Rebuilding forks - fork seals EN500A and EN500C

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Triangles
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Rebuilding forks - fork seals EN500A and EN500C

Postby Triangles » Sat Nov 19, 2011 1:33 am

Edit 9-10-17: rewrite in progress please be patient over the next few days...
28.9mm
Replacing the fork seals and for that matter the construction of the forks on both the EN500A and EN500C are very similar but the tube diameters are different. This How-To originally focused on rebuilding shot forks on an EN500A (first gen. Vulcan 500). I have edited it to include the EN500C after rebuild a pair with new inner fork tubes. If you are just replacing the seals that is covered as well. There comes a time when replacing fork seals alone will not stop the forks from leaking for more that a few hundred miles. There can be two causes for this. First the inner fork tubes where the seal rides upon has become scratched, pitted or both. The second is one or both of the two slide bushings inside the fork have worn out causing excessive play that will cause the seal to fail. In the case for this How-To the EN500A inner fork tube was scratched and pitted and the EN500C had bent inner fork tubes. There is no fix for scratched and pitted inner fork tubes. They must be replaced! You can buy OEM or you can buy "Frank's forks" The Frank's forks use a thicker wall tube and require new aftermarket springs available from progressivesuspension.com. While Franks forks were cheaper the added cost of new springs put the total cost higher than just replacing with OEM. If all you're doing is the seals you only need the seals and fork oil although you should use the new crush washers that seal the screw at the bottom that secures the inner and outer fork tubes.

EN500A Parts required (OEM part# where applicable):
2 inner fork tubes 44013-1286
2 fork tube bushing 44065-1068
2 inner fork tube bushing 44065-1069 (this part is included with the fork tubes, ie not need if you buy the fork tubes)
2 fork seal 92049-1226
2 fork seal snap ring 92033-1193 (probably not necessary, replaced because I wasn't sure my old ones were ok)
2 gasket (crush washer) 44045-051
2 half liter fork oil; Repsol 10W-20

EN500C Parts required (OEM part# where applicable):
2 inner fork tubes 44013-1422
2 fork tube bushing 44065-1115
2 inner fork tube bushing 44065-1114 (this part is included with the fork tubes, ie not need if you buy the fork tubes)
2 fork seal 92049-1494
2 fork seal snap ring 92033-1036 (probably not necessary, replaced because I wasn't sure my old ones were ok)
2 gasket (crush washer) 44045-057
3 bottles of Pro Honda suspension fluid SS-8 10W fork oil

edit:
Tools required:
12mm wrench or socket
Crescent wrench or appropriate socket for axle nut.
6mm, 8mm Allen key socket. (If not available regular Allen keys)
Assorted screwdrivers for pushing down and prying.
Precision or very small flathead for starting to pry on the dust seals.
Home made or store bought seal driver. (scan toward the bottom for how I made my own)
Measuring device for fork oil level
Broom handle or special tool for removing the socket head screw that holds the two tubes together.
Various other tools I forgot to mention :)

The pictures and steps are for an EN500A The EN500C's forks are nearly identical so almost everything should cross over. One difference with the EN500C's fork is that when you separate the inner and outer fork tubes (The part where I used a broom handle below on the EN500A), There is a Hex recess that The head of a bolt will fit into. Unfortunately I don't know what the bolt size is. This is described in further detail in the Haynes manual where you can buy a special tool from Kawasaki or use some tape, a socket extension or two, a socket and a bolt with two nuts works just as well.

Where it all started the before picture:
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You can see pretty clearly the black stripe on the right fork. Oil had leaked down the fork, and was on the wheel, tire and inside the fender. It was in desperate need of repair.

I'll assume you can figure out how to get the front wheel off the ground and remove the forks. The plastic caps on the top of the forks just pull right off.

Step 1 Disassemble fork:
-undo top plug
The top plug is held in by a retaining clip. You need to push down on the plug in order to be able to pry out the retaining clip. Securing the fork in a vise makes this much easier. Be sure to use soft jaws or put something soft around the tube so you don't mark the chrome. There is some spring tension on the plug. With the retaining clip removed slowly let the plug up. It will pop all the way out with the spring tension in the fork.

