sound coming from rear?
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Member
Joined: Sep 2002
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From: Benton Harbor, MI
sound coming from rear?
ok, i hope this is from the same problem as my loose e brake.
(asked in another post)
But after coming to a stop (like at a red light), then starting to go.
i hear a little "Clunk"
Its not the U joints, or rearend. it only happens at stops.
not like when i would just slow then hit the gas.
I'm thinking my breaks are staying ingaged, becouse of loose e-brake.
What is everyones opinons??
scottie
also for got to add:
When i do use the parking brake, i have to pull up with my toe as i release pedal, if i don't the drivers rear will stick and get REAL hot.
(asked in another post)
But after coming to a stop (like at a red light), then starting to go.
i hear a little "Clunk"
Its not the U joints, or rearend. it only happens at stops.
not like when i would just slow then hit the gas.
I'm thinking my breaks are staying ingaged, becouse of loose e-brake.
What is everyones opinons??
scottie
also for got to add:
When i do use the parking brake, i have to pull up with my toe as i release pedal, if i don't the drivers rear will stick and get REAL hot.
Last edited by scottie4x4sport; Feb 13, 2003 at 04:55 PM.
Thread Starter
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Member
Joined: Sep 2002
Posts: 52
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From: Benton Harbor, MI
did you take it to a dealer or shop to look at it?
what did they say, if so?
I think mine has something to do with the Parking brake.
I look today and cable was off drivers rear, and the P brake was pulled forward alittle.
scottie
what did they say, if so?
I think mine has something to do with the Parking brake.
I look today and cable was off drivers rear, and the P brake was pulled forward alittle.
scottie
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Joined: Nov 2002
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Actually the problem first showed up when my dad owned the truck. He took it to a dealer and they replaced the Ebrake cable to no avail. The problem still exists but it is faint and it doesn't seem to be wearing my shoes at all, so I dont really worry that much. 
Member
Joined: Dec 2002
Posts: 82
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From: Clarkston, MI
Well, you guys have part of it right...
The noise is inside the brake drum, and it is caused by the shoes staying out in contact with the drum...but has nothing to do with the park brake system (that I know of anyway).
Drum brakes are self energizing beasts, unlike a disc brake. That means the harder you apply it, the harder it trys to apply itself, assuming the drum is rotating. When the shoes are new, this creates no problem...but when the shoes become worn, usually over 50-75% worn, the delicate geometry balance within the brake gets upset. Usually this is caused by auto adjusters which don't really keep up with lining & drum wear like they should. This creates uneven wear patterns (taper wear from one end of the lining arc to the other).
Then when the proper brake shoe geometry is upset, this self energization is enough to keep one or both shoes 'wedged into' or 'toggled onto' the brake drum. Picture the action of a fold down doorstop...the harder you push to try to close the door, the more force the doorstop exerts to resist the movement.
Anyway, when you release the brake at the stop light and there is no longer any input force to the shoe, and start rolling, the shoe 'pops' away from the drum and releases. That's the clunking noise you hear.
The solution is simple. Replace the rear shoes, free up & grease the adjusters, and replace all the springs in the brake. Problem should disappear until those shoes are worn a similar amount (or more if the adjusters are working better than before). One more thing...drum diameter is a factor in the geometry equation too. Don't overlook checking the drum diameter. The larger the diameter, the sooner the geometry will get out of whack again.
Just another good reason NOT to turn brake drums...
Good Luck!
Tom
The noise is inside the brake drum, and it is caused by the shoes staying out in contact with the drum...but has nothing to do with the park brake system (that I know of anyway).
Drum brakes are self energizing beasts, unlike a disc brake. That means the harder you apply it, the harder it trys to apply itself, assuming the drum is rotating. When the shoes are new, this creates no problem...but when the shoes become worn, usually over 50-75% worn, the delicate geometry balance within the brake gets upset. Usually this is caused by auto adjusters which don't really keep up with lining & drum wear like they should. This creates uneven wear patterns (taper wear from one end of the lining arc to the other).
Then when the proper brake shoe geometry is upset, this self energization is enough to keep one or both shoes 'wedged into' or 'toggled onto' the brake drum. Picture the action of a fold down doorstop...the harder you push to try to close the door, the more force the doorstop exerts to resist the movement.
Anyway, when you release the brake at the stop light and there is no longer any input force to the shoe, and start rolling, the shoe 'pops' away from the drum and releases. That's the clunking noise you hear.
The solution is simple. Replace the rear shoes, free up & grease the adjusters, and replace all the springs in the brake. Problem should disappear until those shoes are worn a similar amount (or more if the adjusters are working better than before). One more thing...drum diameter is a factor in the geometry equation too. Don't overlook checking the drum diameter. The larger the diameter, the sooner the geometry will get out of whack again.
Just another good reason NOT to turn brake drums...
Good Luck!
Tom
Member
Joined: Dec 2002
Posts: 82
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From: Clarkston, MI
Scottie:
One more thing...and it IS related to the park brake system.
Make sure you check for proper release of the parking brake, cable,pedal system. If you don't get complete release, like from corroded cables, etc, then (just like driving around with the park brake not released) you will wear the linings into this unnatural taper pattern and create the same situation I described earlier.
The reason is that the parking brake input force is applied to the shoes in a different position than the wheel cylinder therefore creating a different force distribution (wear pattern) than would occur during normal service braking.
Tom
Make sure you check for proper release of the parking brake, cable,pedal system. If you don't get complete release, like from corroded cables, etc, then (just like driving around with the park brake not released) you will wear the linings into this unnatural taper pattern and create the same situation I described earlier.
The reason is that the parking brake input force is applied to the shoes in a different position than the wheel cylinder therefore creating a different force distribution (wear pattern) than would occur during normal service braking.
Tom