Loud Chattering & Whining coming from drivetrain (1 Viewer)

[BayArea80]

It's been a couple weeks since the truck was down to while I was servicing the injectors. Well I got everything back together yesterday and went for a test drive a noticed a couple noises I never had before. The first was that it seemed the drivetrain was whining a lot. It sounds almost like the trans has straight cut gears (think the sound a car makes when in reverse). Second, once I reached about 20-30 mph I noticed a chattering sound. Most prominently under deceleration, almost like a clutch chatter on a manual transmission when you are in neutral. In the videos below, you can hear the chattering on decel and then I proceed to load and unload the drivetrain by giving it a little gas and you can hear an "engagement" of sorts. Almost as if there was a loose mount allowing something to pivot under load. Or almost like the sound that that a ATV/UTV makes when you get on/off the gas.

Right before taking it out on the test drive I mentioned above, I started to unbolt the front DS at the front pinion as I had a brand new Tom Woods double cardan driveshaft I planned on installing. I then realized that the factory bolts were too short so I torqued them back down and went to the store. That is when I noticed the sound. The sound profile is completely different from what I had intended on resolving with the driveshaft. Whereas that was the u-joints groaning at a low frequency due to the 4" lift, this is a heavy chattering. However, seeing as I had the new driveshaft already, I proceeded to install it in case it was a coincidental failure. Installing the new DC driveshaft did not resolve the issue. It has a double cardan on the transfer case end with Spicer 1310 series u-joints. The only issue I had when installing it was that it seemed about a 1/4" shorter than the stock one, which is odd because I had measured it before. I should have measured the finished length before installing, but I figured since it has a slip yoke, it would be fine.

Some background on the truck...It has a 4" Dobinson's lift (3" springs, 1" spacer) with the Dobinson's caster correction plates. The truck has been aligned and caster is measured at 1.8* and 1.2* (L/R respectively). This is before I added the Trail Gear tube bumper and a 9.5k ComeUp winch which should give me a touch more caster now due to the suspension being a bit more loaded up front.

Here are a few videos to try and help you understand the noise:

First video: You can clearly hear the clunking and the "engagement" clunk when loading and unloading
Second video: The whining is very prominent on decel. You can also hear how the noise profile is almost a bit diesel like. The truck has a stock intake and exhaust so it has been quiet until now. (This was done in first only)
Third video: Again the chattering and the clunking when I load an unload the drivetrain with stepping on the gas

Thanks in advance!

 

[BayArea80]

 

[baldilocks]

If you don’t have a CDL switch installed on the dash, spend a few bucks to buy one and install it so you can remove that drive shaft and drive on the rear only for trouble shooting purposes and to get where you need to go until this issue is resolved.

Your lift is probably closer to 5” than 4” based on experience with Dobinson springs and way too much reading here on Mud.

Can you post a photo of the front drive shaft installed with particular attention to the axle end?

 

[BayArea80]

Just measured center of hub to bottom of gender flare and I get right around 25-25.25" on either side.

Also read that the DS yokes need to be out o phase so I'm going to tackle that real quick. I'll get a photo of the axle end in a few min

 

[BayArea80]

Even with the double cardan there still seems to be a bit of an angle coming off the pinion

 

[nukegoat]

Looks wrong

 

[BayArea80]

Looks wrong

Care to elaborate?

 

[BayArea80]

Took the front shaft off. Clattering/chattering sound is less pronounced, if not fully gone ok decel. It's still whining like crazy.

 

[BayArea80]

So it appears I haven't been looking in the right place. It was my drivetrain but not anything to do with the axle or driveshaft. Here's the transfer case fluid that's maybe 3-400 miles old.

 

[inkpot]

Either you have a severe case of white flies/gnats, or you were running maple syrup full of coconut??

 

[mudgudgeon]

What fluid did you have in the transfer?


Some of these other guys can correct me if I'm wrong, but with a correctly set up DC jointed shaft, in or out of phase becomes irrelevant.

 

[BayArea80]

I am running Redline 75w-90. I double checked and the shaft does appear to be out of phase.

 

[inkpot]

Even with the double cardan there still seems to be a bit of an angle coming off the pinion

View attachment 1714575 View attachment 1714576

A D C has NO effect on the ujoint at the diff!

 

[inkpot]

Have you checked the lube in the axle/diff??

 

[BayArea80]

Yes, that was also changed out immediately once I purchased the 80. Both diffs were drained and refilled with Redline 75w-90.

The diffs and transfer case came out very murky. None had metallic flakes in it.

 

[baldilocks]

FYI- the front driveline needs to be in phase not out of phase as it was from the factory.

You have 5” of lift and what appears to be a bit of angle at the pinion which not ideal with the DC joint. And with 5” lift, you probably have an unhappy rear driveline as well.

Used transfer cases are not to expensive.

 

[BayArea80]

FYI- the front driveline needs to be in phase not out of phase as it was from the factory.

You have 5” of lift and what appears to be a bit of angle at the pinion which not ideal with the DC joint. And with 5” lift, you probably have an unhappy rear driveline as well.

Used transfer cases are not to expensive.

Can you help me understand why the DC should be in phase, opposite from the factory config? I took a look at the photo of the DC from Wit's End and it looks to be out of phase as well?

It seems that my pinion is pointing a bit downwards and would need to be rotated upwards to even up with the DS flange? As for correcting the pinion angle, it seems I would have three options:
- More lift?
- Less castor, I'm at 1.8* now (I have Dobinsons plates)
- 3 link (maybe in the future)

Am I thinking about this right?

 

[baldilocks]

The factory configuration is “out of phase” due to the unordinary relationship of the pinion companion flange to that of the transfer case caused by the high pinion design of the front differential placing the pinion at nearly the same height of the transfer case with the top of each output flange being farther apart than the bottom.

A DC shaft is best with zero flex at the pinion yoke and in phase. A standard shaft mounted between two parallel flanges on different planes (most usual and ideal up to a certain shaft operating angle which is dictated by lift and distance between mounting flanges) also needs to be in phase.

As for you castor vs. pinion angle, there is variance from one 80 to the next. I have castor plates from a different vendor advertised for a 4” lift. I put them in when went to 3-3.5” front springs with a DC shaft and the shaft ran smooth. I went up to 4” springs and pinion/shaft alignment still seemed good and it ran smooth. I then went to 5” of lift. My castor is about .5 deg, my shaft/pinion angle still looks pretty damn close but the front shaft no longer ran silky smooth and silent at highway speed. It was not terrible but I hate vibes and the associated noise on longer road trips so I went part time. I still need to deal with my castor.

If you don’t do a good deal of rock crawling on trails with large obstacles, you might consider dropping down to three, no more than 4” and your problems will probably go away and you will save some money. Overcoming the issues that come up once you lift past 3” gets costlier with every inch.

Can you help me understand why the DC should be in phase, opposite from the factory config? I took a look at the photo of the DC from Wit's End and it looks to be out of phase as well?

It seems that my pinion is pointing a bit downwards and would need to be rotated upwards to even up with the DS flange? As for correcting the pinion angle, it seems I would have three options:
- More lift?
- Less castor, I'm at 1.8* now (I have Dobinsons plates)
- 3 link (maybe in the future)

Am I thinking about this right?

 

[mudgudgeon]

The factory configuration is “out of phase”

The factory configuration changed to "in phase" at some point.

If you don’t do a good deal of rock crawling on trails with large obstacles, you might consider dropping down to three, no more than 4” and your problems will probably go away and you will save some money. Overcoming the issues that come up once you lift past 3” gets costlier with every inch.

Good solid advice.