Does fork seal replacement require a new "slide metal"?

9 replies to this topic
  • Rich_in_Orlando

Posted February 07, 2002 - 09:23 AM


I've been researching the topic of fork seal replacement on TT. The right fork has been leaking just a little bit for the last few rides and I'm sure the oil level isn't correct anymore. I tried the film trick but it didn't seem to fix it. So I'm going to replace the seal. The seal has lasted admirably: almost 3 years and probably close to 10,000 miles of hard riding.

The local dealer has 4 OEM oil seals in stock so I have them holding 2 for me and I'm picking them up tonight. The manual shows that the "slide metal" (a metal ring that sits above the seal) is supposed to be replaced at the same time. I would have to order them and wait till next week to fix the seal. But I don't want to wait. :)

I did a search on "fork seal" and I didn't see anyone mention replacing the slide metal when doing the seals. Could I get a show of hands of who's replaced both, or only the seal? I know Yamaha is trying to cover its butt with specifying new parts like crush washers and seals, but I've found that new parts are not always necessary.

I'm also going to try the PVC trick for driving the seal. Maybe a schedule 40 PVC (thicker walled) pipe may give better results than some I've seen talked about on the list.

Thanks, guys. (And I mean guys in a non-gender specific, diverse sense.) :D

  • YZ400Court

Posted February 07, 2002 - 09:39 AM


I just did my fork seals. When I pulled the forks apart the slide metals were both damaged dou to hitting against each other and the seal when driving it apart. I replaced mine. It kinda frayed the teflon on the edges, and I was afraid a big piece might come off and get into the valving :) . I used a 1-1/2" schedule 40 coupling split in half to drive the seals (and a rubber hammer that would not gouge the fork tube). It was pretty easy :D

  • MOmilkman

Posted February 07, 2002 - 09:42 AM


I assume you are talking about the "wipers". They clean the drit off your forks before it makes it to the seals. Is this right?

If so, then yes, I replace them. The first couple times I replaced my fork seals, I didnt replace the wipers because i didnt think it needed it. (they looked fine) But then the new seals I put in lasted about 2 months. Because dirt was getting past the wipers again.

Its obviously your call, but I say replace.

  • Rich_in_Orlando

Posted February 07, 2002 - 09:57 AM



Nope, I'm not talking about the wipers (a.k.a. "Dust Seal"). Check out this diagram:

Posted Image

The part I'm referring to is identified as 5,25. What you are talking about is number 9,29.

[ February 07, 2002: Message edited by: Rich in Orlando ]

  • MOmilkman

Posted February 07, 2002 - 10:48 PM


Ahhhh, Sorry, you did say slide metal. My bad. That will teach me to read slower :)

I have never replaced mine yet, but have considered it. I actually need to replace mine next time I change the fork seals though because I do remember it having some "slop" last time I put it together.

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  • jamracing

Posted February 07, 2002 - 11:45 AM


The metal slders, or bushings, should be fine. They should only be replaced if the dark slick teflon coating is rubbed off. In all my wrenching years, I have only replaced a handfull. When you snatch the fork apart, the bushing shouldn't be too damaged, maybe some will get snipped off the edge, but nothing to worry about. the main thing is to take the forks completely apart, and clean them with mineral spirits, to get the sludge and debris from the bottom. If you need help, you can e-mail me, and and bring a six pack to my palce. I couldn't imagine working on a bike with a clear mind :)

  • Rich_in_Orlando

Posted February 07, 2002 - 04:23 PM


Josh, I may take you up on the offer. I'm not sure I have the right tool to take the forks completely apart. I read somewhere that I need a 14 mm hex key to take the valve at the bottom of the fork off. Don't have that. But I do have the oil seals just sitting in the garage waiting for me to install them.

