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Rear Brake Woes Continue

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kindofblue

kindofblue

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My LR shoes were dragging. The adjuster was seized. I replaced the adjuster and the drum still won't fit on. The shoes are still tight and I don't know why. I haven't a clue how this could happen.
Meanwhile, I was poking around the RR to see what was different and I must have punctured the rubber boot for the wheel cylinder. Now the wheel cylinder on that side is leaking. At this rate, the car isn't making it to the VTR. Does anyone need a navigator?
 
If the drum came off with those same shoes, it HAS to fit back on again. Make sure the shoes are properly seated in their 'slots' on the adjuster or wheel cylinder, make sure the adjuster is backed OFF all the way, make sure the wheel cylinder slides back and forth...then gently tap up or down on each shoe to get the linings roughly concentric with the backing plate (or drum). Your drum should then slide back on.

Adjust, etc. (after replacing or rebuilding the wheel cylinder on the other side and repeating the above), and head for VTR! (Wishing I could make it; alas, not....)
 
I recently rebuilt mine on my TR4A.

Remember, the rubber boot is a dust cap, not a seal. If you have a leak, you ought to rebuid the cylinder, and that's really simple. There's not much inside a wheel cylinder.

When the adjuster is backed way off, those shoes go on like a breeze, so if something lacks clearance, your piston may be stuck in the cylinder, or just need to be slid back in a bit.

However, if you have leaking, you'll need to rebuild the cylinder, anyway, and loosen the bleed screw and bleed the brakes.

You'll get it. It's basic, and the problem likely stems from your leak, air pockets, the cylinder position, etc.
 
Did you, by any chance push on the brake pedal even a little bit? The reason I ask is that puncturing the cylinder rubber boot would not cause a leak unless the piston is out to far or the piston seal or cylinder bore is bad.

There may have been a little air in the line also that just expended slightly on the pistons.

You might open the bleeder valve and compress the cylinder pistons then close the valve and see if your shoes fit better.

In the old drum brake days we used to turn the drums and be able to get oversize shoes and and then have them turned to fit the larger turned drums but I doubt shoes for our cars come like that.

Wish you luck
 
Be sure the parking brake lever is fully disengaged. Pulling it up would cause the shoes to spread.
 
I have had a wheel cylinder fail wherein it did not leak but also did not return. Had to crack open the bleeder to free the brakes... if the drum had been off the shoes would have remained out and prevented it being fit.

I also like the idea of the piston exceeding it's normal travel in the wheel cylinder, that accounts for both the leak & the drum not fitting.
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:] In the old drum brake days we used to turn the drums and be able to get oversize shoes and and then have them turned to fit the larger turned drums but I doubt shoes for our cars come like that.
[/QUOTE]

I'll bet you still remember the rivet presses used to rebuild the shoes. How about the wide rubber belts that we wrapped around the drums when they were on the lathe to prevent chatter?
 
Heck, we have a shop here with all the gear still in place! I can have a set of Rolly P-II shoes relined in a day and pay $100 for the job... or wait 'til Rolls has enuff orders to justify the run and pay $600 a set!


Gotta love "entrepreneurs"!!! /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif
 
The wheel cylinders on both sides are not sliding. I am guess they are both problematic at this point. I will get new ones. It doens't look like this can be "slipped in" without taking the whole shoe assembly apart. I am not sure I even understand how the wheel cylinders work with the sliding hardware, or what holds them in place.


If I have to take the shoes off, I will get new springs too, just to be on the safe side.
 
Sounds like they are seized up. The cylinder is a straight thru bore with a hole in the center where the fluid is forced in and released. The pistons are self centering by the position of the shoes. Otherwise one shoe might make hard contact and the other not even touch the drum.

The return springs pull the shoes together when the brake pedal is released. When this happens the shoes push the pistons towards each other.

The adjustment places the shoes in relation to each other so that when the brakes are applied the travel range is so that the shoes contact the drums and so that when released the shoes back off and no longer make contact.

There is only very limited total travel because of the relative small amount of fluid pumped by the master cylinder due to the distance of pedal travel, resulting piston travel which is considerably less, and the size of the piston bore which generates the pressure required to operate the brakes. Then the amount of travel by the wheel cylinder pistons to actually move the brakes.

That is why the brake shoes, even if in good condition, may not effectively function and require adjustment. And why the wheel cylinder pistons do not get pushed out of the cylinders if the brakes are not adjusted.

Also, the power booster does not effect these functions except to provide additional force to assist the brake application.

New break linings may, and usually do, require additional adjustment(s) within a short period because of wearing to conform to the drum. Shoes that are smaller radius to the drums, as in installing standard linings in turned drums, will feel spongy when the breaks are applied. This is because there will be enough force to push the shoes to "spring" enough to conform to the larger radius and then "spring" back when released. This will provide poor breaking and be frustrating to adjust.

I wrote this kind of fast and hope it makes sense.
 
kindofblue said:
The wheel cylinders on both sides are not sliding.
Click to expand...
It can take a lot of force to move the cylinders on the back plate; and they don't move very far anyway. If you're sure the cylinder being out of place is the problem (unlikely IMO); then a few well-placed thumps with a brass hammer should move it.

kindofblue said:
I am not sure I even understand how the wheel cylinders work with the sliding hardware, or what holds them in place.
Click to expand...
Basically, the cylinders have a neck where they go through the back plate, which is smaller than the hole they fit through. The body of the cylinder is too big to fit through the hole, and the three clips on the backside keep it from moving the other way. But only friction (those clips are pretty tight) keeps it from moving within the hole.
kindofblue said:
If I have to take the shoes off, I will get new springs too, just to be on the safe side.
Click to expand...
Are you saying you replaced the adjuster without removing the shoes ? Makes me wonder if maybe the shoes are not seated into the slots that all 4 ends fit into. The adjuster pistons, cylinder piston, and the leading edge of the cylinder all have slots for the shoes to sit in.
 
Yes I replaced the adjuster without taking the shoes off. All 4 point are correctly seated. The piston in the wheel cylinders is not moving at all on either side.
 
Sorry, I misunderstood. In that case, you may have siezed cylinders. Just to be sure, try cracking a bleed valve and see if that lets you force the piston back into the cylinder.

If they are siezed, probably the safest thing is to replace them, although there's a chance they can be freed up and reused. Definitely have to remove the shoes (although I would have done that just to replace the adjusters).

If memory serves, many manuals show the clips in the wrong order/orientation. However the written instructions are correct (and contradict the diagram). Both the smallest clip and the large clip with the tabs sticking out go the same way, with the open end away from the handbrake lever, and the tabs sticking out away from the backing plate. Then you put the handbrake lever into place, and tap the third clip into place between the first two, with it's open end towards the handbrake lever. When it's in place, the tabs on the other large plate will drop into the notches, and lock the whole mess together.
 
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