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Front driveshaft spins in 2wd with unlocked hubs

Desert4x4

NAXJA Forum User
Location
Phoenix
So I installed the Yukon locking hub conversion. Now when I go over 65mph the front drive shaft spins causing unwanted vibration. I have verified that the drive shaft is spinning with undercar videos. It will do it even if I run the rear wheels in the air and vehicle stopped (front wheels stopped). Anyone know if this is normal ?
 
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What year and transfer case?
 
I bet one of the hubs is installed incorrectly or your jeep hates you :)


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I bet one of the hubs is installed incorrectly or your jeep hates you :)


Sent from my iPhone using Tapatalk

I don't understand, if the front wheels are stopped how could one of the hubs cause it? I'm testing this when the rear wheels are jacked up and I run them to 65mph. I'm sure I could lock the hubs and then try the same test with the rear tires in the air and the driveshaft will NOT spin. I'm just trying to figure out why there is so much drag causing the front shaft to spin when in 2wd. Perhaps the center diff in the NP242 is not designed to alow the front shaft to be stopped.
 
I'd bet it's simply enough in the t-case to cause it.

Just because it isn't being powered doesn't mean there isn't still enough friction for it to turn. Just like an open diff, if both tires are in the air, both will turn, even tho you can easily stop 1 side with your foot. And the 242 case I believe has a diff in it just like your axle to let you drive in 4wd all the time.

Can you stop it from turning with something easily ?? if you can, then if you lock your front hubs in, I'd bet the front shaft stops turning. (if you try this, be ready in case it comes off the jack stands - We don't know right now for sure what is wrong)


and I would NOT recommend running it up to 65 on jackstands...if it comes off in the least, you're gonna get very hurt
.
 
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You got to remember that the 242 is a "part-time" case.
 
It does spin freely. It won't keep spinning if I spin it by hand though. Hmm. I just don't like having to keep it under 65 to keep the vibes from happening.
 
A few days ago I was hoping that I could just use different fluid to make the front driveshaft less prone to freewheeling. I switch from Mobil 1 ATF to Mobil 1 5W-30, and neither fixed the issue.
 
It is, but... I had angled it to perfectly straight, and the vibration was still there. The driveshaft was also rebuilt, balanced and trued, and the vibration was still there. I also replaced the transfer case, no change.

Do the vibes disappear with the DS removed?
 
This. It happens.

Yep..it happened on my 79 Ramcharger with a NP203 t-case, even after the part time conversion kit was installed....it's just friction.

You could reach up and stop it with your hand, then let go, and in a minute or so it'd be spinning again.
 
Sounds like the driveshaft needs better balancing possibly.
Just to clarify, you are driving in 2wd right?


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