to the reverse motion of the drum. This was a pain to adjust the shoes so you couldn't turn the wheel, if you went too far with the adjuster. You had to get into that little slot with a long thin object, to release the self adjusting wedge so you could back off on the adjuster. On our older Buicks, there were no self adjusters. So you could do just that, tighten the adjuster so you couldn't turn the wheel. Then back off just enough to get you free travel in the brake shoe. In my opinion, this is the best way to adjust any drum style brakes. And yes, it forms the shoe to the drum better. I like to back off the brakes on my Buick, so I can get one full turn of the tire with a moderate amount of force to turn the it. If you do it long enough, you know just where to have them. The more experience you have adjusting brakes, the better you get at it. It's just like anything else we do. These are my opinions, along with hands on experience.