Sound When Shifting from Drive to Reverse 91 FJ80 (1 Viewer)

[jomichael]

I've never owned an FJ80 so I am getting to know the various noises and not sure what "normal" is for these vehicles. This one kinda bugs me though, when going from Drive to Reverse and back again, there is an audible thunk or click. Seems to be the output of the transfercase. It basically feels that gears have a little too much play. When driving at speed if I lift off the accelerator and push it, I can feel the thunk. Not scary, but noticeable. Everything seems very tight from underneath.

Could it be u-joints? If so, how does one diagnose?
Could there be an issue with the transfer case output shaft? If so, how does one diagnose?
Could this be totally normal?

Thanks for all your input.

 

[jonheld]

A fulltime 4WD driveline has a lot of inherent "slop" due to all the interfaces involved.
The FJ80 has always had the "clunk" when going between deceleration and acceleration. Mine started doing that shortly after purchasing it in 1991. It's still running strong with over 300K miles on the original driveline.

A metallic "ting" sound like hitting a piece of pipe with a small hammer is common if the drive shaft slip yolks are dry. They should be first on the list to check. There should be zero rotational play in the slip yolk of each shaft, and the universal joints should be stiff and smooth throughout their movement on each axis. You will need to remove the driveshafts to inspect properly. Driveshafts should be greased regularly with each engine oil change. Do not over-grease the slip yolks. 2 or 3 pumps is all that should be required.

I would not concern myself with the transfer case. With regular oil change intervals they are bulletproof.

 

[jomichael]

A fulltime 4WD driveline has a lot of inherent "slop" due to all the interfaces involved.
The FJ80 has always had the "clunk" when going between deceleration and acceleration. Mine started doing that shortly after purchasing it in 1991. It's still running strong with over 300K miles on the original driveline.

A metallic "ting" sound like hitting a piece of pipe with a small hammer is common if the drive shaft slip yolks are dry. They should be first on the list to check. There should be zero rotational play in the slip yolk of each shaft, and the universal joints should be stiff and smooth throughout their movement on each axis. You will need to remove the driveshafts to inspect properly. Driveshafts should be greased regularly with each engine oil change. Do not over-grease the slip yolks. 2 or 3 pumps is all that should be required.

I would not concern myself with the transfer case. With regular oil change intervals they are bulletproof.

Thanks, I kinda figured it was normal since it is awd. I have an old 55 Chevy NAPCO and it took some getting used to all the gear noises, now I don't even notice! I will start with the slip yoke and then on to the u-joints, but they haven't been greased in awhile. Thanks for the advice.

 

[Izeloz]

Also look at your drive flanges on the front axle. Mine were a bit worn and the source of a little bit of the "thunk" noise.