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  #11  
Old 05-12-2018
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dwb79 dwb79 is offline
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Quote:
Originally Posted by Nutty View Post
The P spring is a work-around that covers up the stock shocks too-tight initial HSC damping and weak rebound damping at the top of the stroke.

Can you elaborate on this Nutty?

To me, those words are contrary.
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  #12  
Old 05-12-2018
Nutty Nutty is offline
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Quote:
Originally Posted by dwb79 View Post
Can you elaborate on this Nutty?

To me, those words are contrary.
Apologies. My lack of care with terminology there Dave.

Given that the HS stack in the top-bolt is logarithmic there is a damping curve associated with the shape of that shim set.

Various high-shaft-speed events will activate more of that shim set than others.

By 'initial' I meant the lower rates of deflection on that HS set, (not beginning of travel). Initial in a physical deflection sense rather than a velocity/pressure/travel sense.

IMO there's a lot of goodness to be gained up there. Ryan Marmont does a billet double-adjuster shock head for PDS shocks and the difference it makes is astounding. NOST made a replacement top-bolt for a while, it was good too.

With both P15 and 20, I (78kg) felt they blew through the first 2/3 of the stroke and then went too stiff. They were good for sand whoops but horrible on a MX track IMO.

I get the idea, trying to get the variable ratio in a PDS a bit closer to a linkage, I just preferred the straight-rate after a few tuning tips from Bluerider. P springs aren't that weird that a good tuner can't get them working really well. I rode a 525 that Terry did with a P20 and it was superb.

As I think I intimated, on a STOCK shock I prefer the P spring.
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  #13  
Old 06-12-2018
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Quote:
Originally Posted by Nutty View Post
Given that the HS stack in the top-bolt is logarithmic there is a damping curve associated with the shape of that shim set.
Thanks for breaking it down Nutty. I have another question.

I understand what a logarithmic equation, action or graph is, but I've never really heard it used to describe a physical part before. What do you mean by the stack is logarithmic?

Once I understand what you mean, I'll show you a damping curve of the comp adjuster (top-bolt) only.
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  #14  
Old 21-12-2018
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Well, it looks like the previous owner has set the spring preload with a hammer and a screwdriver with the bike sitting on the ground as the threads on the shock body are sheared and I had an absolute prick of a time trying to loosen the preload nut to get the spring off.

I was able to find a 2nd hand shock on gumtree from an identical bike and have been provided with a stock spring and a 95kg spring.

After reading the answers here, I'm leaning towards a 7-9kg progressive spring, thanks for your sound advice fellas
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