Drum brakes - do you disconnect the parking brake cable?

I haven't done drum brakes ever but I'm faced with these drum brakes where I'd just like to ask a couple of questions from those of you who have done drum brakes before.
1. I released the parking brake from the cabin and screwed these 2-inch long metric 8mm x 1.25mm threads bolts to pull the drum off the shoes. <
http://www.bild.me/bild.php?fileV87240drum_brakes_0.jpg

2. After blowing the dust out (and not breathing it in), I could see that the front shoe was worn down to about a millimeter or less (after 175K miles), so I'm going to have to buy new shoes and replace them. <
http://www.bild.me/bild.php?file478506drum_brakes_1.jpg

3. I measured the drum to be 2mm smaller than the maximum diameter: <http://www.bild.me/bild.php?file 35528drum_brakes_2.jpg>
4. Where the maximum diameter of 297mm was stamped on the drum itself: <http://www.bild.me/bild.php?file 28041drum_brakes_3.jpg>
5. It was hard to get the drum back on even with the parking brake released from the cabin, so I had to use a mallet to bang it back on: <http://www.bild.me/bild.php?file $34045drum_brakes_4.jpg>
The main question is whether I'm supposed to *disconnect* the cable for the parking brake when working on the drums, and particularly when I put the new shoes on after I buy them.
Also, only one shoe is worn, and it's the front shoe, and it's been on there for 175K miles, but I wonder if the shoes can be switched, so that the front shoe is in the rear and the rear shoe is in the front, since they wore so unevenly (sort of like rotating tires).
But mainly I'm not sure what the procedure is for the parking brake cable. Can you advise?
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On 1/8/2018 2:02 AM, Mad Roger wrote:

It appears the one shoe is unevenly worn. Could be a bad cylinder or another stuck part such as the adjuster. Check them and replace/repair if needed.

Maximum diameter of what? Are you aware of the adjusters? Each side has one and it sits under the cylinder behind the hub. You can see it in this diagram
http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0900c152/80/08/9c/12/medium/0900c15280089c12.gif
It's job is to keep the shoes against the drum and is automatically adjusted when the parking brake is used. Often, this is the reason why drums are difficult to remove. They are adjusted from the other side through an opening using an adjustment tool and often need to be loosened in order to remove the drum. They also need to be tightened after you replaced the shoes and re-install the drum. Retract them and your diameter will be less than the drum.

Back to the adjuster.

The parking brake cable doesn't need to be removed, assuming it's functioning properly. Just ensure the parking brake is not engage when replacing shoes. The parking brake assembly will be removed when the shoes are replaced.

Much depends on the vehicle. Many shoes are identical and it doesn't matter if they are placed in front or rear. Others are specific and require proper position and seating. In your case, the shoes appear to be the same but that wear is something I wouldn't simply "rotate" with the other side. One side wearing more than the other is not normal and should be checked, repaired/replaced then install new shoes with the proper even thickness.

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On Mon, 8 Jan 2018 07:03:33 -0500, Meanie wrote:

Thanks for your help as this is my first set of drum brakes ever.
This is a side view closeup of the front unevenly worn shoe:
https://s13.postimg.org/mezt8lvs7/brakes_drum_4.jpg
I had been, for years, looking through the peep hole, but that showed a lot of meat on the shoes. You really have to remove the drum to see the actual shoe, so, after 175K miles on the same shoes, I finally removed the drum and noticed that the front show lower end, is worn tapering to the middle, while the rest of the shoes are just fine.

Thanks for that advice.
The cylinder seems to not be leaking but that's all I can tell. There have been no unusual braking events so I'm not debugging anything.
I googled a bit, and it seems "normal" for Toyota 4Runner rear brake shoes to wear most in the front show on the bottom half. Something to do with the geometry. I can't complain, as the shoes definitely are original so 20 years is a long time for a brake shoe to finally wear out.

The drum: http://www.bild.me/bild.php?file 28041drum_brakes_3.jpg
In that photo you can see that the inside of the drum has a molded in maximum diameter of 297mm. I assume that means the maximum diameter.
My calipers are in US measurements where 11.615 inches converts to about 295mm.
So I assume the drum is good by 2mm in thickness.

Yes. This vehicle adjusts automatically when you brake in reverse, so I've never dealt with them - but I am going to have to back them out for sure when I put the new brake shoes on.
You can see the adjuster here:
https://s13.postimg.org/senkcelrb/brakes_drum_1.jpg
I'm just not sure what we're supposed to do about the parking brake cable linkages. I don't know yet if they have to be disconnected when putting in new brake shoes.
You can see the parking brake cable here:
https://s13.postimg.org/5egwznnt3/brakes_drum_2.jpg

I understand what you're saying, which is that the brake shoes may be "wedged" against the drum, but I had the vehicle in the air and the parking brake off, so, any wedging shouldn't be too strong.
This is a closeup of the parking brake cable connection to the shoes:
https://s13.postimg.org/b2n7qr2hz/brakes_drum_3.jpg
As it was, putting the two 2-inch long 8mmx1.25 bolts in the two holes for the purpose pushed the drum off easily. I had to squish the shoes a bit to get the drum back on - and if necessary - I would have twisted the adjuster - but I didn't need to.

