I recently replaced the rear wheel cylinders, shoes and hardware on my Dakota. Everything is working great. The truck is stopping great and happy to have replaced the leaking wheel cylinder. The question I have is how do the automatic adjusters work. I read online that applying the brakes in reverse will activate the adjuster but I cannot see how that would work. It seems that the adjuster is part of the parking brake and would adjust the shoes when the parking brake is applied. Am I missing something or is it only when the parking brake is applied. Thank you in advance!!
Help me understand drum brakes
- Thread starter FFeng7
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Well, they're supposed to adjust while backing up and applying the brakes in reverse as well. There is a adjusting bar that turns the sprocket one click when it's working properly. Kind of a simple design however, I can't quite explain it here.
This beats writing it. https://auto.howstuffworks.com/auto-parts/brakes/brake-types/drum-brake2.htm
One thing I will say is the best way to adjust them automatically is to drive in everse and pump the brakes hard a few times. I found doing that every few months gets the pedal nice and firm in vehicles with drum brakes. Just backing up slowly and stopping normally doesn't seem to work as well.
One thing I will say is the best way to adjust them automatically is to drive in everse and pump the brakes hard a few times. I found doing that every few months gets the pedal nice and firm in vehicles with drum brakes. Just backing up slowly and stopping normally doesn't seem to work as well.
Automatic adjusting is nice. I used to have an employee that rode the brakes and never backed up. After every trip he wanted to take the 4Runner to the brake shop for repairs. I took his keys, went out in the parking lot and went forward and backward with hard stops a half dozen times, bringing the pedal up to normal. He could never understand.
When the shoes go out far enough pulling them backwards in the stopping, a lever hits the star wheel and turns it if necessary.
When the shoes go out far enough pulling them backwards in the stopping, a lever hits the star wheel and turns it if necessary.
The shoes rattle around in there somewhat. When you roll forwards a "servo action" makes them clamp better. When you roll back they click the adjuster or the e-brake might do it for patent dodging reasons.
If you ever have them apart make sure the adjuster works freely. If it was stiff, it's gonna be stiff again, and you might want to dismantle it and put some anti-sieze in or something.
If you ever have them apart make sure the adjuster works freely. If it was stiff, it's gonna be stiff again, and you might want to dismantle it and put some anti-sieze in or something.
Originally Posted By: widman
Automatic adjusting is nice. I used to have an employee that rode the brakes and never backed up. After every trip he wanted to take the 4Runner to the brake shop for repairs. I took his keys, went out in the parking lot and went forward and backward with hard stops a half dozen times, bringing the pedal up to normal. He could never understand.
When the shoes go out far enough pulling them backwards in the stopping, a lever hits the star wheel and turns it if necessary.
Yes, the key is pumping and stopping harder than normal in reverse usually does the trick. I have a long driveway, sloping down towards the street. Every once in a while when I back my van out I'll pump the brakes hard a few times and it works nicely.
Automatic adjusting is nice. I used to have an employee that rode the brakes and never backed up. After every trip he wanted to take the 4Runner to the brake shop for repairs. I took his keys, went out in the parking lot and went forward and backward with hard stops a half dozen times, bringing the pedal up to normal. He could never understand.
When the shoes go out far enough pulling them backwards in the stopping, a lever hits the star wheel and turns it if necessary.
Yes, the key is pumping and stopping harder than normal in reverse usually does the trick. I have a long driveway, sloping down towards the street. Every once in a while when I back my van out I'll pump the brakes hard a few times and it works nicely.
Originally Posted By: demarpaint
This beats writing it. https://auto.howstuffworks.com/auto-parts/brakes/brake-types/drum-brake2.htm
I clicked on that but Figure 6 is the only picture it will let me see.
And then it says this to me:
"This content is not compatible on this device."
This beats writing it. https://auto.howstuffworks.com/auto-parts/brakes/brake-types/drum-brake2.htm
I clicked on that but Figure 6 is the only picture it will let me see.
And then it says this to me:
"This content is not compatible on this device."
Good explanations - it's just taking advantage of the small amount of back-and-forth slack the shoes have, to work the mechanism that ticks the adjuster over.
I find on my '85 GMC 1-ton that I need to adjust them manually - maybe the load-sensing proportioning valve doesn't let enough flow through at unloaded height to adjust, I'm not sure, but they never adjust on their own. However, one model I've seen it happen on repeatedly is Buick Lesabre's - it is written, on an ancient scroll, that at some point owners will complain of a grinding noise from the back of their H-body GM. Back up about as fast as is comfortable and slam on the brakes about 4 times, and voila, better brakes and no noise.
