OKA Engine Conversions
OKA Engine Conversions using GM automatic transmissions
4L80E (4 speed electronic automatic transmission)
The 4L80E transmission is similar in strength to the old TH400 3-speed with the addition of an overdrive 4th gear.
The transmission is electronically controlled by the engine management system.
Gear Ratios - (1st - 2.48:1) (2nd - 1.48:1) (3rd - 1.00:1) (4th - 0.75:1)
The 4L80E has an overall case length of 661mm/26" without the extension housing. Depending on the application, the length of our adaptor coupled with the 4L80E will most likely require the cross member and tail shafts to be modified (depending on engine mount locations).
The 4L80E when coupled up to our adaptor housing gives you an overall transmission length of 833 mm.
TH400 (3 speed automatic transmission)
The Turbo Hydromantic 400 is basically the same design as the TH350 but a stronger version. The Turbo 400 is also a 3-speed automatic transmission. The standard GM TH400 will bolt directly to the Chevy V8 petrol, Chevy V8 diesel and Turbo pattern Holden 308 engines. Several case variations of this transmission were manufactured; they bolted directly to Jeep, Buick, Oldsmobile, and Pontiac V6 and V8 engines.
Gear Ratios: Car (1st - 2.52:1) (2nd - 1.52:1) (3rd - 1.00:1)
Gear Ratios: Truck (1st - 2.50:1) (2nd - 1.25:1) (3rd - 1.00:1)
If you intend using a 253 Holden V8 or a Trimatic pattern 308 you would need to adapt the automatic transmission to the engine with another adaptor plate, which are generally available from any speed shop.
The TH400 has an overall case length of 616 mm. When coupled to our 184 mm adaptor housing gives you an overall transmission length of 800 mm/31.5".