pitching driveline angles.

one of the most annoying side effects of drivetrain mods is the occasional situation where the truck develops a harmonic vibration as it hits a certain speed or RPM. Upon assembly of this truck's drivetrain, the first driveshaft segment was obviously pitched at an angle of greater than 3*. this is suggested by my driveline guy to keep the harmonics to a minimum. One of these angle gauges is critical for the following measurements. In the following pic, you'll see the gauge is "zero'd out" on the base of the lift.

next, you'll see the driveshaft that 10* off .

But since the GV is 3* off, some of the angle can be "subtracted" off the total angle on the first driveshaft segment.

there are two most obvious choices for transmission mounts. The original was the thicker of the two, so I put it back in initially, since I didn't know what to expect. later on this week, when time and energy permits, I will swap in the shorter of the two mounts and see how it does.

the rear segment is sitting at a rather shallow angle but currently in the back of the truck is one complete dually rear end assy, 4 f350 rear spring packs and two f250 D50 spring packs. plus whatever assorted goodies from this project.

well....this concludes this post for the moment, for those who are curious, you can post a max of ten pics via the inline format as you have text inserted.

part 2

the problem with changing the mount is the possibility of the front driveshaft hitting the cross-member. well, if you don't try you'll never know. I know it's "simple" to cut and modify the center support bearing mount plate, but my concern is if I do that, it would make reinstalling the non-GV driveline a headache just in case I blow the GV unit out in the middle of nowhere. I'll do it if that is the only option if the mounts don't work.

About the trans mount and front cross member hitting the front driveline. Why not place the cross member under the frame and use a piece of 1/2 inch plate under the smaller trans mount.. Or shim it with whatever works out for clearance. Seems like there is plenty of differance between the trans mounts to "customize" something...

I wonder if you could get away with a one piece shaft?

two piece shafts can be tough to get perfect. I would bet with the added lenght of the gv a one piece would be just fine.

I asked about a 1 piece driveshaft when I added the gear vendors and I was told to go with the two piece. A standard cab 4wd though could get away with a one piece.

My standard cab 4wd (no gv) has a one piece drive shaft, in fact the one that was factory in the 87 was replaced with the one from the 85 F350 I used the axles out of because the 85 was 5 inches longer an allowed me to move the rear axle back, this was good because I added about 13" to the frame for the longer flat bed and dump pivots.

The only standard cab 8 foot that I know of having a 2 piece was 2wd manual.

Being a 4x4 truck, if you are stuck in the middle of no where do this. Pull the rear drive shaft, or at least the back half of it. Lock the front hubs, shift to 4 wheel drive, and drive on the front axle only. It works, I had to do this one time when a rear u joint broke on me. I drove from carmel valley to hollister without issue.

well....
the shorter mount changeout was a success.

the driveline angle on the first shaft was dropped to less than 3*
check out the gauge on the GV and on the driveshaft.

and I still have room on the front driveshaft between that and the crossmember.

It's beer time
buddy brought by some polish beer. good stuff



that is all.
stay tuned for transfer case shifter install and GV hookup.