I find on my '85 GMC 1-ton that I need to adjust them manually - maybe the load-sensing proportioning valve doesn't let enough flow through at unloaded height to adjust, I'm not sure, but they never adjust on their own. However, one model I've seen it happen on repeatedly is Buick Lesabre's - it is written, on an ancient scroll, that at some point owners will complain of a grinding noise from the back of their H-body GM. Back up about as fast as is comfortable and slam on the brakes about 4 times, and voila, better brakes and no noise.
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Basically when there's slack in the shoes, they will be able to rock back and forth. That rocking motion will cause the adjuster to click it tighter one notch until there's no slack. No more rocking motion, no more clicks of the adjuster. Rocking them comes from going into reverse and as other mention, when you slam on the brakes, the shoes shift and the adjuster can click. When you did them, you could have played with the adjuster til you get to the point where the drum stops, then you back it off a few turns. Then it should be perfect til you have some wear and no adjustment kicks in.
Thank you all for the replies. I did adjust the brakes manually untill there was a slight drag on the drum while it was spun around. I did find that the side that was leaking had a frozen adjuster. I was able to break it free in a vise. Both of the adjusters were cleaned a d reassembled with a little antisize. I will keep a eye on them and probably readjust in a few weeks. Thank you again for the insight on drum brakes.
Originally Posted By: FFeng7
The question I have is how do the automatic adjusters work.
Badly.
Originally Posted By: widman
Automatic adjusting is nice.
Even when it works its a pain in the arse, and on the old neglected cars I buy it tends not to, at least initially.
IMO the snag with automatic adjusting, pretty much by definition, is that you have no control.
This means that you end up having to do keyhole rust surgery through a tiny hole in the drum backplate to slacken the shoes off enough to clear the wear lip on the drum, so you can get them off.
This was not a problem with manual adjusters, but these days you'd have to invest in a real classic to get them.
The question I have is how do the automatic adjusters work.
Badly.
Originally Posted By: widman
Automatic adjusting is nice.
Even when it works its a pain in the arse, and on the old neglected cars I buy it tends not to, at least initially.
IMO the snag with automatic adjusting, pretty much by definition, is that you have no control.
This means that you end up having to do keyhole rust surgery through a tiny hole in the drum backplate to slacken the shoes off enough to clear the wear lip on the drum, so you can get them off.
This was not a problem with manual adjusters, but these days you'd have to invest in a real classic to get them.
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Originally Posted By: FFeng7
Thank you all for the replies. I did adjust the brakes manually untill there was a slight drag on the drum while it was spun around. I did find that the side that was leaking had a frozen adjuster. I was able to break it free in a vise. Both of the adjusters were cleaned a d reassembled with a little antisize. I will keep a eye on them and probably readjust in a few weeks. Thank you again for the insight on drum brakes.
I would have just gotten a completely new set of springs and adjusters. They're on rockauto.com. Typically they're only $5-$7 per side so about $15 for all new springs and adjusters. They don't work that well once they're all rusted up. And for about $15, you mind as well get a new set.
Thank you all for the replies. I did adjust the brakes manually untill there was a slight drag on the drum while it was spun around. I did find that the side that was leaking had a frozen adjuster. I was able to break it free in a vise. Both of the adjusters were cleaned a d reassembled with a little antisize. I will keep a eye on them and probably readjust in a few weeks. Thank you again for the insight on drum brakes.
I would have just gotten a completely new set of springs and adjusters. They're on rockauto.com. Typically they're only $5-$7 per side so about $15 for all new springs and adjusters. They don't work that well once they're all rusted up. And for about $15, you mind as well get a new set.
Originally Posted By: Wolf359
Originally Posted By: FFeng7
Thank you all for the replies. I did adjust the brakes manually untill there was a slight drag on the drum while it was spun around. I did find that the side that was leaking had a frozen adjuster. I was able to break it free in a vise. Both of the adjusters were cleaned a d reassembled with a little antisize. I will keep a eye on them and probably readjust in a few weeks. Thank you again for the insight on drum brakes.
I would have just gotten a completely new set of springs and adjusters. They're on rockauto.com. Typically they're only $5-$7 per side so about $15 for all new springs and adjusters. They don't work that well once they're all rusted up. And for about $15, you mind as well get a new set.
Good practice to replace the hardware. Sometimes when the springs rust, they snap in two. Weak springs will cause the drums to tighten up excessively.
Originally Posted By: FFeng7
Thank you all for the replies. I did adjust the brakes manually untill there was a slight drag on the drum while it was spun around. I did find that the side that was leaking had a frozen adjuster. I was able to break it free in a vise. Both of the adjusters were cleaned a d reassembled with a little antisize. I will keep a eye on them and probably readjust in a few weeks. Thank you again for the insight on drum brakes.
I would have just gotten a completely new set of springs and adjusters. They're on rockauto.com. Typically they're only $5-$7 per side so about $15 for all new springs and adjusters. They don't work that well once they're all rusted up. And for about $15, you mind as well get a new set.
