T660 9 speed converting to 13 speed

Eaton built 9 speed transmission called convirtibles they were 13 speed that the back half was never plumb. Plumb an air supply to a 13 speed knob direct it to the shift valve you have a 13 speed

 

Only reason to shorten the shaft is if its a non-convertible 9 speed, in which case the aux section needs to be swapped out.

 

I saw one in a GMC General around 1991. OP wanted a 13 Speed and dropped it off. It had an extended back box. 13 speed tag on the transmission and a 9 speed sticker on the sun visor.
Changed the knob. Found it had a sleeve, like a cut off piece of pipe on on side of the spliter piston, took it out.
He came to pick it up and I handed him his little bill. He kept asking questions and finally said thank you. You could have pressure washed and painted it. Charged me for a new transmission. I never would have known the difference.

 

An actual convertible 9 speed is readily converted to a 13 speed for only a few hundred bucks. No need to change drive shaft.
K3501 by FULLER - 9 Speed To 13 Conversion Kit

 

Ok ,well he will have to check that out i guess. I wasn't aware there was such a transmission. Just curious, why would the manufacturer make one with all the hardware, then disable it? Possibly to keep drivers from screwing it up?

 

Yup i googled that trans. New one on me. Learn something everyday. Like a yard sale purchase and finding a orginal copy of the US constitution tucked in it. Well mayby not that drastic..but.

 

I have been told that your larger fleets bought trucks speced with these transmissions,turn the knuckleheads loose on 9 speeds when they were done tearing the trucks apart they plumbed they tranny as a 13speed and made a couple extra bucks on resale selling a truck with a 13 speed and a back half that has never been shifted

 

No, and yes.

The 9 speed trans marketed as a convertible is a limited 13 speed.

Put the dumb co. drivers in them. At resale time replumb them to 13 speed and sell at a premium. When Werner ran W900 and Classics with Cat motors in late 90's this was thier spec. Not sure, might have been originators of this.


Now without going into piles of part numbers, some but not all actual 9 speed eatons are considered convertible buy adding the back box and shorting driveshaft. Still were considered convertible. In theory even some of the standard 9's not convertible could be, with a main box rebuild.

Confused yet? Point is, some actual 9's were referred as convertible well before 9's were market as a convertible transmission. Which was not a 9 speed, it was a locked out, or not plumbed 13!

See were I'm going here?