Vibrations that go away in 4WD

IVRubicon

New Member
Joined
Dec 31, 2022
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4
Location
Sonoma CA
Happens on the highway, putting the tcase in 4wh makes the vibes go away, I can put it in 4wh for just a second and the vibes go away for a while. I had the front driveshaft rebuilt, all Johnny Joints are good, alignment is good. New transmission mount. Nothing is loose and it drives great besides the vibes. It almost feels like it's pulsating. I had new gears put in about 4 months ago. Any ideas?
 
Have you driven without the front driveshaft?
Did you rebuild it? Put together exactly how it was before? I’m just wondering if the driveshaft is out of balance
 
Have you driven without the front driveshaft?
Did you rebuild it? Put together exactly how it was before? I’m just wondering if the driveshaft is out of balance

Yes they didn't exist with the shaft missing. The shaft has new joints and a rebuilt cardan. The shaft has been rebuilt with good results from the shop. Ill call a out the balancing when they are open. I assume a rebalance is done every time it's rebuilt.
 
Yes they didn't exist with the shaft missing. The shaft has new joints and a rebuilt cardan. The shaft has been rebuilt with good results from the shop. Ill call a out the balancing when they are open. I assume a rebalance is done every time it's rebuilt.

I had symptoms similar where vibes began 45-50 and got worse with speed and didn't appear when FDS was removed.
Recently, DS shop found my FDS was bent. No idea how it happened, no dings /scrapes visible, per DS shop. Shop built new FDS and balanced, problem solved.
I don't think it's common that shafts are automatically rebalanced when rebuilt (ie. new u-joints/ DCs)
 
Pulsating vibes? After regear? Go away in 4wd? You got fucked 🎉!
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You are a victim of a post regear vibes.

Here is official page and it includes links to similar topics, lots to read through, lots of theories and lost brain cells.
https://wranglertjforum.com/threads...ler-tj-vibrations-after-re-gear-thread.32445/
 
Pulsating vibes? After regear? Go away in 4wd? You got fucked 🎉!
View attachment 388272

You are a victim of a post regear vibes.

Here is official page and it includes links to similar topics, lots to read through, lots of theories and lost brain cells.
[URL]https://wranglertjforum.com/th...ler-tj-vibrations-after-re-gear-thread.32445/[/URL]

I've read through it. Mine did not happen right after the regear. Not saying that it eliminates the possibly but its a glimmer or hope.
 
Yah, those are obvious right away.
Try to push/pull front ds in and out of transfer case, there is a bearing around output shaft that wears out and allows in and out play
 
If the vibrations are drive shaft related, which I think they might be, I think you have a loose part in the shaft or in something the shaft attaches to. I know you said the joints and double cardan have been re-built but I wonder if you have some play/slop in your slip and spline. If so, when you are in 2WD the front shaft is spinning but passively and not under load. This means it will be able to rattle around and vibrate. When you put it into 4WD you are putting load and tension on the shaft which could be taking up some of the slop and preventing the shaft from rattling. I don't think it is the balance as the centrifugal force of a lopsided (unbalanced) shaft will cause cause vibrations whether it is spinning passively or under load. That's my theory, either that or something else entirely. More on that here https://4xshaft.com/blogs/faq/diagnosing-drive-shaft-vibrations?_pos=1&_sid=d6ec76a03&_ss=r