Top plug and it's retaining clip
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-Drain fork oil. Use your finger or some other creative way to keep the tube under the plug from falling out as you invert the fork over an oil catch can. Pump the fork a couple times to get as much oil out of the bottom part of the fork.

-Lay out internal parts in order they came out so you can put them back correctly during reassembly. Use paper towel or something to absorb any remaining oil on internal parts.
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-Carefully pry off dust seal with a small flat head screwdriver. BE CAREFUL not to slip and scratch the fork tube!!! There is a metal washer encased in the rubber. This threw me off at first and I destroyed a dust seal trying to figuring out how to remove the dust seal. I started with a precision screwdriver and then moved up to a regular flathead once I had a small gap started.
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-With the dust seal removed, next we remove the fork seal retaining clip. There are little "bumps" that give you a place to insert a precision screw driver or other pointy device to pry the clip out.
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I had a focus issue with the picture of the retaining clip installed so you'll just have to imagine it there in the groove above the fork seal.

-Separate inner and outer fork tubes.

At this point there is a small inner shaft that that is holding the two fork tubes together by the socked head bolt in the bottom of the fork. On the EN500C there is a special tool or one can be fashioned as described in the introduction above. On the EN500A you can simply press against the end of a broom handle and use an Allen wrench. The right hand picture below shows the end of the inner shaft that the broom handle presses up against. This is what you can't see up inside the fork tube. As demonstrated by my lovely assistant, I used an impact gun which was really overkill but it made the job easier. When it came to reinstalling things I used an Allen wrench so that I did not over tighten things. After removing the bolt holding things together, the inner shaft and a spring on it will fall out when you remove the broom handle. Don't worry the pictures below will show you how this all fits back together. Set the inner shaft with spring aside. It is probably a good idea to put them next to other internal bits you pulled out after draining the oil so that you don't lose them.
ImageImage

-Clean the oil off the threads of the inner rod using brake parts cleaner / carb cleaner. This is so the blue Loctite can grip the threads when you reinstall.

All that is left holding the two fork tubes together is the seal. There is also the tapered piece with the bushing and small spring that will come out when you separate the two tubes. Gently pump the inner fork tube as you would a slide hammer to pop out the fork seal and separate the two tubes.
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-If you happen to unnecessarily removed the drain bolt as I did, Now that the lower tube is separated now would be a good time to clean all oil off of the bolt and the hole it goes in. Aerosol brake or carb cleaner are good at removing oil. Get a new copper crush washer and some blue loctite and re assemble the fork oil drain plug.
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-Remove old copper crush washer from bottom of outer fork tube. If it fell out you are lucky as sometimes the old ones are a bitch to get out. I carefully removed the old one using a drill bit in a vise and pressing while slowly turning until the drill bit bit into the old washer then simply pulled the tube back. you could probably skip this but why risk a leak? The second time I did this I did it opposite, Putting the outer fork tube in the vise and tap the drill bit with a hammer and rotate it with pliers. The idea is to get the drill bit to bite into the washer with out going thru it! Don't blame me if YOU screw up here!! DO NOT USE DRILL BIT IN DRILL!!!
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-(Optional) If you want to polish or clean up the lower fork tubes, now would be an ideal time. I polished with a die grinder and buffing wheel, then clearcoated with Protecta clear. I'm skeptical as to how this product will hold up so I can't recommend it at this time. It is easy to apply and looks good but, it will dissolve in most any organic solvent. ie brake parts cleaner. It is also ludicrously expensive.
ImageImage

Step 2 Reassemble fork:
-Now it's time to install the bushings washer and new oil seal on your new inner tube. If you are reusing your inner tube, the bushings have an expansion slot in them so that they can simply be pried off. Pay attention to the order and orientation of the oil seal, washer, and bushing or just refer to the pic below. Remove the old bushings, washer, and oil seal. Save the washer to be reused. If reusing your inner fork tube it is critical that the inner fork tube is clean and has no sharp burrs that could possible damage the new seal when you slide it on. I lubed the entire tube with a little fork oil to make it easier to slide the new parts on.

