dssur
+1y
Originally posted by dropedtoy
u cut the bottom of the frame. u move the trans.cover up . cut the front frame behined motor and front of motor move up
wow, I may have only done one sfbd, but I know that is NOT the right way to do it. If you cut the bottom of the frame off, the tranny will drag on the ground, and you'll have to rebuild every crossmember.
My way: pull the cab.level the frame. Its ok that the rails dont hit the ground because they are lower than the front clip, dont worry about that right now. Just get the front suspension on the ground, and LEVEL the frame on level concrete. I built a jig to lay on because the concrete wasnt level. Building a jig also makes it possible to mark the height and exact location of the centers of the body mounts with pins.
Support the front clip. It will want to fall forward once you cut the rails off, so weld supports from the frame to the level ground (or jig) Also support the tailshaft of the tranny so it doesnt fall. Unbolt the tranny crossmember from the rails but not from the tranny. pull all the brake lines and gas lines off the frame rails, you dont have to take them all the way off just so you can remove the rails.
Pick a spot just forward of where the firewall would be, and chop off the old rails.
Lay out the new rails and slide them up in the front clip a bit. Plug weld and double check for straightenss. Nobody likes a crooked truck.
Weld in new tranny cross member mounts and bolt the tranny crossmember you didnt remove earlier to it.
Build another crossmember under the trans, use a piece of 3" rond tubing to allow an exhaust pass through.
Build a third crossmember back where the back of the cab would be. You will need a big notch in it to allow the driveshaft to move.
Build the rear clip and remount the rear axle using a 4 link (you can make your own 4 link by now, after all this welding)
Rebuild the body mounts, only lower them 2.75 (should be right to lay rocker on a zu) You marked the centers of them earlier, so just make them, no critical measurements needed except the lowering of them.
Drop the core support ears the same amount.
Re run your brake and gas lines, likely your exhaust too. Now is the time to decide if you want a real e brake or will just count on the frame rails to keep your truck still.
Since you have just Z'd your frame (think about it, you made the frame rails as low as the front crossmember) the tranny will likely sit a little high, so section the tranny tunnel and move it up a bit. It may fit though, mine did (on a mazda)
Plop the cab back on and smile as every cab mount lines right back up.
Drive your truck.