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Re: Motorcycle fork oil in lever shocks (was TR-3A - Rear shock absorbe

To: "Peter C." <nosimport@mailbag.com>
Subject: Re: Motorcycle fork oil in lever shocks (was TR-3A - Rear shock absorber fluid)
From: Dave Massey <105671.471@compuserve.com>
Date: Thu, 10 Feb 2000 16:43:48 -0500
Cc: TR List <triumphs@autox.team.net> charset=ISO-8859-1
Peter C. writes:

Dave,
        You're a nice guy and I admire many of your tech tips, however (you
knew
that was coming)...
I happen to be intimately involved with lever shocks. Changing the fluid
(f?) is not the same as altering the valves. Specifically because there are
poppet valves in the end of each piston through which oil must also pass.
This must be allowed to happen quite easily. The spring in the valve is
very weak, like 3 coils of a retractable pen spring operating on a ball
bearing. Stopping up this valve _can_ (not will) destroy the shock in
various ways, most typically by stripping the splines on the shaft.....
I've seen it lots of times. It is quite straight-forward to alter the
valving and I am happy to share that. It is also preferable to change the
rebound and compression at different ratios rather than merely stiffening
both by the same percentage as would occur when adding heavier oil. I will
also say that it is possible to make a leak free shock.
        End of dissertation. Thanks for listening.
Peter C

Oops.  Put me in my place.

My line of thinking goes like this:
Any old wrench monkey (like me, for instance) can drain out and replace 
the fluid in a shock but changine out the valving involves taking out some 
of the BIG, tight plugs on the shock body and playing with the intricate 
mechanisms inside which I am loath to do since I have had no experience
with these things and am willing to pay someone who has experience the 
reasonable amount of pocket change to take care of it for me.  When I sent 
my TR6 levers off for rebuild I opted for the additional $10 for the heavy
duty 
valving which is more rational than taking a freshly rebuild shock and 
changing out the oil, IMO.  (Sorry, they are Apple rebuilds.  Next time
I'll 
use yours.  BTW the TR3 shocks are in need of attention...)

I think you'll agree with me when I say that stiffening up a shock by 
either method will have no different effect on the shock link, the shock 
mount on the frame, the mounting bolts, even the pivot bearings.  

But what it does to the insides, I don't know.  But it is a very common
modification
and I haven't heard a groundswell of problems stemming from this practice.

Thanks for sharing.

Dave

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