driveshaft clunk in park and neutral

[mikeyy]

I have a 1984 300d. When the car was idling in park or neutral I could hear something clunking under the car. When I looked under the car the clunking was the driveshaft turning back and forth. It doesn't do this in drive or reverse. What could cause this?

[BoomInTheTrunk]

torque convertor or flex disc. check the flex disc.

[pawoSD]

the drive shaft will move slightly in neutral or park due to fluid pressure in the transmission......if on a slight incline in park it won't happen. Mine does it too and I have brand new flex discs.......if yours are old do check them, but the "clunk" is normal if sitting on perfectly level ground.

[BoomInTheTrunk]

Originally Posted by pawoSD

the drive shaft will move slightly in neutral or park due to fluid pressure in the transmission......if on a slight incline in park it won't happen. Mine does it too and I have brand new flex discs.......if yours are old do check them, but the "clunk" is normal if sitting on perfectly level ground.

yah but he said it did it in park and doesn't the tranny disengage.

[pawoSD]

Originally Posted by BoomInTheTrunk

yah but he said it did it in park and doesn't the tranny disengage.

technically its "disengaged" in park or neutral but there is still fluid pressure inside the tranny that will transmit a very small amount of power through the shaft....not enough to actually do anything or move the car (it might move slightly in neutral if you rev the engine up a bit) but still a little bit. In park the parking lock holds it from turning more than 1/3 rotation or so, but I bet in neutral with a rear wheel off the ground it would spin at low speed.