Freeway vibration, running out of solutions. (1 Viewer)

[91Cruizer]

I have a 91 with a vibration/ humming problem. It will only do it on the freeway at around 65-70+MPH. It all started around the time I replaced the pinion seal and cleaned and regreased the driveshafts. It is hard to say if that was the cause because I don't drive on the freeway much to test it often. It will do the same noise/ vibration consistently no matter what gear I am in including neutral. I have tried removing the front and rear DS to see if there is a difference, no, replaced the front driveshaft anyway, checked the spindle bushings, looked good and had plenty of grease. I noticed the wheel bearings were loose so I repacked them and tightened to 10ftlbs (thanks Landtank). Rotated,Rebalanced tires, then replaced tires and it is still doing the same thing, although improved slightly, with the tires and repacking bearings.
I am going to replace the steering stablizer since it looks like it is rubbing against itself, I doubt if that will matter. Any ideas on what to try next?

 

[Squash]

Try this
I like the idea of jacking up the truck and slowly removing parts...
You could jack her up and remove the tires to start, them start her up, put in gear and start accelerating, does the vibration stop or continue?

If and when you get to removing the brake pads make certain you allow the driveline to stop on it's own , do not pump the brakes for this will force your caliper pistons out.

Are you lifted or stock???

Tires
http://www.tirerack.com/images/tires/vibechart.pdf

Driveline
The Shakedown on Vibration Issues
Driveline Angles and Vibration
Driveline Basics with Steve Johnson - ORN

 

[jonheld]

Which pinion seal was replaced? Front or rear? Is the vibration front or rear or more in the center? Since you eliminated the driveshafts, the only rotating items that can produce a "hum" would be the pinions in the diffs and the output shafts in the transfer case. Everything else is moving too slow to hum. It would be more of a thump-thump-thump. I'd be looking closely at pinion bearing preload and the wear pattern on the R/P.

With all 4 corners on jack stands and both driveshafts removed, you can lock the CD and put her in gear. Let her run up to highway speed as measured on the speedometer and see if you still have the hum. Hum=transfer case; no hum=axles.

 

[91Cruizer]

I have the OME low lift springs with bilstein shocks and OME stablizer (as of today). I am going to take it on a 200 mile voyage tomorrow and see what happens. I can't imagine anything going wrong but this board will be the first to know if something does.

 

[fishwater]

91,
any follow-up on what's happened with this vibration? i'm having a similar problem. i have a 96 on OME heavies (not J's) with slee's CC bushings on 35's and my caster is w/in spec. i have a vibration that i pick up only when i run ~65-70 and it does it regardless of whether the front or rear drive shaft has been removed. even tho i've had my tires balanced, i'm thinking that they might be the problem...
just curious.

 

[91Cruizer]

I got sidetracked on this due to the head cracking which was a whole different problem. I do like the idea of pulling the drive shafts to check the TC. I may try that this weekend.

 

[peepers]

reviving this as I have the problem. There is a leak coming from the rear pinion (slee 4" lift). when ordering the seal, should I just go ahead and order the bearings too and do it all at once? How many s is this job about?

 

[warpdriv]

I had a humming problem on the 80. It sounded like a tire was out of balance. When I was having a front brake job done on it, the tech noticed the race was pitted. So after popping it out we noticed further that the bearing and race was from 2 different manufactures. After replacing them, the humming stopped.

HTH,

 

[peepers]

I had a humming problem on the 80. It sounded like a tire was out of balance. When I was having a front brake job done on it, the tech noticed the race was pitted. So after popping it out we noticed further that the bearing and race was from 2 different manufactures. After replacing them, the humming stopped.

HTH,

nice. i can check it out but i had the bearings replaced with OEM when the axle service was dont less than 10k miles ago.

since the rear pinion is weeping gear oil, i think i will start there. i guess i will go ahead and do the bearings too.

 

[91Cruizer]

I got this problem solved. I figured it was the conbination of front wheel bearings and an out of balance front shaft. After doing both it went away. No saying which was the bigger cause.