Vibration Question (1 Viewer)

[erose54]

Hello All,

I have read the forums about things to test to find the source of a vibrations in the suspension/drive train, but have a question. I have at speeds between 60mph and 70mph a vibration that only seems to be coming from the rear end. I was told at discount tire that I had 3 bent rims and then took to Les Schwab and they said all rims were ok and they were able to balance the tires. I haven't had them road force balanced yet. But drive lines are both new/rebuilt with new u-joints from <2yrs ago. We do not drive the rig much as I am working on fixing little things and making it reliable for long trips. But since I am going to sell my TDI Jetta Sportswagen back to VW, I will be driving the big gas guzzling beast on a daily basis and want to get the vibration taken care of.

But question is would the rear axle bearings/wheel bearings cause a vibration that sort of shakes the whole rear end? Test steps would be as follows:

1. Check rear axle fluids/possible drain and fill as it is probably been >2yrs
2. check pan hard rods/bushings (cheapest easiest step)
3. Lock the CDL and remove rear drive line and test at speeds
4. Rinse and repeat step 2 except remove the front drive line this time
5. Check tires for being out of round at discount tire where I bought them (BFG KOs)

Any other steps that I am missing? It has the OME .5 lift and steering stablizer and Toyota OEM shocks. Knuckles were rebuilt about 2 yrs ago. Could the output shaft of the xfer case cause vibration if the bearing is going bad? I might reaching and thinking worst case and probably should just stick with the fives items that I have gleaned as the most common issues with vibration.

Thoughts?

thanks
ed

 

[gofast]

Have you checked you drive shaft for phase alignment?

Its unlikely that the wheel bearings would shake the whole rear end. If they were that bad you'd hear them growling. Put the truck on a jack and grab the tire to see how much play there is when you wag the tire back and forth.

the transfer bearing will cause the shaft to vibrate if it is gone and if you grab the shaft and try to move it it you will see a lot of play in int he flange off the back of the tcase if the bearing is shot

 

[BILT4ME]

I will second what @gofast is saying, with a bit of a twist.

I don't see a year mentioned in your post. If you have a 91-93 version, you MAY have a semi-float rear axle rather than a full float rear axle. They will have a few different diagnostic points on wheel bearings.

If 93 or newer, the full float rears, the tires will not tilt from 12/6 to check a rear wheel bearing like you can do with a front wheel because the axle flange keeps it from tilting. All you can feel is straight in-out movement and it's a little harder to detect.

The semi-floats don't have wheel bearing adjustment per se, however, I am NOT the expert on those. (@jonheld or @LS1FJ40 would know more for those.)

What I would check and in this order:
Tire balance/out-of-round/slipped belt
Bent wheels
Bent axle flange
U-Joints. (replaced two years ago) grease them
DS phasing
Differential oil levels
Transmission/transfer case mounting bushings (rubber)
Transfer case oil levels
Transfer case bearing play/slop
Rear differential play/slop (pinion)

If it is a shake, it is typically a balance or something is bent.
If it is a sound (grinding or a sine-wave noise (rrrRRRrrrRRRrrrRRRrrrRRR) then it's probably a bearing.

Good luck!

I DD my 96 and it is perhaps the greatest vehicle I have ever owned!

 

[LS1FJ40]

The very first thing I would do is to mark the rear drive shaft and flange. Then lock your CDL and remove the rear drive shaft. Drive it and see if you still have the vibration. If it goes away reinstall your rear drive shaft ROTATED. Unlock the CDL and drive it.

If you had the u joints replaced somewhere they probably installed them like they normally would, which is wrong.

While the rear DS is out check for grease.

 

[jonheld]

You need to determine the frequency of the vibration. If it is a thump thump thump, then it's wheel rotation related. If it's more of a buzz buzz, then it's driveline related.

 

[erose54]

Still haven't figured this out but then again it has been ugly here in Portland the past week and I just haven't wanted to crawl under the rig to remove stuff and get all wet from ice melting off the rig, snow melting and then of course the non-stop rain.

I will try to get to the testing that was outlined above. I did take the rig in and get the tires road force balanced. They stated tires are fine and rims are not bent. They did not rotate them. It did seem to fix the issue for the 50 mile drive home. Next day at around 60 mph it started again. Only in the rear too. Maybe rotate and balance them again and see if the bobble/vibration moves to the front.

 

[DSRTRDR]

you didn't say anything about checking air pressure ?

 

[erose54]

you didn't say anything about checking air pressure ?

When discount tire road force balanced the tires they measured the air pressure and stated it was in spec

 

[DSRTRDR]

not saying they are wrong, but it's so easy to check that you could assure yourself beyond doubt

 

[jrvyota]

I have had a lot of issued with BFG's not maintaining balance and being out of round, however I can usually pin it to a specific tire when it happens. If it is hard to isolate or feels like it is coming from the center of the truck, I would go straight for the drive shaft.

 

[erose54]

I will go home early today and will remove the rear drive line and give a run to see if that is the issue. Rig has not been driven much since the drivelines were rebuilt 2 yrs ago and now it is becoming my daily driver cause I am selling my TDI Jetta back to VW.