View Single Post
  #4  
Old January 8th 18, 07:34 PM posted to alt.home.repair,rec.autos.tech
Mad Roger
external usenet poster
 
Posts: 61
Default Drum brakes - do you disconnect the parking brake cable?

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

> It appears the one shoe is unevenly worn.


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.

> Could be a bad cylinder or
> another stuck part such as the adjuster. Check them and replace/repair
> if needed.


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.

>> 3. I measured the drum to be 2mm smaller than the maximum diameter:
>> <http://www.bild.me/bild.php?file=9335528drum_brakes_2.jpg>

>
> Maximum diameter of what?


The drum:
http://www.bild.me/bild.php?file=942...m_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.

> Are you aware of the adjusters? Each side has
> one and it sits under the cylinder behind the hub.


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 he
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 he
https://s13.postimg.org/5egwznnt3/brakes_drum_2.jpg

> 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.


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.

> 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.


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

> 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.


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.
Ads