The Stovebolt Site Forums The Shop Area Driveline Six lug to five lug brake drum swap

For my '51 1/2 ton panel, I would like to change my 6 lug brake drums to 5 lug.
What would be required for the swap?
Jerry

The front can be done by swapping the hubs to '49-'54 Passenger parts. The rear would either require swapping out the entire rear end to one with 5 lug, which may also require swapping the transmission and driveshaft to an open drive style, or have the rear axles redrilled for 5 lug.

Bill:
For the rear......... Would just a 6 lug to 5 lug axle shaft swap work?

Of course... would need 5 hole drums for the rear too.

Jerry

axle shaft and brake drum swap will work as long as the offset of the brake drum is the same and does not interfere with the backing plate. Sometimes different years and applications they changed the backing plate (made it sit farther inboard) to accommodate wider shoes.

Thanks for the info Bill and 69Cuda.

No. The shafts are not interchangeable, unfortunately.

Bill:
Too bad they won't swap out. Must be the difference in
axle diameter or length of axle or non-matching splines. (?)

Thanks,
Jerry

I think the splines are the same, but the axle is larger in diameter. There may also be a length difference, and I do know that the truck has different length axles on each side.

Years back I swapped my 46 half ton torque tube rear end with a 54 passenger car's for better highway gears. Still a lot of work, eventually went to later pickup open drive rear end.

Are you saying that while the splines would be the same, the smaller diameter
5 lug axle would not work because of the difference in bearing size?

The parts catalogs do not specify a difference between 5 or 6 lug
drums, shoes, wheel cylinders, or front and rear wheel bearings.
Info from Classic Parts and Jim Carter.

Jerry

Bottom line is that NONE of the 5 lug rear end gears, spyders, axles will interchange with your '51 truck. While the design is the same in pictures and parts lay out, all the truck 6 lug parts are slightly larger that the 5 lug passenger stuff. Longbox55 suggestion of redrilling the axle flange to 5 lug may be the best way to go. Best thing I did for my old half ton was switch to open drive, modern brake come with it and lots of better gear ratios.

Mixing car(5 lug) to truck(6 lug) is a problem because the GVW( gross vehicle weight) is quite different. The engineered weight at each wheel is higher for the truck than the car. If you go with an IFS(off a car most of the time) then the wheels and lug bolt pattern is what the IFS requires. If you change the third member( again, most are from a car) then you get the same application as the car it came from. Brake drum, backing plate and wheel cylinders are a matched group. Most trucks use a larger diameter and wider shoes to stop a loaded truck. Mich heavier than a car.

Perhaps I should have been a little more clear. 5 lug in that era would be Passenger car, and 6 lug was Truck. Truck didn't go 5 lug (5 lug, 5" circle, unlike the Passenger 5 lug, 4.75 circle). The Passenger and Truck do not interchange. However, with the later Truck 6 lug ('63-'70, '63-'87 4x4) and the 5 lug ('71-'87 2wd) share many parts (shoes, wheel cylinders), and the axle shafts can be swapped with some minor alterations. The later 5 lug axle shafts can be shortened and regrooved to fit the 6 lug axle width. The '63-mid '65 also need the spider gears swapped to the later 30 spline verions. I do not believe that the later Passenger and Truck axles swap, though.

Ok..... now I understand. I thought 5 or 6 lug was an option of some sort
back in the early '50s for trucks. If they were all 6 lug, no sense chasing
that path.

Looks like the best option for me is to change the whole rear axel assembly.
If I get a diff with and open drive line, can it somehow be mated the
my stock four speed?

The whole reason I want 5 lug is to be able to put Cragar type mags on the truck.
While the rest will be bone stock, I kinda like the look of fancy wheels. Used
Cragar's are plentiful and reasonably priced.

Thanks for your help and advice Bill, JiMerit and Steve H.
Jerry

I have a later truck than the one indicated in your post but the same concept applies. While it is true that trucks were designed to haul a load vs a car which is primarily designed to haul people. I have a 57 car and a 56 3100 truck. In stock form they both have the same wheelbase, use the same driveshaft and u-joints, the same size wheel cylinders front and rear, the same brake shoes front & rear, the same 3 speed transmission, and basically the same engine(s). The main drive train difference would be the differential and the 6 lug bolt pattern. I converted the truck to front disc brakes 15 years ago using parts from a Camaro/Malibu which are 5 lug. I also had the rear axles and drums re-drilled for 5 lug. It is a daily driver and have had virtually no problems with the system. It is not used to haul heavy loads, however.
Fred