Hack N Tap vibes, need to fix

[87_Pioneer]

Will it hurt anything to drive with no front drive shaft? What about the rear, does the fluid drain out if you remove it? Got some vibes after installing my lift and trying to figure out which shaft they're coming from.

 

[VAhasnoWAVES]

will not hurt, driving with no front shaft.

if your transfer case does not have a sealed output shaft, then the rear slip shaft will leak once the rear shaft is removed, as the slip yoke seals it.

 

[Porch951]

-Pinion angle at zero degrees, as well as up and down from zero

When you say "zero" degrees, do you mean straight in line with the driveshaft, or perfectly horizontal?
The stock spec for the front pinion angle is 6-8*, which basically puts it straight in line with the driveshaft. If you are really running a perfectly horizontal pinion on the front, it's no wonder you're getting vibes...that's not how double cardan shafts are meant to be run!

is the pinion bearing shot? mine vibes with the front shaft in, so i removed it for highway driving.

That's another good possibility.

 

[srmitchell]

Calixj- Upper axle bushings are new. Brand new moog parts, installed in june. However, my upper RC flex joints are not. (They're tight though)

VAhasnoWAVES- My bearings/seals/gears are new and tight. (Whole axle rebuild in june) Is your pinion sloppy? Cause that would leave you with big problems, front shaft or not.

Porch951- Zero degrees as in the difference between the pinion angle and driveline angle.
I used an angle finder on Thursday, and found that both the pinion and driveshaft were at about 6 degrees. (As close to zero as I could get within the limits of my control arm adjustments)

Sorry if this was a total thread hijack, but this is good info.

I have seen many threads on many forums, (jeepforum, cherokeetalk, jeepsunlimited) where some people have just defaulted to removing the shaft for street use. (The same harmonic vibe I have, which disappears with the driveline removed) I think thats a total bummer, and with my tcase skid, it's not easy. I like to travel to the snow, and laying on my back to install a driveshaft is a joke.

 

[VAhasnoWAVES]

VAhasnoWAVES- My bearings/seals/gears are new and tight. (Whole axle rebuild in june) Is your pinion sloppy? Cause that would leave you with big problems, front shaft or not.

a little. but enough to cause vibes that start around 65-70mph. i drive about an hour between school and home to go hunting, and school and the girlfriend almost every weekend... the plan is to install an aussie and rebuild it this summer. i should be able to limp it that long.

 

[Porch951]

I have seen many threads on many forums, (jeepforum, cherokeetalk, jeepsunlimited) where some people have just defaulted to removing the shaft for street use. (The same harmonic vibe I have, which disappears with the driveline removed) I think thats a total bummer, and with my tcase skid, it's not easy. I like to travel to the snow, and laying on my back to install a driveshaft is a joke.

Hmm.
Yeah, i agree removing the shaft isn't a solution. They're a pain to install/remove. I wonder if it's just a harmonic? Not sure what you could do about it then. :dunno:

 

[Whiskey'sXJ]

Hi everybody. No worries about hijacking the thread. If it's helpful info, then bring it on. It's been a while since I last updated this thread and I have since resolved my issue so I wanted to provide the details. I'll start by admitting that I was fed up and decided to take it to a local driveline specialty shop that came heavily recommended through a local 4x4 club site. Less than $300 bucks later and I'm FINALLY riding smooth at highway speeds after all these years. Though they couldn't tell me exactly where the problem started, here is what they did to fix it.

1) Removed and replaced the rear ujoint which was obviously shot (since that ujoint was new when the driveshaft was installed, I don't think this was the cause of the vibes from day 1 but clearly needed to be replaced at this point)

2) Removed, stripped, cleaned, rebalanced and reinstalled the rear driveshaft (this thing looks brand new)

3) Removed the RE HnT flange and noticed that the little piece of metal at the center of the flange (where the bolt goes through) was loose. They didn't believe this to be the cause although noted that they had never seen one that moved like mine did. All the others they have seen where welded and did not move. They didn't know if that was a manufacturer's defect or if it had broken loose over the years due to the vibes. Either way, they had a used flange in the shop that was solid so they installed that one instead.

4) In the process of installing the new flange, they ground down the output shaft from the TC just a hair to make the flange sit a bit more flush at the end of the shaft. The amount that they took off was minimal and though possible, they didn't suspect that to be the cause of the vibes either.

However, after all these things were done, the Jeep rode beautifully. Despite not knowing for sure what the ultimate cause was, I suspect that it may have been a combination of the output shaft being cut and ground slightly off perpendicular and/or the driveshaft being out of balance from the start. Regardless, it's fixed now.

Thanks for everyone's input and good luck to anybody else that has similar problems.

 

[garr]

Thanks for the update.