lowering rear shock


Trialsman

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We did a single track ride this weekend with a lot of "nothing but big rocks". On normal terrain I can reach the ground on my EXR comfortably but here, not so much. One of the things I did to my Husaberg 570 was lower the shock and it made a world of difference. Since I am seldom grounding out anyway maybe I might try lowering the rear an inch or so. Should I use the internal spacer method or possibly work with the linkage arms? I have a mill so I can make parts but has anyone already done this? How did it work for you? How much change in the center to center distance translates to how much travel reduction at the rear wheel? Will this method mess up damping, spring rate, or fender clearance?
 

Philip

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I think Slavens Racing had something that shortens the shock without the need to take it fully apart and then bleed. Like let out the air, push down the cap, add the spacer part, then put it back together, and re-inflate.
 

Trialsman

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Looking at Jeff's video I think I may try the Zeta spacer that goes on top without the need to disassemble the shock. They are on back order until 7/15. Anyone used one of these kits yet? The beauty of this set up is it is cheap, fast to install, and totally reversible if I find I want more or less.
 

enjoythesilenc

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You can make it pretty easily on a lathe. I made one for a past ktm but made it thicker than that zeta item. Lowered the seat by about 1.5-2 inches. You can make them in a split fashion like the Zeta or just turn a solid ring and then cut a birdsmouth in it to slide it around the shock shaft. Cut a small ledge for the shock circlip.

I didn't pay any attention to the piston height as shown in the video but don't remember any ill effects. I think I had a 34 inch tall 525 bike as I also made a 19 inch front wheel for it for tarmac use.

I have a nitrogen set up if anybody in my area needs a shock recharge for this operation or in general.
 

Trialsman

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I have not heard the term "bird's mouth" what is that? I also have a lathe and was thinking I might do it myself rather than waiting until mid July.
 

Trialsman

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I found this on Zeta's website. I took a quick od measurement of about 55mm so I assume we have the 50mm version on the id. Here is a screen shot of their part #.
Screen Shot 2020-06-16 at 10.22.16 PM.png
 

C5tor

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San Ramon, CA
We did a single track ride this weekend with a lot of "nothing but big rocks". On normal terrain I can reach the ground on my EXR comfortably but here, not so much. One of the things I did to my Husaberg 570 was lower the shock and it made a world of difference. Since I am seldom grounding out anyway maybe I might try lowering the rear an inch or so. Should I use the internal spacer method or possibly work with the linkage arms? I have a mill so I can make parts but has anyone already done this? How did it work for you? How much change in the center to center distance translates to how much travel reduction at the rear wheel? Will this method mess up damping, spring rate, or fender clearance?

Just let some air out of the tires! It'll lower it, and I'll throw in some extra traction for free. Bring it to my place and I'll do it for ya. Give you a discount, probably only take a week and cost a couple $100 bucks. If you want some premium vacuum in the tires, it's be a 10% markup.
 

enjoythesilenc

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The slot cut in the ring so you can install it without removing the clevis sort of looks like a bird's mouth but maybe i have an odd imagination20200617_081615.jpg

I guess this design could theoretically collapse inward?
 

Trialsman

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Just let some air out of the tires! It'll lower it, and I'll throw in some extra traction for free. Bring it to my place and I'll do it for ya. Give you a discount, probably only take a week and cost a couple $100 bucks. If you want some premium vacuum in the tires, it's be a 10% markup.
I only run about 5# of pressure with the Tubeliss anyway, but I might consider using a 17" rim if I could get the tire selection (tire profiles are also drastically different in height.)

As for the bird mouth, as a spacer that would be fine but it looks like there must be a continuous seal there as well. I figured I would need to make double the amount of 50mm rings so I can allow for the curf when cut, even with a thin slotting blade. That way I will offset the cut and use the larger of the two halves to come up with the proper 50mm dia.
 
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