Transmission question

#1

I just put in a replacement used transmission in the car.

When in neutral, the rear wheels turn very slowly when the car is off the ground. I can stop the turning by putting my foot on the tires (both sides at the same time).

When the clutch is in, the turning stops. So, it’s something in the transmission.

What could cause that? How does the power get transferred weakly in neutral?

#2

That is normal and is just viscous coupling of the input shaft to the transmission gears.

I don’t know what fluid you have in the transmission, but if heavier than ATF or Redline MTL the viscous coupling will be greater.

#3

Thanks Jim for clearing that up. I do have fairly thick oil in there so that’s probably why.