Forks Fluid Replacment

[SkooterG]

Fork maintenance day today. Flush out the old nasty fluid, and in with the new. During the process I ran into a couple of issues I could use some advice or help with.

Background: 219k miles on the forks. 47k miles since the last service when TWN's GP Suspension valves and springs were installed by a shop.

So, I removed fork caps, nut, spacer rod, and washer. Spring is then removed. Fork is inverted and out comes another washer. On the right fork, one washer comes out. On the left fork, TWO of these washers come out. WTF?!?!

I am assuming these are stock parts, and that the GP Suspension upgrade was only valves and springs. So how did this shop manage to add an additional (and identical) washer to the one fork? Doesn't make me feel real good about their work. According to the service manual, this bottom washer is the 'spring seat' and there is only supposed to be one.

Below is a photo of the let fork internals that I removed. The 'two' washers in question are at the bottom of the photo.

Can anybody provide any enlightening information here?

Guess it wasn't the worst thing, but I guess the fork with the extra washer, or spring seat had some extra preload due to the extra washer. Still pisses me off that a suspension shop wold make such an error, however.

Second issue. A couple months back, I think I began to notice some fork travel irregularites while taking the bike off the centerstand. It seemed as though when taking the FJR off the C-stand, as the forks would compress and then rebound, the travel would not be smooth, but a bit jerky. I remember thinking, 'I need to service the forks'!

Well, I found the problem, sort of, but wonder what's going on.

After draining the fluid, I was excercising the fork dampening rod up and down. Smooth action on the left fork, but there is all kinds of uneven resistance on the right fork. Inner tube and outer tube travel is fine on both. Bushings are only for the inner and outer tube, correct? So they aren't the issue. Dampening rod has to do with the valving, right? So what could be wrong the internal valving parts, or tube, that there is all kinds of resistance there? Anybody?

I am not disassembling the forks any further. No knowledge or proper tools. So I guess now they are going to a shop.

 

[Grumpy]

Don't quit now, you've got the hard part done. Assume it was a tech screwup and put things back together with one washer on top of the spring.....at least as I recall that's where it goes.

jim

 

[SkooterG]

Don't quit now, you've got the hard part done. Assume it was a tech screwup and put things back together with one washer on top of the spring.....at least as I recall that's where it goes.jim

The washer problem is not what's stopping me, the second issue is. And the washers in question go on the bottom of the spring. Between the spring and compression tube, I believe it is called. If this were the only issue I would reassemble with only one washer instead of two.

The single washer that goes on top of the spring is the one in the photo that is above the two identical (bottom) ones.

 

[MCRIDER007]

After draining the fluid, I was excercising the fork dampening rod up and down. Smooth action on the left fork, but there is all kinds of uneven resistance on the right fork. Inner tube and outer tube travel is fine on both. Bushings are only for the inner and outer tube, correct? So they aren't the issue. Dampening rod has to do with the valving, right? So what could be wrong the internal valving parts, or tube, that there is all kinds of resistance there? Anybody?

An extra washer is not that big of deal, just a little extra preload as you said.

Your extra resistance on the right fork is probably due to extra thick crud that has accumulated in the right cartridge...which isn't surprising considering the 47K maintenance interval. You need to use some high powered cleaner or remove and disassemble the cartridge to clean it.

 

[SkooterG]

An extra washer is not that big of deal, just a little extra preload as you said.
Your extra resistance on the right fork is probably due to extra thick crud that has accumulated in the right cartridge...which isn't surprising considering the 47K maintenance interval. You need to use some high powered cleaner or remove and disassemble the cartridge to clean it.

Interesting theory. I have flushed and drained that fork with mineral spirits about 4 times now. Each time, fork tubes AND dampening rod have been excercised repeatedly. So far, it's not getting any better. So use something stronger? Like what? Or keep trying?

And while my maintenance interval may not be ideal, it is better than what Yamaha recommends!

Disassembly of the cartridge is the best idea. But no tools or knowledge there, hence, most likey, it's off to shop where they can do that.

 

[JamesK]

I did most recent fork oil change after 35k or so and the oil was very dirty, but with only 3 flushes with K1 Kerosene the 3rd flush produced pretty clean forks. And K1 is not meant to do any damage to rubber seals.

 

[MCRIDER007]

An extra washer is not that big of deal, just a little extra preload as you said.
Your extra resistance on the right fork is probably due to extra thick crud that has accumulated in the right cartridge...which isn't surprising considering the 47K maintenance interval. You need to use some high powered cleaner or remove and disassemble the cartridge to clean it.

Interesting theory. I have flushed and drained that fork with mineral spirits about 4 times now. Each time, fork tubes AND dampening rod have been excercised repeatedly. So far, it's not getting any better. So use something stronger? Like what? Or keep trying?

Mineral spirits normally would clear the crud but we all know you ..... naw, I am not going to say it. You could call a suspension shop and see what kind of cleaner they recommend but after 47K miles you are probably overdue for new bushings and fork seals so you might as well do it all at the same time.

