Borg-Warner 35 automatic transmission

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From the 1960s to the 1980s , the Borg-Warner Corporation produced the fully automatic three-speed transmission with torque converter of the type M35 or 35 (often abbreviated BW-35) with the later variants BW-36 and BW-37 for lighter passenger vehicles .

development

It was developed in the USA in the 1950s specifically for engines with a displacement of less than 200 cubic inches and was originally mainly used there by the American Motors Corporation (AMC, in the Rambler ) and by Studebaker .

The predecessors like the automatic gearboxes at the time were very inefficient. They required larger engines, which often had a higher compression and were more powerful than variants with a manual transmission. Lower reduction ratios were typically chosen to improve fuel economy in smaller engines. Automatic transmissions, such as those used in the small 6-cylinder engines in the USA in the late 1950s and early 1960s, also became uneconomical due to heavy components. So the need arose to develop a lighter automatic transmission.

The BW-35, presented in autumn 1961, was the first transmission from Borg-Warner with an aluminum housing and was more efficient. This made it the natural choice for European cars, which regularly had much smaller engines than American cars of that era. Production began in the early 1960s at the Borg-Warner transmission plant in Letchworth , Great Britain. It was offered to car manufacturers in Europe and was widely used there.

The "3" in the number refers to the gearbox series. The 30s and the 40s, 50s and 60s series that were later developed from them are gearboxes with an aluminum housing. As the serial number increases, the strength of the transmission usually increases. The earlier cast iron gears with the designations M-8 and M-10ff are stronger than the aluminum models, with the M-60 types tolerating as much as those of the M-10 series. The second number denotes a certain variation and generally indicates a higher load capacity with engine torque, i.e. a suitability for more powerful engines.

In 1965 the BW-36 was introduced, which, unlike the BW-35 , was prepared for an external gear oil cooler . The M-35 case was air-cooled and should have been drilled out for an external cooler. No US model used an external cooler. An external oil cooler made it suitable for heavier vehicles and / or hauling heavier loads.

In 1967 the BW-37 was first mentioned in the AMC workshop manual. There it was used in larger vehicles behind the engine type 232, which had a higher torque. From 1967 AMC had the BW-36 with the 199 engine.

function

When the transmission of the motionless vehicle is put into drive mode, the transmission allows the vehicle to start moving in first gear and then shift to second and then third gear as the road speed increases, depending on the load and accelerator pedal position. Also depending on the load and driving speed, it switches back from third to second and from second to first rank. These gear changes can be forced in anticipation of an overtaking maneuver or an increase in terrain by pressing the accelerator pedal down, the so-called kick-down .

The BW-35 has three forward gears and one reverse gear. The shift pattern and, accordingly, the selector lever vary according to the year of construction and vehicle model. Early models have a shift pattern with the six positions of the selector lever PRN-D2-D1-L for parking, reverse, neutral, driving position 1 (D for drive), driving position 2 and driving uphill (L for lock-up). In position D2 you start driving in second gear. This is for economy in relatively flat terrain and is useful on slippery surfaces such as mud, snow or ice. In position D1, the transmission shifts through all three forward gears. By selecting "L", the transmission can be locked to prevent upshifting. From 1st gear "L" is selected via the engine, maximum, from 2nd gear "L" is selected moderately via the engine, whereby 1st gear is automatically switched to when the vehicle speed falls below 8 km / h . Many users assumed that they had a two-speed gearbox because they expected the first selectable drive mode D2 from "N" to shift through all available gears, as was the case with the automatic transmissions customary at the time. From 1965 there was the then common PRND-2-1 switching scheme. AMC called this "Shift Command" to distinguish it from the D2 / D1 models, as both could be ordered from the Rambler American from 1965 to 1967 .

The machine consists of a hydraulic torque converter and a planetary gear with two sun gears, two planet gears, a planet carrier and a crown gear. The various gear ratios are achieved by engaging hydraulically operated multi-disc clutches and brake bands.

The torque converter drives hydraulic fluid. In that case, as the gears move faster or slower, the pressure of the fluid increases or decreases. The mechanical shifting of the gears is triggered by increasing or decreasing the pressure. There are no electronic sensors or shifts like in modern transmissions. A throttle valve is located in the control valve housing and is connected to the throttle linkage via a cable. This regulates the internal pressure through the throttle position. A secondary function of this cable is downshifting ("downshifting") to a lower gear when the throttle valve is in the full stop position (the throttle pedal is fully depressed) and the vehicle speed is below a mechanically controlled setpoint. Controller on the drive shaft . The hydraulic control system consists of a valve assembly and a motor-driven pump. The automatic transmission contains a planetary gear set consisting of two sun gears, two sets with three planetary pinions in a planet carrier and a ring gear . Different speed ratios are obtained by holding or coupling different combinations of elements of the planetary train. This is done by two belts, two multi-plate clutches and one one-way clutch.

