1960 Rear Hubs

[Joe M.]

I removed the rear hubs to remove rust and paint them. I noticed side by side that there are significant differences. One hub has 3 weights and 3 extra holes. I can understand the weights to correct a balance problem, but why the extra holes? Weight reduction? The GM part number is identical on both hubs.

[Bill M.]

Re: 1960 Rear Hubs

I removed the rear hubs to remove rust and paint them. I noticed side by side that there are significant differences. One hub has 3 weights and 3 extra holes. I can understand the weights to correct a balance problem, but why the extra holes? Weight reduction? The GM part number is identical on both hubs.

The three extra holes were used to rivet the front drum (fyi: your picture is of brake drums) to the front hub. It will work fine on the rear.

[Thomas H.]

Re: 1960 Rear Hubs

Joe,

You've been doing a lot of work on your car, when can we see some pictures of the pride and joy?

Tom

[Joe M.]

Re: 1960 Rear Hubs

Bill, thanks for correcting my nomenclature; hub is all I could think of at the time. What was the purpose in having 3 holes so the brake drum could be riveted to the front hub? I don't understand why the front brake drums would have provision for riveting them to the front hubs and the rear drums do not.

Thomas, you posed a good question. I don't leave the car alone long enough when it is intact to take photos. However, I do have a couple from the Lone Star Regional last month.

I installed the new-to-me welded, re-painted rims with new Coker tires on Friday. I hope that is my last set of expensive Coker tires to purchase, but since I am 55 years old and don't plan to sell the car; probably not the last set of tires!

I have my hardtop taken apart in preparation to install new weatherstrips and new side windows. I am going to buff out the back window and not replace it. A kit to restore plastic lenses on modern car headlights should do the trick, but I have never tried it.

[Joe L.]

Re: 1960 Rear Hubs

I removed the rear hubs to remove rust and paint them. I noticed side by side that there are significant differences. One hub has 3 weights and 3 extra holes. I can understand the weights to correct a balance problem, but why the extra holes? Weight reduction? The GM part number is identical on both hubs.

Joe-----


The number shown is not a finished part number for the drum. It is a part number for the CASTING. The finished part number for one of the drum configurations (i.e. 3 extra holes or not) was GM #3752622. The other was a part number never available in SERVICE so I don't know what the number was. The added balance weights do not affect the finished part number.

The balance weights may have been added when the drum was riveted to the hub thus balancing the drum and hub rotating assembly. Assuming that these drums are original to the car, I would recommend keeping the drums in the same position as when removed although it's very possible that orientation is long-since lost.

By the way, the GM #3752622 was first used for the 1959 model year. It did become SERVICE for earlier model years, though.

[Joe M.]

Re: 1960 Rear Hubs

Joe, to understand what you said, 3752623 is not a GM part number, it is a casting number?

Where would I find the part number stamping?

Why were the front brake drums riveted to the hub and the rear drums were not riveted to the hubs?

Is it unsafe for the front brake drums to not be riveted to the hubs?

I only had one of four brake drums with the 3 extra holes; the other 3 drums were the same.

[Bill M.]

Re: 1960 Rear Hubs

Why were the front brake drums riveted to the hub and the rear drums were not riveted to the hubs?

Is it unsafe for the front brake drums to not be riveted to the hubs?

I only had one of four brake drums with the 3 extra holes; the other 3 drums were the same.

Joe:

I think the rivets were for assembly. The chassis runs along the line without wheels, and the drums would fall off if they were loose. As Joe mentions, they may have been balanced as an assembly.

However, my '59 does not have the provision for rivets on the original front hubs. I think they used tinnerman nuts on the front starting in '59.

I've run my cars without rivets (or tinnerman nuts) for decades; it's not a safety issue.

There were tinnerman nuts to hold the drums on the rear axle on the assembly line.

I have heard that the front rivets were important for the racing drum brake models. All I can think of for the racing application is that the rivets eliminate any possibility of the drums moving relative to the hubs under heavy braking. (A rivet completely fills the void and is the best fastener for a shear load.) I suppose if the drum shifted, you could loosen a wheel.

Bill

[Joe L.]

Re: 1960 Rear Hubs

Joe, to understand what you said, 3752623 is not a GM part number, it is a casting number?

Where would I find the part number stamping?

Why were the front brake drums riveted to the hub and the rear drums were not riveted to the hubs?

Is it unsafe for the front brake drums to not be riveted to the hubs?

I only had one of four brake drums with the 3 extra holes; the other 3 drums were the same.

Joe-----


The 3752623 is a part number but not a part number for a finished part. It is a part number for the brake drum CASTING. Unfinished castings were not available in SERVICE and, thus, the part number is not a SERVICE-available part number.

You will not find a part number stamping for the finished drum. The only place you would find that number is on the bins/racks that the drums were supplied in to the component assembly plant (fronts) or St. Louis (rears) OR on boxes that SERVICE brake drums were supplied in.

I don't know why the fronts were riveted and the rears not. However, it may be that there was no practical way to do it for the rears. Plus, the balance was much more critical for the front assemblies.

Yes, it's very safe to have the front drums not riveted to the hubs. The lug bolts and nuts will be completely adequate for retention. The drums were never intended to be re-riveted when separated for any reason in SERVICE.

It may be that one of your front drums was replaced at some point and the SERVICE drum did not have the holes. As I mentioned, the rivets (and the holes therefore) are unnecessary in SERVICE.

[Joe L.]

Re: 1960 Rear Hubs

Joe:

I think the rivets were for assembly. The chassis runs along the line without wheels, and the drums would fall off if they were loose. As Joe mentions, they may have been balanced as an assembly.

However, my '59 does not have the provision for rivets on the original front hubs. I think they used tinnerman nuts on the front starting in '59.

I've run my cars without rivets (or tinnerman nuts) for decades; it's not a safety issue.

There were tinnerman nuts to hold the drums on the rear axle on the assembly line.

I have heard that the front rivets were important for the racing drum brake models. All I can think of for the racing application is that the rivets eliminate any possibility of the drums moving relative to the hubs under heavy braking. (A rivet completely fills the void and is the best fastener for a shear load.) I suppose if the drum shifted, you could loosen a wheel.

Bill

Bill------


Now that I think about it, I think the riveted front hub-to-drum might have only been used through the 1957 or 1958 model years.

[Bill M.]

Re: 1960 Rear Hubs

Bill------


Now that I think about it, I think the riveted front hub-to-drum might have only been used through the 1957 or 1958 model years.

Joe:

Agreed. They beefed up the hub in 1959 and it doesn't have rivet holes. My original '59 drums, also a new design for '59, don't have provisions for rivets either.

Bill