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Re: trunnion bush length

To: John Loftus <loftusdesign@cox.net>
Subject: Re: trunnion bush length
From: Dave & M <rusd@velocitus.net>
Date: Mon, 20 Jun 2005 13:50:47 -0600
Hi John,

The original bushings are intended to have the steel sleeves clamped
solid before the rubber is clamped. The rubber bushing is a torsion
spring, bonded to the sleeve & clamped into the arms,  which is supposed
to flex/twist as the suspension moves. There was not intended to be any
rotating motion between the sleeve & the suspension arms or bolt. If
there is any rotating motion, there is no way to lubricate the joint &
premature wear will occur. If there is no grease fitting on a bushing it
was never intended to rotate.

The rubber torsion springs actually add a bit to the spring rates. This
is why the shop manuals say to center the suspension travel before final
bolt tightening.  (The part about placing a block of wood between the
upper arms & the shock tower). Also applies to the lower inner front
bushings & rear spring bushings. Centering prevents destructive over
rotation/flex of the rubber.

To repeat, the sleeve should come up tight before the rubber is clamped
to any great extent.

Dave Russell



John Loftus wrote:
 > When tying to install new trunnion bushes (rubber bushes with steel
 > sleeve positioned between the ends of the two shock arms) I was
 > running into great difficulty getting the shock arms to bottom in the
 >  middle where the cross bolt fastens them together. I compared the
 > new bushes with the old and found the steel inner sleeve to be
 > appreciably longer on the new ones (approx. .95" compared with .875"
 > for the old). I ground the inner side of the new ones down to the
 > .875" length (with bench top belt sander) and everything fit together
 >  properly. I plan to bring this to Moss' attention but curious if
 > others have run into this and to alert others who may face the same
 > problem.
 >
 > Cheers, John




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