Please help with transmission/gearing set up

If you have a driver, avoid the 13 speed.

They are more expensive to purchase, they are harder to drive, and they are easier to destroy.

If you have a driver keep it as simple as possible.

 

This is the B. No weight there compared the fertilizer.
My M11 gets along fine at 1900, pulls better at higher RPM but that could get me in trouble.

 

I am going through the same kind of issues but I’m starting from scratch, my 9200’s 8LL took a crap so I’m in the market for another trans. Looking at two transmissions right now are RTO1460A and B, the A has lower ratios in the lower gears. Not sure which way to go, haven’t gotten to run the truck much to know where I am at. Gear is 3.91 engine is Cat 3176 350hp model, running 80-85k mostly flat land.
Thoughts?

 

1460?

 

Oops, 14609A & B

 

You can look up ratios and transmission lengths on Eaton Fuller Roadranger transmission rations ( something like that ) the same as I can.
I believe the 09A is rated for gearing in low and reverse. The 09B is a 22% overdrive. They are both about 3.5 inches short for your driveshaft. A 15 speed has some low gears like the 8LL and an RTO 15 has OD on the top end. A 13 SPD does not have low low gears but you can split all the gears on the top side. They are about 12% OD. Probably about all you want for your 3176. You never mentioned tire size but that is about the best I can tell you anyway. If you have an engine that is over geared you have to shift every time it sees a hill.

 

Thanks for the reply, I have a ratio chart pulled up now, when you speak of the overdrive percentages how do you figure that? So if I’m following the less the better in the case of a smaller engine?

 

If I understand you correctly I believe you are correct. However I am assuming some things. Your truck having an 8LL sounds like it was made for vactional work not OTR.
When the national speed limit was 55 these combinations were common with direct transmissions. 3.90 gears and 11R 24.5 tires. 3.70 gears and 11R 22.5 tires. 3.55 gears and LP 22.5 tires. Depending on the engine they would usually run out about 66 - 72 MPH.
You can also search for road speed calculator on line. Fill in the blanks and see what fits your desires.
I cannot remember all the particulars but a strong 400 Cummings was over geared, for what we did, with a 22% 9 over. It did OK with a RTO1010. It had 3.70 and 11R24.5's.
Another 400 had an unknown model 9 over. 3.55's and low pro 22.5. That did a great job and got good mileage. A 15 in the correct set up works the same way and has some LL gears.
Probably considered rambling so I will stop.
Point being these kind of changes are expensive. I believe a 13 or 18 speed would be a easy swap for your 8LL. Have to consider if it is the same series as your 8LL. Top shifter and all will swap. If different does it come with compatable parts? Those transmissions split every gear on the top side at smaller RPM differences. In rolling hills you can run one of those a gear down forever with no problem. The first 400 mentioned was over geared for that usage. On every small hill it had to be down shifted. After the hill the road speed was to slow to tolerate. Driver shifted all day long.

 

The shift tower is completely interchangeable on all heavy truck eaton/fuller trannys and some rockwells. The bell housing is typically only interchangeable with others of the same series. I would be thinking 13 speed. The B ratio set lines up pretty nicely to just split gears and never move the stick. What speeds do you run?