[Fot] TR3 rear shock conversion

[Bill Babcock]

It almost certainly will solve that problem, which leaves all the rest. I
think the biggest problem is structural--the damping has to happen over a very
short stroke. The lever greatly amplifies the distance to give adequate
travel, but that means the damping has to be much stronger to give a similar
damping force, and occurs over a small stroke. I think the stroke is important
because of the time required for the valving to respond and how fast the fluid
has to move.

That's all just theory, the bottom line is that when you put an armstrong on a
shock dyno it looks horrible. A classic shock damping profile looks like a D
laying on it's back. An armstrong profile looks more like a seismograph during
an earthquake. I know Tony Garmey and Jeff Quick fiddled with armstrongs on
Tony's shock dyno. I don't know if they ever got any improvement. I didn't see
their work, I put all of mine on a shock dyno here in Portland, hoping to
match them up and play with the valving. The guy who ran their dyno thought
they were broken. They weren't.

On Jun 24, 2010, at 2:29 PM, Randall wrote:

>> The lever shock can
>> "foam" the fluid so the damping effect is lost since the shock fluid is
>> now foam rather than pure fluid.
>
> Seems to me that it would be pretty trivial to fix that, if it is really a
> problem.  The solution is the same as implemented in (some) tube shocks;
add
> a divider between the fluid and the expansion (air) space, so there is no
> way for the fluid to get mixed with air (aka foam).
>
> For lever shocks, I'm thinking of an external canister with a bladder in
it,
> somewhat similar to an Accusump (but much smaller of course).  Tap the top
> cover of the lever shock for a fitting, run a line to the canister mounted
> on a frame rail.  Since relatively little pressure is involved (just
> whatever is generated as the shock heats up and forces oil into the
> canister), the plumbing should be easy.  Hardest part is probably filling
> and bleeding the air out of the hydraulic side.
>
> Even some tube shocks use this setup:
> http://www.shockabsorbersworld.com/shocks-reservoirs.html
>
> -- Randall
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