I have heard of frames cracking at the shock mounts. However it is not solely
the fault of tube shock upgrades. They would eventually crack there with the
lever arms as well. When the frames weaken from corrosion and age (metal
fatigue) adding a higher rate shock than the lever arm (even stiffer oil in
the lever arm) can hurry the failure. One sure way to combat this is to add
extra strength to the rear crossmember spring perches and shockmounts. I
believe that Ted Schumacher makes such a strengthening kit. I have also spoken
to TR specialists in England (where they deal with particularly soggy frames
frame age and corrosion) of additional bracing from the back side of the shock
mount to the frame. Especially on "Fast Road" cars with uprated springs and
shocks.
That being said, I do still consider the tube shocks to be an "upgrade"
because they do improve the ride and handling IMNSHO. I too am using the KYB
kit in the rear (John Horton's kit) and Michael does bring up good points
about making sure everything is tight. Which also applies to lever arms for
their bolts will loosen as well.
It's not uncommon with any car that when you "improve/upgrade" one thing that
you also have to "improve/upgrade" another area in order to realize the full
benefit of the first. Especially when it is a performance upgrade vs. a
longevity upgrade.
Shawn
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