Download file Free Book PDF Land Rover Overdrive Manual at Complete Installation Manual Series Land Rovers Options Fairey Overdrive. OVERDRIVE UNIT AND SELECTOR MECHANISM. -. Ye |. 17 Gasket, overdrive to transfer box. Dipstick FITTING INSTRUCTIONS. (in). Fairey Overdrive Fitting Instructions. Page history last edited by Stephen Jarman 10 years ago. Download: Fairey Overdrive Fitting

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It can either couple the input driveshaft directly to the output shaft or propeller shaft 1: The driveshaft is usually a hollow metal tube that requires balancing to reduce vibration and contains no internal bracing. This allows the vehicle to achieve better fuel efficiency, and often quieter operation on the highway.

Achieving an overdriven ratio for cruising thus required a gearbox ratio even higher than this, i. When using overdrive gearing, the car’s engine speed drops, reducing wear and normally saving fuel.

Land Rover S3C / Fairey Overdrive Fitting Instructions

The obvious solution to this problem would be to add more gears to the transmission. Often the final drive ratio varied between models within a range, a “sports” model having a lower ratio. From Wikipedia, the free encyclopedia.

Overdrive was widely used in European automobiles with manual transmission in the 60s and 70s to improve mileage and sport driving as a bolt-on option but it became increasingly more common for later transmissions to have this gear built in. In an era when cars were not able to travel very fast, the maximum power point might be near enough to the desired speed that additional gears were not needed.

The point of maximum power is somewhat lower than the absolute maximum RPM to which the engine is limited, the ” redline ” RPM. Borg Warner provided the box that was factory-installed between the transmission and a foreshortened driveshaft. The most fundamental meaning is that of an overall gear ratio between engine and wheels, such that the car is over-gearedand cannot reach its potential top speed, i. Doing so reduced the torque the driveshaft had to carry, and thus the strength and weight it required.


It is also why more than one overdrive gear is seldom seen in a vehicle except in special circumstances i.

Although the designer was theoretically free to choose any ratio for the gearbox and final drive, there is one additional consideration which meant that the top gear of most gearboxes was 1: Another British company, the former aircraft builder Faireybuilt a successful all-mechanical unit for the Land Roverwhich is still in production in America today. Wikimedia Commons has media related to Overdrives. Under certain conditions, for example driving uphill, or towing a trailer, the transmission may “hunt” between OD and the next highest gear, shifting back and forth.

This article relies largely or entirely on a single source. GKN or Gear Vendors as opposed to having an overdrive built in one will typically have the option to use the overdrive in more gears than just the top gear.

The rotational speed of the wheels for that given forward speed is simple to calculate, it is simply the tire circumference multiplied by the RPM. Indeed, in modern vehicles this is common. With the use of front-wheel drive manul, the gearbox and final drive are combined into a single transaxle.

Please help improve this article by introducing citations to additional sources.

Land Rover Restoration, Tech, Maintenance and Repair – O

If a vehicle is equipped with a bolt-on overdrive e. At overdruve slightly lower speeds than maximum, the total drag on the vehicle is considerably less, and the engine needs to deliver this greatly reduced amount of power. Therefore, a car needs one gearing to reach maximum speed but another to reach maximum fuel efficiency at a lower speed. Using overdrive with the main 3-speed transmission in 2nd gear was similar in ratio to 3rd gear, and with the main transmission in 3rd, the overall ratio was fractional i.

In the days before automatic transmissions were falrey, especially in the s, many rear-wheel drive American cars were available with an overdrive option. Newer vehicles have electronic overdrive in which the computer automatically adjusts to the conditions of power need and load. But as more powerful cars appeared, especially during the faireu, this disparity between the maximum power point and desired speed grew considerably.


American cars with large-slow-revving engines would use higher ratios, European compact cars with small high-revving engines were lower.

By using this site, you agree to the Terms of Use and Privacy Policy. These had a direct 1: As noted earlier, however, this would cause the engine to operate at too high an RPM for efficient cruising. In this case gear changing is still possible in all gears, even with overdrive disconnected. Anatomy of the Motor Car. In an era when different models of car with different wheel sizes could be accommodated by simply changing the final drive ratio, it made sense for all transmissions to use direct drive as the highest gear.

Final drive ratios of 4: Although adding the cruising gear to the main gearbox was possible, it was generally simpler to ogerdrive a separate two-gear overdrive system to the existing gearbox. This was particularly important in the early days of cars, as their straight-cut gears were poorly finished, noisy and inefficient.

The Volvo version kept the same package size as the J-type but with the updated 18 element freewheel and stronger splines through the planet carrier. For other uses, see Faigey.

Calculating these from first principles is generally difficult due to a variety of real-world factors, so this is often measured directly in wind tunnels and similar systems. This meant that cars were often operating far from their most efficient point.

Fairey Overdrive Fitting Instructions

As power is the product of RPM and torquerunning the shaft at higher RPM allowed more power to be transferred at lower torque. At mph, or inches per second, the wheel will be turning Over a period of 40 years, Laycock Engineering manufactured over three and a half million overdrive Units, and over one million rairey these were fitted to Volvo motorcars.

For janual, the overdrive system applied to a Triumph TR5 operates on 2nd, 3rd and top gear.