A new inner fork tube already has one of the slide bushings preinstalled. If you are reusing your inner fork tubes, this bushings the one you'd have to pry apart to remove/install on the end of the inner fork tube.
Image

These pictures show the new fork seal, washer, and bushing slid onto the new inner fork tube. The other bushing on the right is the preinstalled bushing.
ImageImage

At least for the OEM seals there is writing on one side of the seal. This should be oriented up toward the rider.
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-Prepare to reassemble the two fork tubes with the pieces that came out when you separated the inner and outer fork tubes.

This picture shows the order in which things are to be assembled. The inner shaft inserted small end first into the top of the inner fork tube and the bits to the right go onto the end of the inner shaft that sticks out of the inner fork tube after it's inserted. The screw is shown for reference. It is the screw on the bottom of the fork that holds the inner and outer tubes together.
Image

-Put inner shaft inside inner fork tube as shown below.
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-Put tapered bit with flanged bushing and spring on the end of the inner shaft as shown.
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-We are now ready to reassemble the inner / outer fork tubes. First insert the broom handle (special tool EN500C) into the inner tube to hold the inner shaft in place. Rotate the assembly to the vertical position as shown in the picture. The weight of the assembly will be supported by the broom handle end pressing against the inner shaft.
Image

-Install outer fork tube. For the most part this is the opposite of how you took it apart earlier. Use a fresh copper crush washer(gasket part 44045-051) replacing the old one you just removed with the drill bit earlier. 22ft-lbs is the torque spec for that socket head screw. I probably over tightened it for fear of it coming loose and leaking. Apply blue Loctite (medium strenght thread locker) to the threads on the socket head screw. Turn the fork over and you should have something resembling this.
ImageImage

-Next we need to make our own fork seal driver to seat the seal into the outer fork tube. Skip this if you have a commercial one. I used 1 1/2" sch. 40 PVC pipe. I cut several slots and used a hose clamp to adjust the diameter so it is just right.
ImageImage

-Slide this over the inner fork tube as shown and tap the end of the PVC pipe with a rubber mallet to seat the fork seal. This doesn't take a lot of force so don't beat on it too hard.
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A properly driven oil seal will be driven to just below the groove that the retaining ring snaps into. you may have to check several times to see if you've driven it below the groove that the retaining clip sits in. It should look like this (retaining ring not yet installed in the picture):
Image

-Reinstall the fork seal retention clip and dust seal. You should be able to stroke the fork smoothly. If not you have a problem beyond the scope of this guide.

-Add fork oil.
What is the correct fork oil to use? For the EN500A the manual specifies 10W-20. I found Repsol brand fork oil in 10W-20 from my local dealer. I bought 2 half liters (less than one bottle per fork). For the EN500C the service manual says "KHL34-G10 (KAYABA) or equivilent" Not sure what this means but the stuff that came out of my '06 Vulcan 500 fork was red and smelled somewhat like ATF. My local dealer didn't know what the manual meant either but said the "G10" meant it wanted a 10W oil. I found some SS-8 suspension fluid from Pro Honda that is both 10W and red. It also says on the bottle "Use Pro Honda suspension fluid wherever ATF is recommended."
ImageImage

Fill the fork with the proper amount of oil. You should not have inserted the spring and remaining pieces yet. The fork should be in the full compressed position and held vertically. I just set the bottom of the fork on the ground and hand held it vertically with the fork in the fully compressed position. Fill with oil to the specified level. EN500A 128mm below top of fork. EN500C 125mm below top of fork. I used a bent piece of galvanized wire with premeasured marks on it. After putting enough oil in to fill the lower chamber, it helps to stroke the fork several times to try and get all the air out of the lower chamber.
Image

-Finish reassembling the fork. Fully extend fork and clamp in vise as you did when you started disassemble (use soft jaws or put something soft around the fork tube so you don't mark the chrome). put spring, washer and metal tube back in. Push top plug down with a screwdriver or something similar and reinstall the retaining clip. Below picture shows completed EN500C and EN500A forks.
ImageImage

Note: I added some fork shields (aka fork guards) from Traxxion Dynamics (part# FGK1) to my EN500C forks. In theory these will protect the inner fork tubes so that I never have to replace the fork tubes again. They are WAY overpriced, but I cannot find anything comparable in the US for a reasonable price. I am adding a pair to my newly rebuilt EN500A forks as well. On the EN500A forks I had to add a 1-2mm rubber spacer (cut a strip of rubber out of some rubber gasket material I had laying around) that goes in-between the fork shield and fork tube. The spacer is needed to increase the diameter of the top of the fork tube that the shield wraps around.

