Big Red, my 68 3/4 ton GMC

[JORGIE95961]

Originally Posted by Jacfourteen

Had some progress in the last few days. First I had to deal with the driveline. I did some research online and found a site where a guy outlined the steps that he had followed to shorten many drivelines with no trouble, so I figured I'd give it a shot if it was out of balance I'd go get another from the local junk yard for $25. So first I wire wheeled all of the rust and undercoating off of the driveline, I don't know how this thing wasn't out of balance to begin with because all the undercoating was on one side. Next I decided to take the 12 inches out at the splined end because there was no balance weights to mess with. Here it is after cleanup:



So I used a thin cut off wheel on my grinder to cut a shallow groove near the weld on the yoke, it only had to be about 1/16" deep to get through the shaft. Here's a pic:



After that the yoke popped right off with a few taps from a hammer:



Then I measured to see exactly how much needed to be removed, I determined that I needed to cut out 11 and 7/8". Then I clamped it into my chop saw and made sure it was square:



Then I made the cut, and cleaned it up using a file on the inside of the tube and a grinder on the outside and end. Then I had to press the yoke back in, I made a contraption out of 2 chunks of 2x4 and 2 clamps then I had to heat the tube with a propane torch and whack the block with a hammer and keep tensioning the clamps till it was seated:



Next I bolted the driveline into place a spun it and adjusted the runout of the splined section until I got just right. I didn't have a dial gauge to check runout so I rigged up a piece of wire to see how much it was wobbling:



Once satisfied I tack welded a few spots and removed the shaft. Then I welded it up good and used a grinder to knock down any high spots in the weld to help keep things balanced. Then I shot it with some flat black and threw it on.







Then on to the rear shaft...

this so needs to get added to faq's or somethin

[Jacfourteen]

Originally Posted by JORGIE95961

this so needs to get added to faq's or somethin

Thanks! I was gonna do a write up on this in a separate thread but never got time, I guess I could just cut and paste it though. I've had the truck up to 75 MPH and still no vibes from the driveshaft.

[dougminton]

cool build. subscribed

[Jacfourteen]

Originally Posted by dougminton

cool build. subscribed

Thanks!

[JORGIE95961]

Hey bro im almost ready to do my swap from leafs to coil.. did you install the fram stiffener?

[Jacfourteen]

Originally Posted by JORGIE95961

Hey bro im almost ready to do my swap from leafs to coil.. did you install the fram stiffener?

No, I figured that was more for stiffening the shock crossmember. If you are concerned about about it you could just box that section of frame.
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