Rear Brake Clean and Adjust

Old thread, but a lot of good pointers. Still I wonder: is there any need to touch the star adjuster, if it's auto adjusting?

 

Sometimes a driver may not back up enough for the auto adjuster to work - or maybe the mechanism sticks and will not adjust.

 

What grease have others been using for the front and rear brakes?

The attached Toyota diagram calls for:
Lithium soap base glycol grease (front and rear)
disc brake grease (front)
high temperature grease (rear)

I've been using Sta-lube Super white grease (lithium based), drop point 350 degree F.

 

Did this last week and my e-brake is no longer useless. Bonus less brake sqeeks. Here are some pics I took during to process. I was confused on what the bolts were for at first. Thinking I would hammer them off I broke the thread on the drum so got a bigger bolt and drilled it in pushing it off the car.



The bolts go all the way through pushing them off. It will make a pop sound and brake dust will fly.

Rear facing shoe.


Front facing shoe looked slimmer than the rear.






After all is sanded,cleaned,and put back together this part with the teeth needs to be turned from behind the drum with a flat head screw driver until you fell drag on the rotor.




The plug you want is pill shaped. It will take a few trys to get it lined up. When tightening you'll hear clicks but not when loosening.


This side was tricky because a shim was needed for an alignment so I broke off the excess to get to the plug.



Hope someone can now do their brake cleaning faster by learning from my mistakes/spots I was stuck on.

 

Did you lube the contact points between the shoes and backing plate? There's typically 3 tangs on the back edge of the shoe that bear on the backing plate; a little dab of anti-seize at each is good. When the shoe retaining clips (central in that pic) are removed, you can usually pry the shoes away from the backing plate slightly, and just slip anti-seize in there, a small amount on the tip of a slim flat blade screw driver, or knitting needle. You just need to be careful to avoid getting it on the shoe itself.

 

Hmm, I must have missed this a year and a half ago, but just for the benefit of future readers ... the rear drum brakes on a Prius are the sort that adjust due to use of the parking brake, not the sort that adjust due to backing up.

-Chap

 

Sadly I did not lube anything up. If the sqeek gets worse then that will be my next plan of attack. Just happy to have an ebrake again.

 

Yeah, those are the main lube points. The shoes push out, and the three tabs (per shoe) slide a bit on the back plate. The top ones the most I think. If you're not hearing anything you're ok, though.

 

This is a very interesting thread as I had never understood drum brakes. I think I need to give this a try when I do my 30k service. So thanks to everyone for great info.

Now as I understand it ...

1. The brakes are self adjusting but sometimes they don't adjust completely, so you need to turn the star wheel from time to time in order to tighten them up. (Yes?)
2. When you turn the star wheel, you have to turn it just enough to put a little friction into the rotation, so that the shoes are just lightly touching the drum. (Yes?)

What I don't understand is:

1. Why doesn't the self-adjust mechanism do this adjustment automatically, and
2. Why do you want to tighten them until they start to apply friction? Doesn't that mean that the shoes will begin wearing out as soon as you start driving? Wouldn't it be better to tighten until they start to apply friction, and then back it off by one click? (That's what I was told to do on my Honda.) To me that makes more sense.

If anyone can clear up my confusion I would appreciate it.

 

If the auto adjuster is working right, I think you could should just shorten the rod by turning the star wheel. And then the first few times you use the brakes the auto adjuster will work overtime getting the shoes back out.

I'm not that knowledgable about it tho.

 

1) Yes. That has been my observation & experience with drum brakes. Besides, the shoes never wears evenly. Probably does not help when driver forgets to release the parking brake prior to reversing or going forward.
2) Yes.

1) I guess this is where theory meets reality. The self-adjusting mechanism does a decent job of closing the gap as the brake shoe material wears, but it can not maintain the optimal gap for a well functioning e-brake/parking brake lever unfortunatley. This is my opinion based on the cars I have owned having annoying rear drum brakes.
2) I adjust the shoes to the point they barely touch the drum. I hit the parking brake lever a few times to engage the parking brake mechanism. This usually eats up the slight drag, and the drum will spin freely, when the parking brake is completely released. If there is still a slight drag, then I just back-off one click, and hit the parking brake a few times again. This is what I have done, and it works for me.

