Borg-Warner 35 transmission
Encyclopedia
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.
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 sensor
s or switch
es 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.
and less than 100 hp (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 ratio
s 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
The gear ratios were as follows:
Escort and Cortina gear ratios were as follows:
Automatic transmission
An automatic transmission is one type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually...
produced by the BorgWarner
BorgWarner
BorgWarner Inc. is a United States-based worldwide automotive industry components and parts supplier. It is primarily known for its powertrain products, which include manual and automatic transmissions and transmission components, , turbochargers, engine valve timing system...
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.
Description
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
Torque converter
In modern usage, a torque converter is generally a type of hydrodynamic fluid coupling that is used to transfer rotating power from a prime mover, such as an internal combustion engine or electric motor, to a rotating driven load...
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 sensor
Sensor
A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. For example, a mercury-in-glass thermometer converts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated...
s or switch
Switch
In electronics, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another....
es 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
Gear ratio
The gear ratio of a gear train is the ratio of the angular velocity of the input gear to the angular velocity of the output gear, also known as the speed ratio of the gear train. The gear ratio can be computed directly from the numbers of teeth of the various gears that engage to form the gear...
.
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.
Users
Initially produced in the U.S. in the 1950s specifically for engines of less than 200 cubic inches engine displacementEngine displacement
Engine displacement is the volume swept by all the pistons inside the cylinders of an internal combustion engine in a single movement from top dead centre to bottom dead centre . It is commonly specified in cubic centimeters , litres , or cubic inches...
and less than 100 hp (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 ratio
Compression ratio
The 'compression ratio' of an internal-combustion engine or external combustion engine is a value that represents the ratio of the volume of its combustion chamber from its largest capacity to its smallest capacity...
s 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
Letchworth
Letchworth Garden City, commonly known as Letchworth, is a town and civil parish in Hertfordshire, England. The town's name is taken from one of the three villages it surrounded - all of which featured in the Domesday Book. The land used was first purchased by Quakers who had intended to farm the...
in Great Britain. The BW-35 was offered to European automobile producers where it was widely used.
BMC
- Austin 3 Litre
- Austin 1800 "Landcrab" (and derratives) --- transverse installation using a Morse Hy-Vo chain to transmit the drive.
- FX4 Taxi
- Morris Marina
- See MG (below)
- other models
Datsun
- 1967 Datsun RL411 SSS (SuperSportSedan) and 1600 ('Bluebird'); (same engine as the SR311 'Fairlady' roadsters).
- Datsun PL510 - Optional on both sedans and wagons.
Jaguar
- XJ6 Series 1 2.8 and 4.2
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
The Rootes group (United Kingdom) (later Chrysler UK)
- Hillman Minx, Super Minx, Hunter, Minx (Arrow range 1725cc only)
- Humber Hawk, Super Snipe, Imperial, Sceptre, Sceptre (arrow range)
- Singer Gazelle, Vogue, Vogue (Arrow range), Gazelle (Arrow range 1725cc only)
- Sunbeam Alpine, Rapier, Rapier (Arrow range), Alpine(Arrow range), Vogue (Arrow range)
- Hillam Avenger & Plymouth Cricket 1250, 1300, 1500 & 1600
In the mid-1970s, Arrow & Avenger ranges switched to B-W Type 45 4-speed transmission
Volvo (Sweden)
Between 1964 and 1976, BW-35 transmissions were used in the models 120, 1800, 140, 160 and 240.The gear ratios were as follows:
- 1st gear: 2.39:1
- 2nd gear: 1.45:1
- 3rd gear: 1:1
- Reverse: 2.09:1
Ford UK & Australia
- Escort Mk1
- Capri Mk1
- Cortina Mk1, Mk2 & early Mk3 (later Marks used Ford C3)
Escort and Cortina gear ratios were as follows:
- 1st gear: 2.393:1
- 2nd gear: 1.450:1
- 3rd gear: 1.000:1
- Reverse: 2.094:1