rear brake drum loose (how are they secured to the wheel?)

[mugenpaolo]

hi all,

I have a 1999 corolla with 85k miles and still with its original brakes.
recently when i inspected the brakes for the 1st time (i guess i might be blamed for that ), i realized that the drums can be easily slid off.

and when i put them back on, i can actually turned them a little bit until it's limited by the four bolts that are for the nuts to hold the wheel (the one on which tire is mounted, not the one that holds the drum) on.

imagine that since the diameter of the drum's four holes are slightly bigger than those four long bolts, there will be some "free play" if the drum is not secured steadily on the wheel (this is not the wheel on which the tire is mounted, it's the inner one i'm talking about here).

the question is, is that a problem with my drum or the problem with my inner wheel that the drum is put on? how can i tell?

surprisingly, i think this issue actually started back in year 2002. so that's 7 years ago!!!
i remembered since that time, i sometimes would hear some kind of noise like collision of two pieces of metals from the rear of the car when i apply the brakes.
until after i inspected the brakes recently and got to understand the structures. i suspected that the sound is basically the drum hitting the bolts.
i verified that by paying attention to under what conditions that noise will come when i apply the brakes.
and that is if i've braked when the car was going forward, then i let the car go reverse and the first brake will have the sound; similarly, after i stopped when going reverse, and the first brake when i go forward, the sound will come.
this is because when my car is going forward, and i apply brakes, the shoes will stop the drum first, but since the drum is loose on the inner wheel, the drum won't be able to hold the wheel until the bolts are touching the front side of the holes on the brake. and if i drive in the same direction again, since the bolts are already touching the front side of those holes on the drum, there won't be the metal collision noise. but if the car goes in opposite direction, and brake is apply, then the bolts would have to hit on the back side of the holes on the drums.
this is a little lengthy, but i think you guys already got the idea after reading maybe 30% of this part.

so, can anyone explain me how the drum is supposed to be secured on the inner wheel, and any suggestions for my issue? especially how to examine whether it's the inner wheel's problem or the drum's prolbem

thanks very much in advance!

[Dave's]

This is one where I may be going out on a limb but if you have rear drum brakes and your drum is loose enough to move when braking, something's not right. Your wheels should be firmly mounted against the drum. The only thing I can imagine is the center hole of the wheel is too small to fit over the 'axle'. When a car is new the drums usually are easily removed after removing the wheel. (Some have lightweight 'retainers' on one or two bolts but mostly the drums are held in place by the wheel and the lug nuts forcing the wheel against the drum.) The drums become hard to remove over time because of rust/corrosion and sometimes the shoes not backing off. I can't speak for every vehicle out there but I haven't come across one in which the drums are secured by any other means. (Besides the little 'clips' pressed over one or two studs which many simply toss the first time they remove the drum. I suspect these may be used at the factory to retain the drum as the car moves down the line until the wheel is mounted.) JMHO FWIW

[huangxin]

the drums are just secured by the lug nuts which squeeze the rear tire tight on the drum.

yes the holes on the drum are bigger than the lug, but guess what, it's the same on the front disc rotors lol, nothing tricky.

the only way i can think of that might cause your problem other than under torqued lug nuts is rust built up on the outside drum surface which cause the rim unable to squeeze the drum tight.

[mugenpaolo]

thanks very much guys!

i did use a torque wrench to put the lug nuts on (70-80 lb-ft IIRC)
so, seems like there's something wrong w/ the drums, which probably have too much rusts on the outside to be held with the wheels by the lug nuts.

i plan to just get new drums.
would it be a bad idea to keep the shoes when i replace the drums with new ones?

Thanks again for all the inputs.

[Dave's]

Would depend upon the condition of the shoes. Smooth and fairly new I would guess you would be OK although I would replace them. I just can't believe rust would cause your problem. Seriously, the drum should have a large opening which fits over a protrusion on the axle. Make sure your wheel also fits over this protrusion. If it doesn't you could be tightening down the wheel against it and the wheel may not actually contact the drum itself. If this is the case I would consider it a dangerous situation. Of course I have no idea what wheels are on your car so I'm just taking my best guess.

[huangxin]

what Dave said might be possible. i would check all possibilities before spending any money on parts just in case.

