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Bent front drums?
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Author:  Franklyn [ Thu Dec 08, 2011 10:07 pm ]
Post subject:  Bent front drums?
Have a 65 dart with 9" drum front and rear.
has anyone experienced bent/warped front drums?
both of mine seem to be spinning off center and rubbing on each revolution.
seems rare to me that front would warp. am i wrong?
Author:  kesteb [ Thu Dec 08, 2011 10:45 pm ]
Post subject: 
Did you install new shoes? It is normal for slight rubbing between the drum and brake shoes.
Author:  Franklyn [ Thu Dec 08, 2011 11:22 pm ]
Post subject: 
No new shoes on the front but did add new shoes and drum to the rear, which are working great, I've basically had to adjust the fronts out so far , that I'm sortof just using the rears to stop, this feels unsafe obviously.
when i spin the front drums i can see them "pulsing" per revolution, appearing to be out of round, even in the inner hub area, to my eye it seems that these drums are seriously screwed. i wonder why?
Author:  Franklyn [ Thu Dec 08, 2011 11:39 pm ]
Post subject: 
I guess I should clarify that when the front were adjust in further they would grab severely left and right at different times.
Author:  wjajr [ Fri Dec 09, 2011 5:14 am ]
Post subject: 
Pull front drums, inspect for fluid leaks, and oil contaminated shoes. Also check proper preload, or rather wheel bearings are properly tightened.

Grabbing generally is caused by oil, or grease soaked shoes. Humid weather often exacerbates a grabbing problem.
Author:  Doc [ Fri Dec 09, 2011 9:42 am ]
Post subject: 
Quote:
I guess I should clarify that when the front were adjust in further they would grab severely left and right at different times.
Sounds like your typical 9 inch drum brake set-up. :o :wink: :lol:
(Honestly... a 9" drum brake needs to be in "tip-top" condition to perform just "OK") It is normal to hear some light contact as the wheel is spun.

To check, I would remove the drums, measure the thickness and inspect the bearing races to see if any have spun a bearing race in the hub.

If all is OK and there is still some metal thickness at the contact surface, get the drums onto a brake lathe and take a cut on them, that will tell you a lot.

Hate to say it but the factory did not care how concentric these assemblies were, as long as the drum's shoe surface runs 'true' to the bearings.
I see this every time I "turn" brake drums... many of the outer surfaces do not spin true to the bearings / contactact surface... it looks "wrong" but the drums still works OK. (the factory did try to add balance weighting to help "correct" ( hide) this... something that replacement drums lack)

I hope that helps...
DD
Author:  Old6rodder [ Fri Dec 09, 2011 9:43 am ]
Post subject: 
Such are the games with old tin.

Back when I first got Toad on the road I bought some Brazilian drums. The crap couldn't even be turned decently, due to the metal galling on the tool.

I followed that with some Canadian drums through RockAuto. Far better metal, but one of'em had over .060" run-out. Got a replacement that was close enough to be turned true.

Brazil - 0 for 4
Canada - 3.5 for 5
Author:  KBB_of_TMC [ Fri Dec 09, 2011 10:30 am ]
Post subject: 
I had a 1973 AMC Hornet that had old drums that warped after ~1yr of use; I found a spare set that did the same, but by then the 1st set seemed to have unwarped just by sitting on the shelf for a year, and so I just alternated sets every year. Maybe that would work for you.
Author:  Franklyn [ Sat Dec 10, 2011 9:03 pm ]
Post subject: 
Quote:
I see this every time I "turn" brake drums... many of the outer surfaces do not spin true to the bearings / contactact surface... it looks "wrong" but the drums still works OK. (the factory did try to add balance weighting to help "correct" ( hide) this... something that replacement drums lack)
I've never known this before, but interesting, maybe I'll take em down to the local machine shop and see what they think. because the drums definitely look wrong when spinning, they're very "wobbly" on the outer surfaces even to the point or rubbing the inner edge of the backing plate grove once a revolution.

Seems that the inner HUB area also seems to be spinning oval.
maybe they're to far gone.
Author:  Franklyn [ Fri Dec 30, 2011 10:51 pm ]
Post subject: 
well I got new drums, shoes and cylinder kits in for the front today.
hopefully we'll be rolling again by the end of tomorrow.
Author:  WagonsRcool [ Sun Jan 01, 2012 7:44 pm ]
Post subject: 
Well, I've owned & worked on enough drum brake cars that to me it seems to be "the norm" that at least one drum is moderately warped & out of round. 9", 10", 11"- Chrysler, Ford, GM, AMC, - it doesn't matter. All had "bad" drums to varying extants. (I had one customer with a '66 Mustang & "new" drums that were practically square)

That's one reason why I've done front disc conversions on the last two A-bodies I've owned.

Be sure to check for adequate "toe-heel" clearance on your new shoes & drums. You need to have a slight gap at both ends of the shoe lining when it is pressed against the inside of the drum- If you don't then you end up with "full contact" & your brakes with lock up very easily once the new linings seat in.
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