 

You're asking great questions.

The self-adjust mechanism is super reliable and usually does do the adjustment automatically for years at a stretch without missing a click. If that ever stops happening, it probably means the threaded portion of the starwheel adjuster has rusted up or the grease in it has really hardened, or someone had the shoes off and did not get the adjusting lever aligned right when reassembling. You would eventually notice because you would gradually have to press the park pedal further and further down for it to hold.

With the drum off, you can easily check whether the adjuster is doing what it is supposed to. You can see it sitting just below the hydraulic cylinder at the top, it is a round barrel with a threaded portion and a star wheel. At its rear end it notches over the rear shoe and rests against the parking lever (a thick steel lever that runs downward from near the top of the rear shoe, and the parking cable attaches at its bottom end). The forward end of the adjuster notches over the front shoe, and also touches an adjust lever. That animal is a relatively thin stamped and folded steel piece with a bottom end that hooks through the shoe, a small spring, a part that rests on the forward end of the adjuster, and a long "finger" that point toward the rear and can touch the teeth of the star wheel.

What makes it adjust is a sort of one-two action, and you can make it happen before your eyes by moving the shoes by hand.

One happens when the parking brake is used, which you can simulate by pulling forward on the bottom end of the parking brake lever where the cable attaches. You can see this pushes the shoes apart using the mechanical barrel, not the hydraulic cylinder. The top tips of the shoes will spread away from the hydraulic cylinder when you do this. The cylinder doesn't expand because no one is applying the hydraulic brake.
This motion makes the adjust lever lift up. You may hear it "click" past the next tooth on the star wheel.

Two happens when you have released the parking brake, the very next time you use the hydraulic brake. (If you are simulating these things by hand, just let go of the parking lever you were pulling on, so the shoes return to their rest position, then push the top ends of the shoes directly apart, the same way the hydraulic cylinder would.) This motion spreads the shoes away from the mechanical adjuster, and the adjust lever finger moves down again. If it clicked up over a star wheel tooth in One, then on its way back down in Two, it turns the wheel by the width of one tooth.

That sequence of events, One parking brake applied, lever moves up, clicks over tooth, Two hydraulic brake applied, lever moves down, turns wheel, is what keeps your brakes adjusted, moving the shoes outward 0.03 mm every time it happens. When they are already within 0.03 mm of the drum, it will stop happening until they have worn a bit, because as long as they are within that tolerance, applying the park brake won't move the lever far enough to clear the next tooth.

So, by hand with the drum off, you can just repeat motions one and two and see for yourself that it is smoothly and reliably doing what it should. If the threads are frozen up, you may see that the adjust lever lifts up past a tooth, but never turns the wheel on the way down, but only rests on the same tooth without moving it, or slips back down off it. If that has been happening for a while, the tooth is likely to be rounded smooth by the continual slipping, and to fix that you need a new adjuster, but they're just a few bucks.

It's possible to put the adjuster in the wrong way (look closely at the notches in the ends, they are not symmetrical). If the notch at the front, especially, is around the wrong way, you'll see the adjuster can't possibly work, because the adjust lever will be pushed so far up it never gets near the starwheel teeth. If you see that, obviously, it needs to be corrected.

If you have sat there exercising your adjuster several times by hand to see it work, your shoes are probably now adjusted too tight, and you may have trouble getting the drum back on, or it will drag. So you simply need to back the starwheel off a few notches, which you do with one finger (or slim screwdriver) just pushing the springloaded adjust lever off the teeth so you can turn the wheel, and with another finger or tool just spin the wheel a few notches back in the loosen direction. When it's turning as freely as it should, that should be easy with a bare finger.

