
Now that I’m comfortable with the install I decided it was time to make a gear change. The truck was originally ordered with 4.10 gears and when I found the Neway air ride cutoff it also had 4.10 gears. With the 4.10 gears and 40.5” tall tires, I was right at 2200 rpm at 64mph or so. Since I want to have little room to breathe and get around somebody, I figured it would make sense to put a little taller gears in it.
I had asked a question on the Detroit group on FB about what the best cruising rpm is for a 2 stroke and received a ton of responses, from ‘slam your hand in the door’ nonsense to ‘keep it up tight against the governor at all times’. I finally received a couple of practical answers, including answers from Stan A and Joe D. They agreed that anywhere between 1900-2000 was a good cruising rpm for this motor.
I put a spreadsheet together and started running the numbers on the different ratios available for the Eaton 23105S rear, including the original 4.10’s, 3.90’s, 3.70’s and 3.58’s. After looking at the numbers I decided on 3.70’s which would put me right at 2000 rpm at 65 mph. I realize some guys like to run faster than that, but 65mph is a good speed for me. At that time I started looking for a pumpkin and wound up finding one at Global Truck Parts in Archbald, PA, not too far from home.
The rear came out of a Freightliner that supposedly had less that 200k miles on it and still had ‘shiny’ black paint. I was only interested in the pumpkin but it was a package deal so I took the entire housing...

I used the forklift to unload it and then tucked it in the garage to drain all the oil out of it and strip it down...


Once the oil was out of it I took it back outside and used a cup wire brush to clean it up...

After it was good and clean I used the cherry picker to pull the pumpkin from the housing and bring it back in the garage...

More to follow...