8 replies to this topic

[Nev]

Norman Dewis confirmed that new wheels and tyres were added prior to filming in 1971. The XJ13 Log Book states these wheels were made NEW after testing of the car only four years earlier (late in 1967). Excepting possible manufacturing defects, it is perhaps unlikely that they could have deteriorated to the point of failure in that short space of time in storage?

When the tyres were fitted to the car’s new wheels in 1967, they were fitted without the benefit of inner-tubes (confirmed by reference to original XJ13 Log Book). It is possible that the new tyres fitted before filming in 1971 were also fitted without inner-tubes. This, in itself, should not have caused a tyre failure. A more likely culprit may have been an unsubstantiated rumour that a rear tyre was “plugged” to prevent a slow leak before the final high-speed laps?

It is believed that the incident occurred at a speed below those attained during the short period of the car’s active development – although the speed may have been well in excess of 135mph (ref "Norman Dewis - Developing the Legend") it is unlikely the accident could have been caused by “lifting” or other “aerodynamic” reasons.

Another possibility could have been failure of a rear radius arm. Using the engine block as a stressed member, the rear wheels were mounted by a driveshaft (as upper link), a fabricated lower link and two forward-facing radius arms fixing directly to the engine mounting block. This was a rather innovative solution for the mid-1960s. Examination of the wreckage revealed a damaged upper radius rod on the rear right-hand side (offside). However, this damage could have been sustained during the impact. If not, a failure such as this could explain why the car “lurched to the right” before making contact with the safety-fencing at the top of the banking.

[xj13v12]

The wheel broke according to reports of the time and since. A wheel doesn't have to be old to break.

[Philip Whiteman]

It wasn't just that Norm overcooked it, then?

[Nev]

It wasn't just that Norm overcooked it, then?

Of course, that is always a possibility. However I have enormous respect for Norman's driving skills and I feel this may have been unlikely? Can't discount it though.

It has now (today) been confirmed to me by two more independent sources (from within Jaguar) that there was definitely a slow leak and the tyre was definitely plugged before the final high speed laps. Perhaps now rather more than "an unsubstantiated rumour? 135 mph+ may have been just too much for the temporarily repaired tyre?

A deflated tyre allowing the car to run on its rim could have resulted in a damaged wheel?

[Philip Whiteman]

Plugging a tyre on a competition car just about to go out on a high-speed run around a banked track; does that make sense to anyone? Seems like a bloody daft idea to me!

[Bloggsworth]

Plugging a tyre on a competition car just about to go out on a high-speed run around a banked track; does that make sense to anyone? Seems like a bloody daft idea to me!

In those days "Plugging" was the approved method of repairing a tubeless tyre.

[Philip Whiteman]

Even on a racing car? Anyway, I stand corrected and apologise for any slight on those concerned at Jaguar

[Nev]

Even on a racing car? Anyway, I stand corrected and apologise for any slight on those concerned at Jaguar

My "sources" indicate that it was never intended to drive at those speeds at the end of filming. It seems the temptation was just too great ....

[Bloggsworth]

Even on a racing car? Anyway, I stand corrected and apologise for any slight on those concerned at Jaguar

I don't say they should have used a plug, but if you took a tyre to a depot, even Dunlop in Albany Street, it was the only option offered (Unless, of course, it was in the sidewall, in which case you'd be offered a new tyre...); vulcanisation had fallen out of favour, plugs were The new thing.