New drum brakes drag and get hot

[NIck]

I just overhauled the brakes on my 1996 Toyota Corolla and my rear drum brakes seem to be dragging and getting hot.

The right rear drum in particular was difficult to install over the shoes and was not spinning freely at all. I tried the following.
1. fully shorten adjuster until it was loose between shoes
2. opened bleeder and squeezed shoes in (probably not necessary since new return springs should do this)
3. shoes contact new wheel cylinder on top and post on bottom
4. fully loosened parking brake adjustment nut in the center console
5. turned drums down 0.020 inch
6. before and after pictures of installed shoes look identical

The only thing I didn’t do, which I saw another mechanic do, was pull on the parking brake cables to make sure they were moving freely. However, my parking brake lever travels the recommended 4 to 7 clicks and it seems to activate the parking brake arm inside the shoe as designed.

After a long drive, the temperature on the front disc brakes were a cool 110 F and 106 F. The temperature of the rear drum brakes were a warm 132 F and a hot 170 F. Is this normal?

I remember the tight drum spun freely only once while I was messing around with loosening/tightening the adjuster and pulling on the parking brake to center the shoes. However, I think I pulled on the parking brake lever again and the drum got permanently tight again. I guess the parking brake adjusted the adjuster another notch tighter. At this point, I gave up…figuring this could happen anytime I pull up on the parking brake. Does anybody have any suggestions?

Maybe the new shoes are too thick or maybe the new wheel cylinders are too long?? I think only a few extra thousands of an inch could cause the drag. Maybe I just have to wait until the shoes wear a few thousands of an inch.

Attachments:

• IMG_20160505_150941.jpg
• IMG_20160505_150920.jpg
• IMG_20160505_145853(1).jpg

Topic

[Frank Heiser]

You sure you can’t squeeze the shoes further into the wheel cylinder? I can’t be sure but it looks like there’s some more room for the pistons to shove further in there. BTW, you don’t need to open the bleeder to do that, just squeeze and it will push the fluid back up to the master cylinder.
I use a big pair of channel lock pliers to squeeze them in as far as they’ll go, works great both on wheel cylinders and calipers too. Just be careful not to harm the rubber around them.

Even with all new components you should still be able to adjust it down to where it’s loose, shouldn’t be so tight.

[Jay]

Don’t drum brakes have an adjuster somewhere (not the star wheel) for the normal brake that goes together with the disc brake?

Sent from my SM-N9005 using Tapatalk

[NIck]

Thank you for your reply. Yeah, I’m positive the wheel cylinders can’t be compressed anymore.

The brake pedal height may have been a little low, so I adjusted the pedal up 3/8 inch. Then I ensured I had the correct pedal freeplay and the correct clearance between the pedal arm and brake light switch. The pedal freeplay is not directly adjustable, but I did have enough mechanical slop in the brake pedal mechanisms to ensure nothing is mechanically keeping the master cylinder piston pressed in.

After driving the car around 30 minutes, the brake temperatures were:
front/left…153 F
front/right…152 F
rear/left…165 F
rear/right…174 F

So the temperatures are closer together, which I guess is good. Checking another car and looking on the internet…these temperature may be normal.

However, after another drive, and jacking the car up the next day to spin the tires, I noticed all the brakes dragging. With some effort, I was able to spin the front tires around 2 revolutions and the rear tires around 1 revolution. Again, maybe this is normal, but seems like you wouldn’t want your brakes to drag at all….wears out the pads/shoes and reduces your gas mileage.

Two videos make me think this might be normal. One mechanic said the pads lightly touch the rotors when the brake pedal is not pressed. Another Mercedes mechanic was content with his tires barely turning after he spun them.

Someone suggested the booster pushrod might be too long. I might check this….

[NIck]

Jay, I’m not familiar with that. My rear brakes have an adjuster with a star wheel that sits horizontally between the brake shoes. The adjuster is like a turnbuckle with fork ends.

[Frank Heiser]

Sounds like it may have sorted itself out, you DO want a slight drag from the brake pads, but still should be able to spin the wheels and have them keep spinning at least a turn or two on their own before stopping, and it sounds like that’s what you have now.

[NIck]

I think I’m done with this brake job. The wheel temperatures are cooler so I guess the brakes just needed some time to wear in.

Last drive…

Front Wheels…. 123 and 122 F

Rear wheels… 107 and 112 F

I still might jack the car up in a month and see how the wheels spin. Finished! B)

[Nicholas Clark]

Drum brakes should be the same temp or close. They do about 30% of the brake work but are encased in a drum and therefore cool poorly. So it seems you have everything about sorted.

[Author]

Replies