13 vs 18 speed.

most folks round here have 10 spds & never have a prob with power,pulling or m.p.g. I have enough trouble remembering what year it is, much less what gear I'm in.. too many gears.

 

The need to split the bottom side has just as much to do with driving conditions as it does weight. Off road or even in some peoples driveways an 18 can come in real handy even if you are under 80k.

 

It has as much to do with road conditions ( or lack of a road ) as it dose with weight. A tri axle dump truck weighing in to low 70s can benifit from spliting the low gears off road and the other thing is the low gear in an 18 is lower than a 13. The 18 is 14.40 to 1 and the 13 is 12.31 to 1. Thats like useing deep reduction with an 8LL. You may not use it very offten but when you do is a god sent. As far as OTR trucks at 80k its not nessasery but their are times the 18 will be usefull.
I have an 18 now grossing 107,000 every load pulling grades as steep as 12% and love it but I did the same job with an 8LL, 10, and 13 speeds. Any transmission will do just about any job as long as the rest of the truck is set up right. Gotta love the 18 speed though.

 

A 13 speed with a .78(i think) overdrive in 13th is the same as a 18 speed with a .78 overdrive in 18th also a 9 speed with a .78 overdrive is the same in 9th gear.

What I think some of you are thinking if its got more gears its a faster trans. A 13 &18 speed tranny is nothing more than a 9 speed, put a back box on it and all it does is split the gears, not adding more.

 

The top eight ratios in a 13 and 18 are identical (same chart as Post #2)

 

You can't imagine that because you never seen a clutch lasting longer then transmission. Those extra ratios are there to make it live long, profitable life. Local drivers will never know that tho. What local drivers know about truck longevity anyway?

 

Its .73 not .78 but your right all od trans are basicly the same as far as RPMs on the highway. The 8LL and some 10 speeds are .74 over drive but from the driver seat their is no differance. The 13s and 18s are exactly the same in high gear.

 

Funny you say that. When I worked at Ryder, there were guys that would come into the fuel island, I would fuel their tractor and tell them to pull forward to fuel their reefer. They would start out in 4th, 5th or 6th gear some times just to pull up 30 feet. Some times they would even rock the drive shaft. One thing for sure, most drivers start off in too high a gear, when you have to raise the throttle to pull out the fuel island you're in to high a gear.

I don't know why anyone would want to start in such a high gear. I tryed started off in 5th gear on a 10 speed transmission with a tandem Freightliner daycab and empty 48' trailer. With foot fully on the throttle and slowly releasing the clutch, its much faster and smoother to start out in a lower gear. The drivers that start off in 6th gear on a 10 speed really just need a slap upside the head.

 

well said. and thats the same people driving too fast in the truck stop parking lot