$4.00 fork mod
Posted: Sat Mar 17, 2012 9:03 pm
It's time for a fork oil change anyway, so based upon my reading and talking to suspension folks, I'm going to fabricate some new spacers 1/2" longer (12 1/8"), replace my fork oil with Royal Purple MAX ATF, and fill it 10mm higher than spe c.
(on a 08+ bike)
These things combined are supposed to:
Increase preload.
Decrease static sag.
Increase rake and trail a bit.
Improve action.
Stiffen it a bit on heavier compression.
After analysis:
The front sits a little higher, brake dive is reduced and everything's just a little "firmer" and more confident. Here's what you need if you're doing it in conjunction with a fork oil change:
Supplies:
A little over 2 feet of Schedule 40 1" PVC pipe.
2 Quarts of your favorite fork oil.
Some rags
Tools:
Ratchet
6" Extension
8,10,12,19 and 22mm sockets.
6mm Allen Socket or Allen Wrench
(a crescent wrench could be used in place of the 22mm)
A wire hanger
Something to use as a dipstick
(I used a pistol cleaning rod)
A jack
Some kind of saw suitable for PVC
Optional:
A vice or a friend.
Time: About an hour
Start by breaking the caps free on the top of the forks. You can either unbolt your handlebars and do it with the socket or you can use a 22mm or crescent wrench. Also break the caliper, axle and the triple clamp bolts while the front tire is still on the ground.
Jack the front of the bike off the ground and remove the front wheel, then take off the brake caliper and the two cable guides. Remove the fork tubes one at a time.
Once you have them off, take off the top cap. Remove the stock spacer. Bend the wire hanger into a hook and use it to pull out the spring and washer. Wipe all of them down and set aside.
Pour out the old fork oil into your drain pan, and work the forks a few times to purge all of the oil from the voids. Leave them sitting inverted in your drain pan while you cut the new spacers.
The stock spacers are 11 5/8" long. I cut mine 1/2" longer, and according to Fred at Arrowhead, you should not go any more than 3/4" or you risk binding your springs. I marked the PVC with a sharpie at 12 1/8", clamped it in a vice and cut it with a scroll saw. Make sure you make the cut as clean and true as possible and make sure you clean all of the bits and burrs off of the pipe. We don't want those clogging the orifices inside the fork.
Make your dipstick by making a mark 125mm (4.92") from the top (stock manual says 135, but we are adding just a little bit more oil to decrease the compressible space above the oil and make a stiffer "bottom" to the fork)
When your forks are good and drained, wipe them down. Compress the forks all the way to the bottom. Pour in your new fork oil until it reaches the level you marked on your dipstick, making sure you're holding it plumb while measuring.
Once you're satisfied with the oil level, install the spring, washer and spacer into the now fully extended fork.
Now here is the tricky part: The cap is aluminum, the fork is steel and the threads are small and fragile. With the longer spacer, you will have to compress the spring a little when you put the cap on. BE VERY, VERY CAREFUL NOT TO CROSS-THREAD THE CAP. I wrapped a rag around the fork and gently clamped it in a vice to hold it steady while I replaced the cap. I also greased the threads of the cap to ensure that there would be no binding when I re-assembled it.
Once your caps are back on, simply re-assemble the front end of the bike, and double-check that everything's tight.
Enjoy!
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Dooden
A15 Green Ape