The Stovebolt Site Forums The Shop Area Driveline New Brake Drums - Wheel Stud Issues

I purchased new front brake drums for a 1949 Chevy 3100 (with original huck brakes) from one of the vendors several months ago and have ran into a major issue that I am having troubles coming up with a solution for. That first issue is that the inner casting is not turned enough around the holes for the wheel studs so the inner shield does not fit. I fixed this problem by grinding it flat so the shield fit (I was in a hurry and don't have a lathe). The major issue is that the wheel studs that they provided are too short and the knurled portion does not stick out of the drum enough to hold the hub onto the drum.

The problem is that the original brake drums are about 1/8" thick and the new (cast) drums are about 0.325" thick.

Pictures are here:
http://s1285.photobucket.com/user/1866yellowboy/library/Brake%20Drum

I am looking for some opinions on what I can do to solve this problem. The vendor was no help and after 15 emails we got back to the exact problem I told them about in my initial email. They stated the studs were long enough if I did not use the shield on the inside. The shield is factory and I want to keep it. I have looked through the Dorman wheel stud offering and cannot find a wheel stud with a suitable shoulder length and knurl diameter range. The ones that I found that would fit are only knurled on the bottom portion of the shoulder so they would not hold the hub onto the drum. I contacted a couple local machinists and they told me there was no way they would be able to knurl wheel stud shoulders as they were too hard.

Are there any other options? Can I go to the next size wheel stud and still use stock wheels with 1/2" studs/lug nuts assuming I can find the right length(are the domes on 7/16" and 1/2" lug nuts the same)? Should I mill off 1/16 off the cast drum and call it a day?

I wouldn't be too concerned about it. As long as there's enough threads for the nuts to secure the wheels, the knurl going through the drum is really a non-issue.

The main issue with the knurl depth is that there is a chamfer on the hole in the hub so there is not enough shoulder to align the hub on the studs or hold everything in place during a tire change.

Still shouldn't be an issue. The only reason they made them with the knurl securing the drum was for ease of assembly at the plant. The rivets, and later, speed nuts, used on the later trucks serve the same purpose. There shouldn't be an issue when the wheel is removed. The drum might move a little bit, especially if the shoes are out of adjustment, but the drum won't move that much.

If the drum is not centered on the hub i think it is going to have a bad shutter every time I apply the brakes and beat up the brake hardware I would imagine. it would also be hard to adjust the brakes properly because different parts of the drum would be further or closer to the shoe as it came around. Of course the degree that this would depend on how far off center it was. Maybe it would be close enough but I'd rather it be correct.

I took another look at your pics, I notice you do not have any shots of the drum fitted to the hub itself. How close is the fitment to the hub? It should be fairly close tolerance. Most drums, and on modern vehicles, rotors, are piloted from the hub, rather than the wheel studs.

Bill, excellent point! Thank you. I took those pictures a while back before I got pulled away from the project for a while and the hubs were never placed in the drum to check the fit. I had not considered the hubs piloting on the drums. Hopefully I can get to where the truck is this weekend and check that out. I now understand what you were talking about in the posts above.

No problem.

This is interesting in that these drum repops are a one piece casting. I have some new drums for a 38 that are made the same way.

These do appear to be one piece castings. Looking only at the pictures on the several vendors' websites it looked like all of them were cast (for 1949 front drums) when I was looking. Not sure if they all come from a single source as other parts seem to or not.

Looks like the hubs do pilot on the drums with around 0.005" slop so I am convinced the wheel stud length is not a huge issue (Thanks Bill). The hub I was looking at has a much larger chamfer where the wheel studs press in (looks like a previous owner took a countersink tool to it- who knows why) and has less engagement on the wheel stud shoulder. The wheel stud shoulder presses into the other hub (which appears to be stock) around 0.025" which seems to be plenty to hold it onto the drum.

I'm going to venture to say that the reason the reproduction are all one piece is that it's cheaper to manufacture them that way. I've seen the same thing in the aftermarket for late models, particularly on vehicles that used a composite rotor. There is a secondary reason on those, though. The composite rotors have an issue with separation of the center from the rotor due to corrosion.