kz2zx
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Nobody in Particular
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posted February 05, 2005 07:00 PM
OT: Revalving a Shock (no pics)
So, I spent the day revalving a shock for the R6 trackbike. I bought a spare off eBay for $8, and the race-tech internals - yeah, it's not a Penske, but it's an improvement over the stocker, and it's a whale of a lot cheaper. New valves, bladder cap, sealhead, oil, spring, preload adjuster ran me $330, plus 4 hours worth of labor, and a $7.97 tool run to Home Despot at 0600 this morning.
Let's say that on the challenging scale this was a 7 on 1-to-10 scale. Nothing inordinately difficult in itself, but many moderately difficult operations to do in tight quarters with many many different tools needed, and a LOT of measuring. This was right there with trying to rebuild an entire Small Block Chevy (and measuring clearances) in a morning - very doable if you're mechanically skilled, nothing the novice mechanic wants to do him/herself.
The hardest part was removing the top circlip on the sealhead, as you had to get 'under' the clip (not an inside snap-ring), but could not move the seal head down (it was a three-peice assembly from Yamaha and there was a ring under it to keep the head together).
The next hardest part was the valving shims. The valving I needed was pretty different from the bags of valves shipped. Race-tech sells the valve shims in little baggies that should be complete for your needs, but I think they didn't have the right baggies for me, so they sent enough other baggies that I would have the right shims out of all of the bags, and a whole lot of extra (wrong size) shims when done. This meant about an hour of measuring (diameter, inside hole, and thickness) about 150 different shims and sorting them into the sizes I needed.
Right now the shock has 120 psig of air in the bladder, I need to dump that and find a welding/gas shop that will fill it with dry air or nitrogen to 225 psig. I checked with a local bike shop, and they want (hold on to your seats) $18 plus tax to put about 8 cu in of nitrogen into my shock... Only as a last resort.
So, I learned a bit, and sorry I had no camera. The next one will be less worrisome and a bit more fun.
And, looking at the stock valves, I'm convinced the Race-tech will be better. Maybe not as tuneable with the clickers as a Penske, but much smoother and more accurate damping than the stock Yamaha junk - I mean, the stock valve was cast with no attempt at improving the flow of the fluid, and there were only a small number of oddly sized (the steps between the sizes and the thicknesses) shims.
I'll leave the 10R shock stock for a while; I have a race season to go through for one thing, and I'm not sure what I'll be doing with the 10R long-term. Kawi will be visiting my 'home' track with a contingency race in November...
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ASMA 47
WERA 147
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