One caller last week had squeaking brakes and asked Tom and Ray for advice. The caller said he had heard from a friend that if he backed up rapidly, and then slammed on the brakes, it might help. Tom and Ray said they’d never heard of this idea. But I’ve heard of this procedure, at least for tightening drum brakes. Maybe the caller said he had disc brakes. I don’t recall. A lot of cars even these days have disc brakes on the front, and drum brakes on the back. If it was the back brakes that were squeaking, the back-up idea possibly might help.
On some cars of yesteryear at least, slamming on the brakes while backing up tightens the shoes against the drums. There is a little geared-wheel-like mechanism that ratchets the brake shoes down so they are closer to the drums, activated by the backing up and stopping action. True, it doesn’t seem like tighter brakes would affect squeaks, but maybe it would help in some conditions.
Anybody know, do car manufacturers still make drum brakes with this back-up tightening mechanism?
Mostly no. Most disc/drum combos use the parking brake to adjust the shoes to the drum. In the all drum world, backing up and applying the brakes did the adjustment as the parking brake would not work on the front drums.
Even when you backed up to adjust them, you wouldn’t slam on the brakes but instead, pump them. Each pump moved the little wheel a click or two and you had to release the brake to allow it to reset for another click.
This was mostly just to adjust the drums as you wore them down, not for the initial adjustment. For that there was a small slot, had a plastic cover on it, on the back side of the brake plate. You removed the plastic cover and inserted an angled brake adjuster (looked like 2 flat tip screwdrivers shafts welded together) to manually move the adjuster wheel until the shoes started dragging on the drum. As the shoes wore down, backing up would move the adjuster a little and keep the shoes against the drum.
I have never seen the parking brake activate the self-adjusting ratchet on drum brakes. A light to moderate normal brake application in reverse is all it takes to self-adjust. When adjustment occurs one will hear a loud click or two. Is this click that most come to the shop to complain about not knowing that it is both normal and good.
David, if the starwheel is located just under the wheel cylinder, the auto adjustment is done by the parking brake. If the star wheel is located at the base of the brakes and acts as the hinge point for the shoes, then the adjustment is done by backing up.
Japanese cars all adjust by the parking brake as do many new American models.
On most cars ive had you pull the e brake about 4 clicks then slowly reverse and the mechanism will tighten up in the rear drums to allow proper braking. I drive honda toyota and pontiac models mostly hope this helps
Agree with @meaneyedcatz “Self adjusters” rarely work very well, especially on vehicles that tend to have long pedal travel. You can adjust them manually to help bring the travel shorter. I had a 3/4 ton Suburban that required this. Every oil change I’d adjust them a few clicks. Backing up and hammering the brakes didn’t adjust them enough. If I didn’t, the brake travel would add a few gray hairs every time I had to slam the brakes because someone darted in front of me and hit their brakes.
Some people just can’t tolerate tailgating an SUV that big…
Self-servo brakes that need adjusting will shift toward the front significantly on a hard stop in reverse and possibly unstick the self adjusting mechanism but if the mechanism is operating freely just pumping the pedal firmly several times should crank the adjusters out.
On my 2002 Sienna the parking brake definitely adjusted the rear brakes. I posted some years ago that the Toyota dealer near McAllen, recommended parking brake adjustment when it was not needed. The service writer admitted they often do this when a car has a lot of miles because most folks do not use the parking brake. I live in a mountain village and ALWAYS use the parking brake except under my sun roof where it is perfectly level. I was rather unhappy. they wanted $40 for something that did not need to be done at all.
Aloha, I just want to say that I had a rear disc brake freeze on me in the middle of nowhere. The rear brakes were just changed out and rotors turned. I called my mechanic and he thought the backing up maneuver might make it worse. He told me that the pistons were all working smoothly upon assembly. I’m lucky to have a great and trustworthy mechanic. I remember back in the 70’s when disc brakes were referred to as “self adjusting”, and to get them to adjust we would do the back up thing. So, I tried it out in the boonies and IT WORKED!
I backed up about 20’ and hit the brakes a few times. I hit them hard and easy, so I’m not sure which of the two did it. I’ve had no trouble with it since (about 10 days).
I stand corrected in such a nice, polite, considerate manner.
You are certainly head and shoulders above my mechanic.
Maybe if everyone communicated with each other in this manner, the world can continue to go down the toilet. OH Boy!!
sorry, some people just do not suffer fools. Take it on he chin when you are wrong and don’t whine and try and turn tables and make about facts being a popularity contest. That’s what facebook does.
