Fuller 18 Speed

They are different but not by much, .08 is the biggest gap. The 13 just has a larger ratio step from L to H box

Here is a link to all the different tranny specs and ratios
http://www.roadranger.com/Roadranger/productssolutions/SpecificationGuide/LinehaulManual/index.htm

 

The answer for me is a no brainer after having owned both. I will take an 18 over a 13 any day.

 

I like the 18sp for what I do anyway...putting around rock quarries and most of them you have to go loaded up from the pit...4th gear is too slow and you'll spin the tires, 5th is too high and you'll snuff it...but 4 1/2 is perfect at full throttle. But for the general OTR crowd, it's probably not necessary.

 

even if you dont really need it the 18 is nice. i love 18 speeds always a right gear to be in for any givin situation. then when empty or real light you can just put it in the high split and run up and down your gears as a straight 9 speed. crawling in traffic you may find yourself splitting low gears. i always do a lot of off road driving so the 18 is really nice. but i would take a 18 for any thing even if something less would suffice. basicly a 18 speed is a 9 speed a 13 speed and a 18 speed all rolled up into one transmission you can choose how you want to run it i see no downsides to a 18 speed other than cost to buy.

another advantage with the 18 speed is you get a deeper reduction low and reverse gear, that can come in quite handy at times.

 

I have only driven a 13 a couple of times and that was years ago. I have always had an 18 speed and I am considering transitioning down to a 13 or 15 even. But now I am here looking for the difference between.
I want to stay with an 18 speed, but now I wont be driving someone else's. I am in the process of buying my own, but I can't find any 18 speeds! None of which I think are worthy of buying, anyway.
All I am coming across are 10's, Super 10's and 13's. That leads me here, researching and reading what you guys have to say about them.

 

this is why some people get, 1mill + out of a clutch and others wonder why there clutch went out at 400k

 

what will you be pulling, id take a straight 10 over a super any day. and a 13 over either of the two.

 

same thing really, jus don't split till your on the high side and pretty much a 13

 

I ave a 18 and if on a hill loaded I run it likea 18 but usauly leave it in low side until 4th then start splitting gears. And like ezrider said you are always in the right gear

 

I spec'd an 18 in my glider I bought. No regrets. Now to be fair, in a glider, the trans, regardless of gears, would be a rebuilt. I was able to get an 18 factory rebuilt for almost the same price as a factory rebuilt 13. And the deeper reduction, and splits on the bottom have made a difference in some situations. Guess it all depends on what conditions the truck is being used in, what the rear end ratio is, etc. That is why there are so many trans choices... there are no one size fits all solutions.