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--- fork_seal_replacement [2008/08/09 10:15] – 68.91.17.139
+++ fork_seal_replacement [2020/10/19 11:50] (current) – external edit 127.0.0.1
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 In general, 88-89 forks have brake calliper mounting bosses that will only accommodate two piston callipers. 90 and up will only take four piston brake callipers. All outer tubes (lower part of the fork) will fit any inner tube (upper part of the fork) in any combination of year or model (FZR400 and FZR600).
-{{:fork_seal_photo1.jpg?180|}}{{:fork_seal_photo2.jpg?180|}}
+{{:fork_seal_photo1.jpg?360|Click To Enlarge}}{{:fork_seal_photo2.jpg?360x235|Click To Enlarge}}
 First off, start by raising the front wheel off the ground and make sure the bike is steady with whatever you use. You could use a couple of ratcheting straps and hanging the front of the bike from rafters.
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 I stuck a steel bar under front part of the engine above the exhaust header. Place the bar on the forward side of the oil pan. I had a bar long enough that I could put a jack stand on the high side with the bike on the kickstand. Then I took a floor jack and raised the low end of the bar high enough to slide another jack stand under the bar.
-{{:fork_seal_photo3.jpg?180|}}
+{{:fork_seal_photo3.jpg?360|Click To Enlarge}}
 Then loosen the handle bar bolts (in picture #2) and remove the handlebars from the top of the forks. The brake hose for the front brakes was not long enough for me to remove the right handle bar. Therefore, I just left it loose so I could pull the fork out of it later.
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 Loosen the axle pinch bolt and remove the axle and wheel. Picture #4
-{{:fork_seal_photo4.jpg?180|}}
+{{:fork_seal_photo4.jpg?360|Click To Enlarge}}
 Then remove the four bolts attaching the fork brace and fender. Lower the fender out between the forks. (Picture #1 and #4)
-{{:fork_seal_photo5.jpg?180|}}
+{{:fork_seal_photo5.jpg?360|Click To Enlarge}}
 Then all you are left with is bare forks.
-{{:fork_seal_photo6.jpg?180|}}
+{{:fork_seal_photo6.jpg?360|Click To Enlarge}}
 Before loosening the clamp bolts take a wrench and loosen the top cap bolts (Picture #2) DO NOT REMOVE THEM YET. Just loosen them. They may be very tight and it is much easier to get them loose with them in the triple clamps and tightened down.
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 Finnish removing the forks by loosening the top clamp bolts and the bottom clamp bolts and sliding the forks out of the clamps.
-{{:fork_seal_photo7.jpg?180|}}{{:fork_seal_photo8.jpg?180|}}
+{{:fork_seal_photo7.jpg?360|Click To Enlarge}}{{:fork_seal_photo8.jpg?360|Click To Enlarge}}
 With the forks removed, you may be able to drain the oil out of them by removing the drain screw on the bottom of them. (Picture #1 and #4) Not all outer fork tubes have drain screws.
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 I like to lay out the pieces. Lay them out on a clean surface if you don't plan on washing them all up. The cap bolt, collar (spacer), spring seat, and spring.
-{{:fork_seal_photo9.jpg|}}
+{{:fork_seal_photo9.jpg?360|}}
 Next, clamp the fork in a vice by the calliper-mounting bosses on the outer tubes.
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 :!://Use a heavy rag or professional soft vice jaw covers (a piece of old alloy sheet bent over the jaw face will work as well ) so as not to mar the fork when clamping them in the vise. Photo shown is for reference only!//:!:
-{{:fork_seal_photo10.jpg?180|}}
+{{:fork_seal_photo10.jpg?360|Click To Enlarge}}
 You will need to make a tool to hold the rebound dampener when loosening the bolt in the very bottom of the fork. You can make one by getting a three foot piece of 5/8 threaded rod and four nuts (Should be able to get at any hardware store). Run two nuts on the end and tighten them together to lock them and do the same on the other end so you can grip it with a wrench. I made one by welding a 5/8 nut to the end of a rod and using a vice grip to hold it.
-{{:fork_seal_photo11.jpg?180|}}
+{{:fork_seal_photo11.jpg?360|Click To Enlarge}}
 :!:If you use a bolt with a 5/8 head on it and weld it to a 1/2 square section rod 24" long you can hold the bolt headed tool in the vice. (Thus avoiding holding your precious forks in a vice where accidents have been known to seriously spoil the paint or polish) Slide the fork inner tube over the bolt head end of the tool until you feel it hit bottom. Now turn it gently until you feel the bolt head engage in the damper rod socket head. Once you have it engaged you can use the allen key as described below:!:
-{{:fork_seal_photo12.jpg?180|}}
+{{:fork_seal_photo12.jpg?360|Click To Enlarge}}
 Carefully slide the tool into the fork and put an Allen wrench into the end of the fork.
