Shortening a longbed
By: Leadfoot (Tim
This is how I went about
shortening the frame on my `82 longbed.
First off, remove back bumper and unhook
tail and tag lights,then remove the 8 bolts holding bed to frame..
Then you will need to get it on a hard
level surface and remove the fuel tank(s),driveshaft and carrier bearing,but leave rear
Cut a piece of 4X 4 to
around 40 or so to place on top of the jack and support the frame. This will
keep the frame supported and level. Place jack just in front of the back side of cab
about where the carrier bearing was. Placing the 4X 4 on the jack
and running across the bottom of the frame rails jack the 4x4 up to just pre-load jack
Now carefully measure back 6 from
back of crossmember that supports rear of cab and run masking tape all the way around
frame rail. Check it with a square to make sure it is straight and square to the
frame rail. Now measure back 14 and mask around the frame again.
These tape lines need to be exactly
14 apart ALL the way around. This is where the difference is comparing a SWB
to a LWB. If your are cutting a torch, use the tape lines and mark it with a silver
sharpie or chalk and remove tape. If your gonna use a cutoff wheel, use the tape as
all clips connecting to the frame that hold any wires or lines in the designaed cut
area and pull the lines away from frame so you can safely cut the frame rail. You
dont have to remove them, but you must get them out of the way.
Now you are ready to start cutting.
In planning your cut try to leave a little mettal that you can remove to make sure
everything is square. Fire up the torch or grinder and carefully cut that section of
frame out. Once it is out you can roll the rear section into place. Care must
me taken as to not kink brake lines or crimp wires. step back and admire your work,
because now you are now committed to this project.
Check your fit and grind as needed to
get things lined up and square. Using a square across the top of the frame (from
front to back, side to side, up and down) check to see everything is square and level.
Use the jack to to correct any issues. (the rear section rolling makes this lots
easier) Once everything looks correct, tack it in place. Once everything is
securely tacked together, re-check in all directions. After verifying for
correctness, weld it all around..
Leadfoot grinds the weld off of the top
and outside of the frame until smooth, then using a patch cut from the section of
discarded frame he caps it and then weld the patch thoroughly.
Moving to the rear of the frame, the
rear crossmember must be relocated. Using a torch heat the rivets glowing red hot
and take a large chisel and 2lb. Hammer and knock the heads off the rivets. (these may
also be removed with a cut-off wheel if a torch is not handy) then prevents frame damage
from grinder or just cutting them off with the torch.
Once the rivets are out and the crossmember free, move it forward to the
other set of holes in the frame. They are about 6 forward of where it was
previously located. Using Grade 8 bolts, bolt it back in (no drilling required,since the
holes are already drilled in the frame).
Now mark the rear of the frame in the
same fassion as described earlier and cut 6 off the back of the frame rails.
That basically covers the frame,all
thats left is the reassembly details. Holes will have to drilled in the side
of the frame to mount the gas tank brackets. You must use a tank from a shortbed truck to
accomplish this as the longbed tank is too big to fit. A short bed will fit as all
the bolt holes line up to remount the bed. You also must use a shortbed driveshaft, or
have one built. Fuel may need to be modified. Brake lines and rear wiring will
either need to be shortened/ bent or replace with ones from a shortbed.
Reinstall bumper and hook up lights and
your done..sit back and admire your work..