Does anybody understand drum brakes anymore?

toyota
brakes
corolla

#1

My daughter has to push her brake pedal WAY down before the brakes engage. Once they engage, they don’t fade. This happens on every stop.



There are no brake indicator lights on and the brake fluid is new and filled to the top of the reservor. We’ve taken the car to a couple of mechanics and twice they replaced the master cylindar, each time flushing the brake fluid in case there was moisture in the system. We’re told the pads and shoes are fine.



My theory is that the drums are worn but I’ve yet to find a mechanic who’s willing to actually measure them; they all jump at replacing the master cylinder but that seems to be the most involved brake repair they know. They have no ideas about diagnosing the rear drum brakes. I haven’t personally been able to examine the brake drums for signs of excessive wear as the car lives in San Diego with my daughter; we live in Oakland.



I did find that this car either doesn’t come with self adjustors or they were taken out.



I have no idea how I’d check the proportioning valves. Do they ever go bad?



My question: In a disc/drum brake car, what can cause excessive brake pedal travel?


#2

“My question: In a disc/drum brake car, what can cause excessive brake pedal travel?”

Badly adjusted rear drum brakes are the most likely culprit. The pedal has to push so much fluid into the rear brake cylinders until the shoes touch the drum. If this car has no automatic adjustment hardware on it, they were removed. Every car and truck made with drum brakes has an adjuster on them. Any car or light truck made after the 70’s has some form of automatic adjustment.

Find a shop that will fix the rear drum brakes right, and it should fix your pedal problem.


#3

I’m also assuming this car has drums in the rear but discs in the front.

Does the pedal feel firmer, or feel further up away from the floor, if she doubles or triple pumps when she applies the brakes? If yes, there’s air in the line or the shoes are adjusted too far away from the drum surface.

Also, when the car is parked but with the engine running, is there any difference in pedal feel when the emergency brake is on vs. off? If yes, then the shoes are adjusted too far away from the drum surface, or there is too much slack in the e-brake cable (although the latter definitely depends on the rear brake design in general which may not apply to all cars with drums in the rear).

I’ve heard of some drum brake designs which ratchet out “automatically” so the shoes are adjusted right as they wear, but I heard you have to back up and brake abruptly to get them to ratchet out. You could have her try putting it in reverse, get up to about 10 mph, and slam on the brakes…do this a few times to see if that works. If it does, great…if it doesn’t, well, the worst think about it is that she’ll look stupid doing it.


#4

On the brake drum, there’s a stamping that indicates the max inside diameter of the brake drum. Probably in MM’s. Take a brake drum gauge and measure the inside of the drum. If it’s over spec, the brake drums are worn out.

Tester


#5

This shouldn’t be that hard a repair. If you can’t get a decent brake job at a local garage you might be better off going to a Toyota dealer. You’ll pay more, but at least you know they know the car and can handle the drum brakes on a Corolla.

The rear drums are out of adjustment, and perhaps missing hardware due to an incompetent mechanic. There also could be air in the brake lines, again due to an incompetent mechanic not bleeding the system properly. Both these issues could be handled and corrected by just about any good mechanic, but for sure a Toyota dealer can handle it.


#6

Even if the drums are out of spec you can still adjust the shoes to take up the slack.


#7

I did find that this car either doesn’t come with self adjustors or they
were taken out.

I find it difficult to believe the car didn’t have self adjustors from the factory. If they truly have been removed, (and that too is difficult to understand), it would lead to a long brake pedal travel.

You say you’ve not been able to personally inspect the car (due to it being far away), so how can you say it does not have any self adjustors?


#8

Does pumping the brake bring the pedal up? If the problem is air in the lines, pumping should bring the pedal up to normal very temporarily. The cure for air in the lines is to bleed all four brakes a bit.

Does the parking brake work? If it comes on in 8-12 clicks, the rear brakes don’t need adjustment. If it simply swings to the top of its range without applying the brakes, they are indeed misadjusted. The parking brake almost certainly is a manual, cable operated, system that bypasses the hydraulics.

It seems unlikely that the brakes don’t have automatic adjusters or that they have been removed. However, it’s not all that unusual for automatic adjusters to stop adjusting which would cause the brakes to slowly (over years) get lower and lower. It’s also possible on some cars that the adjusters were improperly installed at some point and have never actually adjusted automatically since

None of this should be a mystery to any competent mechanic. What are the chances that there are other factors that you aren’t telling us or don’t know that are leading them to suspect the master cylinder?


#9

Drum brakes are no more complicated than disc brakes and a low solid pedal usually points to a rear drum brake issue; worn shoes and/or drums or out of adjustment, etc. A look at a parts listing shows this car should have self-adjusters but that doesn’t mean they’re actully adjusting anything.

Maybe a measurement of the drum inside diameter and comparing it to the outside diameter of the shoes as installed would show this.


#10

Two clarifications about the self-adjusters:

First, I also remember “back up and jam on the brakes” as the technique by which one activates the self-adjusters. Thanks for confirming that.

