Driveline vibration

[Germy]

While driving, once I hit a little past 2 grand, things start vibrating bad. I shift around 2400, anything above that just vibrates too much. Not sure of even a starting place, this is a gray area for me! Help me out!!!! Thanks!!!

 

[Purple77CJ7]

If you think it is rpm related, start with the engine. Do you have the right balancer. My 401 had a balancer from a AMC 304 , and caused vibration at higher rpms. If that is ok then start looking at u-joints and drive line angles. Also motor mounts. Also do you have a CV driveshaft, to help with angle? If not that would help with limiting vibration. Better u-joint angles.

 

[Saddle Tramp]

It makes no sense to me that the drive lines are involved as when you shift up and the rpm goes down the vibration goes with it until the rpm comes up again (Assuming when you shift up the speed of the jeep increases too) but the balance of the 360 could be a suspect. The AMC V8s are externally balanced so even though the flywheels and balancers will interchange between the different displacements you must have components that are balanced to match the motor. For example, the AMC 304 flywheel will not work on a 360 and a 360 will not work for a 401.

 

[CJim7]

Im with these guys. Driveline vibration wont be RPM exclusive.
Motor mounts, engine balance, tranny mounts, or even wobbly pulleys....that's where I'd start.

 

[Germy]

My pulleys are a little off. One of them is slightly off. Getting wear on one side of the pulley for the ps. I did not even correlate that the vibration could be engine related. One little pulley can cause this big a vibration?I will look closer tonight and post any new findings.

 

[CJim7]

One little pulley can cause this big a vibration?I will look closer tonight and post any new findings.

It might...if your mounts are soft. When I did my 401 up, i used the ps pump from my AMC 258 i6 / 4.2l ...and I had to shim it slightly to get the belts lined up.
But misaligned belts aren't as much of an issue as a pulley that is wobbly because of bad bearings or being mis-seated in the grand scheme of vibration. A bad harmonic damper pulley is always suspect. The rubber mid-section can cause the outer ring to be misaligned if it goes bad and create bad vibration.

Have someone rev up your engine to the suspect rpm and watch the front of the block for bad pulleys. Also note how much your engine moves around (motor mounts)

 

[Germy]

Looks as though the pulleys are wobbly, motor is flexing too much, time for mounts. Do I have to completely pull the motor for mounts? Can I lift it a bit to do the mounts then just drop it back down? Doing the balancer too.

 

[Germy]

I was on bull tears website looking at the serpentine kit. What is an ati crank pulley? I am assuming I have a 4 bolt crank, right?

Bulltear-Online

 

[Purple77CJ7]

You can change motor mounts by jacking up one side at a time. Use a block of wood between jack and oil pan. I used M.O.R.E. motor mounts, I think they are better than the stock ones. My opinion. You might have to call Bulltear, I'm not sure what that is. You should be able to see the balancer bolts, most likely 4 bolts.

 

[BajaEdition]

have the driveshafts been taken out of the vehicle?
by you or the OP
you need to check if they are correct in orientation yoke to yoke

 

[Germy]

Driveshafts have been out by po po. How do I check angles? Is it easy?

 

[BajaEdition]

here is how the Yokes line up

and here is a link for driveline alignment
Driveline Basics with Steve Johnson - ORN