Driveshaft noise

[zdude1967]

So my driveshaft on my 260 makes a noise when at high speeds I take my foot off the accelerator. 

Basically if I am punching it and say OK - fast enough and stop the acceleration and then are coasting with no torque to the drive shaft it makes this same noise it is making in this video, just much more, louder etc. it sounds like the driveshaft is gonna come up through the floor- maybe that's an exaggeration but you get the idea. Is that amount of play in the driveshaft correct? I replaced the universals a while back , doesn't seems like they are part of the play , it seems like either the transmission or the Differental.IMG_4827.MOV  

 

Any thoughts?   

Edited April 7 by zdude1967
spelling

[Zed Head]

Your diff mount looks in pretty bad shape.  But it usually causes a clunk when shifting, not a constant noise while coasting.  The play in the driveshaft (propeller shaft) is normal for the diff, if the tranmsission is in neutral.  Can't tell if the diff gears are stopping the movement or the transmission.

Don't forget the other two drive shafts.  Four more u-joints.

[zdude1967]

It was in neutral. The diff mount looks bad. Do you mean where the driveshaft connects to to Diff or something else

[Zed Head]

The other two drive shafts.  Sometimes called half shafts

[zdude1967]

Zed head- sorry I am not understanding. Is the Diff mount looking bad or the mini drive shafts that you posted?

[Yarb]

The differential front mount where the forward support attaches to the frame. Check the u joints on the half shafts.

[Zed Head]

19 hours ago, zdude1967 said:

Zed head- sorry I am not understanding. Is the Diff mount looking bad or the mini drive shafts that you posted?

I was trying to point at where the noise might be coming from.  Your description, with the video of twisting the propeller shaft, implies a sort of rotating clunking noise.  A bad u-joint in one of the half shafts could cause that.  

Another possibility is the transmission mount.  You can get under the car and lift up by hand on both the tail of the transmission and the nose of the differntial.  Both have a lot of leverage available.  Get under there and move things around.  Use a long screwdriver in the u-joint yokes to see if they're loose.  They're tough, they handle lots of torque.

Many possible causes.

[Mark Maras]

On 4/7/2024 at 11:36 AM, zdude1967 said:

 

 "It sounds like the drive shaft is gonna come up through the floor" is no exaggeration if the nose of the diff. is lifting and falling. With the help of a friend inside the car, position yourself so you can see the front of the diff. A mirror may help. Pull the parking brake on, start the engine, put the trans in first gear, and SLOWLY release and slip the clutch. Look at the diff. nose to see how much vertical movement there is.

[Jeff Berk]

Maybe a video camera or cell phone instead of putting yourself under the car.

Or maybe find or borrow a set of "chassis ears". Unfortunately, you cannot attach them to rotating parts.