Replacing cross sills
 

How hard is it to replace the cross sills? my short bed has some rust in one or two of the middle ones and i was thinking of replaceing them before winter thanks,:chevy: my truck is a 71 swb

Re: Replaceing cross sills
 

Ttt

Re: Replaceing cross sills
 

I have to replace the very front sill on my fleet side (have yet to do it). As far as I know they are spot welded into place. It's just a matter of drilling or grinding out the spot welds. The new sills need holes for rosette welds, you can do that with a drill bit or a punch tool.

Re: Replaceing cross sills
 

Thanks: i havent taken my bed off yet to fully see what is there

Re: Replaceing cross sills
 

There is a little bit of rott on my truck cross sill towards the back and am wondering the same thing.

Re: Replaceing cross sills
 

I got inspired by the question so I dug into the front sill on my truck that needed replacing.

I started by trying to use a spot weld cutter. The spot weld cutter was not successful. Partly because there isn't a lot of room to get the drill perfectly perpendicular to the weld. I did have some success using a larger drill bit and drilling out the spot weld. Eventually I gave up on it as well because the bit became dull (I need a drill doctor).

My final solution was to use an electric grinder to grind down 80 to 90% of the weld then used a pneumatic hammer to break the remainder of the weld. My hands are numb and I think at some point I briefly set myself on fire. Hearing protection with the hammer is a must. I have an old lab coat that I put on when I have to protect my arms from sparks. I think all the lab coat did was trap the sparks against my arms

Not every point where the sill and the bed "folds" meet have a weld. In the middle it can be every other, or every third. At either end it is just about everyone for about three to four spots. I did end up tearing the spot weld through the bed in a couple of spots. My bed is heavily pitted and will be lined with Rhino lining so not a big deal. I'll just use those holes to spot weld from the top.

The round hole at the top of the pic is one weld that I tore out, not terrible and can be easily fixed when the new sill goes into place.

http://lh3.ggpht.com/_YVHtgL4l5sQ/TJ...0/IMG_4415.JPG


This is the sill off the truck, you can see how I ground into the sill to grind down the weld.

http://lh6.ggpht.com/_YVHtgL4l5sQ/TJ...0/IMG_4416.JPG


The bed, post sill being removed.

http://lh6.ggpht.com/_YVHtgL4l5sQ/TJ...0/IMG_4417.JPG

http://lh4.ggpht.com/_YVHtgL4l5sQ/TJ...0/IMG_4419.JPG

Here the sill has been completely removed. You can see the right hand side where it was rotted through. The sill was full of sand and dirt. Even though I have cleaned, and blown this sill out a couple times I had to stop and vacuum up big chunks of rusted metal and more sand. In all this took about 45 minutes even with all the changing of technique.

http://lh5.ggpht.com/_YVHtgL4l5sQ/TJ...0/IMG_4414.JPG

I won't be installing a new sill for some time, the bed is going to be sandblasted so I'll wait till that's complete before the new one goes in.

Re: Replaceing cross sills
 

thanks i am going to hopefully pull my bed as soon as i get this motor project finished