Dave and everyone,
I think Dave is doing an admiral job of playing devil's advocate here and if
his doom and gloom pontificating about the fulcrum pin design weakness saves
one life or one tiger, it will be worth it. He knows he is preaching a bit--
his "high horse" comment was his tongue-in-cheek way of admitting this.
A few things...
1) I am from Zambia, not South Africa, and I am currently living in Sri
Lanka. The pins were being made in Zimbabwe.
2) The EN24 pins are much stronger than the originals and after speaking to
several mechanical and aeronautical engineers this was deemed the best
material for the job (even stronger than the 300 and 400 series stainless
steels.) The only extra things we could have done were (a)to hard-chrome the
bush surface but this would have caused some surface embrittlement which
would reduce the fatigue strength and (b) shot peen the critical areas which
would have doubled the cost of the pins and according to the Air Zimbabwe
engineer who quoted on doing the peening, it would be safer to change the
pins twice as often rather than pay twice as much. Corrosion plus fatigue
are the cause of the original pins failing.
3) Supporting the pins from the outside (as per John Logan's design or
simple weld-on or bolt-on plates) is ESSENTIAL!! Why not do it? It is easy,
cheap and someone should make a kit. It reduces the bending loads on the pin
AND provides redundancy in case of failure.
Hope you all have a safe and fun year. I may be able to get more pins made
when I visit Afica in 3 weeks. cheers, derek
-----Original Message-----
From: owner-tigers@autox.team.net [mailto:owner-tigers@autox.team.net]On
Behalf Of DJoh797014@aol.com
Sent: Wednesday, January 02, 2002 3:35 AM
To: wittsend@jps.net
Cc: tigers@autox.team.net
Subject: Re: front end rebuild
Tom
Please don't tell me that you are betting your life and
car on unknown fulcrum pins that Derek White from
South Africa says are EN24. Does he have any
specifics and guarantees how this relates to SAE
ratings? Are you a qualified automotive engineer
in order to know what you are inducing when you
start modifying the relationship between the
fulcrum pin and bushings. I would gladly submit
you test results to my Phd Metallurgist who is a
stress analysis expert, to get his approval.
Sadly I just spoke to him. He has advanced
throat cancer and is not expected to live.
If you want to make modifications on your own,
do so at your own risk. Are you willing to take the
moral and legal responsibility if someone uses
such a setup only to have it fail 5 or 10 years
down the road?
John Logan tech tip should be required for all
Tigers. It ranks right up there with welding the
shock towers and upper ball joint mounting
sleeve.
Our cars are 37 years old with even older design
technology. As fatigue failures start to surface
it becomes all of us to alert fellow owners of
problems. To keep upping the horsepower and
changing suspension components may be
making changes beyond the capability of the
design. You must know what you are doing.
Time to get down from the high horse.
Dave Johnson, B382002668(under repair) Aurora, IL
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