Oh. OK. The parking brake seems to be a thick black cable that comes in at the bottom of these shoes.

I think I'll replace the shoes, but since they lasted 20 years, I was just wondering if "rotating" them every two or three or five years would have extended the life of them.
It's a late 90's 4Runner.
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On 1/8/2018 1:34 PM, Mad Roger wrote:

They don't always have to leak. I've had a few that were stuck due to some rust within the cylinder. I just replaced them since they were cheap back in the days of yore. Though, I did take one apart and freed it up with some cleaning. It appeared to work fine after that.

I can't speak for normality but I just find it odd that it would wear like that when there isn't a bad part. Usually, I would see one show worn more so than the other, but never a tapered wear.

Most adjusters work with the emergency/parking brake. Though, many people rarely, if ever, use the parking brake and those adjusters can rust up and stop pushing the shoe against the drum.

I have worked on many drum brakes and I have never had to remove a parking brake cable. The cable is attached to the metal assembly and that will just hang on the cable when you remove it and replace the shoes. Though, if it's easy to remove and reattach, then there's no harm in doing so.

Agreed. There should be a slight drag and minor friction when you turn the drum, but never should be too tight where it's difficult to remove the drum.

Yes, attached to the metal assembly which turns that adjuster.

All I can say is I've never "rotated" brake shoes, since IMO, they were cheap when I used to work on many cars. I can sympathize when only one shoe is worn while the other(s) have ample thickness. I hate to see such waste. The choice is yours since it appears the shoes are the same on each side, you could simply swap them and ensure that drag and minor friction partake when you reinstall the drum. Honestly, if it were me in my youth as a poor teen working on my own car, that's what I would do. But now that I'm a wealthy millionaire (that's tough to say without laughing) Ok, now that I'm financially stable, I would just buy them and install. Since you have to remove all the hardware anyway, installing new shoes would be the best option.
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On Mon, 8 Jan 2018 17:20:28 -0500, Meanie wrote:

I have since found out that you are correct and I was wrong. Reversing won't work to adjust the drums. The parking brake lever ratchets the adjustment. My bad.
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Define "many"
Only vehicles with "twin leading shoe" brakes use the same shoe front and back - and I'm not aware of ANY vehicle built with twin leading shoe brakes since the early seventies - and then only British vehicles. The leading and trailing shoe are generally of different lengths as well as often different friction materials.

Actually it IS common - and considered normal, for the "leading shoe" to wear differently than the "trailing shoe" on a servo type (self energizing) brake system - which virtually all recent (modern) drum brake systems are. the leading shoe contacts the drum, and the drag (friction) on that shoe rotates the shoe through the linkage between shoes, forcing the trailing shoe more firmly in contact with the drum. This enhances the brake action beyond what would be possible strictly by the hydraulic force from the wheel cyls.

It generally unhooks from the activbation lever connected to the brake shoes. On soime cars the lever unhooks easily from the shoe and does not NEED to be disconnected from the cable
Again - I would ADVISE you (the OP) to have a mechanic properly repair the brakes.
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On Mon, 08 Jan 2018 13:45:36 -0500, Clare Snyder wrote:

This net picture seems to show the rear drum brake setup reasonably well.
https://s13.postimg.org/hy7ga57c7/Rear_Brakes_1.jpg
I wonder why they put drum brakes in this vehicle when most are disc?
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Mad Roger posted for all of us...

Money, probably existing design...
--
Tekkie

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On Mon, 8 Jan 2018 19:10:52 -0000 (UTC), Mad Roger

Because drum brakes are standard equipment on all but the high trim models
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Clare Snyder posted for all of us...

Clare, prepare for the onslaught...
--
Tekkie

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Just like a boyscout.
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The parking brake is adjustable. This was usually done with a threaded sleeve over a threaded stud mounted between the two shoes at either the top or bottom. On the threaded sleeve is a toothed "wheel" which is used to turn the sleeve from the inside of the brake mount plate when the brake drum is on. There is a special tool for this, which resembles a small pry bar. You can probably find or make something to use.
Before putting the drum on, turn the sleeve in to shorten the link between the two brake shoes. The brake drum should then slide right on. Put on the tire and tighten the lugs to hold the drum properly in position. From under the car access the slot behind the toothed wheel, and using the adjustment tool turn it to lengthen the adjuster until the tire can no longer be rotated by hand. Then back the adjuster off until the tire can just be rotated easily.
BTW, make sure that the longer of the new brake shoes is on the BACK for each wheel.
-dan z-
__ Someone who thinks logically provides a nice contrast to the real world. (Anonymous)
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On Mon, 08 Jan 2018 09:16:15 -0500, slate_leeper wrote:

Is this the mechanism you're talking about?
https://s13.postimg.org/senkcelrb/brakes_drum_1.jpg
Here's the bottom, where the parking brake cable connects:
https://s13.postimg.org/5egwznnt3/brakes_drum_2.jpg

I picked up at Harbor Freight a bunch of brake tools, one an all purpose foot-long pliers, the others the special-purpose spring tool so I should be ok on tools unless there is a Toyota-specific tool required (which I don't think there is).

