Driveline Vibration

[fixit-p]

If your measurements are accurate.

trans- down 2*, front shaft down 3*, back shaft 0*, pinion up 4*.

Then the operating angle of the first U-Joint is good @ 1* the pinion should be parallel with the first drive-line (3* up) which would make the operating angles of U-Joints 2 & 3 equal at 3*. Alternately you can lower the first drive line down to 4* which would cancel out the pinion angle but make the operating angle of U-Joint # 1 @ 2* and U-Joints 3 & 4 @ 4*. At 4* operating angle you can start to see the life of the U-Joint be compromised but you shouldn't see any vibration because of pinion angle.

[Dunenutt]

Originally Posted by Street Smart

^^^^^^^^^^^^^ great pic! and info.
Its hard to get an accurate place to measure the trans angle, nothing looks parallel to the output shaft. So i figured where the bellhousing mounts to the block should be perpendicular, safe to assume?

Use the crankshaft pulley for the trans angle. it is the most accurate.

[Street Smart]

Originally Posted by Dunenutt

Use the crankshaft pulley for the trans angle. it is the most accurate.

That would be good but i have a mechanical fan and shroud, kinda hard to get in there.

[suttoncurt]

Originally Posted by Street Smart

That would be good but i have a mechanical fan and shroud, kinda hard to get in there.

Any updates on this subject - My truck is static dropped 5 1/2'' front and 7'' rear and I have a vibration around 60 -70 mph ?

[Street Smart]

I still have the vibration in my Suburban. I tried different angle shims at the rear, didn`t help. My next move is to either cut the floor and raise the back of the tranny, or getting a driveshaft made with a C.V. joint to eliminate one of the angles.
Keep me posted if you figure something out.

[suttoncurt]

Originally Posted by Street Smart

I still have the vibration in my Suburban. I tried different angle shims at the rear, didn`t help. My next move is to either cut the floor and raise the back of the tranny, or getting a driveshaft made with a C.V. joint to eliminate one of the angles.
Keep me posted if you figure something out.

Hmm... Man this can be a hard thing to figure out . I'm getting ready to go on the HRPT so I have until June to play with diff angle's . I'll report my findings here . Thanks for the reply man