Progressive springs

From: SMTP%"lawrence@aclcb.purdue.edu" 22-MAR-1995 13:31:27.70
To: MEL1523
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Subj: Progresive springs

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Date: Wed, 22 Mar 1995 14:32:52 +0000
To: MEL1523@ACS.TAMU.EDU
From: lawrence@aclcb.purdue.edu (Jim Lawrence)
Subject: Progresive springs

>Date: Mon, 23 Jan 95 13:39:17
>From:
>Subject: Progresive springs
>To: mx%"lawrence@aclcb.purdue.edu"
>Cc:
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>From: MX%"Doug_Wiebe@NeXT.COM" 30-JUN-1994 19:27:15.06
>To: MX%"HawkGT@dsea.com"
>CC:
>Subj: Re: Progressive Front Springs
>
>> In a former Sport Rider article (I think it was called Franklin's Mint)
>> there was a side bar dealing with a suspension tuner's advice for the
>> Hawk's front end. Among the suggestions was to cut the _stock_ springs a
>> certain amount and add a longer spacer. I'm wondering why he didn't just
>> recommend throwing in a set of Progressives.
>
>Sounds like Jim Lindemann, Bay Area suspension tuner extraordinaire. Jim is
>very familiar with Hawks as he has done on lot of work on local race Hawks.
>He told me that he experimented with Progressives for the Hawk but that he
>found that he got better results by modifying the stock springs, which he
>says are high quality. He does recommend Progressives for some bikes but not
>for Hawks.
>
>I had him do his standard "Hawk job" on my bike a while back. As I recall, his
>theory is that the stock Hawk front end has too little low-velocity compression
>damping, too much high-velocity compression damping, and a too soft initial
>spring rate. (low-velocity and high-velocity of course here mean rate of fork
>compression). The lack of low-velocity compression damping and too soft spring
>rate are what cause the stock Hawk to dive excessively under braking and in
>general feel kind of soft in the front end. The extra high-velocity compression
>damping cause the Hawk to not track bumps as well as it could.
>
>His "fix" is to lop a couple of coils off of the stock springs, put in
>longer spacers, thicken the fork oil slightly, and revalve the damping rods
>(enlarging some holes and closing others). The shorter springs and thicker oil
>and revalving improve the low-velocity compression damping. High-velocity
>compression damping is also improved through the revalving. I think he also
>said something about there being less net spring preload for better compliance.
>(If this sounds like nonsense or is impossibly vague it is probably because I
>am trying to recall a conversation with Jim that I had a long time ago about
>a subject (suspension tuning) with which I am generally unfamiliar. I'm sure
>that any errors in concept are mine and not Jim's).
>
>Anyhow, the subjective result was that the front end feels noticeably more
>"taut". There is still front end dive under braking but not as much as stock.
>Compliance seems good but not dramatically better than stock, i.e., I'm not
>sure how much of the perceived improvement there is placebo effect.
>
>Anyhow, if you want to talk to Jim his number is 408-371-6151. There is a
>fellow John that works for him that can also explain things to you but I
>personally had better luck (in terms of getting explanations that I could
>mostly understand) talking to Jim. I'd appreciate any corrections he might
>give to what I wrote above.
>
>- Doug
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>From: Doug Wiebe
>Date: Thu, 30 Jun 94 14:42:58 -0700
>To: HawkGT@dsea.com
>Subject: Re: Progressive Front Springs
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>From: lawrence@aclcb.purdue.edu
>To: LAWRENCE@ACLCB.PURDUE.EDU
>Message-ID: <0098AE4F.2A3CD960.55@aclcb.purdue.edu>
>Subject: Progresive springs
>
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