Drive line thump

[photogod]

Just read a bunch of stuff from the archives on drive line thump and wanted to get more opinions please. My sons fj80 has a thump on acceleration and decel if you let off quickly and step on it quickly. This only happens when the center diff is NOT engaged. When the CD is engaged it does not happen and sounds very tight. This leads me to think it has something to do with the CD and/or its components. (pretty quick ehh)? Since I have no experience with CD locking whoes please give me your .02. Thanks.

 

[concretejungle]

Photo, as long as the drivelines have been well lubed, it's normal. WIth a full-time 4wd system, driveline wind-up is normal. Some have dismantled the drive shaft so it's properly lubed. I wouldn't think too much of it.

 

[Whale]

Just read a bunch of stuff from the archives on drive line thump and wanted to get more opinions please.

Some have claimed that replacing the drive plates on the front axle (and rear on a FF) will virtually eliminate the problem. My truck makes so many other noises, I can't attest to the validity of that theory, but I do know my drive plates were worn badly enough in Moab to shear the teeth off on a little airborne stunt. The new drive plate fit WAY tighter on the birf than the old one did... FWIW...

JJJ

 

[elmariachi]

Every FJ-80 I have owned (7 of them thus far and #8 is forthcoming) did this to some degree. '95 and older were worse IMO. The viscous coupling in the TC lends itself to this. Make sure you are running good clean TC lube and try and live with it. I am not sure its worth attacking until something wears out or breaks, which is likely to be never.

 

[tea LC]

Get a grease gun and lube that thing