I started on disassembling the transmission to a new GTE engine/transmission rebuild that just came into the shop last week. The plan is to split the overdrive unit from the transmission and get it to my rebuilder.
After draining the oil, I power washed the case so I wouldn’t get as dirty wrestling with this gearbox.
Ferrari GTE transmissions have a Laycock type electric/hydraulic overdrive transmission that gives these cars an overdrive 5th gear. They’re pretty reliable units if they’re properly maintained. The later overdrive units came sealed with their own oil, while earlier units shared the gear oil with the transmission. I’m not sure exactly when this split case modification occurred with the GTEs, but this one was an early case sharing its oil with the rest of the transmission.
The reason the later overdrives separated their oil supply from the rest of the gearbox was probably because their requirements for lubrication was incompatible. Most British gearboxes use 30 wt non-detergent motor oil, but the Ferrari gearbox uses a thicker oil. Sharing this thicker oil doesn’t work too well in the Laycock overdrive and can cause shifting problems. This one was also showing signs of very old oil!