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Discussion Starter · #1 ·
On my 2008 ZX-6R, I want a softer ride than I have right now with the current spring preload on the rear shock absorber.

1. After unlocking the rear shock absorber adjustment ring locking ring (the top ring), and looking from top of the shock absorber downward, which way should I turn the rear shock absorber adjustment ring (the bottom ring) to soften the ride? Clockwise or counterclockwise?

2. Is there a special tool required to do this correctly, or can i simply lightly tap the locking ring and the adjustment ring with a hammer and screwdriver?

Jim G
 

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Discussion Starter · #3 ·
Jim you must turn it counterclockwise, there is a specific tool that looks like a hook but be careful not to mark the ring you can do it with a light hammer and a flat blunt screwdriver
Thank-you, Brader! The toolkit that the previous owner passed on to me does not include a shock hook, but that could be because he misplaced it. I THINK I have one of those somewhere from a prior motorcycle, but if not, I'll do the hammer and blunt rod thing!

Jim G
 

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Pursebully
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Loosening the preload nut on your shock will only increase your sag. It will not change the spring compression rate, nor will it change the compression damping of the shock. If you want a softer ride, you'll want to purchase a spring made for your weight/riding style and adjust your damping rates. This will affect your traction (negatively, if done incorrectly).

The spanner wrench ("shock hook") does not come with any kit that I've ever seen.
 
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The spring preload of the shock absorber has a useful adjustment range of 10 mm (between 175 and 185 mm of total spring length) depending on the weight of the person riding the motorcycle. Regulation must be done within that range.
OEM manual, chapter 13-22
 

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I'd also add, if you are going to do this, to take the weight off the back of the bike and clean and lube the threads with a light oil to prevent the threads from binding.They are anodized but have been known to gawl and bind up on occasion. Then you're screwed. Had this happen to my '02.
 

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Pursebully
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...and, depending on how heavy you're swinging the hammer, it's likely that your rod/punch/screwdriver/whatever will deform and raise the edges of the fingers on the adjuster. This can put gaps between the adjuster and jam nut which makes it harder to get the jam nut properly tightened. I highly suggest using the correct tool.
 
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Discussion Starter · #8 · (Edited)
Thanks, Guys! I appreciate the guidance, as playing with rear suspension is new to me. I've generally left it at default factory settings, but this specific bike has good enough suspension that I want to try to actually optimize it. So I have some specific questions:

First, I actually do have somewhere one of those hook wrenches for making the adjustment (cannot remember what motorcycle it came with!), so will try to find it.

Yes, my adjustment ring and locking ring were "stuck" when the Kawi dealer tried to adjust it a couple of days ago while doing a different service for me (fork seals), so he suggested that I squirt in some penetrating oil and then ride the bike right afterward, and see if that would loosen them up without needing to pound on them with a hammer and blunt edge to avoid the damage potential you guys mentioned and its effect. That worked. Both rings now spin readily without applying a lot of force!

I will check out the service manual instructions for the adjustment, as the user manual simply says to have your dealer do it.

If I understand you guys correctly, rotating the adjustment ring counterclockwise (viewed from above) should be restrained by keeping it within 175 and 185mm of spring length. I weight 187 lb, but with my safety riding gear on, I weigh exactly 210 (No kidding. Klim armored Badlands jacket, Klim armoed jeans, Sidi boots, and Klim armored gloves, all add up!).

Given the 210 lb "dressed" rider weight, what length should the spring be set to? And, how exactly do you measure the spring length? Is it accessible enough to get a tape measure in there?

EDIT: I just read the entire section on suspension adjustment in the service manual. I found 2 very interesting things:

1. The service manual and the user manual are inconsistent on SOME of the settings in terms of whether turning an adjustment "IN"(CLOCKWISE) OR "OUT" (COUNTERCLOCKWISE) softens or hardens the action. Since the vast majority of the time both manuals agree that turning adjusters IN hardens the action, I assume they meant this for ALL the adjusters, and just had misprints a couple of times.

2. The rear spring preload is one of the adjustments that seems contradictory. The service manual (page 13-20) says that the acceptable range of spring length is 6.89" to 7.28", but says that you SHORTEN the spring to make its action SOFTER. This seems contradictory, since compressing a spring normally makes it react more vigorously. Is this a misprint in the service manual?

Jim G
 

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Sorry. Not sure about spring length. My '07 has a Pensky on it now and I'd imagine the spring lengths will vary. It's better to adjust the spring preload sag anyway.
 

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Discussion Starter · #10 ·
I found that all the suspension adjustments, front and rear, were at the factory default, except the spring length was at the shortest recommended length (6.9"). Since the spring was right at the "shortest" limit that the service manual prescribes (6.89"), I used the adjustment wheel to lengthen the spring to 7.05, so lengthened it by 0.15". That does not sound like much of a difference, but it removed the harshness that had been bothering me on highway pavement discontinuities. At 7.05", It is now well inside the recommended limits of 6.89" to 7.28" length.

I could lengthen it some more if I want to, but my 21 km test ride after making the adjustment seemed fine. I'll give it some more kilometers before adjusting it any more.

Jim G
 

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Discussion Starter · #11 ·
I cannot believe how nice a difference that 0.15" lengthening of the rear suspension spring made. The harshness over pavement discontinuities at highway speeds is gone. The suspension right now feels about as good as I have ever had on a motorcycle. I guess it is true that small changes in suspension can make a huge difference.

Jim G
 
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