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Lotus Brabham BMW

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#1 Gary C

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Posted 17 October 2001 - 21:13

This follows on from my Chris Williams thread of earlier. Apparently he used to run a Lotus (possibly a 23) with a BMW engine, as he was a BMW dealer. Now, a friend of mine thinks the car was sometimes labelled as a Lotus-Brabham-BMW, but he can't remember why! Does anyone have any ifo, particularly on the whereabouts of the car these days??


#2 Roger Clark

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Posted 17 October 2001 - 23:16

From motor Racing magazine, January 1966

Williams' car (finished in a distinctive gold colour with a black stripe) has been up against Denny Hulme, in Sid Taylor's Repco Brabbam BT8, which is a pretty stiff handicap by any standards. Yet car and driver have had their moments of glory, the 1965 success sheet including victories in an Elva Trophy race at Croft, a Guards Trophy race at Brands Hatch, and 2 litre class lap records at both Croft and Oulton Park.

As its name suggests, the car is mainly Lotus, slightly Brabham, and powered by BMW. It has been built up entirely by Chris Williams and his staff at their Guildford, Surrey, racing headquarters, and is based on a Lotus 23B chassis frame which has been outriggedand considerably strengthened.

The front suspension is also mainly Lotus 23, with an adjustable ailti-roll bar and Triumph Vitesse uprights. Brabham 10.3 inch brake discs are fitted with AR calipers, and are mounted on Vitesse hubs. The 13 inch wheels have 6.5. inch rims at the front, and carry 5.50 Dunlop R6 yellow-spot tyres.

The rear brakes are the standard Lotus 23 equipment, and the rear suspension also basically from the production Lotus. However, all rubber has been removed from the suspension, Rose joints or Oilite bushes being used throughout. A simple form of camber adjustment is provided by left and right threaded two-part top links. The 13 inch rear wheels carry 7.00 R6 yellow-spots on 8.5 inch rims, and special flanges are fitted converting the wheels from 6 to 4 stud fixing.

The final drive from the Hewland Mark 5 heavy-duty gearbox and limited-slip dity is through Hardy - Spicer sliding - spline drive shafts from which an earlier locking problem has been completely overcome by the use of Esso Molygrease.

Steering is by the familiar modified Herald rack and pinion, with Brabham steering arms to provide better leverage and consequent lighter feel.

The car was designed to compete in comparatively long-distance events as well as the short sprint-type races, and matching ll-gallon fuel tanks have been provided on each side of the body with a switch-over tap in the delivery system, which is operated by twin SU pumps. The standard Lotus 23 oil and water radiator is used, and has proved completely satisfactory.

The four-part aluminium body is secured by Dzus fasteners, and has a divided front intake reminiscent of the Ferrari sports cars of some four years ago. The slightly 'thick' nose section of the body was necessary last season because of the need to house the spare wheel and tyre, but the body line is by no means unattractive, and indeed looks both functionally efficient and aesthetically well balanced from the nose to the slight lip over the high Kamm-type tail panel.

The power unit (the drive from which is taken through a Porsche-type 180 mm diameter diaphragm clutch) was built up and has been maintained by the Chris Williams team, and has proved so reliable and efficient that the decision has been made to market replicas and furtherdeveloped versions in 1966.

The unit fitted to Chris' car started life as a normal 1800 (not a TI) and develops approximately 180 bhp at 7,300 rpm on a compression ration of 1 1 to 1. it has an 1800 crank, 1800TI rods, special Mahle pistons, and of course special camshaft, valves a heavily reworked head. 50 DCO carburettors were found second hand, and have been used throughout the season. The engine has a Williams-developed dry-sump system in which the scavenging pump is incorporated in the cast alloy sump, the system being pressurised to approximately 70 psi.

#3 Gary C

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Posted 17 October 2001 - 23:31

Roger, just brilliant! I think that's probably all the info I need, apart from the whereabouts of the car now! Thanks again.