Removed my front driveshaft, now I have a faint driveline whine

[Stylo07]

It all started with my quest to cure vibrations realized at highway speeds. I first removed my rear driveshaft and took it to have new OEM u joints installed. I also had it re-sleeved and balanced since it suffered some rock rash. The final product cured 90% of the vibrations.

At first, I figured I could live with the remaining, minor vibrations that were clearly in the front end. But, my worries got the best of me as I wanted the car to be as safe as possible for when my wife and nine-month-old daughter are in tow. I began my troubleshooting journey by removing the front driveshaft and inspecting the u joints. It was clear (to me, anyway) that the front u joints had a fair amount of wear which could contribute to the remainder of the vibrations. Finally, I locked the center differential and went for a spin.

Hallelujah! Vibe free! "Consider yourself lucky," me said to me.

Not so fast... After logging 50 or so miles in RWD, I noticed a faint whine that increased in pitch as the vehicle picked up speed. It doesn't change with transmission activity, which makes me think axle or center differential.

Is it possible I damaged the transfer case when cranking so hard to loosen the drive shaft from the output shaft? After all, I did snap a two inch extension in half when loosening the screws.

Likewise, is it possible I damaged the front differential's pinion bearing when removing the bolts on the front of the drive shaft?

Lastly, could the whine just be a characteristic of driving a full-time four wheel drive vehicle with the front drive shaft missing? The front axle and front transfer case flanges are just freewheeling with no rotational force (I.e. - drive shaft) to contend with. The whine is quite minor, but it was NOT there before. It reminds me of my old '88 and '89 Range Rovers.

Some basic vehicle info:
- '94 with 150k miles
- front axle rebuild 30k miles ago, including new trunion bearings (original wheel bearings)
- 5k miles on amsoil front diff fluid
- It's been responsibly used for its intended purpose, but is well maintained.
- 2.5 OME medium
- Slee castor correction bushings
- OME steering stabilizer
- 1" spacers up front
- 295/75/16 BFG ATs with 4k miles
- Front end alignment done with new tires

I'll be dropping off the front drive shaft to have new OEM u joints installed tomorrow.

I appreciate any opinions offered!

- Matt -

 

[94SRUNNER]

Did you lock you center diff?

 

[Impreza]

Did you lock you center diff?

About 10 lines down

 

[94SRUNNER]

Thanks....read right past that, it was kind of tucked in there.

 

[Stylo07]

Did you lock you center diff?

Yes, I sure did. Could that cause a faint whine? I didn't notice a whine when driving in front wheel drive while the rear drive shaft was being rebuilt.

 

[Stylo07]

Mornin' bump... Anybody have any thoughts?

 

[thirdmatt01]

I've had a lot of similar issues. When I removed shafts and drive I get whines because things change so much. I also drove on the rear shaft had no vibration, but it ended up being my rear shaft. I think with that lift and spacers you need a dc front shaft or remove the spacers. Its to high for the range of the shaft. And with spacers you need more than caster bushings, you will def need plates. Get an alignment you'll be out if the acceptable range. I'm not an expert but just went through the exact same process on my rig, and shared same frustrations. And became well informed through experts. Also brand new shafts from Beno are very good priced compared to shops rebuilding them. Best of luck

 

[Stylo07]

I've had a lot of similar issues. When I removed shafts and drive I get whines because things change so much. I also drove on the rear shaft had no vibration, but it ended up being my rear shaft. I think with that lift and spacers you need a dc front shaft or remove the spacers. Its to high for the range of the shaft. And with spacers you need more than caster bushings, you will def need plates. Get an alignment you'll be out if the acceptable range. I'm not an expert but just went through the exact same process on my rig, and shared same frustrations. And became well informed through experts. Also brand new shafts from Beno are very good priced compared to shops rebuilding them. Best of luck

I see what you're saying, but the whine began after removing the front drive shaft. It wasn't there when the front drive shaft was in place and the vehicle was in full time four wheel drive. So, I guess I don't feel like the angle is an issue on m 80. I could very well be wrong...

 

[thirdmatt01]

With the shafts out the amount of pressure on things change and some noise go away and new ones start, it really didn't help me solve my issues.

 

[Stylo07]

With the shafts out the amount of pressure on things change and some noise go away and new ones start, it really didn't help me solve my issues.

Gotcha. So, it'll be interesting to see what I wind up with new u joints in my front drive shaft. If all is well, I'll move on. If not, I may look into a DC drive shaft as I want to retain my lift. Thanks for your thoughts.

- Matt -

 

[Stylo07]

Well, I got my driveshaft back with new u joints and installed it. Now I have MORE vibration than before. How can this be?

 

[kidglove13]

Did they balance the shaft after installing the new ujoints?

 

[Stylo07]

Sorry, I should have mentioned that. Yes, it was balanced. At first, they balanced it in phase. I took it back and had them balance it out of phase, as it came from the factory. Also, in the FSM I couldn't find for certain which end the slip yoke is supposed to face. But, based on some pictures, it appears that it should face the differential, which is how I installed it.

 

[Tools R Us]

Sorry, I should have mentioned that. Yes, it was balanced. At first, they balanced it in phase. I took it back and had them balance it out of phase, as it came from the factory. Also, in the FSM I couldn't find for certain which end the slip yoke is supposed to face. But, based on some pictures, it appears that it should face the differential, which is how I installed it.

Yep, the slip goes towards the diff. Try running it in phase, on some lifted rigs they run smoother that way.

 

[Stylo07]

Yep, the slip goes towards the diff. Try running it in phase, on some lifted rigs they run smoother that way.

Oh, man, the shop would love it if I brought it back and asked them to balance it in phase! It was a battle to get it 90 degrees out. I will try that, though.

Aside from that, do you guys have any other thoughts that could be contributing to more vibes than before? I checked the movement of the joints and they felt great.