Now I'm having a new problem that is probably my own fault. I tried to install the Kouba tool I just got in the mail from Kevin in NH. The installation didn't go smoothly. I broke the fuel screw in half and may have damaged the fuel screw threads in the carb. :) Now, I'm just hoping a local shop has fuel screws in stock (so this weekend's ride isn't shot)and when I do get a new one, that it goes in smoothly. Hopefully, the brass on the fuel screw is softer than the material the carb is made of. The new fuel screw may make Kouba tool installation easier, too. :D

  • John_Curea

Posted February 07, 2002 - 04:34 PM



I know this reply is a little late, but next time heat the area of the upper tube where the outer bushing is seated before you pull apart. A propane torch works real good, just heat enough to where you cant touch. This will expand the tube slighty and will allow the bushing to be removed without damage.

Take Care, John

  • John_Curea

Posted February 07, 2002 - 04:41 PM


I found a pretty complete procedure for complete teardown, cleaning and rebuild. It's a little long in the tooth, but, if you want to do the job right......

To avoid the age old sin of plagurism.. :)
This came from our main office at MX-TECH

Disassemble forks completely:

Valving components.
-Remove fork cap.
-Remove bottoming bump components.
-Compression plate
(Note 2001 models have Teflon inserts under fork cap.)
-Remove spring.
-Taking a 14mm Allen socket (Impact style) and a impact wrench remove the base valve assembly. (Apply downward pressure against the fork rod using a clean towel. This insures that the valve is moves outward as apposed to the valve pushing the fork cylinder out.) Use short bursts and not long durations of RPM as this can damage the components.
-Remove the fork cylinder.

Seal and tube dissembnly:
-Using a subtle blade (Flat but small screw driver) remove the dirt scraper. Don’t pry as it may mar the forks appearance.
-Using a smaller blade remove the circlip that holds the seal in place.
-Heat the seal carrier or the portion of the tube that has a unanodized finish uniformly so as to facilitate easier bushing removal with out damage.
-Using quick but not forceful hits drive the tubes apart. (Speed is more important than force and never yank at the end of the stroke.) Use the quick momentum to drive the tube off. Failure to do as described above often results in bushing damage.

Internal component disassembly:

Fork cylinder: The 3228125 Bumper style fork requires that the stakes at the head of the cartridge be removed before the active and rebound valving can be modified.

-Using a 6mm 2 flute end mill, mill the stakes out of the cartridge. The stakes can be identified as 4 dimples at the head of the cartridge or the CV (Cylinder Valve) (It is best to use an end mill because the CV has very thin walls. A drill with sufficient diameter to remove the whole stake will often pierce the CV walls before the edges of the drill have removed the stake.) Mill to 1.8mm depth. It is very important to keep the edge of the mill just bellow the bottom edge of the stake. Failure to do this will result in the last few sealing threads to be pierced and will cause chronic leakage and hence poor fork performance. Be careful to clean all parts thoroughly of AL chips created by the machining. (The chips like to migrate into the CV exit and plug the valving.)
-Using the light to moderate heat warm the area around the now milled stakes. This is important to relive tension and locking agents used in assembly from the factory.
-Using the CV holder place the components in a vice.
-Using a appropriately sized screw driver or round stock turned to the hole diameter, unthread the cylinder form the CV. Uses a back and forth unthreading technique to help prevent thread galling.
-The nut holding the valving components has been staked from the factory and needs to be ground flat past the edge of the stake to remove the nut and separate the valving and piston. (Prior to the grinding process pack the orifice with grease to prevent grinding chaff from entering and being lodged in the internals.)
-After removing the stake the edge of the nut needs to be radiused of its metal bur that develops during grinding. (This bur may come free during fork use and causes numerous problems.) A polishing wheel such as cratex works very well and leaves an excellent finish. Be very careful to maintain proper shim and piston orientation during removal. Also note that may times small spacer shims are placed under the post spacer, or valve these are easily misplaced and will dramatically impact fork performance.
-Now that all the components are free of the stem radius the first thread to prevent thread wear during reassembly.
-The passive valving (base-valve, or foot valve) needs to removed. The nut can be just turned off on these model forks. After the nut and valving has been removed you will need to radius the first thread in the same manner as the active stem. Proper orientation must be maintained to insure the components are assembled properly.
-Wash and clean all components thoroughly before proceeding any farther.

