[SixBanger]

if you read my last question, I was talking about a driveshaft vibration my car has developed in the past few weeks. someone suggested I check if the driveshaft is loose, and it was, so i bolted it back up and I thought that would be it! then I took it for a spin and to my surprise it still vibrates. When I was under the car, I noticed the rear driveshaft u-joint had a lot of play in it, but it had never made noise so I just let it be. Now the car started doing the rear-end clunk again, coming from infront of the differential (so i know it must be the U-joint). I was wondeting, maybe the loose driveshaft was not the cause of vibration (obviously not because nothing changed when I tightened it back on), but a result of it.

Soooooo.... has anyone had a broken U-joint cause a lot of drivetrain vibration (I am almost postitive thats where its coming from)\??? maybe one of the rings holding it in position snapped and it came off-center? anyone ever had this happen?

Thanks,
Alex

 

[Vinhzxt]

I had the same problem with my drive shaft not long ago. The ujoint frozed and end up making the driveshaft not align straight so that's why it vibrates..
Vinh
http://vvu.tripod.com

 

[SixBanger]

thats what I wanted to hear

good to know this could actually happen, thanks for the quick reply. I'll lift it up tomorrow and take a look.

 

[Al 260Z]

U-joint failure...

You get the clunk from a failed u-joint when the needles start breaking up and falling out. By this time, you can take the car out of gear, crawl underneath and by twisting and/or pushing-pulling on the shaft you can easily see something is wrong by the free play where there should be none.

U-joint deterioration starts well in advance of that point with lubrication failure and dimples developing on the cross or cup where the needles bear. Once you're familiar with this you can quickly isolate failing u-joints. They make a fairly distinctive growl, sometimes with a low frequency WOW-WOW-WOW beat frequency. If you take the driveshaft or halfshaft out, or at least loose at one end, you can usually feel that it does not pivot smoothly when you excersise all the possible motions of the joint. Probably it was this vibration that was making your driveshaft bolts work loose.

Be sure to mark your parts before disassembly of the u-joint so that you can put it back the way it was factory balanced. Unbalanced driveshaft will result in vehicle shaking at high speed. Nissan OEM or Spicer u-joints recommended. (Ye ol school o hard knockers!) Some Z driveshafts are difficult to rebuild. Check the archives.

Good luck!
Al

 

[Jerr 76 280]

I agree with Al 260Z,
I had the same issue with my 76' drive shaft that it was not loose to swivel and had started vibrations in the car. Unfortunately, the 76' drive shaft u-joints cannot be replaced so while I was looking for another shaft, I still drove the car. To make things worse, the joint that was bad was the end at the transmission and while driving a few nights later the joint blew apart, scraped the **** out or the tranny tunnel under the car and poll vaulted my poor car. I don't think I have ever stopped that fast in my life. Long story short, having your issue in the back joint is safer if it breaks, but get it replaced or fixed quick...
Good Luck,
Jerr

 

[SixBanger]

al260 and jerr..

Thanks guys, this is exactly what I'm feeling and what I expected. I don't have time to fix the joint before the weekend, so I'll have to drive my backup (dad's z32, hehe) for a few days. It's been snowing a lot here in Denver, and I have to wash the undercarriage before I get under there again anyway. Checker should have the spicers in stock, correct? (is it a common part #?)

Alex

 

[Ron Diederich]

Alex,
Could be the u-joint. Sometimes its the rubber differential
mount which seperates and changes the trajectory angle on the drive shaft.
My 2¢
Ron