13 speed question, help with splitting and rpms with shifting?
Page 2 of 3
So the answers here are
A. Dont bother using the transmissions potential and ignore all those extra gears
B. Ignore rpm because that obviously has nothing to do with shifting, its just "rhythm"
C. Drive it like a (2 so far) completely different transmission that he probably also has never used
D. Shift like "normal" (intimating, like a 10 speed, despite the pattern being different (high range left and down wont be that helpful, and is frequently a problem because that gear is weaker)
The only thing i havent seen is "shift it like a 15"
For internals, it very much depends on which one you have as to whether you can swap the rear box gears and add the splitter
For swapping them out one for another, it also very much matters which 9 to which 13 youre doing. Length for instance may be the same as many share an overall length, but many dont.
Ive driven 13s, 10s, a super 10, a 15 and a 9
Ive also replaced a few.
So to give your attitude back to you:
you do know a 9 isnt a 13,right? Because its literally DIFFERENT. thats what different means, 9 =/= 13
OK I'll add my two cents: Driving a 13 is just like an 18 except with no splitter in the low range. (Is that good, @skallagrime? )
The first time I drove an 18 was for a driving test. I told the boss I had only ever driven a 10 speed. He gave me real simple instructions that I wish I could repeat for you but it was years ago and I'm not very good at making it simple with words. Anyway, I didn't mess up too bad on the test drive, so he hired me. In fact, I remember that I ground the gears once and apologized and he said don't worry about it.
If you can drive a 10 speed, once you have a day of practice, you'll have it down. The pattern is a little different but it's not hard. In fact, I think it's easier since you don't have to do the upside-down U to go from 5th to 6th on a 10 speed. The spot for 6th on a 10 speed is where LO is on a 13 or an 18. You'll probably never use granny gear with normal loads.
The whole point of the splitter is to reduce the drop or gain in RPMs between shifts from about 400 to 200. Helps a lot on hills with heavy loads. An 18 is better than a 13 to get going from a dead stop if you have very heavy loads (over 80k, and really noticeable over 100k).
Last edited: Oct 4, 2023
Reason for edit: Add pretty pictures
On the test drive, which will probably be empty or bobtailing, there's no need to "split" the gears, meaning, "split the ratio you're in, in half". Years ago, truck motors had narrow power bands and to keep the forward motion, you needed to "split" the gear. Today, with modern engines, all this 13, 15, 18 malarky just isn't needed anymore. While I'll be in the cold, cold ground before I drive a truck with an automatic, a 8/9/10 speed goes back a long ways, heck, Dave Dudley shifted one in 1959, ( doing little white pills, I might add) and just use the splitter as the last gear, and fiddle with it later. While you are focusing on that shifter, remember, the boss is looking at the bigger picture, can you handle the rig. Besides, manual transmissions are going the way of common sense, and I'm surprised that company even has a 13 speed in the first place. Good luck, you'll be fine.
Has anyone in this conversation converted a 13 to a 9 and keep on trucking? Been done lots of times in the field when the back box peters out.
Eaton/Fuller/Yale&Clark as it were called back in 1960 when the first air shifted married “road ranger” came out designed them to keep them simple. All the original six 13 speed models from 1965 to sometime in the 90’s were “convertibles” meaning they were the same model as the 9 speed with a compound box added to the rear to split the gears. Same main boxes and gears. Same shift patterns. The original Rt/rto910 10 speeds and rt/rto 915 15 speeds were also convertible. They were same main boxes and shift patterns. 915s just had an extra “hole” gear added to rear to get deep reduction splits. Hence the old hands term of “shift it like a 9 speed” to the high hole then split for the od to cruise.
Years ago I drove for H&W here locally steer’n and gear’n a 1987 K model Kenworth, at that time it still looked and smelled new.
When they bought a new truck it had a 13 speed from the factory, but… H&W had their own mechanic remove the 13 speed shift knob and replace it with a 9 speed shift knob.
This of course eliminated the overdrive position in the transmission, it was their way of “governing” the speed of the truck.
Truck still had a 13 spd so we would get away from the shop and put our own 13 spd knob on till we got back…..
Page 2 of 3