kz2zx
Pro
Nobody in Particular
Posts: 1166
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posted October 17, 2004 12:38 PM
Installing Race Tech - With (too many?) Pictures!
Last weekend I'd posted about performing unlicensed surgery on the trackbike's fork internals. This weekend, after the family vacation finally ended (was an expen$ive vacation), I was able to get to the other fork.
I took pictures...
Starting with the virgin fork, removed from the front of the bike before I started working on the internals last week. The GM floorpads are there so I can kneel while I work...
A view of the top of the fork, the cap, and the retaining spring. The circlip in there needs to come out without deformation, as I don't have a ready source for 40mm (the tube O.D. is 41mm) inside snaprings. This means the cap/plug must be depressed, the circlip fished out, and the spring tension gradually released by lifting the cap/plug out slowly, lest parts go flying, launched by the fork spring.
The way to do this is to replace the fork in the upper triple clamp, and use a c-clamp to drive the plug down so the circlip can be removed...
fishing the fork back up the triple:
Tightening the top triple on the fork in preparation for removing the cap:
The c-clamp and a 17mm 1/2" drive socket I used as a spacer:
The fork cap depressed, and the circlip ready for removal:
Removing the clip:
And the cap is free! See the stock spring preload spacer under the cap:
Removing the preload spacer:
Pouring out the old fork oil. After this shot, I pumped the slider a few times while tipped over and pouring out the oil to work some more through the damping rod internals.
After this, it was just a peice of cake to tip it further and catch the spring and the spring washer. Shown here extracted as I needed both hands...
Time to remove the damping rod screw. It's the screw you can just see as we look up the bottom of the fork.
I placed the fork into the vice loosely. Note the rag to catch the dripping oil under the top of the slider.
The 6mm Allen key ready to remove the damping rod screw:
And, a little gentle persuasion on the hex key, and presto!
Just to remove doubt of which screw was meant if you try this yourself, here it is, partially extracted, from a side view:
Removing the screw means more oil (trapped in the damping rod) drains... so do this over your drain pan.
Time to remove the forkseals! A gentle prying with a flatblade driver and I lift the dust seal:
Under the dust seal you can see the top of the oil seal and the retaining ring:
Gently lift the retaining ring out of it's groove with a screwdriver:
Now, grasp the fork slider, and with some force, slide it up to the upper stop. You're trying to drive the oil seal and bushing out of their seats, so you can remove the slider. This will take several "blows". Don't worry! you won't hurt your fork!
Voila! the slider is out, and the oil is dripping onto the catch rag... Note the black oil seal, the oil seal washer, the copper-colored outer bushing (this gets driven into the fork lower leg, and was the part I removed forcefully with the pulling of the slider out of the lower leg). There is an inner bushing, sort of greyish directly under the outer bushing, and the damping rod is the cockeyed tube with a tapering point - it's cockeyed since it's loose. The screw I removed earlier locates the rod and keeps it upright when installed. * Very important * Lay the fork seal down on a flat surface top side UP, far from where you are working, so that you can compare it and it's orientation later!
Tip the slider upside down - and out comes the damping rod and the top-out spring. Note the small hole cross-drilled through the rod near the taper - this is the compression damping bleed, and is the reason I'm installing the emulators.
Grab your internal fortitude, boys, time to drill out that useless hole in the damping rod. I've got a 5/16" drill bit about to remove the damping...
The stock hole made larger:
Not the best picture in the world, but here are two new 3/16" holes drilled 90° from the first (enlarged) hole, and made far enough apart to not weaken the damping rod.
The unlicensed surgery - note the precision with which I drill these holes (not!). One's slightly offline from the other, but it doesn't matter. The point here is to create enough flow for the damping oil that there is no restriction from teh damping rod.
Okay, cleaning up and chamfering the holes. I didn't take a picture of me with a long ratfile cleaning the inside burrs off, since I needed both hands to do it.
The finished damping rod. I washed all the metal flake out (from the drilling) with a water jet (laundry room sink), then chased the water away with WD-40.
Reinstallation! The top-out and rod about to go back in the upper slider:
The slider assembly inserted into the lower leg. The circle around the slider is the copper outer bushing - we need to drive it into place.
The seal washer over the bushing - we will drive the bushing in place, next:
My *High-Dollar* seal driver tool (no, the seal is not in place, yet) ready for action - see my earlier post on how to make this high-dollar tool, but honestly, you can see how for yourself.
Using a rubber mallet (so I avoid damage to the fork upper/slider), I drive the bushing in place - four raps total - one on each half of the driver tool to drive it, then one on each half to bottom it.
