Did you lift your bed when you added 16.00's?

Common sense would tell me to lift the bed 2" since you added 4" of tire. Also, since 14.00's rub the bed slightly, how about switching that 1x board that is between bed and rail now, for a 4x4?

I saw a pic from 98G where it was done. Anyone else do it?

Good point to consider, I'll raise it 2" when I roll 16's.

Even with 395's (47") the tires can rub the wrecker bed, probably similar on the cargo/etc.

Yeah, someone responded to a thread earlier this week about clearance. Said that with no load in the bed of his 923(A2?), his tires rubbed lightly at full articulation.

Buffalobwana said:

Yeah, someone responded to a thread earlier this week about clearance. Said that with no load in the bed of his 923(A2?), his tires rubbed lightly at full articulation.

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I had asked how much articulation there was before I got my truck. Once I got it home though I quickly tested it and with both rear axles going opposite directions there definitely was some tire rubbage on the bottom of my cargo bed. If I roll 16s like I want to then I would certainly put a 4x4 in place of that 1x4 spacer.

I have installed 16.00 r 20's on only one truck; a M923A0, and the tires barely touch the bed, at max articulation, with NO LOAD. Been running them for 2 years now, with zero issues.

I have heard but NOT confirmed that the Marine ISO beds are built "taller" and will clear the 16.00 r 20's better than the regular dropside beds, with no additional wood added to the marine bed.

The tires I have are just the 14s and they did rub. On flat ground with just a simple hill they don't, but how often are you really going to see a "simple hill" when you're off-roading?

Maybe I was just hard on the old 923 I had 16's on but I could get the tire to bite the bed hard enough to briefly pause rotation. Lifting the bed sounds like a great plan.

We 16'd this one the other day and simply jacking it up to change the tire, you could see how easily it would rub. We will have to put a 4x in there.

Interesting thread! I'm curious, has anyone tried this on an M936 wrecker, and if so, what all is involved in lifting the bed on one of those?

71DeuceAK said:

Interesting thread! I'm curious, has anyone tried this on an M936 wrecker, and if so, what all is involved in lifting the bed on one of those?

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You would run into shaft angles on the 809 series trucks. It would also put the center of gravity higher on the truck. It would break the securing u bolts as well I am sure. Especially on a side lift. You would be amazed at how much they flex. With a 4x4 piece of wood something would snap.

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So in other words, this would not work on a wrecker variant, at least without substantial re-engineering of other things as well?

simp5782 said:

You would run into shaft angles on the 809 series trucks. It would also put the center of gravity higher on the truck. It would break the securing u bolts as well I am sure. Especially on a side lift. You would be amazed at how much they flex. With a 4x4 piece of wood something would snap.

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I’m going to have to put in a 4x4 in place of the current 1x4, there’s just no way around it for me since I had engineer the ISO frame out of 8” C channel and I beam (cost, money, & weight) vs using 10” or 12” material. I’m going to make up the difference between the 8” and the current lift of the bed with a 4x4, however I will taper it like the original one is so that there is still enough flexibility in the chassis to avoid breaking costly parts.

Just make sure your rocker arms nuts are tight first.

71DeuceAK said:

So in other words, this would not work on a wrecker variant, at least without substantial re-engineering of other things as well?

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If you want to see how much a frame on these trucks can flex check out my video with the JD710 back hoe climbing a mountain. My frame flexed so much under the torque and load that you can see the bed of the truck tilt to one side. That was from the flex and it actually kicked the 4x4 out from under the bed frame rail It had all its bolts in there and the 4x4 had lag bolts into it with steel pieces to keep it from walking to the inside. It stripped those right out of the 4x4s and tossed the it under the truck and the bed dropped back down.

One reason those springs are on the front bed bolts is to account for the frame flex.

In a way, I'm maybe thinking I shouldn't mess with it, as the original engineers knew what they were doing in terms of calculating frame flex, distribution of tension/stress/weight/etc and I don't...

That’s always a safe bet but if you’re gonna be like me

Are you asking about something like this? My truck had 16.00r20s, a deuce bed, and frame extension welded to the back when I got it. It did ok, but my truck is an M818 with a shorter frame. Shorter frames with no weight on them don't flex as much as the longer ones.

71DeuceAK said:

In a way, I'm maybe thinking I shouldn't mess with it, as the original engineers knew what they were doing in terms of calculating frame flex, distribution of tension/stress/weight/etc and I don't...

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They didn’t think we would put 16.00’s on it either. That would just be plumb stoopid!!

If you don’t raise it, do your tires a favor and weld a nice wide piece of 1/4” or 3/8” flat steel where the tire would normally bite the bottom of the bed. At least this way you won’t loose chunks of your tire to the bed frame.