Not-Good-Good-Good-Good Vibrations

[Skipper51]

Well I went to Rocklin in the jeep to pickup two DS so I can put one in the front and have a trail spare.

When I get up to HWY speeds, speedo says between 75 and 85 to 90 mph I pick up some shaking vibrations. If when the vibration starts I take my foot off the gas it stops, mostly, and when I apply the gas I starts up again.

I am going to start by checking the angle of the DS because Blondjon had some concerns around if the angle was correct or not so I need to find an angle finder.

When I do get my muckers on one what are the angles that I am looking for?

I will check tomorrow when I install the front drive shaft that everything is tight and all that but other ideas are welcome.

 

[goodwilljeeper]

Well ik with mine it was cause I didn't have a sye. Idk if u have one. And if u do when Eric and I were doing angles. U want the rear to match the angle driveshaft. My ds is 13 1/2 and my rear pinion angle is 14. So close as close can get

 

[blondejoncherokee]

Is the pinion u joint good

 

[Skipper51]

Is the pinion u joint good

I am 95% sure Jon but I will check again tomorrow when I put in the front DS. :repair:

Tom is coming up too, so I will have him take a look and see what he thinks.

 

[Skipper51]

Is this the angle that I will be looking to do???

 

[EricsXJ]

Yes but you want the pinion anywhere between 1 and 3 degrees lower to account for axle wrap.

 

[GordoSmasho]

That sounds like a bad driveline ujoint/cvjoint.

 

[Skipper51]

So when I look at my set up this is what I see.

I really, really wished they didn't line up so well. I check the U-Joints tomorrow and swap out this drive shaft for one of the other two I got today. If that does it and the U-Joints are good I guess I'll get the DS balanced.
Other ideas??

 

[DaveNJeep]

So I've just got to ask Skipper, what in the heck are doing 90 mph in a lifted jeep for anyways? No s..t are you having vibs, you're going to dam fast, lol!

 

[Skipper51]

So I've just got to ask Skipper, what in the heck are doing 90 mph in a lifted jeep for anyways? No s..t are you having vibs, you're going to dam fast, lol!

Yeah Dave, it is my warped sense of humor. I have 31" tires with 4.88 gears so the speedo is a little off..... like me. :greensmok

I am sure I was in the 65 to 70mph range.

 

[rockclimber]

Yeah Dave, it is my warped sense of humor. I have 31" tires with 4.88 gears so the speedo is a little off..... like me. :greensmok

I am sure I was in the 65 to 70mph range.

but your shaft is spinning like you are going 90 because of the deep gears.


your pinion should be a degree below what your driveshaft angle is because it will tend to lift on acceleration.

that vibration sounds like a worn out slip-spline or a slight misalignment. a worn CV or u-joint will vibe much sooner than that.

 

[Skipper51]

So I went down to the Groundhog Day Garage and changed out the drive shaft for one that I got yesterday and took it for a spin. No vibrations so it was the drive shaft like someone said. Installed the other one in the front so I am cocked, locked and ready to rock crawl.

Thanks to everyone for chiming in with your ideas and thoughts, as it really help me to figure how to approach it.

 

[rockclimber]

So I went down to the Groundhog Day Garage and changed out the drive shaft for one that I got yesterday and took it for a spin. No vibrations so it was the drive shaft like someone said. Installed the other one in the front so I am cocked, locked and ready to rock crawl.

Thanks to everyone for chiming in with your ideas and thoughts, as it really help me to figure how to approach it.

I'm willing to bet its the slip spline.

with the shaft still bolted up under the rig, try to "bend it" by pushing up on it right in the middle of it. if it has any play at all the slip-spline is too worn out to balance.

eventually it will wear out so much that it will vibrate even in the front.

 

[GordoSmasho]

Really glad you got it finally figured out Tim. Looking forward to seeing you at Sierra fest man.

 

[Skipper51]

Really glad you got it finally figured out Tim. Looking forward to seeing you at Sierra fest man.

Thanks Gordon. This latest adventure showed me how far I was from making the Reno Run even though I felt I was really close to ready.

Looking forward to Sierra Fest as always but I would like to get out once or twice before than too.

Too much of this :repair: made me want to do this :explosion but now I am all about this .