I jacked up the truck and placed it on the riser-blocks today so I could crawl under it and start figuring out all the driveshaft angles and such. After taking some measurement and looking at the surrounding structure that I needed to avoid with the driveshaft I have decided that I will need to use a two-piece driveshaft with a center bearing. The total span between trans yoke and diff is just a tad under 54” so a single-piece driveshaft would need to be 3.5”-4” diameter, which would add to my clearance issues, whereas a two-piece could be 2-2.5” diameter.
The first step was to adjust the engine trans angle some more. It was set it up for 3.5 degrees to clear the floor but that was a little more that the 1-3 degrees usually recommended by driveshaft manufacturers. I was able to find an old driveshaft and yoke among my junk pile so I cut it up so I could test the yoke clearance to the cab floor. It showed ample space so I then made a few 1/8” thick aluminum shims to place between the trans cross-member mount. Raising the mount 3/8” changed the engine angle to 2-1/4 degrees...which was just about perfect.
The plan is to set the fwd driveshaft that will pass thru the center bearing up about ½ degree from the 2-1/4 degree on the engine/trans (so the u-joint will work & not wear prematurely) which will be at about 1-3/4 degree angle. The center bearing will be located approx 18-20” aft of the yoke pivot point so the rear driveshaft will be approx 3 feet long....this should be close enough to the 40/60 ratio of front to rear driveshaft length that I also read was recommended.
I set the rear diff on some 2x4's cut to rest the truck rear diff at ride height so I could see how it will all route. Everything looked good. I will need to cut the crossbrace that holds the four link (I just installed it straight across) so I can add an arch to it to clear the driveshaft. I will try and start fabbing that next. I also need to buy two more bumpstops for the rear diff since I apparently cut these off too short earlier.
I also surprisingly received the Lokar shifter that I ordered a week or so ago from Speedway Motors. When I ordered it they said it would ship from the vendor in early April so I did not expect it so soon but it arrived earlier this week. Since I had cutout the trans tunnel that I had installed a while ago I went ahead and temp installed the shifter. This is needed so I can get an idea of how the new tunnel will need to look. The Lokar shifter can be located fore/aft anywhere along the mounting rail but the fwd-most position more closely replicates the original position so I placed it there. The instructions stated that using this position might require the need for an additional bellcrank to keep it from binding...and that looks to the be the case. I might try to move it back one space and tilt it a little further forward (it is adjustable) to see if it will miss the seat and eliminate the binding. If not, then I guess I'll buy the bellcrank kit.
1949 Chevy Panel Truck A Project Journal I'm old but I make up for it by being immature.
