I'm chasing a driveshaft vibration in the XJ. It starts at about 68 and gets progressively worse as speed increases. Today's project was to climb under it and see what the problem is.
I started with driveshaft angles. They are within 1/2 of a degree.
I found a couple of issues. First up, the straps on the rear u-joint caps are worn and were letting the caps move in the differential yoke. I "adjusted" the straps to solve that until the new straps come in. That helped some, but didn't completely stop the vibration. The joints are tight.
Next up is the slip joint at the transfer case has some movement in it. How much is too much? It's enough movement to feel, but not really see. I am considering ordering a driveshaft to see if that eliminates the vibration. I figure the new one will also be balanced.
Any other ideas for things to check.
In reply to Toyman01 (Moderately Supportive Dude) :
Did you take it out of gear and Jack it up to spin the driveline?
Our band van had a similar vibration that I couldn't figure out. I shook the u joints and they seemed tight. Finally after taking out of gear and manually spinning the driveline I found that the u joint had ate it's way into the cap and under normal pressure it would stay there, under heavier driving conditions it floated back into center and vibrated like hell
It took me an annoying amount of time to figure that out
Check for damage to the shaft itself. I had a customer once who had ran over something and dented the drive shaft. Was very hard to spot, but was enough to cause a vibration.
Also look for missing weights. Little bits of metal about 1/2 X 1". Search for broken tack welds.
On a vehicle with stock ride height and nothing damaged, it's usually a weight fell off.
I inspected it for missing weights and dents or bent areas. I didn't see anything obvious. I also jacked up the rear and spun it with the transfer case in neutral. Again I didn't see anything obvious. A driveshaft is fairly cheap so I ordered a new one and a set of cap straps. We will see if that fixes it.
If you can't see the movement in the slip yoke, it is probably okay. There should be a spec out there for radial runout. I spent a lot of time chasing a similar vibration and replaced that tailshaft bushing (4L60E) only to end up with the same slight amount of play as before. Eventually I found a spec, and I was well within it. Could just barely see the seal face move when I had someone else yank on the driveshaft. That slight amount of play is needed to allow the yoke to run on an oil film.
My problem ended up being a driveshaft that had basically no angle at the universals causing the cross pins to wear out in 10k miles combined with a small dent in the middle of the shaft. Sounds like that probably isn't your case though.
So.. did you try putting the rear end on jackstands and actually spinning the driveline at 70 mph yet? Rear tires of course HAVE to be off the ground but it also helps if the whole vehicle is close to level because tilting the vehicle forward too much will unload the rear suspension a bit from its normal 'ride height' which may contaminate the sample, so to speak.
In reply to Vigo (Forum Supporter) :
I was working on it by myself so I didn't do that.
That is how I checked the balance on the Datsun driveshaft I built.
In reply to gearheadE30 :
I too would make sure the tail shaft on your transmission is not bouncing around. Good advice.
New driveshaft installed. That took care of about 60% of the vibration.
A new front shaft is only $150. XJ pricing for the win.
It's on order and should be in next week.
