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-   -   Drum Brake Question (http://www.hotrodders.com/forum/drum-brake-question-98102.html)

EazyDuzIt102 09-14-2006 01:12 PM

Drum Brake Question
 
How do you adjust drum brakes?What is the best way to do it?I cant seem to get both sides the same.I have a 65 Impala and the brakes always pull to the sides.Sometimes seems like one side is working better than the other.I also took off both drums and had someone press the brakes down.I noticed that only one side of the brake cylinder is pushing out.Its doing it on the passenger side and driver side.Arent both sides of the cylinder supposed to push outwards at the same time?I replaced those cylinders about 2 years ago so they are somewhat new.Any info will be helpful.Thanks,

Eazy

poncho62 09-14-2006 02:39 PM

You adjust the brakes by turning that star shaped thing. There is a little rubber plug that you remove on the backing plate, so you can do it with the drum on. Turn it until it is just starting to rub when you spin the drum.

Another thing to look at, is your rubber brake hoses may be old and are deteriorating causing the flow through them to be uneven. More common than you would think.

66Caprice 09-14-2006 02:56 PM

Did you try bleeding the brake lines?

EazyDuzIt102 09-14-2006 03:24 PM

Yeah I bled the brakes already.Twice.I replaced the hoses when I put the new cylinders in.Do you think it would help if I got the drums turned?

daoldbuick 09-14-2006 04:03 PM

Only one side is supposed to push out when you push the peddle down with drums off.This is because return springs are of unequal strength. I believe the front one is the stronger of the 2 but don't quote me.If your getting pulling I would have drums turned.

matt167 09-14-2006 04:33 PM

seized wheel cylinder maby. both shoes should come out with the drums off unless the 2 springs are diffrent colors. hold a screw driver on each side that way you don't blow the pistions out.

Henry Highrise 09-14-2006 04:45 PM

Have the drums turned then adjust as Poncho said to do.

66Caprice 09-14-2006 05:00 PM

Also, check to make sure the primary shoes (the one with more pad area) are in the right position on both sides.

I am now preparing to get whapped on the head :spank: - my manuals are still in boxes in the garage since I moved and I don't exactly remember - so please, don't whap me too hard if I'm wrong - I think the primary shoes are go towards the rear for the front brakes and towards the front for the rear brakes. If one side is on backwards, you could have imbalanced braking - happened to me once. :eek:

poncho62 09-14-2006 05:03 PM

Quote:

Originally Posted by 66Caprice
Also, check to make sure the primary shoes (the one with more pad area) are in the right position on both sides.

I am now preparing to get whapped on the head :spank: - my manuals are still in boxes in the garage since I moved and I don't exactly remember - so please, don't whap me too hard if I'm wrong - I think the primary shoes are go towards the rear for the front brakes and towards the front for the rear brakes. If one side is on backwards, you could have imbalanced braking - happened to me once. :eek:

Whapp, Whapp................all shoes go with the longer pad on the rear side (towards back if car) ...............

Henry Highrise 09-14-2006 05:07 PM

Oh man...a double Whap....Oh the Humanity! :D

66Caprice 09-14-2006 05:12 PM

Quote:

Originally Posted by Henry Highrise
Oh man...a double Whap....Oh the Humanity! :D

Hey that hurt! I should have only got one whap for being half right, or maybe half a whap.

Oh well, I've been re-educated!

matt167 09-14-2006 06:08 PM

the primary shoe is the shorter of the 2, as they said. some times, tho not common they are the same length by eyeballing them, you have to measure to realize there actully diffrent. putting the shoes on backwards would go togther but it would nearly eliminate the self energiaztion.

jimfulco 09-14-2006 06:44 PM

Assuming the hydraulics are all in order, it helps to have the drums turned and then have the shoes arc-ground to match the curvature of the drums. Also, make sure your adjusters (star-wheels) will turn freely and are lightly lubricated.

To adjust, tighten the adjuster until the brakes are just tight enough that you can't turn the drum with two hands. Go push the brake pedal as hard as you can, then make sure you still can't turn the drum. Then back off the adjuster 3 to 6 notches (you'll need to push the self-adjuster arm away from the star-wheel with a thin screwdriver or icepick before it will turn backwards freely) and hit the pedal again. The drum should then turn, but drag just a little. It may take a few more notches, depending on if you have fine or coarse notches, but do all 4 wheels the same.

That's the only way I've ever been able to get drums adjusted evenly.

EazyDuzIt102 09-14-2006 09:42 PM

Well I got the brakes adjusted and I think I found the problem with why my wheels are shaking when I press the brakes.There is an arm that is connected to the frame that bolts to the tie rods.Well it is loose and looks like it is damaged.Not sure what this part is called.This is the only part I didnt replace when I put my new suspension kit in.Now I remember why,I cant get it off.When you turn the nut on the top the bolt spins with it and there is no way to loosen it.How do I get this part off?I have the new one to replace it but I cant get the old one off.

cucumber1949 09-14-2006 10:01 PM

Regarding the observation of only one side of the wheel cylinder extending when the drums are off:

With the drums off, one side will push out first. This is sometimes misleading because you think that is also what happens with the drums on. With the drums on, the one side will push first, but eventually that shoe will come in contact with the drum, not allowing it to push any further on that side. What happens next is that continued pressure to the wheel cylinder results in a pushing reflex back through the wheel cylinder and begins to push the other shoe toward the drum. When this second shoe contacts the drum, it has a 'servo' action, that is, it gets dragged around a few degrees with the rotating drum and eventually kind of 'wedges' itself into the drum, thereby multiplying the effect somewhat. This is especially true of rear drum brakes.

With the drums off, all the wheel cylinder is doing is pushing out the one side, perhaps until you eject the piston out of the cylinder if the springs are a lot stronger on one side - essentially there is no drum there to limit the travel of the one piston and start the 'extension' of the second shoe.

Older front drum brakes on some cars had two wheel cylinders on the front, thereby allowing both shoes to go into this servo effect, essentially 'biasing' more braking to the front for weight shift, and to prevent the rears from locking up first, possibly causing a control problem.


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