For those of you considering the 10% under-drive gears, the low range gears, or both inside transfer case, here are my thoughts as I recently installed both sets into my transfer case.
To begin with, my 80 is very well maintained, it's pretty quiet running down the road, and I know it intimately. Going into this, I was not so much worried about noise from the low range, but with some recent concerns popping up on MUD about the UD gear noise and the warning from OTRAMM that some people experience gear noise, I was worried. I like my rig to feel solid and without any weirdness, especially in the drive line. I picked up the low range gears quite a long time ago and then the under-drive gears from Cruiser Brothers when they were running the sale over the holidays. For me, getting the final drive ratio back to stock for only about $400 plus my labor was a no-brainer. I also had a bearing in my t-case that was making a bit of noise when it was cold, so I wanted to fix that too. The plan was to replace all the seals, the front and rear output shaft bearings, and then only the bearings appearing to have more wear than I was comfortable with. Only one additional bearing was replaced.
Beyond the awkward, heavy, and dirty transfer case, the installation is pretty straight forward. Some of the press work and pulling is odd, but if you can think through it and be a little creative it will go down without a hitch. I highly recommend watching the
@OTRAMM videos a handful of times prior to digging in. Those videos, plus the FSM proved invaluable.
Here are my impressions of the drive-ability after installation.
- WOW!! The low range gears are totally worth it! Huge change, and I can’t wait to get out on the trail. This is the thing I can’t get out of my mind. I am certain it will pay dividends on the trail.
- The 10% under-drive is worth it, although during my first few drives it almost seemed imperceptible. By this, I mean, its like you know something is different but you’re just not sure what. It just seemed more right, but was really hard to point to exactly what made it seem that way. I drove from Colorado Springs to Denver today to get some highway time and it is just better. In a very simple way, it’s just better. Cruise control set at 75 just sticks there, even with the hills in between the two cities. The truck seems to be more comfortable cruising along at all speeds. Easier to accelerate, decelerate, merge, etc.
- Noise - I am only getting a faint gear whine from the under-drive gears. It also really only comes in about 55-65 mph. I am going to sound deaden the tunnel to get rid of what I hear, but I doubt my wife will even notice. I would also be surprised if it doesn’t get better as they wear in a bit. I am running 85w90 oil for the first 100 miles and then I may go thicker to see if it helps. The noise potential was my biggest concern, but after today’s drive I am totally fine with the noise level.
- I now want to get the speedo corrected. It’s weird to have everything better and feel right, but have the speed off. I think I will just run the yellow box.
Dealing with the front output shaft bearing and putting the transfer case back into the truck were my biggest frustrations. Beyond those two things, it’s all good and I am happy I did it.
. All my pics and documents are good old film and paper.
