Solved: Another Vibration over 50 mph after driveshaft u-joint change thread

Rut Row said:

I've read all the vibration posts I can find and I'm stumped.

Background: This is a 2003 TJR that ran fine, no vibrations, no problems at all. I'm the third owner and the TJ has 160K on the clock. This is preventative maintenance since I had no idea when or if the u-joints had ever been replaced. There were no indications that the driveshaft u-joints were bad. With the exception of the centering yoke, I replaced all u-joints with Spicer non-greaseable u-joints. I installed a new Spicer greaseable centering yoke. The old u-joints were greaseable.

The u-joints in the front driveshaft had been replaced somewhere along the line. The rear driveshaft had the original u-joints. I know this because they had the plastic injected retainer. Replacement went ok and afterwards all joints are properly seated as shown in this image from @Jerry Bransford (see this link (https://wranglertjforum.com/attachments/u-joint-jpg.275904/)

Problem: Very slight vibration in the 30-40 MPH range and quite noticeable vibration above 50 MPH. The vibration increase as speed increases. I've double checked that the u-joints are properly seated in the yokes.

What is the next step in troubleshooting the vibration?

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I don’t know if it was just how you worded your post, but the joint in that picture is not properly seated.

I didn't see it mentioned in your post but did you mark the driveshaft to yoke orientations before removing? If not, you could try rotating joints with a test drive after each one to see if the vibrations are reduced.

NashvilleTJ said:

I don’t know if it was just how you worded your post, but the joint in that picture is not properly seated.

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X2, probably just mis-worded I hope.

Rut Row said:

Is it possible that it is just overly tight u-joints and that the vibration will go away as they loosen?

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Possible as the bearing caps can sometimes get seated too hard/deeply. If they don't pivot freely a BFH can make good use of inertia to move the bearing caps back out a tad to free them up.

Jerry Bransford said:

Possible as the bearing caps can sometimes get seated too hard/deeply. If they don't pivot freely a BFH can make good use of inertia to move the bearing caps back out a tad to free them up.
View attachment 496586

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This is exactly what you need to do. If it's seated too hard to one side, it can cause a vibration.

Rut Row said:

gave the front yoke ear a substantial love tap with my favorite BFH as prescribed by Jerry.

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Darn know-it-all.

Don't worry about your ego, you fixed the problem.

Rut Row said:

So, I crawled under the TJ and gave the front yoke ear a substantial love tap with my favorite BFH as prescribed by Jerry. Imagine my shock and horror when a c-clip popped off. I fixed that and triple checked all the others whilst tapping with the BFH.

The test drive was perfect and the TJ is fine. My ego, though, is severely damaged.

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Look at it this way. It’s fixed, you learned from it, and you still didn’t have to pay someone to fix it (or the error).

Your ego should be fine

Rut Row said:

So, I crawled under the TJ and gave the front yoke ear a substantial love tap with my favorite BFH as prescribed by Jerry. Imagine my shock and horror when a c-clip popped off. I fixed that and triple checked all the others whilst tapping with the BFH.

The test drive was perfect and the TJ is fine. My ego, though, is severely damaged.

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Don’t be feel to bad at least you caught the error and didn’t blow up your tcase like I did.

Rut Row said:

Ya, that definitely was a bummer. I had this vision of the cap flying off at 70MPH on the interstate. I've been working on sh*t since I was 14. I'm still gobsmacked I didn't get that clip seated.

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Shit happens. I'm 43, and took my first lawn mower apart at 6 or 7. Have had tools in my hand ever since. I've experienced a number of times that I've missed something stupid simple. I remember a johnny joint I rebuilt that I didn't get the snap ring fully seated in. "what is that clunking noise?" Oh, shit....I feel dumb. Then there was the time I heard a little squeak from the rear end, Never could find it...Until the wheel fell off. One of my wheel adapters loosened up. I checked the lug nuts on the wheel, but forgot about the adapter at that time.

Then there was the time I was working 12 hours shifts, on the overnight. Wife's car needed brakes and at the time, we were still climbing out of debt so I was the primary mechanic. I got the brakes replaced and wheels back on. Took it for a test drive to bed the pads and called the job complete. She called me on her way to work the next day..."why does it sound like my tires are about to fall off?" I could hear it in the background...Yeah, I forgot to torque the lugs. That time, the tires DIDN'T fall off, but instead of stopping like I told her too so I could come fix it...she took it to a shop. That mechanic asked if I wanted her dead

Incidentally, she told her dad...who now always gives me a hard time about it...

joelachr said:

I didn't see it mentioned in your post but did you mark the driveshaft to yoke orientations before removing? If not, you could try rotating joints with a test drive after each one to see if the vibrations are reduced.

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I've never understood the thought process behind this. The driveshaft is balanced on its own, not with the yokes for the axle/case attached. There's no way that installing a driveshaft either 90 or 180 degrees out of alignment from how it was set up the first time, depending on the yoke/flange type, would cause vibrations.

IOwnCalculus said:

I've never understood the thought process behind this. The driveshaft is balanced on its own, not with the yokes for the axle/case attached. There's no way that installing a driveshaft either 90 or 180 degrees out of alignment from how it was set up the first time, depending on the yoke/flange type, would cause vibrations.

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My guess is stacking of tolerances. It's unlikely the driveshaft was balanced perfectly to zero. Then there's also the runout of it and the yokes. Different orientations cause those to potentially either add up or cancel out. Whatever the reason, the FSM recommends marking driveshafts for orientation before removal.