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Brake Drum Issues?

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firefighterco2

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Ok ill try to make this as short as possible. 87 k5 factory 10 bolt rear. Been having a grinding noise in the rear brakes since I bought it. Finally traced it down to the drum rubbing on the backing plate(I think that is the correct terminology). I have new shoes, all new springs, new wheel cylinders, the drums are both also new. I have been through 4 drums in the last 2 days trying to find one that didn't grind or wobble like the wheel is going to fall off? The guys at the parts store know me by name now.

Is there anything that could be causing this on my blazer? The backing plate doesn't look bent? When I switch sides with the drum the problem goes with it. The other drum is fine. Is there any way that I could have put the c clip that holds the axle in wrong when I replaced the bearings? is there anything else I'm missing???

Sorry for the long post and thanks for the help.

Jeremy
 
firefighterco2 said:
Ok ill try to make this as short as possible. 87 k5 factory 10 bolt rear. Been having a grinding noise in the rear brakes since I bought it. Finally traced it down to the drum rubbing on the backing plate(I think that is the correct terminology). I have new shoes, all new springs, new wheel cylinders, the drums are both also new. I have been through 4 drums in the last 2 days trying to find one that didn't grind or wobble like the wheel is going to fall off? The guys at the parts store know me by name now.

Is there anything that could be causing this on my blazer? The backing plate doesn't look bent? When I switch sides with the drum the problem goes with it. The other drum is fine. Is there any way that I could have put the c clip that holds the axle in wrong when I replaced the bearings? is there anything else I'm missing???

Sorry for the long post and thanks for the help.

Jeremy
Click to expand...

Check the runout on the axle shaft.
 
firefighterco2 said:
Not quite sure how to do that? I have spun the axle with no drum on it and it seems to turn without any wobble.
Click to expand...

Then what makes you so positive the backing plate isnt bent? Is there any chance that perhaps the wheel cylinder is only pushing on one side and cocking the shoes funny?

O and to answer your question about the axle being in incorrectly: its either in or not. If it wasnt in believe me youd know. You could always try to bandaid it for now and put an 1/8in wheel spacer inside the drum. As long as you get a spacer that doesnt have slotted holes theyre safe.
 
Stomis said:
Then what makes you so positive the backing plate isnt bent? Is there any chance that perhaps the wheel cylinder is only pushing on one side and cocking the shoes funny?

O and to answer your question about the axle being in incorrectly: its either in or not. If it wasnt in believe me youd know. You could always try to bandaid it for now and put an 1/8in wheel spacer inside the drum. As long as you get a spacer that doesnt have slotted holes theyre safe.
Click to expand...
im with stomis,the axle shaft and c clip only go in one way.im not sure on 10 bolts but are the axleshafts the same length?maybe you swapped them from one side to the other.maybe one one the shafts is bent.try putting it in neutral whith front wheel chocked,and lift that side wheel and spin it by hand to see where it rubs.that would be the easiest way.
 
At this point I'm not positive about much. I do know I didn't switch the axle shafts. I believe the backing plate isn't bent because if I put the other drum on it doesn't grind or wobble. The wheel cylinders are new(not saying they can't be bad) but it really looks like the drum is warped or something and when it wobbles it catches on the backing plate. There are little raised spots that are right behind the shoes and the inside edge of the drum is rubbing it. If that makes sense? I am really leaning towards it being bad drums I just have a hard time believing I got so many bad ones from 2 different manufacturers.
 
firefighterco2 said:
At this point I'm not positive about much. I do know I didn't switch the axle shafts. I believe the backing plate isn't bent because if I put the other drum on it doesn't grind or wobble. The wheel cylinders are new(not saying they can't be bad) but it really looks like the drum is warped or something and when it wobbles it catches on the backing plate. There are little raised spots that are right behind the shoes and the inside edge of the drum is rubbing it. If that makes sense? I am really leaning towards it being bad drums I just have a hard time believing I got so many bad ones from 2 different manufacturers.
Click to expand...


If the drum is rubbing on the spot where the shoe rides on the backing plate then the drums are too small.
 
What brand of drums have you been getting and what is the part number? I have a brake book I can look in to see if they are the correct drums. IIRC there are 2 different sized drums for a 10 bolt and the difference was pretty small IIRC.

EDIT: I just went and checked and you should have a part number 8846 and it should be 11 5/32" x 2 3/4" the other drum was for earlier years and was 11" x 2"
 
Sounds like you nailed it, Scott. If he doesn't have the part numbers handy, he should be able to lay one on top of the other and see that much difference.
Or side by side to see the different width.
5/32 might not show up. But 3/4 should.
 
The brake drum height difference is only .300" even though the shoe width is .750" different.
 
Ah, those were shoe measurements. Not drum measurements.
That makes it a lot harder to compare.:doah:
 
From O'rielly auto:

BrakeBest Select - Brake Drum
Part Number: 2592DGS

Line: BBR
  • UPC: 753497974834
  • Rear
  • With 11-5/32 Inch X 2-3/4 Inch Brakes
From Advance Auto:

Wearever Brake drum
part# YH140600

Edit: quote from review of advance auto one:
"These drums are absolute junk! They do not fit because they forgot to machine the lip where it fits into the backing plate. A waste of money."
 
And these are the Shoes on it:

BrakeBest - Brake Shoes
Part Number: 473
Line: BB
  • UPC: 52948993517
  • Rear
  • Riveted
  • 11.16 x 2.75 Inch
:dunno:
 
So I think these are the correct drums? Do any of you guys have a brand that you like... Thinking about ordering the wagners from o'riellys?
 
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