TYPE 35A BUGATTI


Ron Roycroft, Type 35A Bugatti.

In 1952 Ron Roycroft was racing a 1925 Type 35A Bugatti which was giving him considerable trouble and he had insufficient time to prepare the car properly. When I offered to attempt to get it right for the coming Ohakea race meeting, a collection of parts promptly arrived in my workshop.

Ron had a type 38, as well as the type 35A. and both motors were very similar. Both were two litre straight eights, comprising two cylinder blocks, with non-detachable heads incorporating three valves per cylinder, operated by a single overhead camshaft. The crankshaft is constructed in two pieces and runs in three large ball bearings.

The large assortment of parts were washed off and laid out for inspection. The next day I was in for a nasty shock when I inspected the crankshafts, which had been left in the sun to dry. Many black lines were in evidence, which in fact, consisted of oil coming out of fatigue cracks. Out of the four sections of crankshaft only one was sound, the others having several cracks showing.

A conference was called and in view of the fact that to make a proper job the elderly motor also needed new blocks, valves and guides, it was decided to assemble the best parts and trust and hope regarding how long, what best we could do, would last. This decision, as well as only ten working days being available to complete the task in hand, resulted in one of the best value for money jobs I ever did. I most certainly do not approve of assembling what amounts to a sick motor in a hurry, but in this case it was the only option.

The crankshaft assembled had several cracks in one half section, the worst being over half way through. It was found possible to drill and tap from the end and fit a 5/16 inch set screw, as a means of strengthening this fault.

The water pump was badly corroded. Fortunately Ron checked with me in time, when I was about to fit the type 38 pump, which it turned out was intended for slower speed operation. As a result a new impeller was milled from a piece of bronze shaft, as a replacement.

Grinding the hard to reach valves in the top of the cylinder blocks seemed a never ending task, and impossible to do well. In order to remove the exhaust valve the associated screwed in guide had to be first removed and never went back exactly as before, so that it was just as well that the stems were a sloppy fit as a result of wear.

When the time came to adjust the valve clearances, Ron's complete pit crew gathered around to assist. The procedure involved the assembly of the cam box onto the cylinders in order to check and adjust each of the twenty four clearances, using shims cut from feeler gauges. These were fitted inside the valve stem caps. The finger type cam followers were worn and this did not help matters. The results were not that good but near enough, all things considered. After two frustrating attempts we became short on time.

After assembly was completed Ron arrived for the much anticipated start up and trial run. He went through his drill of inserting matchsticks under the throttle stops and swung the crank handle. A short run on the road suggested all was going well and we forthwith packed up for the quite long drive south from Auckland to Ohakea. The run in company with other competitors was enjoyable, with most of the cars used in competition being driven to the event on the road.

Ron finished eighth in the Trophy Race. Unfortunately a throttle connection came adrift during the first lap. This was one of several items, which missed being checked due to lack of time. We stayed in Palmerston North for the rest of the week and the time was spent checking over the car. Warren Parkinson then drove the Bugatti to Waikanae where Ron joined us for the 50 mile N.Z. Championship Beach Race. Ron finished in second place behind George Smith in his GeeCeeEss Ford V8 Special.

After returning home and competing in some local events, about five of us set off for events in Napier. The twisty road over the Titiakura hills was loose metal in those days. Ron driving the Bugatti disappeared far ahead and we eventually found him waiting for us on the outskirts of Napier, beside a well cooled off Bugatti. An enjoyable weekend followed which included a kilometre sprint and a hillclimb. Some of us drove back and enjoyed the scenery via Lake Waikaremoana.


Bugatti, Pit Stop, Ohakea 1952.

Early in the following season, after competing in some local events, Ron and the Bugatti were again on the road to Hawkes Bay. When near Napier the crankshaft broke, at which point it had done well over 2,000 miles both racing and on the road. The car was left with a friend, Charlie Black, who later fitted another section of crankshaft and drove the car to Ohakea for John Mansel to drive in the Trophy Race.

Many years later when restoring the Type 35A, Ron brought me the crankshaft to look at. Encouraged by finding the 5/16 inch set screw still intact and with plenty of time available to consider the problem I was able to do a much better job. All the crank pins were drilled and 7/16 inch bolts fitted and torqued up to their elastic limit of approximately 3 1/2 tons. It was hoped that this would keep all the cracks under compression, so that no further fatigue could occur.

Bugatti shafts had a tapered joint inside the centre main bearing and in my experience seldom run true after being assembled. Every care was taken with the tapers being reground and this resulted in much greater accuracy being achieved. In order to reduce stresses I also advised that the low, compression pistons, i.e. 5.5 : 1, should be fitted.


BUGATTI COMPETITION RECORD

02/03/52 Ohakea Trophy Race, 70 miles. Placed eighth. One pit stop, due to a throttle problem.

09/03/52 N.Z. Championship Beach Race, Waikanae, 50 miles. Placed second. Winner G. Smith, GeeCeeEss Special. Time, 54 mins, 26 secs.

15/03 52 N.Z. Championship Hillclimb, Wairamarama. Sealed road. Placed first in the under 2000 c.c. class. Time 64,3 secs.

12/04/52 North Island Championship Sprint, Hawkes Bay. Standing Kilometre. Placed first in under 2,000 c.c. class. Time 33.4 secs.

14/04/52 North Island Championship Hillclimb, Hawkes Bay. Placed first in under 2,000 c.c. class.

07/05/52 Auckland Car Club, Mt. Eden Hillclimb. Placed second in under 2,000 c.c. class. Time 35.2 secs.

16/06/52 Northern Sports Car Club Sporting Trial. Road event for road cars.

21/09/52 Northern Sports Car Club Hillclimb, Wairamarama. Sealed road. Placed first in 2,000 c.c. class and third F.T.D. Time 60 secs.

07/12/52 Mt. Wellington Road Races. Time trial section. Partly loose metal road circuit.

14/03/53 Ohakea Trophy Races. Driver John Mansel.

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