Deanoko Posted June 26 Share Posted June 26 I recently replaced a drum which had a chunk missing out of the perimeter, with a whole one bought on eBay, from one of the usual suspects. I had the local NAPA machine shop turn it and install the best bearings they had. It spec'd within tolerances listed in the manual. The bearings appear to be seated properly. The issue is that the back of the brake drum portion rubs against the backing plate, with the associated nasty noises. The backing plate is not bent and the rubbing is uniform around the circumference.. Where there variations of drums? They looked identical to me, but my eyeballs are not doing thousandths. Can I have a machinist friend shave a bit off the offending drum lip surface ? At this point I am a bit frustrated. Link to comment Share on other sites More sharing options...
1965rivgs Posted June 26 Share Posted June 26 15 minutes ago, Deanoko said: I recently replaced a drum which had a chunk missing out of the perimeter, with a whole one bought on eBay, from one of the usual suspects. I had the local NAPA machine shop turn it and install the best bearings they had. It spec'd within tolerances listed in the manual. The bearings appear to be seated properly. The issue is that the back of the brake drum portion rubs against the backing plate, with the associated nasty noises. The backing plate is not bent and the rubbing is uniform around the circumference.. Where there variations of drums? They looked identical to me, but my eyeballs are not doing thousandths. Can I have a machinist friend shave a bit off the offending drum lip surface ? At this point I am a bit frustrated. Dean, You installed a '65 hub/drum assembly onto your '64. Yes, you can cure the issue with minor machine work. Tom Mooney (Not your usual suspect) 1 Link to comment Share on other sites More sharing options...
Deanoko Posted June 26 Author Share Posted June 26 Thanks Tom. I am planning on having the Napa guy shave ¹/16th off unless you know it would require more. Link to comment Share on other sites More sharing options...
EmTee Posted June 26 Share Posted June 26 Hmmm... Why the difference for '65? Did the backing plate change in '65? Link to comment Share on other sites More sharing options...
Deanoko Posted June 27 Author Share Posted June 27 BTW, ¹/16th off did not solve the issue, so it's back to the shop tomorrow for at least another 16th haircut. Machinist did not charge me, which was nice. Link to comment Share on other sites More sharing options...
RivNut Posted June 27 Share Posted June 27 2 hours ago, EmTee said: Hmmm... Why the difference for '65? Did the backing plate change in '65? I don’t know but Scarebird disk brake adapters have a different bracket for 63/64 than for 1965. Something to do with the spindle? Tom Terrific can probably tell us. Link to comment Share on other sites More sharing options...
Deanoko Posted June 27 Author Share Posted June 27 In case anyone is having problems picturing the issue here are a couple of pics. The shiny inner ring on the drum is the culprit. The highlighted ring on the backing plate is the contact area. I consider myself very fortunate to have a 4 post lift with a sliding axle jack, otherwise this would be fairly miserable work. 1 Link to comment Share on other sites More sharing options...
XframeFX Posted June 27 Share Posted June 27 8 hours ago, 1965rivgs said: You installed a '65 hub/drum assembly onto your '64. Dean, proceeding with this, are you now going to have your 1964 wheel center on the Lugs, not the wheel hub diameter? I recall all 1965 and later wheels use that annoying register ring for the smaller diameter. Link to comment Share on other sites More sharing options...
Frank DuVal Posted June 28 Share Posted June 28 (edited) What's with the yellow in the second picture? I was trying to see the witness marks, but they are covered up. Are you saying the shiny ring inside the drum, where the shoes might be hitting the drum's face is what is the issue? Is the width of the drum (not diameter) where the shoe friction touches the same as the width of the shoe? Is the drum the same width as the drum on the other side? Edited June 28 by Frank DuVal (see edit history) Link to comment Share on other sites More sharing options...
Deanoko Posted June 28 Author Share Posted June 28 The issue is the inner drum inner edge rubs against the backing plate/dust cover. That is the only issue. The yellow was digital highlight so you could tell the involved area. Link to comment Share on other sites More sharing options...
Frank DuVal Posted June 29 Share Posted June 29 he width of the shoe matches the width of the drum I would put a "washer" on the spindle to move the drum away from the backing plate. I would also place a chunk of modeling clay on the shoe to see how close to the face of the drum it is. The old carpenter rule, measure twice cut once. Hard to put metal back on the drum! Link to comment Share on other sites More sharing options...
Deanoko Posted June 29 Author Share Posted June 29 Update to the issue: There is an additional interference point, which is that the raised lip of the backing plate contacts the deep groove between the inner drum and the outer cooling fin. I don't see how it is possible to just move everything outboard with a washer, since the axle is fixed and the drum rotates. That would make it a wear part. Link to comment Share on other sites More sharing options...
EmTee Posted June 29 Share Posted June 29 Weird --why would Buick do this? Must be a difference in the backing plate? Does anyone have a picture of their '65 front brakes showing the outer circumference of the plate? Link to comment Share on other sites More sharing options...
Frank DuVal Posted June 30 Share Posted June 30 (edited) Yes, there may be precession of the washer placed between the inner bearing cone, and the backing plate. This is because the washer will not be held tight due to "play" in the two roller bearings. But trimming the drum inner edge (away from the face) to clear the backing plate means the width of the drum is getting smaller than the width of the shoes, also not a solution! Plus then the inner face of the drum will start to rub the shoes!😮 Or, as you found, other parts of the drum touch the backing plate. Shim the inner bearing race (in the hub) to move the drum outward. I know, not easy! But, made the OD and ID of the inner race and set with Locktite, maybe. Or shop for a 64 drum? Edited June 30 by Frank DuVal (see edit history) Link to comment Share on other sites More sharing options...
Deanoko Posted July 2 Author Share Posted July 2 Problem is solved. After taking ⅛" off the drum lip, there was still rubbing, but it turned out it was just the lip of the backing plate rubbing on the channel of the drum. I was able to do a little Dremel round headed die grinder work and now it is silent running, without having to put any funky spacer on. 2 Link to comment Share on other sites More sharing options...
EmTee Posted July 3 Share Posted July 3 Hopefully it'll still be OK hot. If it's that close it will probably clearance itself within a couple of miles... Link to comment Share on other sites More sharing options...
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