High Speed Vibration!!!!!

[Matt99XJ]

Here is my problem. I am getting a vibration/humming noise once I get over 65 mph. It gets worse with speed. If i take the front driveshaft out it stops. That led me to believe it was either out of balance or the pinion angle was off.

I have already tried the following:

1. Balanced the front driveshaft
2. Checked the front pinion angle. 1* lower than pinion.
3. Checked the rear pinion angle 2* lower than pinion.

I can't think of anything else it could be. With the front driveshaft off it drives perfect. Do you think that my CV joint could be going bad?

 

[RCP Phx]

With that lift pinion vs. castor is a problem.My stock shaft has always felt loose from the factory.If youve got any miles at all on this thing take it to a shop and let them check it out!

 

[Matt99XJ]

I just pulled the front shaft out and one of the U-joints in the CV was pretty bad. I am going to replaceit and i will post back.

 

[RCP Phx]

Also check the slip-spline,I only have 15K on mine and it feels sloppy!

 

[gptherezonlyone]

Mine vibrates at 70 and up and it ain't the tires. Let us know what happened. I wouldn't be surprised if it was a u-joint cause I have replaced three within the last two weeks.

 

[keith haw]

Let us know what you find.. Mine does the same thing. Even had the front shaft checked and it checke good to 80mph. Tried shims on the LCA's and it helped alittle. Moved it from 60mph to above 65mph.

Keith

 

[keith haw]

Did you ever come up with a fix on the vibration?

 

[MudDawg]

I don't know much about the newer units...guess it must be full time for the front shaft to run at 65mph...or are you guys running trails at that speed?? Or are you running a locker like a power trax in a disconnect type front end?? Curiosity has the best of me. I can run clean up to the rev limiter (4.88 gears and 33's) with no real vibration problems.

 

[keith haw]

Don't know about the others but I'm running an 87 witha 242 case. The front shaft turns all the time in 2 or 4wd

 

[MudDawg]

Thanks Keith...I have a lot to learn...my 85 model has a NP207 and a front disconnect.

 

[Matt99XJ]

OK I have fixed the problem. I replaced the u-joints and centering joint in the CV and it rides great. I think that the pinion angle being off before I set it cause the u-joints to wear too fast. Hopefully this is a permanent fix.

 

[juicexj24]

you could also check the carrier bearings. Mine just went out and took the whole diff with it. Same sound at 55-70mph, until it blow up.