New to me Freightliner cabover...DD 60 tire size and governor questions

It is set both ways in a way. Max RPM and road speed are programable.

 

You can switch the tires from lo pro to tall R-11 22.5’s and get more top speed at the same RPMs. Maybe that’s what the Truck originally had. You can get even more top speed by going to 11/R24.5s, but would need new rims. Lo pro 24.5’s and Tall 22.5s are almost identical height. Play around with Spicers or Wellers calculators, to get a good idea. The speedometer can be calibrated by flipping the dip switches on the backside. Different settings for different drive lines combos. The settings can be found online. You should have a Ametek brand speedometer.

 

I checked the calculator. Looks like each tire size gets you about 2-3 mph more. The trans must be a 9 spd direct. Might be better to convert it to a 13spd. if it can be converted. If so, I think you’ll run about 65 mph at 1400 RPMs. With the same tires. As long as you’re hauling light, that would be ideal IMO. You could swap to a 9 OD. But a 13 would be nice, giving you more top gear choices. Those 11.1 get great fuel economy. Better than the 12.7s. Never saw one with a 13spd. Looks like 1800 RPMs would put you over 80 mph!! Lol. Looks like the directs serial # ends in A, and .73 final ratio 9 spd. OD ends with a B. I had a 9 OD with 390s. I loved it. I honestly don’t know much about it all. Just interesting to me. Others on here can help with numbers and ideas more than myself.

 

I don’t know, mine was a simple double H pattern. That makes me wonder if you can have the top two gears swapped out, and have OD by using the goofy shift pattern. Some of the old transmissions were modified that way.

 

@wore out would probably know.

 

Is it an RTO or RT?

the RTO 9 speeds were horseshoe pattern the RT were H

 

Your gonna have to look at the model tag on the transmission itself