New Driveline Vibration or What?

[RAMINSPEED]

I have this new resonating vibration that that started yesterday. It’s a fast (not actual speed) pulsating (vvvvvvvvv vvvvvvvv vvvvvvvv ) vibration from 1600 to 1800 RPM (58 to 70 MPH) in OD only and most prominent under acceleration. I think it might be the rear driveline since I recently added superlift’s 2” rear blocks. Superlift in their infinite wisdom made the blocks flat with no taper. I figure if it is the rear driveline I would hear the noise in drive at the same speed but I don’t. Has anyone had such a vibration and of so what is it and how did you fix it?

 

[NDanecker]

From an engineering stand point, you'd want both the output shaft of the transmission and input pinion of the rear parallel to each other. If you put angled blocks in, you'd not only space the axle 2" further away from the centerline of the transmission, but you'd put an unwanted angle between them.



As for the vibration, did it come on immediately after installing the blocks???

 

[RAMINSPEED]

Originally posted by NJTackle

From an engineering stand point, you'd want both the output shaft of the transmission and input pinion of the rear parallel to each other. If you put angled blocks in, you'd not only space the axle 2" further away from the centerline of the transmission, but you'd put an unwanted angle between them.



As for the vibration, did it come on immediately after installing the blocks???

I installed them last weekend and didn't notice anything. Then on Wednesday I did. It seems to be getting worse. It is very prominent under acceleration.

 

[Yo Hoot]

I have the same vibration on a stock brand new truck. Keep us informed please.



Thanks

 

[DE Jeeper]

I would bet it is either a bad universal or the driveshaft angle is too far out of wack. Also, re-check your u-bolts with a torque wrench. If they loosened the axle may be rotating a little.



Remember under acceleration the pinion will rotate up 1-2* because of spring wrap. This is why you don't hear it coasting or decelerating.

 

[Yo Hoot]

One fellow is reporting that changing the driveshaft AND transfer case cures it entirely.

 

[cpizz]

I think there is an design flaw with the drivelines in some of these trucks. I have a pulsating vibration that just started at 6000 miles. When you first start ut in the morning it is not noticable. After everything warms up you start feeling it. I have also noticed that the u-joint just behind the t-case is slinging a little bit of grease. Seems like it maybe in a bind. Funny thing is that my '03 did the same thing. It was identical to my truck now. I wonder if the t-case is sitting at the wrong angle or if it is something else? Anybody got any ideas?