Dana 18, Is This Bad Or Normal?

If I was positive it was a driveshaft issue and not a bearing problem I would do just that, but I don’t know where that awful noise is being generated yet. It’s more alarming in person than the video makes it sound.

 

Remove the rear drive shaft and drive on the front. If it goes away then it is for sure the rear drive shaft.
There of course will be a little front drive shaft vibration..... but it should isolate the rear....

 

Well there you go being all logical and stuff... good idea

 

You gotta get crackin! All this hard work.... axles, twin sticks..... gotta see it through to the payoff...aka Rubicon

 

This. ^
And don’t just unlock the rear hubs. Your shaft would still be spinning and vibrating. It needs to come out.

If it is the angles that are the issue, a set of shims is all you’d need.

 

James, you live so close just tow it . have fun, come home and repair as needed. I flat towed for years with no issues. Went from Lincoln to Casper, WY and back yearly. No problems so going to the Rubicon should be no problem.

 

If the hubs are unlocked how will the shaft still spin? Unlocking the hubs disconnects the hub from the axle shaft so they don’t spin. If the axles don’t spin how is the propellor shaft going to spin?

 

If testing for a vibration in front-wheel drive, the t-case must be in 4wd. The rear shaft is still being spun by the t-case, even though it’s not connected at the rear hubs.

 

We are speculating that the noise may actually be coming from the drive shaft and resonating out through the transfer case/transmission.

 

My theory is that the noise in the transfer case is being caused by the out-of-sync u-joint angles. With the joints out-of-sync, the driveshaft vibration isn’t cancelled out and is being transferred into the sloppy t-case where it is being heard through the gear slap. The risk of testing it in front wheel drive is if the angles aren’t correct in that shaft either, the noise could still be there, albeit from the front shaft causing it instead of the rear.

In the current configuration, if you were sitting on the rear driveshaft, the front u-joint is pointing up at 10:00 and the rear is pointing up at 2:00. It’s forming a corkscrew shape. The rear needs to be shimmed up a little so the rear joint is pointing down at 4:00.

 

Yeah, I’ve had two D18s completely split in half while rolling down the highway. Old junk can only be abused for so long. But I’m thinking if the noise is only being caused by the driveshaft, the D18 probably has plenty of life left to crawl for a few days. Just trying to keep the eye on the prize.

 

How about dropping both shafts and running through the gears and ranges?

 

While the rear shaft is out, might as well run it with the rear hubs locked AND unlocked to rule out the rear end, the rear end is also fairly new to the equation. James, were you getting noise before the rear end swap?

 

Oops! I misread it and thought you were talking about flat towing it. What I get for posting at 2mam

 

I cannot handle 2mam’s.. no way.

 

Yes but it was nothing like what I have now.

 

I will try and pull driveshaft tomorrow evening and test, me and the Jeep aren’t really on speaking terms right now so we’ll see.

Unfortunately the prize is off the table anyway, once I pulled the plug on Rubicon last week we rescheduled my time off to go to Texas and buy a house near Texas A&M. My daughter starts there in January... unless I can talk the school into no out of state tuition then she would start in August. Apparently C19 means you can negotiate college tuition costs.