C1 Brake Drum to axle fit

[Donald H.]

I finally got around to adjusting the brakes on my 1960 restoration project. I finished the chassis restoration about a year ago when I installed new shoes and new brake drums. I had a problem adjusting one of the rear brakes so I decided to pull the drum and check everything. I had a huge problem getting the drum off. These are new shoes and drums, the car has never been on the road. There was no rust and I had the adjustment all the way in, so the shoes were fully contracted. As I wiggles and beat on the drum, it seemed that the drum was caught on the axle not the shoes. I finally got the drum off by using penetrating fluid and heating it around where it fits on the axle.

I believe the center hole in this aftermarket drum is either slightly to small or even a little off center and gets jammed on the axle when I put it on.

Will it hurt to grind out the center hole of the drum so that it does not fit quite so tight? I don't know if the drum is centered on the axle by this center hole or by the lug holes or both

Thanks,

Don

[Terry D.]

Re: C1 Brake Drum to axle fit

Donald
It won't hurt a thing. Just grind out as little as possible to fit on axle. Did this on a ralley wheel for my 62 over 18,000 miles ago. No problems with it.
Terry

[Jim L.]

Re: C1 Brake Drum to axle fit

Will it hurt to grind out the center hole of the drum so that it does not fit quite so tight? I don't know if the drum is centered on the axle by this center hole or by the lug holes or both

Thanks,

Don

Don,

Do NOT grind the hub hole in a brake drum. Brake drums and rotors are located by a very close fit between the hub hole and the pilot of the hub, or in your case, the axle. If you enlarge the hole, the drum won't be concentric and you'll risk having brakes that shudder and vibrate.

Jim

[Donald H.]

Re: C1 Brake Drum to axle fit

Don,

Do NOT grind the hub hole in a brake drum. Brake drums and rotors are located by a very close fit between the hub hole and the pilot of the hub, or in your case, the axle. If you enlarge the hole, the drum won't be concentric and you'll risk having brakes that shudder and vibrate.

Jim

OK understand. Last question - the fit is so tight that I can not get the drum back over the axle pilot hub. I will either need to use a mallet or lug nuts to snug it on. Is it supposed to be that tight?

Thanks,

[Jim L.]

Re: C1 Brake Drum to axle fit

The drum should be an easy slip fit over the hub pilot.

If you have a set of calipers, verify the hub hole diameter is between 2.813" and 2.818" and that the hub pilot is no larger than 2.813". Of course, it should be slightly smaller than that.

Jim

[Donald H.]

Re: C1 Brake Drum to axle fit

The drum should be an easy slip fit over the hub pilot.

If you have a set of calipers, verify the hub hole diameter is between 2.813" and 2.818" and that the hub pilot is no larger than 2.813". Of course, it should be slightly smaller than that.

Jim

My problem may the the axle hub pilot. I measure it with calipers and got 2.15" up to 2.818" at different locations. The drum measures 2.819" in the hub hole. I looked closely at the axle pilot and do not see any obvious damage that would cause the diameter differences. There are no dings or dents from someone hammering on it or anything.

I may try to clean the hub pilot with some emory cloth lightly

Thanks,

[Thomas H.]

Re: C1 Brake Drum to axle fit

I may try to clean the hub pilot with some emory cloth lightly

Thanks,

I had the same problem with the new drums I put on my 60. I ended up going over the axle hub area with an emery cloth to remove the years of built up dirt and a bit of rust. Then used it on the drum center hole to remove the paint that was left over from when the drums were painted by the manufacturer. Doing this helped a lot, but they still fit tight.

Tom

[Jerry W.]

Re: C1 Brake Drum to axle fit

After market drum suppliers ( unless authorized by GM ) do not normally have GM drawings, hole sizes or applicalble tolerances. The after market drum is a measured copy of the OE sample drum. If the copied OE drum was at the low side of the OE hole tolerance...chances are that the hole size of the after market drum might be tight because of the after market low side tolerance from the measured nominal of the sample OE drum.

[Keith R.]

Re: C1 Brake Drum to axle fit

I had the same problem recently - couldn't get the drum off no matter what. Had to borrow a BIG A** two arm brake puller from a Chapter member and that popped it right off. Once removed, I had to take a Dremel tool with sanding drum to sand down the outer diameter of the hub which showed some evidence of hammer damage from someone in the past. If you do this, just Dremel the outside edge of the hub leaving the inside diameter the same. Once I did this, the drum slipped on and off easily.