Lockheed "Thin-disc" brakes

Prior to the introduction of the 1098cc Austin-Healey Sprite Mark 2 by BMC in the autumn of 1962 all Sprites, and the Midget Mk 1, had been fitted with 7" drum brakes to both front and rear. The Donald Healey Sebring Sprites, as well as those modified by John Sprinzel, were generally converted to disc front brakes of Girling type using their Type 10 caliper. In many cases the rear brakes were also converted to Girling using 8" drums from the Riley 1.5. However, there was another alternative, particularly if bolt-on wheels were to be retained (rather than wires) and that was the Lockheed set-up shown here and which has, over the years, become known as the Lockheed Thin-Disc set-up. With the 1098cc car came another Lockheed disc brake which was carried right through the Sprite and Midgets range of models until production ceased in 1980. The presence of a 'Thin disc brake set-up' on a car can often be initially identified by the larger brake fluid reservoir fitted on top of the master cylinder, very similar to that used on the MGA.

Reproduced below is an article from 'The Autocar' of 13th Jan, 1961 also depicted right:

"Disc Conversion for Sprite

Any owner who wishes to fit Lockheed disc brakes to the front of his Austin-Healey Sprite can now undertake the work himself by purchasing a conversion kit costing £45 from the Donald Healey Motor Co., Warwick. The work required is simple and straightforward, well within the capabilities of the average owner undertaking his own maintenance and repairs. Only a minor modification to the existing master cylinder is required, and the necessary parts for this are included in the conversion kit. An important feature of this conversion is that the standard disc-type wheels can be used and one does not have to buy wire wheels, as has been necessary with previous disc brake conversions.

The modification to the master cylinder is very important and must not be ignored. As the one fitted to the Sprite is of the integral barrel type, with twin bores for clutch and brake operation, it is necessary for the existing residual pressure valve body and cup to be replaced and an extension added to the fluid tank. As disc brakes have no powerful shoe retraction springs to help the return of fluid to the storage tank, it is essential that none shall be trapped in the brake lines, to exert pressure and thus set up wear on the friction pad. Extra fluid is required because of the self-adjusting feature of the Lockheed brakes; as wear takes place, extra fluid is introduced into the system to compensate for it. The discs are 8.75in. dia with the calipers mounted in a trailing position behind the wheel centre-line, and carrying quickly replaceable friction pads which have a thickness of 0.375 in."

Return to top