Winter XK Project work and Engine Testing

A substantial rebuild was on the cards following the 2012 mishaps!

My 2012 race season was one, in the main I would like to forget, apart from the Silverstone Classic, which still shines brightly as the highlight of the season. The net result of breaking a drive-shaft at Brands, rolling the car at Donington and breaking the clutch at Spa in September, was to my mind time for a complete rethink and rebuild strategy for the XK140. With the bodywork now straight and true, it was a question of what to do about the engine, the gearbox, the suspension and the brakes. Firstly, the engine and gearbox were completely removed and the engine separated from its original gearbox and Overdrive unit.

THE ENGINE

The engine went back to Peter Lander at Sigma Engineering for a complete refresh. On disassembly, the crank was found to have moved forward, the bolts securing the clutch to the flywheel were all lose with one of them actually shearing and jamming the clutch release and this was the reason that the clutch would not engage nor disengage gears at Spa. The harmonic balancer was also damaged. Luckily, all journals, Rods, Pistons and the Cylinder Head were perfect.

THE GEARBOX

I decided that because I haven’t used the overdrive in any race for the past two seasons, I would not refit this unit to the car. Instead, I have bought another standard Moss Gearbox from the 1950’s and completely re-built and re-fettled it with new bearings, needle-roller bearings et al. By not using the Overdrive this will save me at least 15 Kgs in additional weight. This would then only constitute a longer prop-shaft to make the whole drive-train fully operational once more.

SUSPENSION & STEERING

The car has been riding very high since I started racing her so, Keith (My Mechanic) and I decided to lower her by approximately one inch. I now have a car which looks meaner as she sits a little lower and more square-on than she did before. In addition, all last season, the steering had a tendency to pull to the right during slow driving. It was nothing dangerous, but more annoying than anything else, not to mention the uneven tyre wear. We will only be sure that this has been eradicated once the lightweight XK aluminium wire wheels have been readied by Dan at the MWS workshop and re-shod for the coming season. But all the tracking, camber and castor checks have been completed. Fingers crossed!!??!!

BRAKES

The last item on the Winter agenda is brakes. Since the demise of the Carbotech Kellate-metallic brake shoe linings, we have all struggled to find lining material that does the same job as Carbotech once did. I have found a company in California who ‘Can’(?) supply such a shoe lining with a forecast that they are as good if not better than Carbotech. The jury is out on this particular subject, as many companies will make such claims until you try them and you find yourself back at the drawing board once more. I will keep you posted on this one, when they finally arrive from the US and are tested at Goodwood in anger, in March.

ENGINE TESTING

Finally, the car is back together and on Thursday the 17th January, yes, the day before the snow arrived (I was very lucky!), I towed her over to Sigma Engineering for engine re-commissioning! The first session was to run the engine in and smooth off any re-build sharp edges before I start racing once more. Peter sat in the cockpit and did the running-in whilst having his ‘Tuck Box’ lunch surrounded by at least a 100 db. (BRAVE MAN?). The second phase was to get the Air/Fuel ratio correct throughout the rev range. This took some time, as she was running rich at the high end and very lumpy and lean at idle. Carburettor needles were taken out put in the pillar drill and emery-clothed down a number of times to get the correct mixture at 800 RPM (Tick-over) up to 6500 RPM. This was finally achieved and a Performance Run proved to be very satisfactory. BUT, I am not disclosing the results, as we boys need to have some secrets. However, on the graph they couldn’t understand that ‘Drag Power BHP' was a lot less than last year’s readings. Then I realised, that this was due to the fact there is no Overdrive which increases ‘Drag’ and hence I have more power at the wheels.

In summary, we have gone as far as we can now until the ‘Shoes’ arrive and I am ready for my first Track/Test day and once I collect the 16” wheels from MWS with fresh rubber to go ‘A racing’. That’s it for now!

I will post my Race Calendar once I decide what Race Series I’ll race in for 2013.

All the best and have a happy, healthy and prosperous New Year.

John

John Davies Roberts