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Rear Axle


Like most of my builds, I try to use parts that are readily available. In other words; cheap. The dump truck is going to be right at 5 feet wide. With dual rear tires at about 10" a piece, I needed a fairly narrow axle. I tried looking at golf carts, cushmans, tractors etc but couldn't really find anything.

So I looked towards small trucks. The best I could find was an S10. The rear axle is narrower in 2wd models by 4". Total wheel mount to wheel mount width was 54". It was still a little too wide and I felt that the single end bearing, semi float design wouldn't be strong enough for a dual tire set up.

I had previously picked up a Chevy 14 bolt rear axle out of a one ton pickup for my Jeep. This is a full float axle with hubs that have two bearings each and ride on spindles welded to the axle tube, independent of the axle shafts. However, the center section is way too much for this build. The whole axle weighs around 550lbs according to information I've found.

As mentioned in a previous post, I've decided to take both axles and create one hybrid axle out of them. So I picked up a 2wd S10 axle about 2 weeks after first picking up the 14 bolt.

Not only would I get better support at the wheels, I was hoping that the hubs would help narrow the axle a little bit without having to cut axle shafts. So I started modeling things to see how it would layout.

Here is the stock S10 axle. Still too wide.
My original idea was to cut off the outer tubes of the S10 axle and weld on the tubes from the 14 bolt axle. Then I would machine and drill the stock S10 axle shafts to bolt to the flange of the hub. The tube OD of the S10 axle measures 2.625" and the OD of the 14 bolt axle measures 3.5". I'm told that these axles have a half inch wall thickness. I haven't cut into it yet but I'm hoping it does. Then I can machine the tube just a little and slide it over the S10 stubs.

The green tubes are from the 14 bolt. I would slide them over what is left of the S10 tubes (orange) and weld them on.
I would then machine the flange of the S10 axle shafts to bolt to the hubs of the 14 bolt axle. You can still see where the original bolt circle pattern was.
I was hoping that by doing it this way I wouldn't have to mess with shortening axle shafts, but as you can see, it's still too wide.

So what I'll most likely end up doing is making my own drive flange and weld it on to the axle shaft. I'm not too worried about strength but if it makes me feel better, I may broach a few key ways in the flange and cut the shaft. There won't be that much torque going into this thing but I haven't figured out those numbers yet.

By cutting it to the length I want, the hub flange will be right between the two tires.

The potentially finished axle. S10 center section with 14 bolt outer tubes, spindles and hubs.
So I think I'm pretty happy with my plan for the axle. Yes, I know I have to remove the hub to remove the the inner wheel but I'm fine with that. It's not hard to remove those hubs. And how often am I going to have to remove them?

The next problem is attaching the wheels to the hub. I had planned to use skid steer wheels because of the simple steel construction. The problem is, they are 8 lug with an 8" bolt circle. The 14 bolt hubs are 8 lug with a 6.5" bolt circle. So I have 3 options.
  1. Purchase skid steer wheels with 1.5" of back spacing and machine adapters. The adapters would sandwich the hub flange and the wheels would bolt to the adapter. Would be a fair amount of machining to make 4.
    The hub adapter with the two different bolt patterns shown in green.
  2.  Purchase H1 hummer wheels. They are 16.5" rims with an 8 lug 6.5" bolt pattern. So far it looks like it may work. I would just need 1" spacers and I would run a long bolt thru the whole setup. They are a two piece wheel so they have all the extra hardware to hold them together. Not sure I like that look.
    Shown with hummer wheels.
  3.  Purchase just the skid steer rims and make my own center plates with the correct bolt pattern.
So that's next. I need to decide what to do then buy a few to make sure the measurements match what I've found online.

Update 9/2/2015

I went ahead and purchased two skid steer tires (10-16.5 10 ply) and two 12 bolt hummer wheels. I'm glad I did because the cad model of a hummer wheel that I found online didn't quite match what I got. That is exactly why I buy things ahead of time so I can double check measurements.

Got one mounted. I really like being able to easily mount the tire by myself. This will come in handy when I have to do all 6 and then take them off again in the end for paint.
I haven't finalized the axle width yet until I know exactly how I'm going to change the offset of the wheels. However, since space is a premium around here, I decided to chop up the axles.

S10 Rear Axle
I chopped the S10 axle first. I plan to use the center section of this one.
I left 4" stubs on each side. That's the longest boring bar I have and I think that's enough. The tube OD is 2.625"
S10 Rear Axle
I made this stand a very long time ago when I was upgrading my Jeep axles. Not my best work but I'm glad I saved it after all these years.
Next up was the 14 bolt. I cut these tubes long until I figure out the final length. I plan to use the tubes and hubs from this axle.
Why use the band saw to do this? I didn't feel like making a mess with the plasma cutter.
The OD is 3.5" and the ID is 2.5". All I have to do is bore it out to 2.625" and it will slide right over the S10 tubes.
14 bolt center section. Should get a few bucks in scrap for this.
This is what I have left.
I've had a lot of comments stating I should use the center section of the 14 bolt instead of the S10. I'm planning on using a mid 20 hp 2 cylinder engine on this project. I will be using a hydraulic motor to drive it. And top speed is going to be about 5 mph. I haven't figured out torque numbers yet but I highly doubt it will be an issue. I'm trying to keep the weight of this project under 2,000 lbs. The 14 bolt center section is just too heavy. That axle was design to handle something like 10k lbs in the bed and be able to tow 14k lbs. I am not going to do that with this project.

Next on the list is to make a rotary weld positioner. I think I have a pretty good design. Should cost just under $200 to make not counting the steel. I will need this for what I'm going to do to the Hummer wheels.

Until next time....