While rotating my tires today, I noticed that one of the rear brakes is rubbing. (?) While off the ground, the wheel will rotate freely for the majority of the cycle but then slow momentarily before starting the next cycle. Is this abnormal? I haven't checked the other rear tire yet, but wanted to see first if anyone can offer any insight into my observation.
The self-adjuster may be out of whack, or the parking brake cable may be too tight. See Hobbit's web site for illustrated disassembly essay.
I have this exact problem. So it's not normal right? Was thinking maybe things are not self centering cause from what I can see all the grease in between the backing plate and the shoes are all dried up. Is it possible to relube everything without taking it all apart? Is it worth it to take it all apart and clean and relube everything? I mean the rubbing doesn't seem to be effecting anything except I can hear it inside while driving slow if it's quite enough, but would it be affect mpg significantly?
If you can hear it while driving then I would say definitely get it fixed. Have you been keeping records of MPG?
No, not written, but it's been about 42 mpg, unless I go 55 mph than it goes up into the 50's. So basically if everything is working right you shouldn't hear anything when going down the road in stealth mode with the fan off?
In this post http://priuschat.com/forums/gen-ii-...st-efficient-speed-best-mpg-4.html#post385271 you will find a graph of MPG vs. speed for gen 2 (2004~2009) Prius for a rough comparison. Your 2002 (gen 1) may be a little less efficient. Also that graph shows MPG after full warm-up. In regular driving there is more fuel used for warm-up. Let's make sure the sound you hear is from the rear brake rubbing first. Was the sound once per rev. (faster with higher speed)? Did you jack the car up and spin the rear tire to confirm?
Woah Nelly, LOL: A bit of whisper when rotating drum brake wheel is the usual, in my experience. The shoes are very near the drum, and invariably some portion of the drum is slightly closer. Try applying/releasing the emergency/parking brake a few times, and then spin the wheel again. It may diminish the sound and drag, or it may remain about the same. I remember talking to a Service Manager, about one of first cars, and that's basically what he said: a slight drag and bit of noise, just at some point in the rotation, is normal.
Yes and yes, when I jacked the passenger rear (where the sound seemed to be coming from) it spins easy through part of a rotation than gets tougher at one spot where you can also hear something rubbing. I took the drum off and have about 3mm of pad left (supposedly good till 1mm according to manual).
True, I guess there always must be some runout, either the drum is not a perfect circle or there is some tiny amount of play in the bearings, probably both.
OK that confirms it being brake rubbing. Yes but it still doesn't have to be rubbing without applying the brake though. Maybe it needs some adjustment. Patrick?
1. You could use brake parts cleaner to clean off the old grease, then apply new grease at the points where the brake shoes contact the backing plate. 2. It would be better to remove the brake shoes, then reinstall after cleaning the backing plate and applying the grease. 3. It is not obvious that lack of lubrication is causing you to hear the brake shoe rubbing against the brake drum when you are proceeding at a slow speed. 4. It is possible that the brake drum is out of round, causing the noise problem. There is a spec for this. 5. If the brake drum interior meets spec, then you could adjust the brake shoes so that they will not rub against the drum until the brake pedal is depressed. Of course this means that the parking brake will not engage until the pedal has been pushed down more than before. 6. The mpg impact depends upon how much incremental friction results from a shoe briefly rubbing against the drum with each rotation. If this is a slight contact then the impact will not be noticeable.
