brake humming?

[2dooreighty5]

ive done all new pads on my 1985 caprice and now after like 4 months im getting a humming noise coming from my rear brakes...only happens when i press lightly on them like 1/4 pressure...never happens when pressed hard all the way..sounds like its vibrating the whole car...anybody know what this could be?

[Tech II]

Were the rear brakes, shoes or pads?

If shoes, were the drums turned? How was the hardware? Properly adjusted? Wheel cylinder OK?

[j cAT]

Originally Posted by 2dooreighty5

ive done all new pads on my 1985 caprice and now after like 4 months im getting a humming noise coming from my rear brakes...only happens when i press lightly on them like 1/4 pressure...never happens when pressed hard all the way..sounds like its vibrating the whole car...anybody know what this could be?

your 1985 caprice has rear drum brakes. what is correct is to replace these drums every 30-40,ooomi. do not use chinese crap as well.

never cut a brake drum ! the drums are made for the shoe radius. if you cut the drum this radius does not match that of the shoe and you will have poor braking and thiswill damage the front rotors by over heating caused by little rear brake effort.

the reason brake drums"" now"" must be replaced at this low mileage is the fact that asbestos is no longer used for the shoe material. also the drums are made of a softer metal than in 1985.

make sure the park brake cable has slack in it. adjust the shoes properly .

IF THE SHOES ARE WORN ONLY AT THE TOP THE DRUM IS TOO BIG !

COULD ALSO BE A BAD REAR WHEEL BEARING/OIL ON THE SHOES..........

[2dooreighty5]

thanks for quick response guys...im gonna get into the project tomrrow...i think ill pull both rrear wheels off and check out whats going on...inspect the drums and see how the shoes look...ill let you know what i find...thanks

[2dooreighty5]

ok so against what J cat said i had them re ground or turned...it was only 12 bucks a drum and solved the problem...brake'in isnt as nice but im gonna adjust the shoes so they fit better...but no more humming or grinding and they work great! thanks for advice guys

[j cAT]

Originally Posted by 2dooreighty5

ok so against what J cat said i had them re ground or turned...it was only 12 bucks a drum and solved the problem...brake'in isnt as nice but im gonna adjust the shoes so they fit better...but no more humming or grinding and they work great! thanks for advice guys

with what you did will cause the front rotors/pads to do more braking effort. the result will be warped rotors and a loss of brake power.

like I stated before when the top of the shoes are worn only this is because of the drum being too large. you cannot change the radius of the shoes to match the larger radius of the drums.

even if the drum cut was free , with ABS you should not have this in balance between front /rear.

[2dooreighty5]

so as i understand it the brakes only make up for 10% of the overall brakeing...also i never said that the shoes were worn down only at the top...i replaced the shoes in the back like 2 months ago and they look alomst brand new...with the freshly grounded drums im thinking my scott free...also there is that adjusting screw under the shoes which should be able to either expand or retract how close the shoes are to the drum...if theres humming im guessing they are too close and if its breking shitty then they are too far?....thanks for your response let me know what u think

[j cAT]

Originally Posted by 2dooreighty5

so as i understand it the brakes only make up for 10% of the overall brakeing...also i never said that the shoes were worn down only at the top...i replaced the shoes in the back like 2 months ago and they look alomst brand new...with the freshly grounded drums im thinking my scott free...also there is that adjusting screw under the shoes which should be able to either expand or retract how close the shoes are to the drum...if theres humming im guessing they are too close and if its breking shitty then they are too far?....thanks for your response let me know what u think

I don't understand 10% of what ?

the rear brakes should do 40% braking. the fronts 60 %.

like I stated before , I said radius , not the distance. you have 2 circles . now when these get to a different sized circle by too much then you get this top wear of the shoes. then you loose brake effort because you want the whole shoe surface to touch. this is where rotors are superior to drums.since as the rotors/ pads wear ,this does not change. the brake effort stays almost the same even if the pads/rotors wear up to a point which can be quite worn.

unless you used a dye marker on the NEW shoes ,you will not notice where the shoes got some worn. after 5-10,ooomi this will show.you could also find brake pulsations as well,,, as mileage builds up.

with new shoes and or drums the park brake cable need be loose. sometimes this is adjusted because the drums and shoes are worn out then when new stuff gets installed , you can get all kinds of problems.

post back after you run this for several thousand miles ,with these cut drums .

[2dooreighty5]

YESSSS. Its all making sense no

ok so because i cut the rotor the shoes will naturally get worn in unequal proportion since i changed the drum size...

and because of that the front rotors will be overworked....

ok its all coming together...i think i will try riding it for 5,000 miles check the rear shoes see how they are getting worn and then do new equipment accordingly...

its funny that the guy at the auto shop doesnt question why im having hit cut the drums...

thanks for the help man