-Reassemble bike

-Enjoy leak free forks

As always information can be dangerous! Use the information in the guide at your own risk!
I still have to edit some pictures (circle parts or add notes) but I think this guide is 99% done. Let me know if any part is not clear.
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Burkerust
Posts: 5
Joined: Fri Sep 05, 2014 1:59 pm
I ride: 2005 Yami TTR-250 2001 Kawi Vulcan 500 (rebuilding)

Re: Rebuilding forks - fork seals EN500A

Postby Burkerust » Wed Sep 24, 2014 11:56 am

I think you need another step to drive the "Guide bushing" into the lower before driving the new seal into place. I didn't drive it into place first and damage a new seal. I don't think I thought it through before I started whacking the seal in place unless it's different on the LTD model. The manual that I didn't read before this step says to use the old guide bushing to drive it into place. Since I re-used my bushings, I just drove the washer on top of the guide bushing until bottomed. Then drove the oil seal after that. Other than that every thing worked fine.

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Triangles
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Re: Rebuilding forks - fork seals EN500A

Postby Triangles » Thu Sep 25, 2014 9:39 pm

Burkerust wrote:I think you need another step to drive the "Guide bushing" into the lower before driving the new seal into place. I didn't drive it into place first and damage a new seal. I don't think I thought it through before I started whacking the seal in place unless it's different on the LTD model. The manual that I didn't read before this step says to use the old guide bushing to drive it into place. Since I re-used my bushings, I just drove the washer on top of the guide bushing until bottomed. Then drove the oil seal after that. Other than that every thing worked fine.

I assume by "Guide bushing" you mean the left most bushing shown below. It's the copper looking thing. The bushing that is below the oil seal in the top of the lower fork tube.
Image
I haven't had my LTD forks apart yet so I don't know how much different they are. IIRC on my EN500A this bushing did not require significant force to be seated in the lower fork tube. It's been so long since I did that though I don't remember for sure. I'll add a note to the how-to.

If this is an issue on the LTD I'm glad you brought it up. I need to replace my fork tubes on the LTD. I recently discovered that I bent my fork tubes in a fender bender I had 5,000 miles ago. It will likely be a while since I am very busy and I think the risk of a catastrophic failure is low.
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Burkerust
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Joined: Fri Sep 05, 2014 1:59 pm
I ride: 2005 Yami TTR-250 2001 Kawi Vulcan 500 (rebuilding)

Re: Rebuilding forks - fork seals EN500A

Postby Burkerust » Mon Sep 29, 2014 10:36 am

Yes the copper bushing that the Kawi manual calls a "guide Bushing" required some significant driving home on my LTD. I did manage to get them finished this weekend with another oil seal. The all balls kit fits really well and is a lot cheaper than oem. http://www.amazon.com/gp/product/B003CJYOOO/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1 from amazon.

Burkerust
Posts: 5
Joined: Fri Sep 05, 2014 1:59 pm
I ride: 2005 Yami TTR-250 2001 Kawi Vulcan 500 (rebuilding)

Re: Rebuilding forks - fork seals EN500A

Postby Burkerust » Tue Sep 30, 2014 10:29 am

Image

Getting there a little at a time. :roll:

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Triangles
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Re: Rebuilding forks - fork seals EN500A

Postby Triangles » Tue Sep 30, 2014 9:19 pm

Burkerust wrote:The all balls kit fits really well and is a lot cheaper than oem.

FWIW I have heard from a pseudo-reputable source that the OEM seals last longer than the aftermarket. I have wondered if this is true. Keep us in the loop if you develop problems with your aftermarket seals. I figure there probably isn't a difference but considering the time and labor to redo the seals I paid extra for the OEM seals.
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charnotx
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Re: Rebuilding forks - fork seals EN500A

Postby charnotx » Mon Aug 17, 2015 3:02 pm

Just a friendly reminder, but make sure you know which way those seals are suppose to go on the forks! I accidently put mine on upside down. I didn't even realize until I couldn't get it below the line for the retaining clip. Ended up having to take the uppers and lowers completely apart again to do it right, luckily the seals were still good.
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