[Tigers] Lower fulcrum pin

Allan Ballard aballard at ix.netcom.com
Thu Aug 17 11:46:09 MDT 2017


Under what type driving conditions are fulcrum pins prone to failure?

I understand that highway driving produces very low risk while auto cross type driving heightens risk?

Is there any truth to that?

TIA

Allan Ballard
Mk1a
v6 Alpine

Sent from my iPhone

> On Aug 17, 2017, at 1:14 PM, Jay Laifman via Tigers <tigers at autox.team.net> wrote:
> 
> ... and never go near full lock when backing up.  
> 
>> On Thu, Aug 17, 2017 at 9:29 AM, Tom Witt via Tigers <tigers at autox.team.net> wrote:
>> Richard,
>>   I never received the original email with your picture so I can’t comment to what it shows.  That said my understand is there are two points of failure. One at the point where the pin pinches in and the thickness narrows for the clamping bolts. The other is as Ron stated where the pin curves/tapers. Apparently not only a point of weakness, if the nuts work loose the curved washers rubs on the pin, work hardens them, and thus increases the likelihood of failure.  Last I knew the best fix is to purchase the non-rubber (Urethane???) bushings, remove the center steel insert and use a pin that much thicker. There are (at least were) a number of people who made the oversized pins.  Given the rarity of a Mark II and the associated value it might be money well spent to consider that upgrade.
>>  
>> From: Ron Fraser via Tigers
>> Sent: Wednesday, August 16, 2017 8:48 PM
>> To: 'Richard' ; tigers at Autox.Team.Net
>> Subject: Re: [Tigers] Lower fulcrum pin
>>  
>> Richard
>> 
>>                 My 1st guess would be that those marks are from a jack stand.  I’m not totally familiar with where the stress cracks occur but I believe they form where the square bar is turned to round.  Machining marks are generally where stress risers occur and a crack will start.
>> 
>>  
>> 
>> Ron Fraser
>> 
>>  
>> 
>> From: Tigers [mailto:tigers-bounces at autox.team.net] On Behalf Of Richard via Tigers
>> Sent: Wednesday, August 16, 2017 8:42 PM
>> To: Tiger List <tigers at autox.team.net>
>> Subject: [Tigers] Lower fulcrum pin
>> 
>>  
>> 
>> While cleaning under the Tiger today I noticed a mark on the center of the  left lower fulcrum pin.  After I sanded off the paint the marks in the attached picture appeared.  They are not as deep as they appear in the picture.  There a couple on the right side but not nearly  as much as on the left.  They kind of look like they were made by something  holding the pin at installation?  They don’t appear to be stress cracks, but knowing the history of fulcrum pins  failing, I would appreciate the expertise of the List.  The car is a 67 Tiger MKII, speedo showing 42000 miles, don’t know if they are original.
>> 
>>  
>> 
>> Thanks
>> 
>> Richard
>> 
>> 
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>> 
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>> 
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>> 
> 
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