Driveshaft vibration diagnostics

[Modest_Man]

Had the bushing redone at a pretty good shop here locally about a year ago but hadn't driven the truck any distance until recently. Now when I go over railroad tracks or hit a pot hole at 35-40 the drive shaft vibrates like crazy for 5-10 seconds and then be okay again. It happened for the first time about 30 minutes into a 45 minute drive and then happened several more times over the drive. Not sure if the road was just crappier or if prolonged driving exacerbated the issue. It may have happened once at a stop light on acceleration, I don't exactly remember.

So, any more professional opinions as to if it is bad U-joints, the new bushing, or if it just needs to be balanced? I am leaning toward the U-joint, but driveshafts aren't my strong suit. Maybe I installed it 180 degrees out?

Original 1 piece driveshaft, if that matters.

[Chknlyps2]

Originally Posted by Modest_Man

Had the bushing redone at a pretty good shop here locally about a year ago but hadn't driven the truck any distance until recently. Now when I go over railroad tracks or hit a pot hole at 35-40 the drive shaft vibrates like crazy for 5-10 seconds and then be okay again. It happened for the first time about 30 minutes into a 45 minute drive and then happened several more times over the drive. Not sure if the road was just crappier or if prolonged driving exacerbated the issue. It may have happened once at a stop light on acceleration, I don't exactly remember.

So, any more professional opinions as to if it is bad U-joints, the new bushing, or if it just needs to be balanced? I am leaning toward the U-joint, but driveshafts aren't my strong suit. Maybe I installed it 180 degrees out?

Original 1 piece driveshaft, if that matters.

Are the u joints clocked correctly? Check these links, they might help.

http://www.behlingracing.com/behling...-installation/

https://www.youtube.com/watch?v=gmV4qwLfOMY

[hamjet]

How do know for certain its the DS vibrating? sounds like worn front end parts to me..

[special-K]

Bumpy roads should have no effect on driveshaft in any way. With it going out of true, then back, and only after a rough spot I'd suspect the shaft is moving in the carrier bearing bushing. If u-joints aren't clocked or worn out the issue will be constant, though maybe more noticeable at certain speeds. Another thought would be the rear axle moving.

EDIT: Now I see you said you have a ipc driveshaft. So, what bushing are you talking about?

[geezer#99]

Strap your motor down on the drivers side, you could have a broken motor mount.

[Modest_Man]

Sorry I misspoke. It is the stock two piece driveshaft. The new carrier bushing has about a 1/2" of flex if I shake the driveshaft. Is that normal? U-joint at the carrier bushing is new, U-joints at the end are not.

I guarantee it is not engine related, as I can push in the clutch and drop the rpm's to idle and the vibration will continue. If it was related to the engine then it would change with engine rpm's, correct?

Here's a photo of the "new" bushing. I had it done last year but the truck has about 60 miles on it, 50 of which were the one longer drive where I discovered the vibration.

[Modest_Man]

Can anyone tell me if 1/2 of movement at the bushing is normal?