There wasn't very much grease. And they did only grease the one side, which is why some is blue and some red. Would be nice to know if they greased it before or after balancing. The wood dowel is 3/8 for reference.

Also sure does look like they used a lot of weight, but what do I know.

Anyway, cleaning out the grease didn't make a noticeable difference. I'll be calling the driveline shop tomorrow.

 

Unless the zerk fitting is removed, and the hole for the zerk fitting plugged with the same mass of material that was there before the hole was drilled, will the driveline have been returned to the condition it was in prior to the drilling and zerk installation that triggered the driveline balance issue?

 

You and I both know that's not even a possibility. Yeah, I could get 1/4-28 set screws and grind them short so they're flush with the outside of the yolk body while not interfering with the slip joint, but that's still not "been returned to the condition it was in prior to the drilling and zerk installation". And besides, if I used zirks from the same lot, screwed them in the same distance, and positioned them quite precisely on opposite sides, how could that possibly throw off the balance to completely change the dynamics of the vibrations in the chassis? The guys at the driveling shop didn't think it would make a difference. Maybe they're just idiots I guess.

And besides, it's very possible the driveline issue happened because I didn't do a good job of marking the alignment before taking it apart to replace the center support yolk.

 

I took the driveshaft back to the shop, and they gave it another go. He said it was off at the center by 0.008" and they were able to get that down to 0.005". They added another weight to the front of the rear section. He said it couldn't hurt to replace the center support yolk even though it's only 5 months old as an out of balance driveshaft can wear that out in short order, and even though a defective yolk "usually" shows-up during balancing. He recommended trying to find a yolk in which the bearing is molded to the rubber, as opposed to the Timken I bought at Autozone with the bearing simply pressed into the bushing. Also their machine has a max speed of 1700 rpms.

I'll take it on the highway tomorrow and see how it does.

 

I don't mean to hijack the thread, but this is sort of pertinent: I thought that the 2 driveshafts on the crewcab trucks were "system balanced" meaning that they were balanced together? Is that right or wrong?

 

You are correct.

 

So, Chris, did they balance both driveshafts together or just one? I didn't see that in the thread anywhere, did I just over look it?

 

It wasn't mentioned, but yes, they balanced it as a complete assembly.

 

I went through my shop manual which has an extensive section on trouble shooting vibrations. Somewhere it said that rumbling type vibrations are typically wheel bearings. So I pulled the rear axles along with the outside hub bearings and they looked good; everything was smooth with just a little bit of play in the drivers side hub. Re-torquing took care of that, but it didn't make any noticeable difference in the vibration. Also pulled the lower shock bolts and ran them through their range of motion and they were smooth like new. Also had the wheels rotated and balanced and that made no difference.

I attempted to return it back to factory by replacing the zirks with set screws and it made things worse. Everything about this is counter-intuitive. On some roads I don't notice the vibration at all, and other roads are consistently terrible. There's a 50 mph road by the house that I drive everyday. It used to feel smooth but now it feels like a lot of other roads around here that have ripples and typically make the truck feel like there's a tire out of balance. It seems rational with that kind of behavior that it would be wheel or suspension related. But the experience of changing driveshaft dynamics by removing zirks suggests its still a driveshaft problem.

I bought a digital angle finder to layout pinion angles and such (even though my suspension is stock) but my shop manual only shows angle tolerances for one piece driveshafts. Besides a parts diagram, this is all I've found about 2-piece driveshafts:

Coupling Shaft/ Center Bearing Alignment

Vehicle noise and vibration can be caused be a dislodged or failed driveshaft center bearing support rubber insulator, a contaminated driveshaft center bearing support, or excessive compression of the rubber insulator.

Bearing Shimming

Drive-away shudder is the predominant symptom associated with driveline angles condition on vehicles with two-piece driveshafts. Drive-away shudder can usually be corrected by shimming down the driveshaft center bearing bracket.

If the drive-away shudder cannot be corrected by shimming down the driveshaft center bearing bracket, check the driveling angles in this section.

Driveline System - General Information.pdf

 

Here are current driveline angles. Does anyone see any problem with the current setup?

 

Pretty sure I found the problem. I was planning to take the driveshaft to another shop for an inspection on Tuesday, and decided to crack open the differential first, since it was sunny, mild temps, and no wind. Glad I didn't waste my time with the DS.




I've decide to do a complete rebuild on the rear-end and I've decided to put a tru-trac in also. The ring and pinion look good; no chips or obvious uneven wear. Based on the look of that carrier bearing, how would you guys feel about re-using the ring and pinion?

 

That's interesting to say the least.....
Personally, if the R & P are good then there's not a thing wrong with reusing them. You'll love the Tru Trac. Good manners and virtually maintenance free. Just be sure to use the recommended weight of gear oil for the TT.

 

Chris, any history on the diff's fluid changes or evidence of water intrusion?

The bearing-race do no show the wear that would have skewed the R/P.

 

I'd use the ring and pinion gear without question.

 

What did the oil look like coming out?
Did it have any silver to it?