Interesting. Yes, there is at least some possibility the vibration could be brake related. If you have drum brakes in the rear you could do the experiment of backing off the shoes to see if it affected the vibration. W/discs on the back, it’s not really possible to back off the pads without major effort, but you could measure the disc run-out and make sure the calipers were sliding freely on the guides. I had a grinding noise that was brake related on time on my own truck, but that one only occurred during low speed turning.
@GeorgeSanJose
Got a break in the weather. Jacked up the rear. Put it in neutral, released the brake. Chocked each rear tire in turn and rotated the other. The left tire, driver’s side, drags every rotation, so that’s where it is. I need to pull the drum and do some fiddling. I doubt that’s what’s causing the vibration, though, although I could be wrong. There is still that death rattle to track down. Cuzzin Mike thinks it’s the pinion yoke bearing. I made some more vids and need to look 'em over. For some reason the camera injected a high pitch whine into everyone of them that I have to try to take out with the soundcard equalizer. More tomorrow when I have a full day of sunshine.
@GeorgeSanJose @Sloepoke @“Honda Blackbird” @keith
I couldn’t think of anything else to try so I pulled out the Moogs and put in the Neapco u-joints. No joy. The first test on the freeway seemed promising. I sensed minor vibration at around 55 and nothing after that up to 75. Got off, turned around got back on, got up to speed and there it was again. The only thing left that I can think of is to drop the rear half of the draftshft and run it up to speed and see if it vibrates at 55 to 75. If it does, that makes the carrier bearing look mighty suspicious.
What I don’t know is how it will affect the balance of the front half of the driveshaft with the rear half removed.
I have been following this since the beginning and I have to wonder what the frequency of the vibration is? In my business if I replace a driveshaft a customer might return complaining of a tire vibration, they are more observant of problems after a repair.
A tire vibration is observed as a rapid shake. The driveshaft rotates 3 1/2 times faster than the wheels and is observed as a buzz at highway speeds.
There is an inexpensive device to assist in identifying the frequency of vehicle vibrations, sirometer;
The vibration did not exist before changing the u-joints and carrier bearing. I think the tires can be ruled out.
Dont tell me you are confusing brake noise and vibes with the recent changes to your driveshaft ! LOL…that would be a little funny…and would also explain why more angle decreased the symptoms… More angle would induce more friction and basically dampen out the effect of your diff yoke going from the easy spin area to the hard to spin area. With more resistance added on it would “hide” that easy/difficult to spin situation a little more than if the shaft were perfectly straight with no angle induced.
It’d be a different story if your legs were powering all of this…you would know right away that you induced more friction overall if your poor legs had to power that shaft.
That yoke should spin at Least 3X before the wheels make one rotation… Unless you are running 2.73 ratio in the rear…but I seriously doubt that. A truck like yours should be well into the 3’s
Blackbird
@“Honda Blackbird” The stiffness was caused by the driver side rear breaks. I pulled the drum and ratcheted back the automatic adjuster and the stiffness was gone, but that didn’t eliminate the vibration when the rear end was jacked up. I was never able to recreate the grinding noise in the first video, so that’s still a mystery. The pinion yoke rotated freely and without slop with the driveshaft removed.
The only troubleshooting technique I can think of is to remove the rear portion of the driveshaft and see if the vibes kick in at 55-75. I’m not sure how dependable that would be, as it’s my understanding that a two-piece driveshaft is balanced as a unit but it’s all I can think to try.
Do yourself a favor and pull OFF Both rear drums …I think you might have some brake parts wandering around loose in one of those drums. Happens all the time. The vibes could have been brake related as well… Need to pay close attention here… I know you are making so many changes at this point that its easy to confuse yourself. Vibration and Driveshaft are scary words to me, so be careful. Hope you figure it out. Its easy to confuse yourself when you do things like this…trust me, I can relate.
Also…do the same test you did before…but with “naked” rear axle… No Drums, No wheels See what the vibration situation is like that. When you are finished with the test…just shut the engine off…because it will be hard or impossible to stop the rear from spinning with no rear brakes. Dont want to shear off your Park Pin in the tranny if its an automatic now do we?
Blackbird
@Honda Blackbird
“The vibes could have been brake related as well…”
Funny, though, that the vibes only started after I changed the u-joints and carrier bearing. I guess it wouldn’t hurt to pull the other drum.
"Also....do the same test you did before...but with "naked" rear axle... No Drums, No wheels"
Yeah, I thought of that. That’s great idea! and not to hard to set up. I’ll do it today.
What do you think of this scenario:
The old rear u-joint had only dust in one cap and remnants of needle bearings in the other three. The other u-joints had the their needle bearings intact, but little to no grease left. As the rear u-joint deteriorated, it starts to rattle around, stressing the pinion yoke bearing, which starts to degrade in such a way as to compensate and the two cancel each other out.
Does that sound plausible? Soon as I finish my tea I will set up the ‘naked axle’ situation and report my findings. Shouldn’t take more than a couple of hours.
There is a general rule of troubleshooting, if a new problem arises immediately after maintenance, you go back over the maintenance. Most of the time, someone made a mistake or an “out of the box” defect was installed.
@“Honda Blackbird”
Both rear tires and drums pulled. Still have the same vibration.
Since this is a 2 piece shaft , can you buy each 1/2 separate or if you buy a new one can you only buy the complete shaft ? The reason I ask is because if you can buy the 2 pieces separate , I would think each piece would be balanced separately . If that is the case you should be able to remove the rear piece without throwing things out of balance . You had mentioned trying that before .
"Most of the time, someone made a mistake or an "out of the box" defect was installed."
