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.

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.

3. I measured the drum to be 2mm smaller than the maximum diameter:

4. Where the maximum diameter of 297mm was stamped on the drum itself:

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:

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?
Reply to
Mad Roger
It depends on the cable. Some have a spring that keeps the cable end firmly in place. Those can be tough to put back on. In that case, I'd leave the c able attached. The parking brake arm is held on with a clip so you really d on't have to detach it. Just clip it on the new shoe with the cable attache d.
Your photos don't show any spring attached so it could just fall off when y ou detach the arm from the shoe. Make sure you take a lot of pictures. I wa s working on some brakes a couple of weeks ago and just blanked out on wher e to attach a spring. Your brake looks pretty simple so that's a good thing .
It's normal to have one shoe worn more than the other - they were designed that way. Brake shoes are cheap, so replace both. A hardware kit with new c lips and springs are nice if you can get it. Good luck!
Reply to
dsi1
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
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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.
Reply to
Meanie
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)
Reply to
slate_leeper
On Mon, 8 Jan 2018 07:03:33 -0500,
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:
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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:
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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:
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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:
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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:
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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.
Reply to
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.
Reply to
Clare Snyder
On Mon, 08 Jan 2018 09:16:15 -0500,
Is this the mechanism you're talking about?
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Here's the bottom, where the parking brake cable connects:
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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.
Reply to
Mad Roger
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.
Reply to
Clare Snyder
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.
Reply to
Clare Snyder
On Mon, 08 Jan 2018 13:36:04 -0500,
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.
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This is what someone wrote about why the Toyota wears in the front bottom
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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:
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Here's a picture of the parking brake setup:
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And a closeup of the parking brake cable:
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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!
Reply to
Mad Roger
On Mon, 08 Jan 2018 13:45:36 -0500,
This net picture seems to show the rear drum brake setup reasonably well.
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I wonder why they put drum brakes in this vehicle when most are disc?
Reply to
Mad Roger
On Mon, 08 Jan 2018 13:48:33 -0500,
I see your distinction between the service brake and parking brakes!
This picture from the net seems to show them both:
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Reply to
Mad Roger
I once owned a 1950 Ford car. One day when I was driving and one of the rig ht front wheel brake shoes came loose. That caused the car to make a sharp right hand swerve to the right, RIGHT NOW! Good idea is to check the brakes and brake fluid once in a while. Sometimes it is more important to STOP th an keep on going.
Reply to
allisellis851
Drum brakes in the rear work perfectly fine for most vehicles because most of the braking is done with the front brakes. The reason 4 wheel disks are popular are mostly because people want it because it sounds cool. The probl em with disk brakes is that it's less effective as parking brakes. Some rea r disk brake systems will have an integrated brake drum and separate mechan ical drum brake system to use as a parking brake.
You should know that the starwheel adjuster will have left and right parts that are not interchangeable. One side will have a right handed thread.
To set the initial clearance, start with the adjuster completely in, then t urn it out a couple of turns. If the drum slips on easily, turn the wheel o ut more turns until you feel some resistance. Once you get the drum on, ste p on the brake to center the shoes. You might then have to adjust the clear ance some more. Set the shoe clearance until you hear some light brushing w hen turning the drum.
Reply to
dsi1
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.
Reply to
Tekkie®

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