Time for the seals! Here, I compare the new seal to the old, for diameter, height, and installation orientation. This is the UP side facing up.
Verifying the DOWN side looks wrong...
I put a light coat of fork oil on the new seal surface so it won't tear on installation:
Slide the seal down, and with GENTLE raps on the driver (I only use half of it at a time for the seal), seat it. You'll have to work around the seal in 120-180 degree movements, until you get it flat on the washer. This pic shows the retaining ring grove is even across the whole seal surface.
Slide the retaining ring in, and seat it with a gentle nudge from a flat-blade driver:
Time to start the damping-rod screw. Compress the forkleg, and rattle the internals until you can get the screw to bite. After it starts, extend the forkleg to put some pressure on the damping rod, and you can get a few turns on it. An air ratchet will do the job in seconds. With hand tools, you'll need to wait until the fork cap is back on (and the spring preloaded) to torque the screw, but get it most of the way now.
The emulator - it replaces that simple 1.0mm hole that I drilled out to 5/16".
I'm a big, heavy, agressive rider, and I like a firm suspension. This bike will never see the street again, so I increased the damping spring preload from the Race-Tech stock 2 turns to the Race-Tech recommended (for racing) 4 turns.
You can now see a gap between the backing nut and the emulator body, so this gets snugged-up with a 3/8 wrench (the same two extra turns).
You can't see it, but the emulator is now down the tube and sitting on top of the damping rod - screw side up.
The new spring and washer - this is a 1.0 kg/mm spring. I used the new washer, though the old one would have sufficed.
The spring and washer were dropped over the emulator.
This is the point we add the Race-Tech sticker - right before the oil goes in the fork, but after most of the handling of the fork is done. I cleaned the exterior of the lower with a paper towel and some carb cleaner, and installed the sticker:
I put the old preload spacer in the fork (this spring is taller), and mark it's level height with the marker.
The new spacer material (the aluminum tube on the right), I line up the bottom edges of the two tubes, and transfer the mark. I didn't just stick the new tube in the fork to measure because it is covered in aliminum filings from the previous fork's preload spacer being cut off the raw stock, and I didn't want aluminum filings to contaminate the fork internals.
The line on the left is adding 20mm (Race-Tech's recommended preload for my weight, spring, riding style, etc). I'll cut it on this line.
The high-precision cutting station - hacksaw in hand...
Deburring the cut - green Scotchbrite did OK, but sandpaper would have been better.
The spacer. I cleaned all the filings out with water, WD-40, and a paper towel. Careful you don't cut yourself cleaning this part...
The spacer installed. Note my cut wasn't even, or even close...
The rebound damping is controlled by the 1.3mm (or so I guess it to be) hole at the top of the damping rod (the one I didn't drill and didn't photograph), and the weight of the fork oil. This is 15W oil.
I used 330ml on the other fork, so 330 on this one as well...
In she goes...
Race-tech recommended 4" oil over the top of the emulator, and I used this dowel to confirm, but the camera would not focus on it:
The fork cap went on the same way as it came off, with the c-clamp and a (shorter) socket to compress the cap/spring until I could get the circlip on. Now, tighten the damping rod screw if you'd not done it yet!
Clip-on reinstalled, upper and lower triples torqued, and ready to recieve the wheel after I get new rubber later this week.
Total time this fork: 1hr 10 min. Total time first fork? 4 hrs...
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ASMA 47
WERA 147
www.dhowellbooks.com
  
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beansbaxter
Needs a life
Posts: 5911
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posted October 17, 2004 08:37 PM
Oh my...I wonder if I can do all of that.
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Hells Dark Lord
Needs a life
living life, and loving it.
Posts: 7981
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posted October 18, 2004 01:42 AM
great thread...thanks for taking the tim4e to post it....
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When in doubt, lean farther and go faster....
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swft
Needs a life
Full throttle!
Posts: One MEEEEEELLION
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posted October 18, 2004 01:53 AM
Mmm...A bag of charcoal, fork oil and a steam vac...That's the makings of a party! 
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burgerking
Expert Class
Posts: 193
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posted October 18, 2004 09:46 AM
Great job, very clear 
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avdigigeek
Expert Class
Posts: 128
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posted October 20, 2004 12:17 PM
Thanks for posting all the pics.
Great Job by the way
I didn't see a single pic of your buddies standing around drinkin beer telling you what to do and what your doing wrong....
That is usealy a crucial factor when we do any type of engineering....
thanks again
I'm still affraid of taking any of my forks appart. even the CR 250
Smiley
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00 CBR F4
00 CR 250
03 ZX6R
04 ZX10R
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