[mugenpaolo]

thanks Dave.

yea, after thinking about it more, the "rust explanation" didn't make sense to me.

also, i guess i might have to rethink what i thought i already knew.


initially, i thought that the drums are supposed to be tight on the inner wheels even w/ the wheels (the one w/ tires mounted on) taken off. and i thought that the drums are supposed to be somehow tightened on the inner wheels.
but certainly i knew that wasn't true after you two explained to me what it should be.
now, i need to reconsider what actually generated that sound.
i was suspecting that the drums hitting the bolts. but since w/ the wheels and tires on, the drums might not be moving with respect to the bolts any more. so the sound may possibly be something else.
i think i m pretty sure that i got the wheels (the ones w/ tires mounted) on properly. in fact, ever since this issue started, i've let costco technicians changed my tires at least ones, and did tire rotation quite a few times. i also took them off a couple of times. and the issue remains there for 7 years already (about 50k miles)....

now, i plan to take off the wheels again to look...
are there specific areas you guys would recommend me to pay particular attention to?
any suspicion you guys have about that noise?
again, the noise happens when i brake if and only if in my last braking the car was going the opposite direction.
like: car goes forward --> brake to a halt --> car goes reverse --> brake = sound comes --> go reverse again --> brake = sound won't come
and vice versa.....

[mugenpaolo]

took off the wheels and drums again.

nothing special that i can notice.
also, when i spin the wheels by hands w/ the rear of the car lifted on jackstands, the issue is not reproducible.

and the center hole on the drum is big enough for it to be inserted all the way on the axle"


any ideas?


my shoes are 1/8 inch left and the drum's diameter is 200mm (spec says 201mm max dia.)
i guess new drums and new shoes will be in before long. i'll see if that'll solve the issue if i still can't figure it out before that.

[Dave's]

What I was referring to was the center hole on your wheels being large enough to fit over your axle. Believe it or not the wrong wheel may not have a large enough hole. Then it would be held out away from drum in the center. If the lug nuts were tightened evenly it might actually work. However, I'm sure your tire people would have noticed. It seemed pretty remote but about the only way I could conceive that the drum could be loose with the wheel being torqued down. Good luck on finding the noise.

[mugenpaolo]

thanks again Dave.

oh, sorry, i misremembered it.
i'm still having the original steel wheels on this car which came when i bought the car new from a dealer.
so it's not likely that the hole on the wheels would somehow became smaller after 3 years (bought in 1999, and noise started in 2002).

also, it's now uncertain to me that whether the drums are actually loose.
but after i took off the wheels today to check, i spun the drum a little bit to let it hit on those bolts, and the sound really sounded like the noise i hear in scenarios described above.

[Dave's]

OK, since you seem determined to solve this problem I went over your symptoms and discussed with a friend. You can give this a try. Remove a drum. Grasp each brake shoe near the bottom (about the height where the star adjuster is located). Try moving the shoes back and forth. You should see that the whole assembly kind of 'pivots' on the top anchor. This isn't a test, just gives you a better understanding of how the brakes work. Now examine closely how the star adjuster is positioned. There should be a self-adjusting 'arm' touching the star wheel. You may need to push this back slightly to turn the star wheel. Spread the shoes and/or adjust the star wheel until you can remove it. Take it apart and clean with brake cleaner or other suitable cleaner and verify the star turns freely on the threads. Reassemble and slide the drum 1/4 to 1/2 way over the shoes. Check the clearance. Center them and tighten the star wheel until the drum just slides over the shoes with a bit of friction until seated. Repeat on other side from removing the star wheel on. Install wheels/tires as you normally would. Test drive. If this solves your problem then you need to find out how your vehicle actuates the self-adjusters. American cars were usually by braking in reverse. Some Camry's used the parking brake. Anyway, the problem may have been the brakes were not properly adjusted which could be because you weren't activating the self-adjustment and/or the star wheels were gummed up. There is a leading shoe and a trailing shoe. They reverse when you change direction. If the shoes are too loose the leading shoe may contact the drum first and the assembly 'pivots' possibly causing a popping or snapping noise. Everything's fine until you reverse direction and the other shoe hits first.

[mugenpaolo]

thanks a lot Dave!

i got the idea.

hopefully i'll be able to give it a try this weekend and post updates here..

[loci]

Originally Posted by mugenpaolo

thanks a lot Dave!

i got the idea.

hopefully i'll be able to give it a try this weekend and post updates here..

Any progress on this issue? I actually have the exact same problem.