Morphing a Sierra with a Silverado

[AdioSS]

I'm betting you'll need a Sawzall or maybe even a plasma cutter

Between the two, you've got at least 1 good frame, but you might need to get friendly with an autobody professional.

I betcha the block is still good. Keep tearing into it and keep us informed.

[04DOOR]

After tearing down the front end I got to what I was looking for. The frame was just like I thought. Perfect! Well almost, the bumper brackets in the center were slightly tweaked. Nothing a larger hammer couldn't fix. It was a good clean hit that got close to the frame but didn't mash it. The only thing that got smashed was the passenger front brake line.

[04DOOR]

So my next task was to fix that brake line. No sweat I had the Sado to take parts off of. Before I disconnected anything I took a look at both trucks to compare brake lines. This is when I made a big discovery about the differences between Silverados and Sierras.

It may be common knowledge here on the forums but I found out that in 2004 Silverados sit higher than Sierras.

I discovered this because on the Silverado the brake lines run on top of the frame rail to the abs block. But on Sierras the lines run on the sides of the frame rails because there is no space on top between the body and the frame.

The brake lines won't switch over from a Sado to a Sierra. They will however switch from a Sierra to a Sado.

[04DOOR]

[04DOOR]

[04DOOR]

So after that discovery I decided to go to the junk yard and find a replacement and just splice the brake line at the radiator support. I ended up finding a 2007 Silverado that basically just the frame and brake lines were left.

The strange thing about this Sado was that the brake lines looked just like the ones for the Sierra. They were routed along the side and not the top of the frame rail. Maybe the junkyard screwed up and miss labeled the truck or maybe sometime later all the trucks used the same frame. I'm not sure but you can see that in 2004 they are different.

So I bought the line and took it home to put it on the Sierra. I guess on the new body style the radiator crossmember is closer to the engine than in 2004. The brake line was the right diameter and the fittings were the correct thread but the line was short about 3 inches from the radiator crossmember. No big deal again I just rebent the line a little to make it fit. These brake lines were very soft and you could bend them with your hands. I was just careful not to kink them. It turned out perfect. I redrilled one of the holes for the plastic clips but that was all.

[04DOOR]

I'm betting you'll need a Sawzall or maybe even a plasma cutter

Between the two, you've got at least 1 good frame, but you might need to get friendly with an autobody professional.

I betcha the block is still good. Keep tearing into it and keep us informed.

As bad as the front end was smashed all I needed was a large pry bar and an air ratchet. Ill use the Sawzall and plasma cutter when I chop the Silverado up!

[04DOOR]

O I forgot to mention that the crankshaft pulley, a/c and power steering pump were untouched in the crash. Awesome. That means there is a good chance that the engine is still good. I figure that the water pump took the brunt of the hit and just pushed against the iron block. Which is attached to the trans which is supported by rubber mounts.

I ended replacing the engine mounts with the Silverado ones. The rubber was good on the engine mounts but the brackets were hammered!



The trans crossmember is bent and so is that large block piece that is between the trans and the crossmember. I haven't gotten around to swapping that out yet.

The only thing im worried about now is the driveshafts and the output shaft housing of the trans. I took a look underneath and they didn't seem bad. The carrier bearing was pushed back though about 1/2." Im guessing it needs at least a new output shaft housing seal but other than that I think its ok. I will take a second look and make sure. Do you think the driveshafts have enough flex room in them to be ok?

[txarkitekt]

Damn dude...you've got a lot of work done! Nice write-up too...

Ok, as for the drivetrain on the GMC...consider it trashed. I would not reuse or try to fix anything. There should be enough flex in the driveline to where the rear end should still be good. I would take the motor, motor mounts, tranny, and driveshaft out of the GMC and replace it with the Chevy stuff. Of course you will need to get a new CCSB driveshaft for the GMC. I would save the motor and tranny from the GMC to use as your own parts stock.

From the looks of the frame, you are good--just swap over everything from the Chevy that you take off the GMC. It should be a pretty straight forward swap.

Good work--keep us updated!

[04DOOR]

Sry about this newb question. What is a CCSB driveshaft?

I need to post some more pics to try to catch up to where I am today. Maybe this weekend i'll get caught up here on the forums. Thanks for the encouragement.