Good practice to replace the hardware. Sometimes when the springs rust, they snap in two. Weak springs will cause the drums to tighten up excessively.
My dad used to take the two pieces apart, clean them with a brass brush and then put some wheel bearing grease inside the hallow section of the one piece so it moved nice and freely. Then he would reinstall and when setting up he would put the drum on, take off the adjustment access rubber cap on the back behind the drum and use a flat screw driver to advance it forward just enough that the brakes were slightly grabbing the drum when spun by hand. Pump the brakes a few times before doing this adjustment to allow fluid into the wheel cylinder first though.
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I had a Toyota with rear drum brakes about thirty some years ago and the adjuster was activated by the parking brake. Think the vehicle was a 4W drive Tercel station wagon.
Originally Posted By: Lubener
Originally Posted By: Wolf359
Originally Posted By: FFeng7
Thank you all for the replies. I did adjust the brakes manually untill there was a slight drag on the drum while it was spun around. I did find that the side that was leaking had a frozen adjuster. I was able to break it free in a vise. Both of the adjusters were cleaned a d reassembled with a little antisize. I will keep a eye on them and probably readjust in a few weeks. Thank you again for the insight on drum brakes.
I would have just gotten a completely new set of springs and adjusters. They're on rockauto.com. Typically they're only $5-$7 per side so about $15 for all new springs and adjusters. They don't work that well once they're all rusted up. And for about $15, you mind as well get a new set.
Good practice to replace the hardware. Sometimes when the springs rust, they snap in two. Weak springs will cause the drums to tighten up excessively.
I've had rusted springs snap in service before, so now whenever I touch the [censored] drums I buy a new hardware set. A couple bucks is better than needing a whole drum and shoe set, plus hardware kit when they break. Gotta love the rust belt!
Oh and wheel cylinder bleed screws are ALWAYS seized...
Originally Posted By: Wolf359
Originally Posted By: FFeng7
Thank you all for the replies. I did adjust the brakes manually untill there was a slight drag on the drum while it was spun around. I did find that the side that was leaking had a frozen adjuster. I was able to break it free in a vise. Both of the adjusters were cleaned a d reassembled with a little antisize. I will keep a eye on them and probably readjust in a few weeks. Thank you again for the insight on drum brakes.
I would have just gotten a completely new set of springs and adjusters. They're on rockauto.com. Typically they're only $5-$7 per side so about $15 for all new springs and adjusters. They don't work that well once they're all rusted up. And for about $15, you mind as well get a new set.
Good practice to replace the hardware. Sometimes when the springs rust, they snap in two. Weak springs will cause the drums to tighten up excessively.
I've had rusted springs snap in service before, so now whenever I touch the [censored] drums I buy a new hardware set. A couple bucks is better than needing a whole drum and shoe set, plus hardware kit when they break. Gotta love the rust belt!
Oh and wheel cylinder bleed screws are ALWAYS seized...
Originally Posted By: Smoqueed
Good practice to replace the hardware. Sometimes when the springs rust, they snap in two. Weak springs will cause the drums to tighten up excessively.
I've had rusted springs snap in service before, so now whenever I touch the [censored] drums I buy a new hardware set. A couple bucks is better than needing a whole drum and shoe set, plus hardware kit when they break. Gotta love the rust belt! [/quote]
I thought that was standard practice... Guess because I grew up in the Rust Belt.
Good practice to replace the hardware. Sometimes when the springs rust, they snap in two. Weak springs will cause the drums to tighten up excessively.
I've had rusted springs snap in service before, so now whenever I touch the [censored] drums I buy a new hardware set. A couple bucks is better than needing a whole drum and shoe set, plus hardware kit when they break. Gotta love the rust belt! [/quote]
I thought that was standard practice... Guess because I grew up in the Rust Belt.
Thank you all for the information. I did replace all the springs and hardware. The hardware kit did not come with adjusters. So I did take them apart and clean them well with a wire brush and a little antisize on the threads. Hopefully they will stay free for the next few years.
Originally Posted By: FFeng7
Thank you all for the information. I did replace all the springs and hardware. The hardware kit did not come with adjusters. So I did take them apart and clean them well with a wire brush and a little antisize on the threads. Hopefully they will stay free for the next few years.
I would not use antiseize. Antiseize isn't designed to lubricate over and over, it's designed to stop a bolt from seizing. I would use brake grease on it
Thank you all for the information. I did replace all the springs and hardware. The hardware kit did not come with adjusters. So I did take them apart and clean them well with a wire brush and a little antisize on the threads. Hopefully they will stay free for the next few years.
I would not use antiseize. Antiseize isn't designed to lubricate over and over, it's designed to stop a bolt from seizing. I would use brake grease on it
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