Assembly of fork tubes.

-Place the axle bracket in a vise and firmly tighten down.
-Placing a bag over the tube lube the seal and install the dirt scraper. (Remember that seals always work with pressure so if orientation becomes unclear use that as your guideline.) Install the circlip, oil seal, backup washer. With round edge toward the seal. Bushing outer and then bushing inner. (After the oil seal is installed remove the plastic bag.)
-Use a 46mm seal driver to drive the seals and bushing into the seal carrier. Install the circlip and then install the dirt scrapper.

Assembly of the Active compression and rebound damping.
-Build the stacks specified and then install them on the stem. By very careful not to misalign any washers or components as they could be permanently damaged by doing so.
Double check all components for proper assembly.
-Tighten the nut down after a small amount of blue loctite has bee placed on the threads. Make sure that the nut is not lose or over tightened, clean all components with compressed air to blow off any extra loctite.
-Put the rod and CV back into the holder and apply a small but uniform amount of blue loctite to the CV threads. (This will serve as both a lubricant and a sealant during reassembly and use.) Tighten the Cylinder down. (Very tight)

Assembly of the Passive compression valving.
-Install the valving components on the base-valve stem add a drop of blue loctite to the threads. Tighten the nut down firmly but do not over or under tighten. If your revalving build the necessary components and stacks.

Installing internal components:

-Place and align the fork cylinder in the tube. Grease the base-valve threads and piston o-rings. Using downward force to the rod place the base-valve in the axle bracket and tighten the valve. Once the threads have been engaged use your impact wrench to finish the job. Tighten in firmly, using quick short bursts. Long and high speed rotations are damaging to the components.
-Place the fork upright and fill with fluid. Let the fork oil settle into the gaps between the tubes by refilling every few moments or until the level stops falling. At this point thread the fork cap on the rod 1 to 2 turns and lift both the outer and inner tube to full ht allowed by the cap. Quickly compress the fork full travel. That should initiate fork bleeding. Refill the tube and bleed the rod by stroking up and down until the action becomes consistent and smooth.
-Set the oil ht by measuring from the fluid level to the edge of the fork tube.
-Double check the jam nut tension on the rod. Do this by firmly holding the rod in your hand and tightening the jam nut down as hard as possible. (Do not ever grasp the rod in anything other than a holder.)
-Extend the rod completely and lay the fork over to a 45 degree angle. Quickly and precisely slide the spring down over the rod. Place the fork cap and bottoming components on the rod.
-Holding the rod with your thumb and index finger tighten the cap down till it seats on the top of the rod. Then insert a thin 17mm and tighten jam nut up to the fork cap. Firmly tighten jam nut to fork cap.
-Bottom fork cap to the tube but do not tighten. The top triple clamp is responsible for keeping the cap on.

Check for improperly placed rods during rebound clicker setting. Compare the depth of screw in fork cap left and right when rebound is full hard. (This is a quick test.)

Reset your clickers and enjoy!

  • Dan_from_HB

Posted February 07, 2002 - 08:17 PM


It depends on how well your front end is aligned, and whether there is binding due to proper/improper assembly. If you truly have 10,000 miles on the bike, or even half that, I would do the bushings (slide metal). It can cost you a fork stanchion tube (the smaller diameter chromed tube), or worse due to metal-to-metal scraping. If the aforementioned teflon material wears down to expose metal, your stanchion tubes will soon be history. I had to replace a complete set of forks, less the damper assy and triple clamps on my son's CR250. Very ugly. Pro Action helped out significantly, but it was still very expensive. My $.02.


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