The Stovebolt Site Forums The Shop Area General Truck Talk Convert to dually??

Got a 1 ton 49 GMC with a dump body on the way home. I don't have alot of details yet, such as current wheel size etc, but I was wondering, in general what would be involved in changing the current single rear wheel configuration to dually? I plan on making this a flat bed, and the idea of dual wheels is very appealing.

Thanks!

Hy loadmaster235, the mounting of duals in the rear basically only requires two things, studs which are long enough to allow two wheels to be mounted, and the wheels with the correct offset so they can mount and not interfere with each other or any chassis component. The front wheels are a different story, they require a special hub which moves the mounting flange away from the brake drum to allow a single dual style wheel to be mounted and maintain a front track width as close as possible to original, hope that helps.

I'd like to piggyback a question here rather than post a new topic. This for 3B, do you know if the front drum on a dually is the same as a single wheel vehicle? I'd like to replace my front drums buy don't want to buy something, have it shipped and find out it doesn't work for the above reason. Typically the companies who sell the replacement parts for these old trucks are not a good source of technical info.

Hy orchidskip and guys, on the lighter trucks, up to one ton the wheel mount pattern is transfered from its original location at the drum to a location 4-6" outboard, but I believe the drum remains the same as the single wheel vehicle, I hope that answers your question, if it doesn't ask me it again with some more info so I can zero in on what you need to know.

You guys should talk to Fatweed (possibly others) as he has a '54 1-ton duallie.

V/R
John

On my 59 1-ton, I believe the outboard front wheel bearing is contained in the extension piece. That suggests to me that the spindle, and/or the drum might be a different item, as compared to the front end for the non-dually front end.
Jerry

On all of the older duallies I've seen, the extension was merely a bolt on part, the hub/bearings are the same as non-duallie. The extension bolts on in place of the wheel, then the wheel bolts to that.

That's what I was hoping. Now for the really important question. Is it "Dually" or "Duallie"?

Don't want to muddy the waters here but as concerns the original question from Mr. Loadmaster, I'm wondering if the rear hub of a single wheel will accomodate the two sets of wheels. It appears that a dually hub is a bit longer and that the center of the wheel is actually supported by an area on the hub that is specifically machined to accomodate both wheels. They fit snugly around that machined surface and as such are hub supported rather that lug supported. Don't know if that makes sense and I could be totally wrong here in my limited experience with my dually rear end.

Chevy parts book shows the rear hubs 3/4 and 1 ton the same from 46-59 with either single or dual wheels.

The front brake drum for the 1-ton w/duals is unique for the years 47-52. Might be hard to find.

I'm in the process of converting a '55 second series GMC 3/4 ton from singles to duals. I'm also adding disk brakes to the front, new single piece 16" rims, and a 14 bolt rear-axle from an '87 flatbed truck.

\'55 GMC Dual Wheel conversion.

I thought I'd share some thoughts on my '55 second 3600. It had dual rears when I bought it from a body shop- they had been using it as a tow truck since 1957. It had 6 16X6 split rims- which were just normal offset rims. I've taken a picture of the rear hubs to show how the rears were mounted. The hubs are very heavy, and the bolts have flats allowing them to be tightened by wrench to the truck before adding on the outer wheels. When I changed to modern duals I needed adapters(of different depths) for the front and rear to position the wheels correctly. This seems in line with OlBlue's reference to the parts book but orchidskip's rear duals are hub centered in 1957. It's entirely possible that my truck had 17" single wheels which were also rated at 6900 lbs. GVWR and then converted sometime after it became a tow truck in 1957. There was a handwritten bill of sale under the seat that described the truck as a "1955 Stake Bed". If the hubs were indeed the same- single or dual in '55, I wonder if the mounting configuration that I found on the rear were actual Chevy parts.
Kim

obs2kl-- Those pieces look like the adapter/ conversion that they used to sell in the mid 80's-early 90's to convert S-10's to duallies. Same concept anyway.

Kruizeag, you're right, but these were on the truck for sure in 1957, perhaps sooner. Since the 6900 gvwr trucks had either 6 16X6 wheels OR 4 17" wheels, what type wheel did the factory use in a 1955 dual rear 3600?

I have a '68 C20 factory dually and all six wheels are hub piloted; ie, the lug nuts only hold on the wheels, the hub centers them up. The rear wheel lugs are obviously longer to accomodate the double wheels. The front hub has an additional casted piece that bolts to the drum that offsets the wheel outward. As Hotrod Lincoln mentioned, the outer front wheel bearing is mounted in the extension otherwise, there would be a tremendous load on the wheel bearings. All six wheels are identical and are flat-faced in way of the lug nuts allowing any two to be mounted back to back without the tires rubbing which means a pretty significant back-space to allow this to happen. (This is also the reason for the additional cast piece on the front because with the required back space the correct tire would hit the frame in a modest turn.)

I converted my 54 one ton to a dually. The back just needed longer lug bolts. The front needed different hubs. The drums and wheel bearings are the same. If you dont want to use original wheels you might have a problem finding wheels that will work. I just put on some original wheels that I cleaned up and painted.

Kim, I see you got those new wheels. Very excellent!
OlBlue, Nice job changing out that rear end. Looks like a nice fit. I'd be interested in seeing what you do for front discs since that is a hot topic around here.

My'46 3/4ton came with an aftermarket add-on adaptor for duallies. It's an old set with extended lug's that uses the original rims. JCWhitney still sells them if that's what you're interested in.