Turnertech engineering, turning, milling, welding in Corsham Mechanical engineering workshop Wiltshire and South West

Motorsport engineering and custom components for Wiltshire & the South West.

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Our involvement in UK motor sport is usually evident in the Turnertech workshop in Wiltshire: Formally in the form of our supercharged 1975 Honda drag bike, latterly our Honda CB125T based Sprint Bike and new 1929 Brooklands replica 500cc Sprint Bike. We design and manufacture special components produced for kit car, rally car and Formula Ford etc, Classic cars and classic racing cars, classic bikes and rally cars.

Hand built vintage racing motorcycle, shed built

Latest racing venture is my Brooklands Sprint Special 'spirit of Brooklands 1929' racer, designed and built completely from scratch, yes engine and gearbox too! No castings, no CNC all hand machined and made in my spare time over a 4 year period. Photo above from first ever track tests in October 2016 when it went very well!

Honda CB125T engineered in Wiltshire

Our accounts manager Sharon seen performing one of her 'spirited' launches against a CBR400RR. Based on a 1978 Honda CB125T this sprint bike has been developed by us to a point where it now produces more power than the famous Honda CR93. It's performance is truly stunning, as owners of many modern sports bikes have discovered. R1, ZX14 and 996 owners beware! Classic racing motorcycle custom parts are our specialty

Turnertech engineering put to the test at Wroughton, near Swindon

Theoretical physicist Dr. Dom prepares for another ear splitting launch of the Turnertech supercharged Honda CB500T.

The Turnertech Engineering CB500T dragbike was based on a classic 1975 500cc Honda twin: Very little of the original machine remained, with extensive redesign of the engine and chassis undertaken in our engineering workshop. Utilising the broad range of skills we have from CAD, through milling, turning and fabrication in steel, aluminium and fibre glass. Due to research commitments, our theoretical physicist rider has had to take time out and was replaced from 2009 by his sister who is a University Science Technician.

One off oil pipe take of union to suit a Suzuki Hayabusa engined Fisher Fury race car. This was produced to take up less space than the existing fitting but with greater flow, whilst offering higher strength.

Suzuki Hayabusa oil pipe union

Produced overnight for a Formula Ford competitor, just days before a crucial championship round at the Castle Combe Circuit, this rear suspension bearing support incorporates more material under the retaining bolt heads.

Formula Ford rear wishbone support

Designed to suit our Honda drag bike as a result of changes to the cylinder block and cylinder head: This replacement engine cover incorporates an external spin on oil filter, external oil feeds to the cylinder head, off board starter shaft and an access cover for the clutch. Fabricated from several machined aluminium components, precision TIG welded for minimum distortion.

Clutch cover

Shorrocks C75B supercharger drive shaft/flange. This flange is a known problem component in the Shorrocks supercharger, especially since most of the units are now at least 40 years old. This one off replacement incorporates a number of subtle modifications to help prevent premature failure. Installed in a classic car in the USA, this has performed faultlessly for over 6 years.

Shorrocks supercharger drive plate

Having problems with your Muffett differential/reverse gear box? These units have a habit of destroying the pinion bearings, now there is a solution. Designed in collaboration with James Johnson at PJ Motors, this modification allows the pinion end float to be controlled. James also recommends another modification produced by Turnertech to replace the inferior aluminium drain plug insert.

For all enquiries regarding car parts please click on the link below to contact:

P J Motors

Muffett differential modificatiion to end cover to make cure unreliability

Early experiments with the Honda engine of our drag bike in normally aspirated form, included raising the compression ratio dramatically to take advantage of the high octane petrol allowed in this form of racing. Special pistons were not readily available in the UK so a pair where manufactured in house to our exact requirement, with valve pockets finish machined after a trial assembly.

Billet piston

As part of the ongoing development of our dragbike; the decision was taken to supercharge. Also methanol fuel and an increase in cylinder bore (to utilise commercially available forged pistons for a larger Kawasaki), required that a new cylinder block be machined from solid. Photo shows the finished item prior to installation of the liners.

Billet cylinder block

A perennial problem with kit cars when utilising motorcycle engines, is arranging a reverse gear. In kit car racing this is normally mandatory. Common practice is to have an electric motor driving a gear sandwiched between the prop shaft and differential. This particular item is for a Fischer Fury, and incorporates a hardened steel gear with lightweight aluminium centre designed to locate prop shaft and gear in perfect alignment and thus retaining balance.

For all enquiries regarding car parts please click on the link below to contact:

P J Motors


Kit car reverse gear

Honda VFR 750 lock up clutch designed and manufactured for a fellow competitor in the National Sprint Association.

Honda VFR750 lock up clutch, designed and built in Wiltshire

Designed for a supercharged Honda Goldwing trike, this relief or 'blow off valve' was designed to meet a number of requirements. The space available was very limited at 65 X 65 mm and it had to be adjustable as the owner intends to "turn up the boost" for occasional racing appearances, it would also be nice if it weighed next to nothing!. The finished item achieved all these goals and is only 60 X 43mm. The design also allows easy disassembly for cleaning without upsetting the adjustment.

Adjustable supercharger blow off valve
Rally car rear axle brace

Rear axle support for this classic Opel rally car helps to prevent damage to the differential, when subjected to a pounding the original car was never designed to withstand.

Whilst restoring his Porsche 911 a new customer found 2 broken jets in one of the Zenith carburettors, having drawn a blank sourcing replacements he gave us a call and here is the result. Restoration and racing, for all your automotive engineering problems in Wiltshire and Somerset call Turnertech.

Porsche 911 carburettor parts remanufactured in Wiltshire