9-spd vs. 10-spd transmissions?

It makes some difference, just as having 13 or a8 makes a difference.

Even the last two auto trucks I have driven, a ProStar with a 10 speed and the Cascadia with a 12, more gears are usually better.

 

A 9 feels like an 8 with a granny. Gears are spread really far apart. Thus the winding out and lugging feel when upshifting. The more gears on top, the better a tranny performs. A 9 has 4 on top. The 10 has 5. 13s and 18s have 8.

 

Wait a sec,,, a 9 feels like a 18 minus what on top now?, once motors got over 400 hp, there was no need for a splitter and kind of dates us. I drove a Freightliner with a 500 Detroit and a 13, and never needed to split the gears. Unlike the old 238s, where you may as well drop TWO gears while you're at it,, , they were great if paid by the hour.

 

First truck I drove had an 8.3 Cummins (235 hp) with a 6 speed. But it also had a 4.33 rear ratio. Didn't have to shift much

 

I drove an international S2200 with a 190 Cummins, 5.7 liter, and 5 speed.

 

The ONLY TIMES I had a problem with a 9 speed were when I was worn out at night and thought I had a 10 in a early 90's (or mid 80's) Pete flat top pullin' 53' dry vans.

I really LOVED a 13 and it only took a few scratches after not using one for a few years to get it together.

 

As far as I'm concerned 9 and 10 speeds are almost twin brothers. The Super-10, not very common, is different in regards to the mechanics the driver uses in the cab, but it is so uncommon I don't want start a thread about it. They both just use a forked H pattern. Maybe one has reverse and granny gear in swapped positions, but that's about it. Most of my driving was in 9 and 10 speeds before autos took over.

 

Original question was on the difference. The difference is performance. That’s the very reason why motors got over 400HP. The 500 Detroit would outperform every Detroit before it.

 

The hard part about this is there is a question about which 9 speed and which 10 speed as there are numerous versions with different gear ratios, overdrives etc.

While Eaton annoyingly doesn't have consistency across their charts in their sales brochures, the peaks below are about the same but you have to ignore the troughs.

One 9-speed


One 10-speed


While there is a small amount of difference, except remembering where to shift when you go to high range I don't notice a diffrence.

Some of the 9 speeds are convertible to 13 speeds, which has more value IMHO but really should have just been bought as a 13 speed in the first place.

The above 9 speed can be converted to a 13 speed which has the chart below.



While it may just be the versions I have driven, 15 speeds which typically shift like a 9 speed with a low-low range vs upper splits is the only one with really odd spacing I have had.

But the non-spliting modern transmissions weather they be 9, 10, 8ll etc... all seem to act the same on the road to me.

Some 9 speeds have a really high ratio reverse though and that can be problematic based on your use case.

While opinions differ, if you want absolute fuel economy or drive in the mountains the 13/18 speed transmissions are a huge step up but I don't care enough about the minor differences between the non-splitting transmissions enough to care. A useful cup holder is higher in priority IMHO for highway use compared to 10 vs 9 speed.