18 gears. WTF Chuck?

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When I drive a 13 I split the gear ahead of time then just let up on the throttle then gas on it to shift it.I couldn't do it that way with a 18.The truck I had that had a 18 was geared to high and it had me shifting too much in the hills.I like a 15 to use the deep reduction sliding tandems and backing into docks.

 

Cant agree with you on this one...
Just a ten speed with 5 gears in deep reduction. Not argueing about their not being an excellent transmission, had one in a ten wheeler, loved it.
Shift whatever gears needed in deep reduction then slide into the next lower gear in low range. Example: shift up into fourth gear in deep reduction, shift into low range and slide shifter into third gear for closest numerical ratio. The fifteen is not a "splitter" transmission. The Roadranger website will confirm this.
To lazy to search, but this has been discussed before in one of these forums....

 

splits on my 13 are more like 200rpms apart full gear swaps are more like 400 rpm, also Direct Drive is a proven more fuel effecient than running a OD trans. the 1:1 gear is putting more hp to the rears than a OD gear will running the 2.64-3.08 gears to get any speed out of the set up makes it a no go for me I won't even start the spill about off road and heavy wt.

 

The eighteen speeds that I've driven could be shifted that way just like a thirteen speed.

OK...But that has nothing to do with the transmission...The rear ends were probably geared too high for the way the truck was set up.

I only drove a 15 a few times and never used the deep reduction so I have no real input other than it's just a ten speed with deep reduction and has all the drawbacks of a 10 speed except too high of a low gear.

 

what he said....

 

Ratios and Steps:
Low Inertia Concept:
This innovative, patented design is identified in the Eaton
Fuller nomenclature by the letter "L" (as in RTLO-14913A).
These transmissions feature a simple mainshaft which is not
splined to the auxiliary gear. This unique design eliminates the
added mass, drag and inertia of the entire auxiliary section.
During upshifts, where both the lever and splitter button are
moved together, the low-inertia mainshaft is quickly brought to
synchronous resulting in fast, easy shifts.
Shift Pattern:
GEAR RATIO % STEP
8th H 0.73
8th L 0.86
7th H 1.00
7th L 1.17
6th H 1.38
6th L 1.62
5th H 1.94
5th L 2.28
Range Shift
4th 3.23
3rd 4.43
2nd 6.11
1st 8.59
Low 1 12.31
Reverse-HI 3.50
Reverse-Low 13.22
Overall Ratio: 16.9 to 1
1800
1600
1400
1200
MPH
0 10 20 30 40 50 60 70
RPM
Based on 1800 RPM engine
operating at 1636 RPM/62
MPH [100 kph].

Ratios and Steps:
Clutch Housing Size:
• SAE #1 and #2.
• Cast iron and aluminum available.
PTO Openings:
• Two SAE standard openings.
• Right side, regular duty, 6-bolt, short length.
• Bottom, heavy duty, 8-bolt.
PTO Drive Gears:
• Right side, a 45-tooth, 6/8 pitch gear.
• Left side, a 47-tooth, 6/8 pitch gear. Both gears turn at
.79 engine speed.
Oil Capacity:
• Approx. 28 pints [13.3 liters].
• Integral oil pump standard.
• Oil to water heat exchanger standard on 18918B,
20918B and 22918B (Requires 2 pints [.95 liters]
additional lubricant. Adds 10 lbs. [4.53 kg] to weight).
GEAR RATIO % STEP
8th H 0.73
8th L 0.86
7th H 1.00
7th L 1.17
6th H 1.38
6th L 1.62
5th H 1.95
5th L 2.29
Range Shift
4th H 2.73
4th L 3.20
3rd H 3.74
3rd L 4.38
2nd H 5.16
2nd L 6.05
1st H 7.30
1st L 8.56
Low H 12.29
Low L 14.40
Hi Rev H 3.43
Hi Rev L 4.03
Low Rev H 12.85
Low Rev L 15.06​

Overall 19.7 to 1

 

You probably misunderstood my reply to the other poster....I was talking about the similarities between the thirteen speed and the eighteen speed box and didn't really address the fifteen speed at all.

Fifteens were good tranmissions for off road applications but were kind of useless in a highway truck if you ask me.

 

For some reason the 15 spds were very durable?

 

I think we are agreeing to agree I pointed out my gears were too tall in the truck I drove with the 18 but it wasn't my truck not my call I have drove many a truck with the 15 and loved having the deep reduction for when I wanted to use it but my overall favorite is the 13.

 

I don't even know how I messed that last post up it wasn't intentional.