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Re: [Tigers] fulcrum pins

To: AAAGLASSS@aol.com
Subject: Re: [Tigers] fulcrum pins
From: Tom Hall <modtiger@comcast.net>
Date: Sun, 08 Feb 2009 17:51:49 -0800
At 04:06 PM 2/7/2009, you wrote:
>Any comments on this????????????????????

Hopefully to complete this discussion, there are a few factors to 
keep in mind.  First the Fulcrum Pin failure mechanism is due to 
cyclic metal fatigue.  The original design was done a long long time 
age when narrow bias ply tires were the state of the art.  It was 
also done for a vehicle that was powered by a 4 cylinder engine of 
less than 100 HP.  The design was certainly not the best in the 
world, but likely adequate for the intended service life of the 
original vehicle.

So here we are about 50 years after that design was conceived and 
were talking about a radically different vehicle which was redesigned 
into a sports car.  The power was increased initially by a factor of 
two and uncounted owners have increased the power by several factors 
above that level.  The vehicle was handicapped by a design compromise 
in the steering mechanism that was accepted by the manufacturer to 
save money.  Now we add to this the additional stress of tire 
compounds and stiffer shock absorbers, and the occasional use of this 
system close to the limits of the new composite assembly.

So the fulcrum pins on your vehicle have seen a lot higher stress 
that they were ever designed for.  They may have also managed to 
endure this increased load for 40+ years, a lot longer that anyone at 
the factory ever dreamed of.  Still the number of failures are really 
small in comparison to the number still in the field.  The failures 
also range from those resulting from backing into a parking space 
(the worst possible loading short of an accident) to those that have 
occurred on the highway at speed with disastrous results.

The problem is that the failures are instantaneous and can and do 
lead to a total lack of control.  This problem with the fulcrum pins 
has also been known for a long time.  Long before this list 
existed.  I wrote tech tips on this problem so long ago that I can't 
easily find my original files on the subject.  A substantial number 
of the population has had the pins changed at lease once if not more 
often.  I don't know of any knowledgeable shop or individual that 
would reuse a used fulcrum pin when they replace the suspension bushings.

If you are new to this Marque or this list, you are likely not aware 
of many of the situations that can effect the safe operation of a 
Tiger.  The risk is very personal and I recommend that you spend the 
time to become aware of the potential situations and alternative 
solutions that many of the rest of us have lived with and talked 
about for up to 40+ years.

Tom Hall
ModTiger Engineering LLC
Support Team.Net  http://www.team.net/donate.html



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