NP205 4low and hubs not turned in

[wazzabie]

NP205 was set at 4low and hubs were not turned in - I heard a bunch of grinding noises. Did this do any damage? I quickly turned off the engine. The noise may have come from the tcase.

To clarify I had the hubs unlocked and was just starting under power. Also the mounts on the crossmember are really bad. I have some new ones to install.

 

[lectric80]

It won't cause any damage unless there was already damage there. With the hubs unlocked the driveshaft will turn the diff, but the axles aren't engaged to the hubs. I would check clearances around drivelines as well as u-joints, and make sure the 205 has oil in it. It could be it wasn't fully engaged and the engagement gear was grinding a bit, but that seems unlikely.

 

[Fordum]

Only way you could damage anything that way would to put the rear tires in a very heavy load.
When you put it in low range, you have a lot of torque available. Normally its split between the front and rear axles.
Without the hubs turned, the rear axle gets it all.

But, the same thing can happen when a front wheel comes off the ground or is in a slick patch while the rear tires are on dry ground.

So, its not something to worry too much about.

And, I have had my transfer case fail to engage completely from time to time and it makes a grinding noise.
Try shoving it hard into 4low and see if it still makes the noise.

 

[diesel4me]

One day when I was showing off in my 72 K5,I put it in 4-LO without getting out to lock the hubs,and did some awesome burnouts and donuts in third gear--then heard a awful grinding noise,and the truck refused to move,no matter what position I put the transfer case lever in!--I had it towed to a local tranny shop,I figured I had wiped out the splined coupling between the NP-205 and the SM465,I had replaced on before that was damaged by worn splines on the tranny's output shaft--but the guy called me and said "I locked the hubs and drove it into my shop OK,so its not that coupling--I think you might have blown the rear end!...since I was low on cash,I told him I'd just pay him for the "diagnosis" and I drove the truck home in 4wd--I had another axle I could swap in it if I had too--but I found out the rear pinion flange for the U-joint had stripped out all the splines,nothing happened to the diff itself!--after raking out all the metal left behind in the splines on the pinion shaft,I was able to replace the yoke,I had one off a camaro 12 bolt that was the same..got lucky that time!..

You need to realize you multiply the torque two times more than usual in 4-LO,and one axle alone may not be able to withstand the loads..when its shared between both axles with the hubs locked,its a lot easier for them to handle the additional strain..