Second, ten minutes of practicing answer (1) lead to my asking our mechanic if the self adjusters were rusted. That’s when I was told there weren’t any. I have not, though, had a chance to peer into the brakes myself and diagnose the problem; I’m depending on “hearsay.”

This repair began with our daughter’s return to school looming. When the mechanic said, “It’ll stop; I’m just not sure about those adjusters.”, both car and daughter bolted for SDSU.


#11

How low is LOW?

The reason I ask is that when I bought my Camry back in 2003, I was astounded how low the pedal went before the brakes engaged. To be sure it was normal, I searched the internet and then went on a few fake test drives of the same make/model/year Camrys. Numerous people seemed to agree that their Toyotas seemed to have lower pedal engagement than they were used to with other makes/models. So I took the next step and drove a couple under the premise of a test drive before buying and found them to be consistent with mine. I learned to live with it…


#12

Here’s a picture of Toyota’s rear drum. It has a different type of adjuster, witha a latch and a lever instead of the more-common rotating adjuster at the bottom. If these are missing, they should be replaced so that your brakes adjust correctly. If you mechanic can’t do this, find one who can. Toyota mechanics should be familliar with it.
http://wwww.gordosoft.com:443/echo/echo%20rear%20drum%20brake%20components.jpg


#13

The response from 'Oldschool" brings up my biggest “issue” and it ties in with my experience fixing a set of really worn drum brakes. The most worn set of drum brakes I ever replaced had a “trench” so deeply worn into the drum that we couldn’t pull the drum off. Adjusting the shoes down didn’t seem to be helping so we ground the ends off the little retaining rods that hold the shoes to the backplate, allowing us to pull the brake apart. New rods cost us about 50 cents.

The point is: You’re right - one can adjust shoes out a long way to accomodate worn drums.

With this, I’m lead to re-state my original question - not my snarky title, but the actual question at the end - “Why can’t we adjust drum/disk brakes on a Toyota Corolla in such a way as to remove the very long travel before the brakes take hold?”


#14

“Texases”, thanks for the diagram. Toyota’s little arms are vastly different from the sweeping, 'cross the brake, arms on older American cars. This is great.

I’m back to wondering if, through drum wear, we’ve exceeded the adjuster’s ability to…um…adjust…by having reached the last step on the lever.

Any thoughts on the issue of “travel”, or is “TwinTurbo” right - the excessive travel is irritating but, nonetheless, “as designed”?


#15

If you can’t find the adjustment hole in the backing plate it might be in the drum. My 1999 Camry is that way, you have to take the tire off to adjust the brakes.


#16

You need to get the inside of the drums measured to see if the I.D. is within spec. If it is, and if the shoes have adequate remaining lining, then the brakes need to be adjusted to eliminate excessive brake pedal travel. If adjusting the rear brakes correctly does not solve the problem, then check and see if the front disk pads are worn.

This all assumes there’s no air in the system - have they been bled?


#17

I had a shop teacher in about 1970 that told us it as common in the industry at the time to replace the self adjusters with manual ones, the mechanics just did not accept the self adjusters still and they had been out for years by then.

Durning a low point in my mechanic carrer I worked for a Brake repair chain and the thing that gave the most trouble to the largest amount of mechanics was correctly assembling rear drum brake hardware.


#18

Japanese drum brakes do NOT work like American drum brakes, at least not like the drum brakes of old. Newer American cars have adopted the Japanese system, which I think is inferior to the older systems.

Having said that, the Japanese drum brake is NOT adjusted by backing up and hitting the brakes. They are adjusted by pulling up on the parking brake handle. If the parking brake handle goes up more than 12 clicks, it moves the star wheel out one turn. The self adjuster cannot be removed in this system or the parking brake will not work. The star wheel can become stuck or the pawl on the parking brake linkage can get worn out so the self adjuster doesn’t work.

It is important to measure the drum diameter from time to time. As the drum and shoes wear, the self adjuster adjusts the brake shoes from the same end that the brake cylinder is attached. As the brakes wear, the brake cylinder could reach the point where the seals pop out the ends and you loose all brakes, suddenly. This did not happen with the older American style. This can happen even when the shoes are within their wear limits.

More bad news, getting a quality drum and shoes is getting very hard to find. The shoes and drums coming out of China offer absolutely no stopping power. You will need to stick with the much more expensive Toyota parts.


#19

Keith, OldSchool, Texases and everybody else who replied,

Your answers have been fabulous. They are just the mix of knowledge, experience and insight I was hoping for.

Thank you all!

 Chris

#20

“I did find that this car either doesn’t come with self adjusters or they were taken out.”

You can’t expect the brakes to work properly until the missing parts are replaced…A dealership or a decent brake specialty shop should have no trouble doing this. Wait. Missing Parts. Take it to a dealership because that (or a salvage yard) is the only place you will get those parts…

Restoring the rear brakes at a dealership will be fairly expensive…