12 replies to this topic

[Roger Clark]

This is from Thomas O'Keefe's Atlas story on Jim Clark and Dan Gurney. THe first paragraph is from Peter Jowitt's report on the accident, the second is O'keefe's

As soon as a side load is put on [a cut tire], in cornering, the tyre becomes unstable, and cannot generate the cornering force that the driver would expect. With the right-hand rear tyre deflating, the effect in a right hand corner would be some oversteer. Correcting this by steering left would put a heavier cornering load on to the unstable right-hand tyre, which would give rise to a fairly vicious right-hand oversteer. Correction in the opposite sense, at high speed on a very wet track, would clearly be difficult. The tachometer in the car, a mechanical type, indicated that Jim had the power on right up to impact, clearly trying to hold the car. There are, however, situations in which even the unearthly skill of Jimmy Clark will not suffice.

Call me a Clark fanatic or a conspiracy theorist, but that last sentence just does not sit well with me, putting too much blame on Jimmy Clark and almost completely exonerating Lotus and the Firestone tires. Think about it: if you have one of the following three people or entities to blame for a fatal accident in a Grand Prix car and you have Lotus, Clark and Firestone to choose from, which way would you lay the odds? It should be noted that Peter Jowitt was also called upon to examine Jochen Rindt's Lotus 72 at Monza after his fatal accident during practice for the September 6, 1970 Grand Prix. There is also controversy surrounding that accident, where Rindt was running in an experimentation mode without winglets on the front of the car, when the brake shaft broke under maximum braking and the Lotus 72 hit the Armo barrier.

I have read much about the accident and its causes. The consensus seems to be that it was the tyre that failed. this is, I think, the first time I have ever seen any doubt cast on the integrity of Peter Jowitt, whose profession was an aircraft accident inspector.

[David McKinney]

I can't see that Jowitt's comments in any way blame Clark. The way I read it is that's he saying the circumstances were such that even the best driver in the world could do nothing to avoid an accident

[Roger Clark]

So do I. It's O'Keefe's first sentance I can't understand.

[Bernd]

Here is Colin Chapmans account of the crash

'Jimmy probably picked something up in the tyre on the 4th lap. It didn't need much loss of pressure for the effect to be felt and, when Clark started to go through the twisting part of track in front of the grandstands, the rear tyre pressure was possibly down from 15 psi to 10 psi. When he reached one sharp left-hand bend a fellow driver saw him slide then quickly correct it. As the next corner was a sharp right-hander, the weight of the car would have been thrown onto the left-hand side and away from the right-rear tyre, and it was assumed that Jimmy put his trouble at the previous bend down to the greasy surface of the track. Even if the pressure had dropped to 8 psi, the tyre would have stayed on the rim as it was a slow right-hand corner. However once he opened out to the back straight, the steadily rising speed and steadily deflating tyre brought the power of centrifugal force into play. In tests following the accident it was found that, under these conditions, the tyre would begin to grow and at a crucial point, the sidewalls would be drawn in, and there would be an explosive depressurisation as the air rushed out. From that moment the accident was inevitable'

A exploding tyre similar to Mansells infamous Adelaide incident robbed us of Jimmy Clark, the car was proven mechanically sound so those blaming the fragility of Lotus cars were for once mistaken.

In practice the previous day, Walter Habegger had broken the crankshaft of his car in a big way, and a small fragment of metal may have been lying in the road. In my mind this is the most likely reason for the fatal tyre depressurisation.

[Ray Bell]

I can't see how any comparison could be drawn with Mansell's Adelaide incident... the tyre wasn't delaminating or fragmenting or tearing itself to shreds as was Mansell's, but simply deflated.

Some of the effects might be similar, but with Mansell's car, which it should be observed also had much less forgiving suspension, got tossed all over the shop.... with a front wheel off the ground, which Clark wouldn't have suffered.

[Bernd]

Ray it was described in the Accident Investigation report as an 'explosive depressurisation'

Draw your own conclusions but really we will never know because no one saw the incident. A marshal saw Jim fighting for control after it happened but that is all.

[Bernd]

Though to clarify the tyre was not blown to bits like Mansells and stayed essentially intact.

Basically what I meant was that it was a simple tyre deflation that cost Mansell the title and Clark his life.

But it HAS been proven that Jimmy Clark was certainly not at fault.

[Ray Bell]

Nobody ever doubted that, I'm sure.

[buzard]

Derick Bell's bio has a different view. Derick's first F2 race
was Hockenheim. He said he overheard Clark complaining
that the engine would sometimes cut out completely. Not
missfire, but stop running entirely.

Bell is convinced tht halfway through the turn the engine cut
out and started to slide, Clark corrected just as the engine
started running again and it took him off the track.

He thinks Clark underestimated how dangerous the problem was.
I think that practice was in the dry and it did not rain until
the race, but I could be wrong.

That problem would be bad in the dry and really bad in the wet!

buzard

[Bernd]

Bells view is pure conjecture, it was proven that the tyre problem took him off.

It is correct that Jim had been having engine problems all weekend but I think though the car was down on power during the race its misfiring problems had been fixed.

It really shows what a true racer he was to continue with the weekend at all the way it had been going, problems upon problems the car did not have gremlins it was a gremlin.

[Ray Bell]

We have to welcome our new member with his first post... come on in, Buzard, I'm listening even if the popular opinion is that the tyre did it...

Derek's a mate of mine...

And don't forget to go to the Introductions thread.

[Bernd]

oops Sorry I didn't realise Welcome Buzard!

[buzard]

That was pretty much all Bell said. Not anything to add.

And I post an entry in the introductions topic!

buzard