Transfer Case or Tranny?? Which is KILLING me? (1 Viewer)

[elhombre]

I have been chasing a vibration for 800 miles now. It is a harmonic that is in your butt/dash at 60 MPH. First, I change all 4 u-joints because one had a small hang up. No change. I take the driveshafts and get them balanced. No change. After a bunch of other tries, I go old school. I know it is Dangerous because there is a reason farmers/ranchers are in the Top 10 deadlyist jobs. I put the truck on 4 jacks and start it up. Find big vibration at 27 MPH. Hear it, feel it outside with my hand on the truck.

Take all 4 tires off, turn front/rear lockers on, Lock center diff, Same vibration
Take rear driveshaft off, Same vibration. Doesn't matter if selector is in "D" or "2"
Take front off, Now No driveshafts, Not smooth, but nothing like before.
Replace rear driveshaft, remove front. Its definitely back, just not as loud, but still bad-bad
Take front off, take rear off again, replace front with OLD one from scrape metal pile, Big vibration
Put In LOW, tranny in "D", run it up, Not as loud, but can be felt outside for sure. Engine is turning some RPMs now so it is not as easy to hear.

To recap, No vibration when driveshafts are removed, but a little vib at 60 MPH. Vibrates like crazy when only front or only rear is on. Vibrates same when old worn out shaft is on front only too. I think I have eliminated the entire rear end, front end, and driveshafts. Next in line is transfer case.

Can't feel play in either output flanges. Only have wet dirt at speedo connector. Even sent transfer oil to Blackstone, and they said negative bearing metals.

I am going to lay down the time and money to get a used transfer case Monday unless anyone of my Cruiser brothers has another idea or suggestion. Thanks for any help/ideas you can give me.

 

[Pin_Head]

A likely culprit is that your U joints are operating outside of their angular operational limits. Measure the angles at the differential and transfer case flanges and report back. Also measure the distance from the center of the hubs to the bottom of the flares for all 4 wheels and report that too.

 

[tominboise]

Before I bought a transfer case, I'd look for a failed motor mount, transmission mount or transfer case mount. I don't know if one of these are the problem but for something that just showed up, I'd be looking for simple and cheap first.

 

[greentruck]

You changed out the U-joints and balanced the shafts...how much grease did you pump into the slip joints? Because if it's even a little too much, it can set up vibes. You had them in and out, so I'm not sure I followed...but you might try removing the slip joint zerks just to see if there's any pressure in the slip joints. You don't want any pressure, just grease in them. I know it sounds absurd it would be this simple, but it's also easy to verify whether an issue or not and just as easy to rectify.

If not, I'd still work some more on diagnosis before buying a replacement. The transfer case is rarely the source of problems, but often gets the blame.

 

[elhombre]

Front of truck
21.75 ----- 22.25

22.5 ------- 23.5

It's still on jacks.

Rear diff angle to transfer output flange difference 3 degrees
Front diff angle to transfer 6.5 degrees
I have had Slee's blue castor correction bushings in for 40k miles

Transfer case mount looks good. Engine mounts have equal space between the two plates on both sides. Don't quite know how the check the engine mounts other than a visual.

Thanks, Keep it coming!

 

[inkpot]

Are you running double Carson drive shafts? If not, those flanges should be parallel .

 

[inkpot]

How much lift on your rig?

 

[elhombre]

OME 2.5 inch lift with heavy springs and heavy shocks. I have always read about people chasing down vibs and getting DC driveshafts, but don't recall seeing it done on my minimal lift.

I went down this road before with the 98 Taco I had with a 3 inch lift. It had the stock DC rear driveshaft. I put plates under the spring perches to make the flanges parallel to each other, and it made it worse. The fix came when when I got the diff flange to point directly at the transfer case output flange.

I have been on MUD long enough to know the transfer case and tranny almost never are problems. That's why I have reach out to the forum . Thanks for all the input.

 

[Dave 2000]

I noticed the line 'No vibration when driveshafts are removed', so what makes you think it is the TB?

Regards

Dave

 

[moodytico]

I am curious to see what you discover as I have pretty much the same issue. I have a vibe right at 2200 rpm (right at 60mph) 2.5 lift, dc front shaft, new ujoints etc. Only difference is I have MAF arms for caster adjustment.