That makes a lot of sense, so I will do that when I put the new shoes back on. I probably should have turned the toothed wheel a few clicks even when I inspected it and put it back on, as it was a bit tight getting the drum back on. I had to use a mallet.

This makes a lot of sense!
It would adjust the brakes to the minimum, where the automatic backing up in reverse will fine tune it, I guess.

Ah. That means that the two shoes are NOT identical!
That negates the idea of "rotating" them every few years like we do tires every five thousand miles to get more even wear out of them over time.
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On Mon, 08 Jan 2018 09:16:15 -0500, slate_leeper

That is the SERVICE BRAKE adjustment - the parking brake adjustment is separate - on the cable - and on the VAST majority of vehicles on the road today the parking brake is totally self adjusting, as is the service brake. Different schemes are used on different vehicles and understanding how it is supposed to work is CRUCIAL to doing a safe and effective repair.

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On Mon, 08 Jan 2018 13:48:33 -0500, Clare Snyder wrote:

I see your distinction between the service brake and parking brakes!
This picture from the net seems to show them both:
https://s13.postimg.org/6n4sla81j/Rear_Brakes_2.jpg
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On Mon, 8 Jan 2018 19:11:52 -0000 (UTC), Mad Roger

Doesn't show the handbrake (e-brake) adjuster - which is on the cable or part of the pedal/handle.
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On Mon, 08 Jan 2018 17:06:20 -0500, Clare Snyder wrote:

You're correct that the handbrake is what adjusts the drums (I was wrong in assuming it was the action of braking in reverse).
People seem to say that the "bellcrank" needs replacing, so I dug into the terminology to find this parts diagram.
https://s9.postimg.org/h7kn548n3/parts_diagram.gif
I think the bellcrank are the funny shaped pieces.
https://s9.postimg.org/gi1ussaof/dorman_parts.jpg
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On Mon, 8 Jan 2018 07:02:22 -0000 (UTC), Mad Roger

Take the vehicle to a mechanic and have the brakes professionally repaired. You are not mentally equipped to do the job (not saying you are stupid, but you don't understand the implications well enough to do the job adequately. You LIKELY need new cabvles, and ot cyls, and or adjusters along with the shoes - which you MOST CERTAINLY can NOT just swithch positions. The adjusters should have been backed off to replace the drums.
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On Mon, 08 Jan 2018 13:36:04 -0500, Clare Snyder wrote:

That may be true, but I think I should be mentally equipped for something as simple as a brake job (for example, I've done disc brakes for decades). I've just never touched a drum brake before so everything is new.
That's why I'm doing my homework before tackling the job, which is why I ask you for advice.
My main question was the PROCEDURE, which seems to not need me to disconnect the parking brake cable anywhere other than actually inside the drum assembly. That was the main question.
The secondary questions will abound, based on what people ask me, such as someone asked why I considered 295 mm to be 2mm on the safe side over the 297 mm drum diameter.
Also the implication that "something is wrong" is perfectly natural since the front bottom half is worn more than the rest after 175K miles, but it seems from Googling that this is normal on Toyota rear drum brakes.
There's something in the math as shown here - but it's too triggy for me.
https://s13.postimg.org/4g0jxrng7/diagram_0.jpg
This is what someone wrote about why the Toyota wears in the front bottom
https://s13.postimg.org/l3s1zwn93/diagram_1.jpg

I would be happy to replace anything that seems bad, but nothing seems bad at this point other than the shoes are worn. Other than leaks (which I don't see, nor is there any indication of loss of brake fluid), what's the test for new cables, and cylinders and adusters?
Here's a closeup of the adjuster:
https://s13.postimg.org/senkcelrb/brakes_drum_1.jpg
Here's a picture of the parking brake setup:
https://s13.postimg.org/5egwznnt3/brakes_drum_2.jpg
And a closeup of the parking brake cable:
https://s13.postimg.org/b2n7qr2hz/brakes_drum_3.jpg
What is the test for worn condition?

This is an important question, which you've now answered (as did someone else who said the larger shoe is the rear shoe). This means "rotation" every few years isn't possible.

I see that now, as the drum required a good few mallet hits to get it back on. Not too many. But a few. Next time I'll turn the star adjuster before putting the drum back on.
Thanks for the advice!
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Mad Roger posted for all of us...

No mad man you have not researched anything, you ask everybody and argue and then criticize. If you HAD researched you would know all about the cables, shoes and adjusters. You are too busy taking pix and asking questions. 1) Take pix of brake assy after pulling drum. Go to NAPA and ask for a brake kit and linings and cylinders because yours will leak after you push the seals back or rebuild the cylinders. Measure the drums as they may be shot after this debacle.
--
Tekkie

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