Replacing bed cross sills on 2000 chevy silverado 1500...

mp2008 · May 9, 2016

Well, just another thing to take my hard earned money. After putting about 1000-1200 bucks into this truck in the last month, I went to take the bed off to replace the fuel pump and realized all four bed cross sills were gone and beyond fixing. Can't even get the bed off without torching the sills off the frame. Gm must have tack welded nuts into the sills and then bolted to the sills through the frame mounts. Well, every single one was so rusted they broke loose and now the nut and bolt just spin through the frame mounts and sills. So, my solution is to torch the sills off the frame. Pull the bed off, cut the sills off the bed and frame, buy steel square tubing the same height as the old sills (roughly 2"), mig weld the tubing to the bed and then bolt the sills/bed to the frame mounts. Just wondering if anyone has attempted this and if any advice can be given? Also need some advice regarding welding the tubing to the bed and what thickness tubing I should use. I have very little experience mig welding and anyone I'd have helping would have very little experience welding too. The old sills seem to be .083" thick, I'll double check with calipers tonight at work. So this is the thickness I'm thinking of going with for my square tubing but not sure if I should go with .125" instead. I'd like to go with the thicker tubing but I'm thinking about weld-ability to the bed. .125" would be supstantially thicker than the bed and would be more difficult welding to the thinner sheet metal of the bed would it not? Just a few photos to show you what I'm dealing with and thickness of metal they used:

xrs8pp · May 10, 2016

We deal with this all the time on our fleet of coaches.. I can post pics later of what we use for metal but it basically slips over the rotted out support and you weld that onto solid metal of the bed. Hope that makes sense. That is the accepted repair by DOT standards. If you cannot weld I would trailer it to someone who can.

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mp2008 · May 11, 2016

We deal with this all the time on our fleet of coaches.. I can post pics later of what we use for metal but it basically slips over the rotted out support and you weld that onto solid metal of the bed. Hope that makes sense. That is the accepted repair by DOT standards. If you cannot weld I would trailer it to someone who can.

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Hmmm... thanks for the reply. I would appreciate it if you could post some pics so I could see what you're talking about. The way I plan on doing it now just sounds like a headache but I'm not seeing many other options. I don't really see how I'd remove the old sills from the bed when they are welded every 4 inches or so. The welds arent really visible cause I think when it was manufactured, they had holes in the flange on the sills and filled the holes of the sill while welding it to the bed. So it's not like a weld on the edge of the sill to the bed.

What I'm thinking of doing is torching the sills/bed from the truck frame. Removing the bed and sills from the truck and flipping it over. Then torching the top of the sills off so there's only the flange and whatever part of the side walls of the sills I didn't torch off still welded to the bed. Then after taking care of any rust on the underside of the bed, getting square tubing that will fit between the remaining side walls of the sills and using them as the new sills. However, if I left the remaining flange and side walls of the old sills attached, I probably wouldn't have room to weld the square tubing to the bed since it would be sitting inside this remaining material, so I was thinking of drilling holes in the bed and square tubing and bolting them together instead. There would be 4 new sills altogether in place of the old ones about 5 1/2 feet in length from side to side (one shorter due to wheel wells) and with probably 4 heavy duty bolts per sill bolting the bed to the square tubing. What do you think about that plan?

I'm also curious as to the thickness of the metal you used over the old sills? I was planning on using .083" steel square tubing. I think .125" would be a bit overkill but am not sure. That's just one plan I have running through my head, any thoughts or advice will be appreciated!

xrs8pp · May 11, 2016

You are on the right track.. I will take pics and measurements when I get into work later today. I think the sills we use are perfect for what you need to do.

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