-{{:fork_seal_photo13.jpg?180|}}{{:fork_seal_photo14.jpg?180|}}
+{{:fork_seal_photo13.jpg?360|Click To Enlarge}}{{:fork_seal_photo14.jpg?360|Click To Enlarge}}
 It may take a lot of force to break the bolt free in the bottom of the fork. Try using a vice grip on the Allen wrench or another open-end wrench on it to get it loose. Just make sure to keep the Allen wrench seated in the bolt. (Stripping the head of the bolt will make much more work.) Then spin the bolt all the way out of the end of the fork. There is a copper gasket on this bolt so do not lose it (may be stuck to the outer tube). Then pull out the tool for the dampener.
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 Next, carefully pry the dust cover off the top of the outer tube with a flat screwdriver using a twisting motion. Be careful not to scratch the inner tube.
-{{:fork_seal_photo15.jpg?180|}}{{:fork_seal_photo16.jpg?180|}}
+{{:fork_seal_photo15.jpg?360|Click To Enlarge}}{{:fork_seal_photo16.jpg?360|Click To Enlarge}}
 Slide the dust cover out of the way and look at the snap ring. Notice there are loops in it. Put your screwdriver in one of the loops, pry it away from the outer tube, and remove it.
-{{:fork_seal_photo17.jpg?180|}}
+{{:fork_seal_photo17.jpg?360|Click To Enlarge}}
 Now to you can remove the inner tube. To do so, slide the inner tube all the way into the outer tube. Now firmly grasp the inner tube and sharply pull on it with medium force. Repeat until the outer tube is free. This is what it will look like when it is apart. When you are pulling out the inner tube, you are driving out the bearing in the top of the fork (Bearing #1) from its seat. You will have to drive it back in when re-assembling the fork. (Not difficult)
-{{:fork_seal_photo18.jpg?180|}}
+{{:fork_seal_photo18.jpg?360|Click To Enlarge}}
 To clean them up, remove the dampener from the inside of the inner tube (slides out when you tip the top end of the inner tube down), soak all parts in warm water with your favourite soap. Run a green scouring pad through the inner tube and the outer tube. Clean with soap and water and rinse with clean water. Dry parts and re-assemble.
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 Then slide on the dust cap and tap into place with hammer.
-Hold the fork upright and with it fully compressed and no collar or spring installed fill it with fork oil to 3.98 inches from the top of the fork through the cap bolt opening. Be sure to fully extend and compress the fork a few times do distribute the oil. There are many different types of oil people have used. Automatic transmission fluid, engine oil, and different weights of fork oil have been used. Yamaha recommends 10-weight fork oil. It will take about 15 ounces per fork. Yamaha sells fork oil in 16-ounce cans. You will need two cans which costs about $12.
+Hold the fork upright and with it fully compressed and no collar or spring installed fill it with fork oil to 3.98 inches from the top of the fork through the cap bolt opening. Be sure to fully extend and compress the fork a few times do distribute the oil. There are many different types of oil people have used. Automatic transmission fluid, engine oil, and different weights of fork oil have been used.
+===== Technical note by Y-G =====
+ ATF is about 10wt BUT whilst it is designed to resist foaming & high temperatures unless you are about 140lbs or less it is not "thick" enough to give much damping.
+Motor oil does not have enough anti-foaming agents in it and will allow the shocks to "fade" ie will absorb may be the first dozen or so highway joints but will allow the fork to "bottom" out & cause the bike to "jar" the riders arms & cause fatigue very quickly.
+Any good synthetic oil intended for fork oil use is fine , my personal favourite is Bel-Ray simply because I know I can mix oil wt's to get say 17.5wt rather than off the shelf 15wt or 20wt. Other makes are just as good my friends tell me but hey that is just me .
+=====  =====
+Yamaha recommends 10-weight fork oil. It will take about 15 ounces per fork. Yamaha sells fork oil in 16-ounce cans. You will need two cans which costs about $12.
 After filling to the proper height, fully extend the fork and insert the spring with the spring seat on the top, and then the collar, and then screw on the cap bolt. It will be had to get the cap bolt started but take your time.