Need help with drive line noise

[lan240]

I have a 72 240z and while driving I am getting a metallic tinking sound from the trans tunnel. I am thinking that I have a U Joint going bad. Just wanted to see what you all thought before I get home and get it up in the air.

[59ghia]

I had the same noise, lasted about two weeks , then the heavy vibration set in.....rear u-joint.

good luck,

Dave

[lan240]

OK Put the Z up in the air last night and the u joints look good. Greased them up and thought every thing was good. On the way to work the noise is back What to check next. Any help? I can always turn up the tunes but that will not fix the problem.

[Bambikiller240]

Originally posted by lan240

OK Put the Z up in the air last night and the u joints look good. Greased them up and thought every thing was good. On the way to work the noise is back What to check next. Any help? I can always turn up the tunes but that will not fix the problem.

How do you mean that the U-joints "look good"? Did you check for any slop in the movement of them, or roughness in the motion? The only way I know to really check them out for damage that would cause slight noise (as opposed to the major noise that would be accomanied by vibration) is to pull the driveshaft and rotate and wiggle the u-joints in all directions while looking for slop AND feeling for roughness within the yokes.

I do not know if the U-joints in your car are causing the noise problem (only a thorough inspection can tell), but I'll warn you that you do not want the U-joint to completely fail and come apart while driving the car. Such a failure will beat the hell out of the transmission tunnel of your car (and may ruin brake and fuel lines that run through the tunnel) and most likely will ruin the driveshaft as well.

[lan240]

The noise is not constint and only happens some times. Most of the time when at crusing speed. It will quit when I throw in the clutch or let off the gas. From what I can tell there is no play in the U joints. Any help would be great

[59ghia]

Neither did mine while it was in the car. Thats why I kept driving it, BambiKiller is correct, you need to pull the driveshaft to really check 'em out. Mine were a total PITA to remove, damn cups would not budge! And I have a press! Order a new set now and by the time you get them you'll HAVE to change them!

Dave

[Bambikiller240]

Originally posted by lan240

The noise is not constint and only happens some times. Most of the time when at crusing speed. It will quit when I throw in the clutch or let off the gas. From what I can tell there is no play in the U joints. Any help would be great

It could be a Clutch Release bearing too, but you'll never know until it starts to "scream" constantly. U-Joints are far more likely IMHO to be the cause. When they start to fail there is very little to no play, however that changes dramatically in a short period of time. The noise will occur more frequently and loudly, soon vibration will become apparent, followed quickly by total destruction. The only "help" I can give you is the warnings and advice I've already posted. Good Luck.

[lan240]

What u joint brand should I use when replacing them?

[Bambikiller240]

I have had bad luck with the brands sold in local parts stores like GMB, etc. My opinion (others may disagree) is that Nissan OEM u-joints, or Spicer Heavy Duty ones are the only way to go if you want them to last a long time. I also reccomend taking the driveshaft to a machine shop for installation (after you remove driveshaft from the car) unless you are very experienced with removal and installation of j-joints, and have a press. It will cost more than doing it yourself, but will be done quicker and correctly.

just my $.02