2. Of course you don't want to adjust, and leave it adjusted, to where the brakes drag. You have your choice of a couple approaches:

Option a. Put the drum on, snug it up with lug nuts (otherwise there's nothing making sure it's on straight). In the backing plate behind the star wheel is a rubber plug, pop that out so you can stick a screwdriver in and touch the star wheel teeth. Give the wheel one click at a time until you just notice drag when turning the drum. Now back it off by a click or two. (That's the secret step for not leaving it dragging.) To back it off, you need two small screwdrivers poked through the opening, one to hold the adjust lever off the teeth so the starwheel can turn backward, the other to push on the teeth and turn the wheel. (It's an easier trick if you practiced before putting the drum on, to see what you're doing.) Then pop the rubber plug back in.

Option b. Just get the adjustment somewhere close, turning the starwheel by hand before putting the drum on, so you can still put the drum on easily, snug it down with lug nuts, and spin it with no drag. Now just have the adjustment mechanism do its own thing. You can go up to the front of the car and repeat the same one-two sequence you were doing by hand before, only using the brake pedals. Put the parking brake on, once (one). Release it. Press the regular brake down once (two). Release it. Every time you repeat this one-two you will be reducing the clearance by 0.03 mm until it stops adjusting, and you're done.

If you are in a sufficiently quiet place, then each time you apply the parking brake (one), you can hear the lever click past a tooth back at the brake. (You may have to press the park pedal pretty hard before you hear it, at least it feels hard if pushing with your hand, which I'm usually doing for this job. Using your foot, it probably does not feel like much.)

When you stop hearing that click on every one, it has reached proper adjustment and you're done.

-Chap

 

^ Damn, this man is the MOSES of brakes!

Thanks, Chap!

One think I'm having: it's a good idea to use the parking brake regularly?

 

Umm, thanks, I guess?

Wait'll I toss this staff on the ground and you see it morph into a vacuum bleeder setup.

exactly. Every time you use the parking brake, an angel gets an adjuster may get one click.

-Chap

 

This may seem like I'm off topic, but bear with me. I've had my BRAKE ((!)) VSC ABS indicator lights on for awhile. Torque Pro said that there weren't any codes, but after a lot of effort I got Techstream working and it said that my left rear brake had a hydraulic issue. I was going to take the back brakes apart and check them, and I was wondering if maybe the left rear brake might be out of adjustment which was causing the pressure to remain low. First thing that I was going to try was adjusting them to see if that helped. I had assumed that the drum brakes adjusted like other cars when you applied the brakes when backing up, but maybe that one was stuck or dirty. I guess that was a wrong assumption.

As I promised, back to the topic. I have to admit that I'm not one to use the parking brake. I always did when I had a hand lever, but I could never get used to using the parking brake pedal like some 60s car. It occurred to me that maybe the adjuster wasn't dirty at all and just wasn't being used. I took my laptop out to the car and while it was booting up, applied and released the parking brake probably a dozen times. I also pushed on the hydraulic brakes a few times too just for good measure and to make sure that if things were adjusting, they were adjusting everywhere. Hooked up the laptop and told it to clear the codes. When I had tried this before, the lights came back on as soon as I applied the brakes. This time though....

Yes, using your parking brakes occasionally will do more than help an angel get it's wings.

I owe you one ChapmanF!

 

I'm not sure the star adjuster on rear drum is moving anything. Is it a right hand thread that with the shoe off and looking straight at the hub I would be turning the star adjuster from bottom up to draw in the shoes which I believe is a regular right hand thread. Putting brakes back together after replacing the wheel hub and the brake backing plate whose little tabs that hold the bottom of the brake shoes from moving around.rusted off causing the shoes to shift positions causing cylinder damage
I'm not sure if I turned the adjuster in the wrong direction possibly unthreading it's two pieces. I foolishly removed the shoes with the top spring around the star adjuster in place attempting not to break the spring.
I promise not to make my further posts epistles like this one.

 

I don't mind it being an epistle ... I just can't tell whether there's a question in it.