The Borg Warner 35 was developed for use with automatic transmission fluids (ATF) of the type F, which is much less common today than the Mercon / Dexron type.

commitment

AMC

together with the 6-cylinder engines 195.6, 199 and 232.

Austin

Citroën

Daimler

Datsun

  • 1967 Datsun RL411 SSS (SuperSportSedan) and 1600 ('Bluebird'); (same engine as the SR311 'Fairlady' roadsters).
  • Datsun PL510 - Optional for sedans and cars.

jaguar

MG

Morris

Reliant

Used in the Reliant Scimitar GTE SE5 with the Essex V6

The Rootes Group (UK) (later Chrysler UK)

In the mid-1970s, the Arrow and Avenger series switched to a 4-speed BW 45 transmission

The Rover Corporation, later British Leyland UK Limited

Saab (Sweden)

Between 1970 and 1993, BW-35/37 gearboxes were used in models 99 and 900.

triumph

Vanden Plas

Between 1964 and 1976, BW-35 gearboxes were used in the 120, 1800, 140, 160 and 240 models.

  • 1st gear: 2.393: 1
  • 2nd gear: 1.450: 1
  • 3rd gear: 1,000: 1
  • Reverse gear: 2.094: 1

Ford UK and Ford Australia

Escort and Cortina gear ratios are as follows:

  • 1st gear: 2,393: 1
  • 2nd gear: 1,450: 1st
  • 3rd gear: 1,000: 1
  • Reverse gear: 2,094: 1

Ford (Australia)

Early automatic-shifting Ford Falcons used the two-speed Fordomatic from 1960 to 1965. This was then with a modified form of the Borg-Warner 35 (first as "Fordomatic 3S", then "Fordomatic" / Cruise-o-matic) and finally "Cruisomatic" added together with the C-4 and FMX automatics, whereupon the names were discarded with the XC Falcon update), which was used on six-cylinder Falcons until 1988. The gear ratios of the Ford Falcon XD specifications (3.3 and 4.1 liter six; Borg-Warner 35-3) are typical for all and are as follows:

  • 1st gear: 2.39: 1
  • 2nd gear: 1.45: 1
  • 3rd gear: 1.00: 1
  • Reverse gear: 2.09: 1

The 4.1 liter Six (as an optional transmission) and the 4.9 liter V8 used the Ford C4-3. The gear ratios of the Ford Falcon XD specs are typical of all and are as follows:

  • 1st gear: 2.46: 1
  • 2nd gear: 1.46: 1
  • 3rd gear: 1.00: 1
  • Reverse gear: 2.20: 1

The 5.8 liter V8 was equipped with the Ford FMX-3. That was an upgraded three-speed Ford-O-Matic (designed by Borg Warner Corporation ) over "MX" and "FX" ( Cruise-O-Matic ) transmissions become FMX in 1968. The gear ratios of the Ford Falcon XD specifications are for everyone typical and are as follows:

  • 1st gear: 2.40: 1
  • 2nd gear: 1.47: 1
  • 3rd gear: 1.00: 1
  • Reverse gear: 2.00: 1

Chrysler (Australia)

From 1967 to 1981 the Borg-Warner 35 gearbox was also used in the Australian 6-cylinder Chryslers, Valiants, Chargers and Centuras. The specification change from the Torqueflite automatic transmission to the Borg-Warner 35 was due to a need for more local content. The Borg-Warner 35 gearbox was used behind the Hemi 6 engines. The Borg-Warner units of the 40 and 50 series have been continuously converted to later series models and, like Ford Australia, are part of the product suppliers.

Individual evidence

  1. ↑ New Small Automatic Transmission Introduced , September 19, 1961, Commercial Motor , historical overview of the Borg-Warner Inc. of the same name, attributed there to a company "Warner Gear"; The English-language Wikipedia article, however, assumes that production began in the 1950s
  2. ↑ Repair instructions for Rover 3500 automatic, British Leyland UK Ltd., 1972, chap. 4 (for BW-35 and BW-65)
  3. ^ A Brief History of Ford Automatic Transmissions . Baumann Engineering. Retrieved on November 20, 2011.  ( Page no longer available , search in web archives )@1@ 2Template: Dead Link / www.baumannengineering.com