The Borg-Warner 35 transmission (BW-35) is an automatic transmission produced by the BorgWarner company.
It has three forward and one reverse gears. The selector lever follows a quadrant which has six stations (Park, Reverse, Neutral, Drive, Second gear and First gear). The "3" in the model number refers to the number of forward gears.
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When the transmission of the motionless vehicle is placed in Drive, the transmission allows the vehicle to move off in first gear, then will change to second and then to third gear based on increase in road speed. The BW-35 will downshift from third to second and from second to first, also based on load. The transmission is equipped to produce kickdown and will upshift after kickdown if accelerator pressure is released following a kickdown.
As is common in automatic transmissions of its generation, power brought to the transmission via the torque converter drives hydraulic fluid. As the gears move faster or slower, pressure of the fluid increases or decreases in the case. Mechanical switching of gears is triggered by the increase or decrease of pressure. There are no electronic sensors or switches as found in modern transmissions.
The Borg Warner 35 automatic transmission comprises a torque converter and a fully automatic 3-speed hydraulically controlled epicyclic gear box. The automatic transmission provides three forward and one reverse gear ratio.
The hydraulic control system consists of a valve arrangement and an engine driven pump. The automatic transmission contains a planetary gear set consisting of two sun gears, two sets of three planet pinions contained within a planetary carrier and ring gear. Various speed ratios are obtained by holding or clutching various combinations of elements of the planetary train. This is performed by two bands, two multi-disc clutches and a one-way clutch.
The Borg Warner 35 was designed for use with Type F Automatic Transmission Fluid (ATF), which is far less common today than the Mercon/Dexron type.
Initially produced in the U.S. in the 1950s specifically for engines of less than 200 cubic inches engine displacement and less than 100 hp (75 kW) (American Motors Rambler and Studebaker mainly). Prior and contemporary automatic transmissions were very inefficient and would only work with larger, more power engines, and even when used in those applications, the engines would often have higher compression ratios and more power than the manual transmission versions.
In addition, lower ratio differentials were usually used in other automatic transmission applications to improve gas mileage (again due to the inefficiency of the earlier automatics). The BW 35 was a more efficient transmission and was quite successful in the USA with the smaller engined cars. This also made it a natural for European cars that usually had much smaller engines than American cars of that era. Production was transferred in 1960 to the Borg-Warner plant at Letchworth in Great Britain. The BW-35 was offered to European automobile producers where it was widely used.
optional on MK2 and S type and was also used on the Jaguar Mk2-derived Daimler V8 2.5litre saloon and the later V8 250 saloon
In the mid-1970s, Arrow & Avenger ranges switched to B-W Type 45 4-speed transmission
Between 1964 and 1976, BW-35 transmissions were used in the models 120, 1800, 140, 160 and 240.
The gear ratios were as follows:
Escort and Cortina gear ratios were as follows:
In the early 1970s, The Borg-Warner 35 was also used in 6-cylinder Australian Chryslers, Valiants and Chargers. This was due to the Torqueflite autos being replaced for the need to have more local content. It was used behind the both the slant 6 and hemi 6 engines.