Are you using 10W30 or Gear Oil in TC?

1979 W150 and FSM calls for 10W-30 in Transfer Case. I had that for awhile and everything seemed fine. Had a trans shop fix a minor leak, and they put gear oil in it. Everything was still quiet though so I kept driving for awhile. I decided to put 10W-30 back in the case. I very rarely switch from Hi-loc to Lo-loc because I don't go off road. I decided to get into a little mud the other day, and it performed very well, but there was some grinding when I switched back and forth through Hi and Lo. I don't know if it was a coincidence or the switch back to 10W-30. Do these older ones prefer gear oil, and it's ok to use it? Yes, I was in neutral.

Thanks. Larry

79 203 wants 10w30 and is happy with it. Splash of heaver won't kill it. The 230? 3sp manual also wanted ATF. The tc is supposed to grumble a little bit when shifting, that's how ya know ya shifted it.

Haha, okay, thank you.

You are supposed to be in park when shifting from high to low range.

I could swear the owner's manual says N. I will look again.

You do not want the transmissions output shaft to spin. If it does you will get gear clash and you should avoid it. The way I like to shift between ranges is like this. Best way is even surface and wheels straight. As the truck is rolling shift the transmission to neutral. When stopped shift to park and make your hi to lo or lo to hi range change and put the transmission back in gear. It is a simple procedure that works well with the 203 case. Doing it this way you relieve the drieline bind and the case will shift between ranges quietly and easily.

I guess I can try that. I did double check owner's manual, and it definitely states to shift TC while engine on, trans in neutral.

You can shift it any way you want however an automatic in neutral and the transfer case in neutral trying to go into high or low there will be a lot of grinding. Even worse if the idle is high. Selling and working on these since new we learned what to educate customers to do. You can shift it but it needs to be rapidly or else grinding will happen. To me the instructions were designed for manual transmissions. The way I explained takes any torsional load off the drive line and it will not grind.

I always shift it quickly and foot off gas. I'll try your suggested process. Thanks.

Best way is to stop truck, put trans in neutral, shift from high to low range, or low to high range rather in one quick motion. If you found yourself in neutral and don't want to hear all that grinding, you can momentarily put trans in reverse, then back into neutral right before putting case in gear. OR shut truck completely down, then put case in desired position.

Stopping, Neutral, and shifting quickly is what I've always done. Just started to hear some grinding, so I asked this question.

So shift it the way you have been and enjoy the grinding.

I was letting you know that I always shift quickly, not slowly through the shift process because of what "buildanother" wrote. AND that the noise just started. I also wrote that I WILL try what you suggested. Don't get your feelings hurt.

NITROUSN, looks you were RIGHT! At least one test yesterday. Rolled to stop in Neutral, put it in Park, and shifted through the TC gears with absolute quiet! Not even a bit of grinding! I'll try it a second time next time I have it out! Thank you!