 

[baldilocks]

So you were fine for the entire 40k since installing the castor bushings and then, for no apparent reason, the vibration started?

 

[elhombre]

10 years ago I got the truck and immediately put the lift in. I always can remember a small vibration at 60 MPH, but nothing ever like now. It went away with more or less speed. I went through the yellow castor correction bushing (OME) for +50k miles. Then replaced them with blue.

I took drive plates off the front, and front driveshaft off to stop all front drive line rotation, and I still had 60MPH vibration. Put it back together. Removed rear axles and rear driveshaft, drove, still 60MPH vibration. It's harmonic. Vroom---vrooom---vroom Every second or more. Putting it up on 4 jacks and getting this crazy shaking and noise at 28 MPH is just the latest in trouble shooting. (See first post)

I feel like I have eliminated the front and rear drive line because there was no change in vibration on road tests. BUT, numbers don't lie and PinHead's request for degree numbers show a big difference in the front. My angle finder from the Taco time has hit the floor a few times, so I am going to get a new one tomorrow for a second set of numbers. T case seems to be getting a loud gear noise.

I also will get some thicker 140 gear oil in the T case and see if that changes the driving gear noise I have.

Coming back from Big Bend this past T-day, I could hear the vibration growing louder, now at 75 MPH. 2000 miles ago. That has started me on this wonderful quest.

 

[Dave 2000]

Just checking, your axle stands are under the axles right, and not under the body work/chassis? The harmonic sound normally comes from a bearing that has a bad area on the tracks, this will coincide with a few worn ball bearings at a certain time this is what brings the harmonics.

regards

Dave

 

[Dave 2000]

Another thought for the OP (sorry grey matter getting old), when you get the vehicle to the speed that the harmonics were working, did you try turning the vehicle to the left and right on bends? The change in weight when unloading/loading the wheel bearings would change the noise. Turning to the left unloads the left side but loads up the right, this is how in the trade we identify wheel bearings that have noise but no play.

regards

Dave

 

[elhombre]

The jacks are under the axles.

It does not seem to matter with respect to the vibration if I am going in a straight line or taking a sweeping turn on the road.

 

[BlueCruiser84]

You need to use some chassis ears.

 

[Corbet]

I think it's a driveshaft most likely the front.

Flanges should be parallel with OEM driveshaft. If you switch to a DC the the pinion should point directly at the T-case

 

[Dave 2000]

The jacks are under the axles.

It does not seem to matter with respect to the vibration if I am going in a straight line or taking a sweeping turn on the road.

Which removes the likelihood of it being, axles, bearings, differentials. That leaves drive shafts and Gear/trans boxes. Dropping back to your comment about no vibes with shafts removed, that leaves a shaft issue.

Mentioned earlier, the excellent comment about over greasing the sliders is so often the problem, also noted the shafts being balanced but, what if one of the joints is not up to snuff? Semi seized joints often can be freed up only to seize later. Also, why were they balanced? Unless the got bent or a weight thrown off they (and of course the joints are good) then there could be an issue missed by the balance shop?

regards

Dave

 

[elhombre]

Got a new angle finder. Pretty much the same one from Home Depot $8. So it can only do what an $8 tool can do. Rear angle difference is 2.5 degrees. Front is 8 degrees. If I remember right back when I was dealing with the Taco, the diff would shift one degree downward because of torque. That was with leaf springs. Does the 5 link system of our Cruisers do the same? If so, I would thing the rear is pretty dang close.

I had the shafts balanced to take that out of the equation. New Mr. T U-joints. The shop pretty much just welded weights on either end of the shafts at the same places Mr.T had done it at the factory. Don't really know how to check their work without taking it to someone else.

When I did the u-joints, I pulled the shafts apart, dug out the old grease. Replaced them back on marks. Pumped grease in till they started to expand. Unscrew zirk, compress all the way. Replaced zirk. Had to expand them some to get it to make the distance between flanges.

I could not find straight weight 140 gear oil at Napa, Autozoo, or Tractor Supply.

I am thinking real hard about getting someone to use their audio sensors too. All good stuff. Thanks for all the comments.

 

[Pin_Head]

The numbers are about normal for a 3 inch lift. Check the phasing of the front shaft. The U joint caps on the shaft should be directly in line with the caps on the flange. This is referred to as 90 degrees out of phase. In phase is when the caps on the shaft are in line and the caps on the flanges are in line.