Drive Train Vibration Help (1 Viewer)

[bcolvin]

Hi all,
I have had a drive train vibration problem for awhile and I can't seem to solve this one. Unfortunately, I don't have a very good baseline since I bought this cruiser when it wasn't really running (pouring oil out) so I never really had a good feel for what it was like before I started working on it. I put on an OME Medium (removed a leaf) and replaced all of the gaskets so it stopped leaking.

At this point I had a vibration issue at 25mph and some after. Here is the order in which I tried to address the vibration or just general maintenance that I would hope would help. Replaced all U joints (front and rear), 2 degree shims in the front, tried shims in the rear (fat part facing toward the rear of the vehicle) made vibration worse, measured the difference in TC flange and differential flange angles (rear differential is 1.5 degrees lower that TC), had the drive shaft balanced both front and rear, drove without rear drive shaft (no vibrations while doing this), reasealed transfer case, replaced clutch, did rear main and resurfaced flywheel, rebuilt rear differential.

So what are your thoughts now? Should I try the rear 2 degree shims with the fat end facing the front? That would even out the driveline angles (but from what I understand the rear diff should be 1 degree lower). Have the rear drive shaft rebalanced or at least checked again, Call Tom Woods and go with one of his? Any suggestions would be totally welcome. Thanks

 

[tmxmotorsports]

Lift?

 

[metro55]

Deja Vu for me.
after all new suspension/shocks etc
Vibration for me was BAD at 120 KPH (75MPH) but slightly noticeable at lower speeds
I installed "2" extended shackles and had the same issues you have I did the following.

Balance rear shaft (new U joints) problem persisted
new rims and tyres (tires your end) problem persisted

I did not notice the vibration before the new tyres as the Cooper 33's were very bad for
vibration and tracking (neg 50 offset with rims).

2 deg shims (fat at the back) problem persisted
4 deg shims (fat at the back) problem persisted
3 deg shims (fat at the back) problem persisted
Left the 3 deg in there then replaced rear wheel bearings (Full Floater)
I noticed left rear bearings were quite loose (not sloppy) , replaced after
reading several guides on this forum regarding pre-load.

Problem is now almost gone, I suspect the slip yoke may be contributing to
the very slight vibration, the company that balance the shaft stated it was a little worn
I found it interesting that there was no noise from the loose bearing just vibration.

Not sure if that helps you ... good luck with it.

metro

 

[bcolvin]

@tmxmotorsports I did an OME medium on this from Cruiser Outfitters. The previous leafs springs were toast, flat, and broken. So even with with the 2 inch lift it looked substantial. After the lift I did put on larger tires. Last week I swapped out my tires with a buddies to see if that made a difference. It did not.

@metro55 Thanks for the detailed response. I forgot to mention, I replaced the rear bearings and seals when I did the rear differential. I also did the drag links and tie rod ends too. I feel like I have hit most everything but clearly something is missing. It is quite smooth when that rear drive shaft is removed. It is kind of leading me to wonder if I can ask NAPA to respin the drive shaft and see if something is going on.

 

[relaxedcruiser]

The fact that you were able to worsen the vibration with the shims at the rear axle and that the vibrations are gone without the rear driveshaft circles it in this part of the vehicle. As far as I know and from my own experience you don't need shims at the rear - at least not for a moderate lift. They are rather build to adjust your caster angles at the front axle.
I have the CS005R Springs and when not loaded the 60 sits quite high - yet there are no vibrations.
A Important factor with all cardan driveshafts is that you want the same angles on both sides - otherwise you'll end up with vibrations sooner or later due to the fact how a cardan or universal joint is working. Have you double checked that the "Forks" of the actual shaft are in the same plane ?

 

[relaxedcruiser]

Just found that after a quick google search.
Phasing is the proper term for aligning those yokes.
The Z-Arangement is what I wanted to describe in my post above.
The W-Arangement can be found on front driveshafts with tilted up diff heads.

 

[bcolvin]

@relaxedcruiser — thanks for all of the information. I feel like I know enough to be dangerous but not enough to understand the nuances of what im dealing with. So my rear drive shaft is in that z arrangement. My two flanges have somewhere around 1.5 degrees of difference. With absolutely no practical experience, but what I have read, when accelerating the rear transfer case will rotate up nearly a degree. This would the. Create a 1/2 degree of difference which I would think would be tolerable.

When accelerating through the 20-30ish mph I feel the vibration the most.

I am pretty sure my ds is in phase as I’ve marked it up before I pulled it the first time but I’ll quadruple check this.

What really irks me is that my buddies and I have done about 5 of these suspension kits in the past year or so and this one is the only one that has given us fits. I am sure there is something that I am missing… so I’ll keep scratching my head. Thanks again for all the ideas

 

[relaxedcruiser]

I've had it before that a sudden change in ride height due to lifting could cause vibration because the part worn universals are working outside of their "worn in" "comfort zone" angle wise. But you have already replaced them.
I'm sure you have done it already....but a rear diff pinion with the slightest amount of play /without the required preload can cause rumbling noises and probably vibration. Just thinking as you have worked on the diff. Sometimes it pays to go back and check on the alternations / repairs you have done just before the problem occurred.