Drum Brakes:To drag or not to drag...
Drum Brakes:To drag or not to drag... ...that is the question. Talked to a few mechanics and they both said to drag. One said he adjust them enough to hear a consistent noise, the other said he adjusts them enough so that the wheel can barely make one revolution when turned by hand. My chiltons manual says to adjust until you feel a slight drag, then back off so there is NO drag. Ive tried both ways and I like the way the brakes feel when theres a nice amount of drag, but the gas mileage suffers, with no drag I have to apply more pedal pressure.
And to top it off the drums feel out of round and keep warping on me. I even bought the expensive oem equipment(drums and shoes), put them on and they were out of round. Got the drums turned and they still felt out of round, got them turned again and there still out of round/warped. Whenever I come to a stop they pulsate and you can feel the drums getting tighter on certain spots during the revolution. And I know its the rears because the steering wheel doesnt shake and I did the e-brake check. This is driving me crazy!!
Thought some ls1techers would have some insight. Thanks in advance.
And to top it off the drums feel out of round and keep warping on me. I even bought the expensive oem equipment(drums and shoes), put them on and they were out of round. Got the drums turned and they still felt out of round, got them turned again and there still out of round/warped. Whenever I come to a stop they pulsate and you can feel the drums getting tighter on certain spots during the revolution. And I know its the rears because the steering wheel doesnt shake and I did the e-brake check. This is driving me crazy!!
Thought some ls1techers would have some insight. Thanks in advance. 
TECH Addict
Joined: Jun 2009
Posts: 2,012
Likes: 0
From: Tulsa, OK
Drums are supposed to have a slight drag to them. As to the pulsation, when you had the drums turned, did you have the shoes arced as well? If not, that's probably what's causing it. Most people don't do that anymore, and most places no longer have the machine for it. The pulsation will go away with time as the shoes wear in to the drums, unless it's also being caused by a warped rotor up front.
So what would your definition of a slight drag be? If I spin the rear wheels how many revolutions should they rotate before stopping, 1, 2, or should they spin rather freely with a slight dragging noise.
Your fuel economy will not suffer from dragging drums for long because you will wear the shoes down to where they're not dragging pretty quick. When you do this, however, the drum is getting so hot, you will warp it when you have the brakes applied at a standstill.
Slight drag is ideal because that way you can guage the balance between left/right so they are equal. Other wise the tight one will want to lock up. When you are adjusting, it's good practice to pump the wheel cylinder between adjustments in order to centre the shoes on the backing plate.
As far as your pulsating, I doubt it's the drum if you had them turned more than once. There's probably something (rust?, dirt?) on the flange of the axle that's causing the pulsation. Scrape it smooth.
Slight drag is ideal because that way you can guage the balance between left/right so they are equal. Other wise the tight one will want to lock up. When you are adjusting, it's good practice to pump the wheel cylinder between adjustments in order to centre the shoes on the backing plate.
As far as your pulsating, I doubt it's the drum if you had them turned more than once. There's probably something (rust?, dirt?) on the flange of the axle that's causing the pulsation. Scrape it smooth.
Well. Its not only a pulsating its a grabbing. Say when Im going really slow and have the brakes applied lightly, as the wheels make their revolution there will be a point where they will grab more. I just did the drums on another one of my cars and when I was adjusting the drag I spun the wheel and there was a nice consistent slight drag, and that car brakes just fine. When I adjust the drag on the car in question(1990 oldsmobile delta 88)when I spin the wheel you can hear and feel it get tighter at certain spots in the revolution. Thats telling me that its out of round, but I have allready had them turned twice and Im tired of throwing money out the window. I just think its riduculous that Im going to have to have expensive oem drums turned 3 times. And who knows if theyll be ok after that.
Launching!
Joined: Sep 2009
Posts: 236
Likes: 0
Drag. I like it to make three revolotions of the wheel witch a nice consistant drag, but with drums, there is almost always a little inconsistancy of "grabbing" harder at certain spots. It certainly sounds like your accusing the drums of what the rotors are doing though... did you ever turn them? if you feel pulsation in the wheel, or the pedal, 95% of the time is it the fronts. You can try driving to a high speed and pulling the e-brake, if it pulsates, your drums are getting over adjusted to keep warping them. if no pulsation with ebrake, than your fronts are to blame.
Ive allready done the e-brake check and its the rears. Maybe ill have all four turned next time just in case. I know the sound when adjusting the rears isnt supposed to be perfectly consistent but its way to tight in certain spots, and those tight spots are magnified when braking from higher speed.
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Oh, and there is no pulsation in the steering wheel. Ive had warped rotors before so I know the symptoms. thanks for the help. Its more of a grabbing than a pulsing. Thats why im looking at the rears.
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