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Re: Warning on Fulcrum pins

To: CoolVT@aol.com
Subject: Re: Warning on Fulcrum pins
From: Theo Smit <tsmit@shaw.ca>
Date: Mon, 12 Jun 2006 22:06:08 -0600
The "best available" solution from a pin strength point of view, is 
probably Dale A's pins where the minor pin diameter is increased so that 
it includes the inner bushing for the control arm. However, that just 
moves the problem to the next weak point, which is the four 3/8" bolts 
and their mounting in the lower crossmember. I had stresscracks 
radiating out from the mounting pads on my crossmember... checked yours 
lately?

The better answer from a system perspective is to adopt John Logan's 
solution or some variant of it, to retain the outboard end of the pin in 
a positive way. This allows the control arm loads to be dumped into the 
crossmember over a wider area, and it also puts the pin in double shear, 
which is a much better way to control heavy stress loads. Note that John 
Logan's solution is not everything to everyone... it doesn't allow 
fitment of oil pans with kickouts, and it also doesn't support the pin 
in vertical loads. Also, in order to give good support to the pin, every 
part of it has to be at least as strong as the pin, and it has to fit 
very precisely on the pin, otherwise it will just fret on the pin 
bushing and the retaining nut. A better answer would be to extend the 
inside pin pushing so that it was a snug fit inside the added outer link 
plate.

The take-no-prisoners approach would be to replace the crossmember and 
use properly located (double shear mounted) urethane bushings or 
spherical bearings to support the control arm, much like what Bob 
Hokanson posted last week. It's not stock, but if you want a Tiger you 
can drive to 9.9 tenths frequently without putting your front suspension 
on a scheduled component replacement cycle, then you have to make some 
invasive changes. As Bob said... it's just a bolt-on, no permanent 
chassis changes are necessary.

Theo




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