Jaguar D Type Gearbox

Jaguar XKD Gearbox Gear Box

Jaguar D Type Gearbox

Jaguar D Type Gearbox:  We have recently completed our Jaguar D Type gearbox re-manufacturing programme. Our gearboxes are FIA compliant and correct in every respect.

The ‘D’ type gearbox was originally developed in the mid 1950’s as an improvement over the gearbox used for the ‘C’ type and indeed shared many components including, but not limited to, the main case casting and the selector cover along with numerous internal components. The early ‘D’ type gearbox was similar to the very last ‘C’ type gearbox which, likewise, was a four speed unit with synchromesh on 2nd 3rd and top gears and the gears were either close ratio for competition use or standard ration if specifically requested. The main visible difference between the ‘C’ type and ‘D’ type gearboxes being the Plessey brake pump extension, sandwiched between the main case and the new tail cover which itself incorporated an additional rear mainshaft bearing, relieving the load on both the mainshaft’s front roller cage bearing and the rear main case bearing, a feature that most of the Moss gearboxes lacked. The Gearbox had an oil pump situated in the tail cover, which although generated little if no pressure, ensured good oil circulation. The other main difference being that the ‘D’ type gearboxes had a different bell housing to account for the engine being angled over at 8 ½ degrees and to house the new design of competition clutch assembly, in all a far more advanced design than it’s predecessor.

Jaguar D Tyoe Gearbox GBDThough many of the racing ‘D’ types and Lister Jaguars used the early 3 synchromesh gearbox, Jaguar, in association with the Moss Gear Company had been developing an experimental 4 synchromesh gearbox using the same castings, somewhat differently machined where required. The gearbox was, although designed with racing in mind, also intended for production. This experimental 4 synchromesh gearbox proved to have so many inherent design flaws and was so unreliable in general, that Jaguar called a halt to its production and it never saw its way into the later ‘E’ types as Jaguar might have hoped. It was not until much later that Jaguar designed and introduced a successful ‘all synchromesh’ gearbox for the later production ‘E’ types.

It is for the reasons detailed above that we have concentrated on restoring and manufacturing the more reliable and stronger early ‘D’ type gearboxes and having had the benefit of studying several original Jaguar ‘D’ type gearboxes on loan to us, we have been able to accurately reverse engineer a period correct, strong and reliable gearbox for both road and competition use, one which will surely be welcomed by the FIA for Historic Motor Racing events.

Our ‘D’ type gearboxes are available with standard gear sets for road and competition use, or the close-ratio gear set as was originally designed for competition. All of the gearboxes incorporate the unique ‘Interlock’ mechanism which automatically locks 1st and 2nd gears in position until the clutch is disengaged. Plessey pump and related drive gear can be ordered additionally where required; our standard gearboxes have the pump aperture blanked off. The clutch release bearing and bearing carrier are included and are compatible with the roller release bearings such as those supplied by AP racing and are normally in stock. The bell housing and clutch slave cylinder are supplied and fitted along with the ‘interlock’ operating push-rod and spherical rod ends enabling the gearbox to be bolted directly to the engine with ease.

£14,790 + VAT

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Plessey Pump for Jaguar D Type

Plessey Pump

The Jaguar D Type Sports and Racing Cars had a continuous flow Dunlop hydraulic braking system which incorporated a Plessey Hydraulic Pump. This pump was driven via a reduction gear arrangement, the under-slung helical spur gear shaft being driven by a skew gear splined to the mainshaft of the Jaguar D Type gearbox.

The Plessey Company was originally based in Vicarage Road, Ilford, Essex, where they were designing and manufacturing airborne and ground support electronic devices during World War 2 and from 1946 the company held numerous manufacturing licenses for other products associated with the aircraft industry as part of their involvement in the war effort. Borg Warner was among the licenses held for aircraft engine starters, fuel pumps and gear driven hydraulic fluid transfer pumps. The Licence for the hydraulic pump was for a split-bearing design which among other key features included and provision for a wide range of fluid transfer flow rates and pump speed ratings, these were known as the Alpha range. By 1955 the hydraulic industry was growing rapidly and global demands were significant. During this period it was decided by the Directors of the Plessey Company to divide this sector of the company’s interest into two separate divisions.  The Hydraulics moved to Swindon, Wiltshire and the Fuel Systems division was re-located at Titchfield, Hampshire.

By the time the Company had established the division, the original Borg Warner licence had been superseded by Plessey’s own developed products, namely the invention of the ‘figure eight’ bearing and dual ended pressure loading designs. These new pump types were known as the Beta pump and soon became, and remained the industry standard.  Important relationships were established with David Brown, International, Ford, Massey Ferguson and numerous other manufacturers. The first custom designed pumps were made for Ford circa 1955 and these were of the original ‘dinner plate’ configuration. In addition to the agricultural supply, the Company continued to serve the aerospace industry and were also commissioned by Jaguar Cars Ltd of Coventry to produce small batches of hydraulic pumps for use as a continuous flow brake circulation pump in their Jaguar D type racing cars.

One early advertisement published by the company read as follows:

The Plessey Company: A NEW range of gear-type hydraulic pumps has been introduced by the Plessey Co., Ltd., Ilford, Essex. There are 98 different models varying in capacity from 0.27 g.p.m. to 42 g.p.m. They are assembled for either direction of rotation, with three different arrangements of drive shaft and 25 choices of port layout. Full details are given in a booklet published by the company.

The Swindon business continued to expand with production of hydraulic rams, mono-block valves and cam lobe motors for hydrostatic steering systems and by 1970 there were 1,145 employees in Swindon including more than 50 highly skilled engineers in two separate departments. The ‘Licence to Manufacture’ agreements were now reversed as Plessey Company sold licences throughout the world enabling other manufacturers to benefit from their proven designs and patents.

By the end of the 1970’s the Swindon, Wiltshire plant had become the most successful of the Plessey Company Divisions.

Our new Plessey Hydraulic Pumps are built to the exact specification as the original pumps which were commissioned by Jaguar Cars for use in their D Type Jaguars. Each pump body and mounting casting is precisely machined on our Société Genevoise Jig Borer adopting the same process as was originally used (without CNC) to achieve perfect results and ultra close tolerances. Our pumps are tested in our pump test facility prior to assignment.

£590 + VAT