The GMC CCKW

My truck came with hardwood bearing strips attached to the main frame rails. The water tank sat on these. Since my conversion is more akin to a shop van, should I leave these in place or build right on the rails?

The reason I ask is, I am concerned about overall height. 2 inches is the difference between bending over inside all the time and being able to stand upright in the truck.

Any thoughts?

Neil

Huh? The wood strips were there to be drilled for the rivet heads in addition for being spacers. If your body is metal, you must have the strip with the drilled holes or have the drilled holes in the bottom of the metal body frame runners.

Neil,

I have been watching the progress of your truck on your site. Nike work!

You are going to need some type of rails parallel to the frame to mount the perpendicular supports to. You should not drill the frame for those (joist) supports. Not being an engineer I do not know what minumum thickness of wood is necessary to safely support the weight of the wood body you are building. The bearing strips need to support the weight as well as make sure that the weight above them does not go flying off on bumps becasue the strips splinter.

Also on CCKW Cargo's (with flat floor) the strip height takes into account vertical wheel travel clearance issues.

I would imagine that your wood comm body is going to be heavier than the fire body that came off the truck. You may even have to increase the diameter of the strips.

Perhaps there is someone here who can solve this engineering puzzle.

Bill

I would think if you go over 2 or 3 inches, you should probably laminate the wood to give it strength.

Bill is correct about the clearance. If you can measure a cargo CCKW directly above the tires to the bottom of the body, that it the important figure you need to keep in mind. That is when one side of the axle is all the way down and the other side is all the way up and the other rear axle is letting it do it's worst case movement. You surely don't want to hit the bottom of your body.

dr deuce wrote:I would think if you go over 2 or 3 inches, you should probably laminate the wood to give it strength.

Bill is correct about the clearance. If you can measure a cargo CCKW directly above the tires to the bottom of the body, that it the important figure you need to keep in mind. That is when one side of the axle is all the way down and the other side is all the way up and the other rear axle is letting it do it's worst case movement. You surely don't want to hit the bottom of your body.

That is good advice. I have always wondered why the fenders on the radio van sit so high up. It never occurred to me that the worst case is when the axle pivots. That would definately explain it. I will make sure I keep it up where the original pictures show it.

The main box is wood so it will be wood bearing on the wood rails. The box will likely weigh less than the fire truck tank when it is filled with water. It is certainly less than any loaded shop van. The radio box is really a mobile office not a workshop.

I will keep the wood bearing strips and sit the box on top of that.

Bill thanks for the compliment. I finished the structure of the cab roof this morning just in time for the rain. There were no leaks and the water ran off where it was supposed to! I now have to form the drip edge and put the metal skin on the roof.

Neil