Rear Driveshaft Vibration

[Samuel Orr]

1997 TJ Sport 4.0L
History:

1. 2.5" lift, no vibration from rear DS.
2. Brackets holding U-Joint near rear diff loosened up causing the joint to fly off. U-Joint replaced, and noticeable vibration from the rear began 20mph and diminished at 75mph.
3. (3) Replaced rear DS + U-Joint in case of either failing [No SYE had/has been installed]. Vibration remains starting at 20mph, but does not disappear at 75mph anymore.

Additional:

• I do not plan to go off-roading, this is a daily that I only need to work comfortably.
• Diff fluid has not been replaced, I am prepared to replace and update if suggested.
• Tires are brand new, only a week old and it rode like a Cadillac prior to U-Joint bracket failure. Therefore not an issue with wheel balancing.
• Link to product information for new rear DS: https://www.ebay.com/itm/1852893251...pid=5337789113&customid=&toolid=10001&mkevt=1
• A Klein digital angle meter is being delivered to me soon. I may report angles to see if it's a pinion issue.

I checked other threads and haven't quite found a solution. Please leave your thoughts; I appreciate any criticism and will try to update/respond consistently, with pictures, for others facing similar issue.

 

[machoheadgames]

When your driveshaft flew off the first time, it might have bent the t-case output. I can't explain why the vibe would change at 75 after the first u-joint replacement and doesn't minimize at 75 now with the new driveshaft, but that could just be an anomaly.

Maybe the new shaft has balance problems of its own, in addition to maybe problems at the t-case? Hard to say.

 

[Ashim]

Was the rear yoke replaced? It may have been damaged when the shaft came off. Inspect the ears of the yoke and make sure the U-joint is fully seated.

 

[Samuel Orr]

Was the rear yoke replaced? It may have been damaged when the shaft came off. Inspect the ears of the yoke and make sure the U-joint is fully seated.

The rear yoke has not yet been replaced. Upon my inspection it doesn’t seem to have any deformities.

 

[Samuel Orr]

When your driveshaft flew off the first time, it might have bent the t-case output. I can't explain why the vibe would change at 75 after the first u-joint replacement and doesn't minimize at 75 now with the new driveshaft, but that could just be an anomaly.

Maybe the new shaft has balance problems of its own, in addition to maybe problems at the t-case? Hard to say.

Would you say dropping then inspecting the T-case is wise? Perhaps there’s other methods of testing it without uninstallation; I’m prepared to do any diagnostics.

 

[mrblaine]

The rear yoke has not yet been replaced. Upon my inspection it doesn’t seem to have any deformities. View attachment 608874View attachment 608875

I've yet to see a quality u-joint cap that can be dented. Are those dents in the cap in the last picture?

 

[mrblaine]

When your driveshaft flew off the first time, it might have bent the t-case output.

You're correct or at least you and I would be iffen we was betting folks. Almost no way that output isn't bent, but stranger things have happened.

I can't explain why the vibe would change at 75 after the first u-joint replacement and doesn't minimize at 75 now with the new driveshaft, but that could just be an anomaly.

Out of round and out of balance cancelled and now don't.

Maybe the new shaft has balance problems of its own, in addition to maybe problems at the t-case? Hard to say.

That driveshaft scares me.

 

[Samuel Orr]

I've yet to see a quality u-joint cap that can be dented. Are those dents in the cap in the last picture?

They’re scratches to the paint. It received a little tap from a wrench to ensure it’s secured.

 

[Ashim]

The rear yoke has not yet been replaced. Upon my inspection it doesn’t seem to have any deformities. View attachment 608874View attachment 608875

Looks like I can see daylight between the strap and cup on the top photo. Maybe someone with more experience can comment.

 

[Samuel Orr]

You're correct or at least you and I would be iffen we was betting folks. Almost no way that output isn't bent, but stranger things have happened.

Out of round and out of balance cancelled and now don't.

That driveshaft scares me.

What brand do you recommend for driveshaft? I know almost everyone likes Tom Woods SYE, but I’m in the market for humbler parts.

 

[rasband]

almost everyone likes Tom Woods SYE

Tom Woods would be the drive shaft, SYE (slip yoke eliminator) is a transfer case modification for peasants with the 231.

Yank the shaft and drive around in front wheel drive (4H) to try and isolate the shaft being the issue. I imagine it was a bit more exciting than "the u joint jumped ship and I replaced it" and other trauma happened to the drivetrain.

 

[OldBuzzard]

I would put the rear axle up on very good jackstands, block the front tires well, and run it in 2WD to see if that rear driveshaft is wobbling at either end.

I'm not saying you should do that, I'm just saying I would.

 

[mrblaine]

Looks like I can see daylight between the strap and cup on the top photo. Maybe someone with more experience can comment.

Typical.

 

[Samuel Orr]

Tom Woods would be the drive shaft, SYE (slip yoke eliminator) is a transfer case modification for peasants with the 231.

Yank the shaft and drive around in front wheel drive (4H) to try and isolate the shaft being the issue. I imagine it was a bit more exciting than "the u joint jumped ship and I replaced it" and other trauma happened to the drivetrain.

Tom Woods would be the drive shaft, SYE (slip yoke eliminator) is a transfer case modification for peasants with the 231.

Yank the shaft and drive around in front wheel drive (4H) to try and isolate the shaft being the issue. I imagine it was a bit more exciting than "the u joint jumped ship and I replaced it" and other trauma happened to the drivetrain.

In 4HI with rear DS removed, no vibration occurs.

 

[Samuel Orr]

Update: yeah, that’ll do it.

 

[Samuel Orr]

A week later, I’ve put my rear diff back together with new DANA 35 spider gears from ExtremeTerrain. Gave the diff a thorough clean and filled with good fluid. It now shakes a little less, but still very noticeable. It occurs between 25mph and 55mph, which is a shorter range than before but not perfect.

What might we look to next? Might just send it to a local 4x4 shop to do it.

 

[machoheadgames]

Spiders needed to be replaced, but that doesn’t mean they were the cause of the problem. It would be unusual for them to cause a driveshaft style vibe. My bet is still on the t-case output.

 

[Samuel Orr]

Spiders needed to be replaced, but that doesn’t mean they were the cause of the problem. It would be unusual for them to cause a driveshaft style vibe. My bet is still on the t-case output.

I do not have a picture to share here, but I did pull the ds after my last comment and spun the output. It was going in a cone pattern… Rebuild on the way I reckon. Might as well be replacing these parts anyways.

 

[machoheadgames]

I do not have a picture to share here, but I did pull the ds after my last comment and spun the output. It was going in a cone pattern… Rebuild on the way I reckon. Might as well be replacing these parts anyways.

Yep, order up a tail shaft and a rebuild kit, ideally. Fix that and I bet you’ll be doing a whole lot better.

Or, SYE and DC shaft if you’re going to be staying at whatever lifted height caused this problem to begin with. The stock driveshaft is great in stock form, but doesn’t really like any extra angular load put on it.

 

[rasband]

The stock driveshaft is great in stock form, but doesn’t really like any extra angular load put on it.

It's also a minimum of 19ish years old... So even if good it could at least use a refresher.