I can only suppose that the carrier bearing may be defective, as I changed the new u-joints for the ones the shop recommended.
(an hour later) When comparing the position of the carrier bearing to the photos that I took before doing any work, It seems that the shop did not press the new bearing on in the same position as the old one. These two photos were taken from the same angle. The old bearing was pushed close to the large slinger. The small slinger on the right was not pushed on as far as it was originally. Not sure if this is a big deal or not.
@Sloepoke, the two-piece driveshaft is not available as a new replacement part anywhere. moparwholesaleparts.com lists a discontinued “2WD; TWO PIECE; FRONT; AUTO TRANS; 7 1/4 GEAR”. http://goo.gl/Q22b6Z So they were sold separately at one time. Not sure why they list the differential size. I assume that’s what “7 1/4 GEAR” refers to. Anyway, I’m off to drop the rear section and see what stirs.
Is the large slinger that is now bent up welded to the shaft or what ? Wonder if you could use a ball peen hammer & beat it back closer to its original shape ? Sometimes small things that a person wouldn’t think matters much does .
@Sloepoke I just dropped the rear shaft and spun it up. I got the same vibration but had to spin it up to 75 mph to get it. I meant to try to reshape the slinger yesterday when I switched the ujoints, but darkness fell and I was eager to get the DS back in and test it. I will now go pull the front section and do as you suggest.
I expect you already know there are specialty places that specialize in driveshaft diagnoses and repair. Some of them offer custom driveshaft building too. So that’s always a backup if you run out of diy’er ideas and can’t find an off the shelf solution. From what I can tell it seems like you are on the right track, and your idea that the shop who did the prior work did something to the driveshaft that caused it to go out of balance seems very plausible. That mis-shapen and wobbling disc definitely looks suspicious.
OK, here’s what I think the deal is. After talking to Cuzzin Mike and his lovely wife, both of whom have experience in the distant past in these matters, and tossing around what-ifs, taking into consideration everything that I have previously posted on this thread, I think I received a defective carrier bearing. If it doesn’t have a full complement of bearings or if the size of the bearings is not within acceptable tolerances, that could explain the indicator rotating around when it was on the balancing machine. It would also explain the vibration. Given that I put in two sets of good ujoints and that did not eliminate the vibration, the only thing left is the carrier bearing. I treated those shafts like newborns when I took them out, and made sure not to stress the yokes when I changed the ujoints.
Here is a list of companies from Rockauto that put their names on available carrier bearings for my truck:
WESTAR (the one I bought)
ANCHOR
DEA
MEVOTECH
NATIONAL
TIMKEN
SKF
The only name I recognize is Timken. I’m sure these are not all parts manufacturers, just rebranders. O’Reilly’s sells the same Anchor as Rockauto, but 75% more expensive, even after Rockauto shipping charges.
Hmmm Same vibes with a naked rear end eh? If you had a slow failure of the old U-joint in the shaft …it may have been degrading or present in an out of balance sort of manner for a LONG period of time… Especially if it turned one of the poles bearings in the U joint to “dust” that takes some force over a long period of time to accomplish. I hate to suggest it but…if a shaft was out of balance for a long time before it got so bad you noticed it… It may very well have smoked the diff yoke bearing in the rear pumpkin, which could have then spread damage to the ring gear as well. You now need to pop the Pumpkin pan and look at your diff gears. I’m sorry to say this…but its what I would do. Besides those gears haven seen you in a long time and they miss you. I know you don’t want to hear that…but that bearing has its hands full enough with the diff duties… it doesn’t need nor can tolerate an out of balance driveshaft assy as well on top. Know what I mean?
I hope you figure this out. Like Keith mentions…we should have never moved forward without the shaft being balance and ready for re-install… In fact that shaft FAILED that test…sxxx should have stopped right there… I would be Very keen to try and get my driveshaft back over to that shop that has the test unit…at least then you can rule out the shaft at a certain point. Because until you can rule out one or the other…you have quite a large suspect pool at the moment. 3 suspects…The Shaft…The U-Joints and the yoke bearing in the Diff. Right? Without fancy machinery that you do not own…it will be difficult at best trying to figure this out. So try to eliminate everything that you can before installing the shaft again. You WILL figure it out…but the more suspects…the longer it will take.
Keep plugging away man… The shaft really does need to be “dead nuts balanced and correct” before re installation… I still suspect the new damn U-joints…because that is where things started getting wonky…right after the new joints. You are close to the solution I promise…but you will never ever get there without a balanced shaft assy prior to re-assy. Hell if it comes down to it…go yank one from a yard and install it directly onto your truck…see what happens…they cost about 25 bucks near me. You must reduce your suspect pool…it has only grown since the shaft was rebuilt…and the shaft itself was never given a good bill of health. It MUST pass muster on that machine before you get under your truck again !
Blackbird
@"“Honda Blackbird”
The last time the diff gears saw me was when I changed the rear wheel bearings many years ago. They looked splendid at the time. And being as how I still got the vibes after jacking up the rear end, pulling the rear driveshaft section and running the the truck up to speed with only the front DS section, I think the likely culprit is the new center support bearing. I’m betting that I got a bad one. Especially as how I swapped out the new Moog ujoints for the Neapcos that the driveline shop recommended and there is only on ujoint at the transmission in this configuration. I can get an Anchor carrier bearing tomorrow and you can bet I won’t waste any time swapping it out. Some guy in Minnesota did it with a hammer and chisel and posted the video to YouTube. I tracked him down and called him. He also pried the bearing off using the slinger, just like the shop did.
87 Dodge Dakota Drive Shaft Center Bearing Carrier