hopak wrote: I wonder what would happen if I just bolted the rear rim facing outwards give me a nice wide track for stability but would that over torque the axle and bearings?
Yes, I think it would put a big moment on the bearings and probably not do you any good. The rear axle on a dually "sees" the dual tires as a single tire with zero offset, so you'd essentially be replacing that single zero-offset wheel with a 5"+ offset.
How does that differ from what the front unit bearings see as far as moments go?
It differs in that the spacers on the front wheel hubs are there specifically to make the centerline of the tire line up with the correct offset for the bearings. The only reason to have a "dually" wheel with a large offset on the front is to make it possible to rotate tries through all positions. You could just as easily have dually wheels in the back and get rid of the spacers in the front. Or, another way to explain it, running a single dually wheel on the rear axle would be analogous to running a dually wheel without the stock spacer in the front, or the same as running a dually wheel on the front axle of a factory SRW truck.
BoilerEE wrote: I'd be interested to see what the actual width difference is between the SRW and DRW axles measured flange to flange.
Can't speak for all trucks, but for my year range of truck ('86-'97 F350), using the Visteon 10.25" rear axle, the hub to hub width difference between the DRW and SRW versions of that axle is 4 inches total. The load rating difference is 2000 lbs (6250 srw vs 8250 drw).
Cool, that makes sense too since the offset on an average dually wheel is around 5" or so, but the dually usually has narrower tires than the SRW on each rim, so that math works out. Either way, the distance from the inner sidewall of either a DRW or SRW setup on the equivalent truck should be about the same.
hopak wrote: But I like the idea of mounting the wheel with the flair outwards for better stability with a camper. That should just reverse the torque,or will it somehow increase the torque?
I think that would be a bad idea with the weight of the camper in the bed because yes, that will put the load center a long distance outside the bearings. Look at it like this, lets say for the sake of argument that the center of the two wheel bearings is 3" inside of the wheel mounting flange. With both dually wheel mounted like stock the load center is right under the flange, so the engineers designed the axle to have the load center 3" outside the centerline of the bearings. If you mount a single dually wheel facing outward you're moving that load center to 8" outside of the bearing centerline. I think you can see even without running the numbers that you'd be putting a much higher strain on things than was ever intended.
Anyway, I think the best option still is to ditch the front spacers and buy a set of zero-offset 19.5" wheels and tires. If those are too expensive and your camper's not too heavy, you could also do the same and just go to a 16 or 17" tire/wheel combo.
BoilerEE wrote: I'd be interested to see what the actual width difference is between the SRW and DRW axles measured flange to flange.
Can't speak for all trucks, but for my year range of truck ('86-'97 F350), using the Visteon 10.25" rear axle, the hub to hub width difference between the DRW and SRW versions of that axle is 4 inches total. The load rating difference is 2000 lbs (6250 srw vs 8250 drw).
Cool, that makes sense too since the offset on an average dually wheel is around 5" or so, but the dually usually has narrower tires than the SRW on each rim, so that math works out. Either way, the distance from the inner sidewall of either a DRW or SRW setup on the equivalent truck should be about the same.
Well... sorta...
In the above-mentioned years, the rear springs on the F250 and srw F350 pickup are 3" wide but the dually F350 pickup had 2.25" wide springs. I presume this was to allow clearance for the inner tires, because the F350 and F-Superduty drw chassis-cab trucks of those years had 3" springs, but the frame was narrower on the chassis-cabs than the pickups (34" vs ~37"), so there was room to clear the inner tires with the wider springs.
The stock size tires on the dually were 235/85-16. The srw trucks came with 235/85-16 as the standard size and 265/75-16 as the optional size. I'm running 285-75-16 on wheels with similar offset as the stock single wheels in an 8" width on my srw truck with 3" springs with no clearance issues.
* This post was
edited 06/14/08 07:47pm by SoCalDesertRider *
Yep, Stockton will build you whatever you request, and do a good job on it too! That is a good price too! What rim size did you order? I'm sure you'll be very happy with them.
The ones I got from them are the Power Wagon, series 24, if I remember right. I posted a few pics of them in my wheel upgrade post in this section of the forum.
Talked to fred goeske at wheel adaptors.com. He suggested saving the money for custom wheels and get a ford 350 16" wheel with spacers to put the track in the center of the duallies with a 12 ply tire.
Next step is to weigh my bigfoot. I was figuring on a max weight of 7000lbs fully loaded. But I want a fail safe system.
So as I see it, paraphrasing hopak's words, the plus side of this conversion is:
1) Reduce Mexican tolls by 50%
2) Drive on roads with weight restrictions while avoiding the possibility of a fine.
3) Realize a small improvement in fuel economy.
The down side as I see it:
1) Approach the max load rating of the single rear wheels.
2) Reduce the side to side stability of the rig, especially in a cross wind.
3) Loose your margin of safety should you have a blowout.
4) Spend a rather large sum of money to do the conversion.
5) Spend even more money to replace the dually bed and make it all look “nice”.
It doesn’t pencil out for me, but I didn’t include the fun factor involved in going against the grain.
..Mike
2004 GMC Sierra 3500 4x4 D/A EC LB DRW
Ride-Rites, RS9000X, TorkLift, Fast Guns, Superhitch
2007 Lance Max 1181
Hopak, a stock F250/350 16" single wheel is most likely not going to have a high enough weight rating to be able to run it single on the back axle of a dually with a load. Unloaded or lightly loaded, yes, but not with a heavy camper that needs a dually to haul it. This is why I went with the custom made Stockton wheels. There were no single wheels available in 16x8 with 8 on 6.5" bolt circle with a weight rating of 4000 lbs at 80 psi or more. That is the only way I could safely haul my utility body and pull the trailer without exceeding the single wheel weight ratings, or upgrading to either dual rear wheels or 19.5" wheels. I upgraded the springs, the wheels and the tires. Next on the list is the axle itself.
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