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Amazon brake drum castle nut

spock345

Well-known member
Joined
Nov 3, 2016
Location
Livermore, CA
I've gotten a new set of brake drums for my amazon. The one piece kind sold by VP and IPD. I tried to install them but ran into an issue. It appears that the nut won't go on enough to expose the hole enough in the end of the axle so I can thread the cotter pin through.

Has anyone run into this issue before? Any ideas on what to do?
 
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If the drum isn't sliding over the woodruff key all the way I can see that being a problem with getting the nut on far enough. Or possibly not sliding over the brake shoes enough. Try turning the adjustment so the brake shoes are in as far as they go. Also check the height of the drum compared to the old one and see if it's higher.
 
How far off is it? And how much are you torquing the nut? It is stretching that hub over the tapered axle shaft.
 
I measure the old and the new drums. The inside surface the pads sit on and length of the tapered bore on the old are 58 and 72 mm respectively. The new is 59 and 72.

I need a couple millimeters more to fit the cotter pin.
 
I put a bit of anti-seize on the axle shaft (and I'll certainly defer to the experts as to whether that is a bad idea or not?).

And it might not hurt to warm the drum up to expand it a little?
 
I put a bit of anti-seize on the axle shaft (and I'll certainly defer to the experts as to whether that is a bad idea or not?).

And it might not hurt to warm the drum up to expand it a little?

I often see some debate regarding lubricant on the shaft. The heat option may be a good idea though.
 
So I figured out the issue. I decided to try the other side with a new drum and it fit without any issues. Which is puzzling. I decided to compare the old drum and the new again. The little snout that comes out of the wheel mating surface on the front of the drum is a bit taller than the old drums. Just barely.

I also compared the thickness of the washer and nut from either side. The side with the problem had a slightly thicker nut. About a millimeter, maybe less. So If I equalize the two heights by taking a little bit off the washer or the nut (or just go find thinner ones) then it should be able to fit the cotter pin. I'll go see what washers the hardware store has. I need some more cotter pins anyway.
 
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This is what I encountered with my 123GT when inspecting the rear drums three or so years ago. When assembling the passenger side, the castle nut stripped while torquing it down. After some looking around and research then on recommendation purchased a replacement castle nut through McMaster/Carr. At the same time I picked up a thread tapping tool for the hub to chase the threads.

After tightening the M/C castle nut in place, it did not allow for the installation of the cotter pin. When comparing the old and new ones, it was evident the new one was taller. Using a Dremel tool, the recesses were ground down in order to create the clearance for the cotter pin, then put things back together. About two months later a 122 showed up at one of the area boneyards and I grabbed both of the castle nuts from the carcass, reinstalled one of the back on to the 123GT and the other is in reserve.

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I guess I'll do a bit of grinding on the nut today to match up the dimensions with the one that looks original. That'll get the car back on the road in the mean time.

I checked McMaster Carr and noticed the same thing comparing their castle nuts to one from my car, the slots were different depths. I think at one point the nut on my car's right side was replaced because of how it doesn't match the other one. The luster and tarnish on it is different.

Combine a different nut with a new drum that hasn't had decades to "stretch" over the tapered axle and the clearances don't work out.

Either way I cleaned up the mating surfaces with some light sand paper on the still original nut and cleaned up the slots with a needle file. There were a few burs sticking out. It goes onto the axle without any problems.
 
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