 

[dcarver]

Given the washer problem, I wonder if they installed the valve stack correctly on the right fork?

FWIW, both of my dampners, when pulling up, are kind of 'herky-jerky', no worries here.

If you have the $$, put them tubes back together, ride up to GPS and see Dave..

 

[Bungie]

Wasn't it GP that fuxored up Feejers bike.. and I recall it was a spring seat issue?

 

[HaulinAshe]

It's not imperative to remove ALL the crud. The dark stuff that's stuck to the metal surfaces is not your major concern. The particles that float around in the fluid are what needs to come out.

Using K1 or mineral spirits, do the best you can. Follow up with a small flush of fork oil that gets disposed. You'll be just fine.

But BTW, your lower fork tube bushings are toast. They needed replacing a long time ago.

 

[ShinyPartsUp]

Mistakes happen when humans are involved. I bet if you shot Dave at GP a description of your issues and pictures he would give you advice. In my experience he tries to take care of FJR owners and (in my case) gave advice on how a local mechanic could service my forks, which materials to use, etc. He didn't give a standard, "send it to us and trust us" answer. YMMV, but it would be a start.

 

[JamesK]

It's not imperative to remove ALL the crud. The dark stuff that's stuck to the metal surfaces is not your major concern. The particles that float around in the fluid are what needs to come out.
Using K1 or mineral spirits, do the best you can. Follow up with a small flush of fork oil that gets disposed. You'll be just fine.

But BTW, your lower fork tube bushings are toast. They needed replacing a long time ago.

Thanks Jeff, you're right i forgot to mention the final flush with new oil.

Are the lower bushings something you need to replace every X miles (if yes, any general rule, say 20k)? Or is there an easy way to tell if they are worn?

 

[SkooterG]

Wasn't it GP that fuxored up Feejers bike.. and I recall it was a spring seat issue?

Just to be clear, GP was NOT the shop that did the work on my bike.

FWIW, both of my dampners, when pulling up, are kind of 'herky-jerky', no worries here.

I don't know Don, 'herky-jerky' doesn't seem right to me. Regardless, this problem I have on the one fork is not present on the other fork. Nor was it present the previous two times I serviced my forks. And since I felt it taking it off the C-stand, I really feel it needs to be fixed.

Using K1 or mineral spirits, do the best you can. Follow up with a small flush of fork oil that gets disposed. You'll be just fine.

Jeff, that's what I have done in the past - last flush with fork oil that is disposed of. In terms of 'be just fine', I still think I need to repair whatever sticktion issue I am having with the one fork dampening.

But BTW, your lower fork tube bushings are toast. They needed replacing a long time ago.

I did most recent fork oil change after 35k or so and the oil was very dirty, but with only 3 flushes with K1 Kerosene the 3rd flush produced pretty clean forks.

Are the lower bushings something you need to replace every X miles (if yes, any general rule, say 20k)? Or is there an easy way to tell if they are worn?

Concur with the dirty oil, but I am no so sure about the bushings being bad.

Here's my forks complete history:

Approximately 39k miles: did my first service. Rode out to Santa Babs to finally meet TwoWheelNut in person. Since I had never disassembled forks, he helped me install my new Wilbers springs. Fluid was nasty.

At 90k miles, I flipped flipper for the second time. Thought forks might of been bent, and seals were blown. So I sent them to a recommended shop in Kali. He returned my bushings (originals with 90k on them) and they were shot. Almost no Teflon left on them.

159375 miles: Serviced the forks mysef flushing out old oil. With 70k since the last service, oil was NASTY. Took about 7 or 8 flushes of mineral spirits before it was coming out almost clear.

171550 miles: Forks serviced by (new to me) shop in Kali and TWN's GP Suspension valves and springs installed. Shop said they replaced the bushings, but even though I asked them to, did not save them for inspection. :angry: I assume they did replace them. IIRC, he said old looked ok.

219K: Current service going on.

Funny how Yamaha specifies no service interval for fork oil nor bushings. While I agree it's most likely best to replace fork oil around 30k or so, what's the problem with taking it longer? And based on my limited experience, I would say GEN I bushings last 60-80k miles. Now, word is that GP Suspension said they were really surprised to find out that when they were doing GEN II FJR's forks, the bushings were wearing very early. I believe Iggy said they were pretty much worn out around 30k or so?

And as a side note, my Wilbers rear shock was installed at approximately 30k. Rebuilit for the first time just over 100k. (Nothing wrong with it at the time) I haven't had it rebuilt since and detect no issues. So with 60k before the first rebuild, and now with almost 120k since that rebuild, I'm not so sure I buy into those recommendaitions that say shocks should be rebuilt every 20k miles or so.

Of course, YMMV.

 

[JamesK]

Wow Scooter, 120k and your rear shock is still ok. My Penske turned to crap with around 52k since new (it's on it way to Traxxion right now for a rebuild).

It would appear that the Gen1 FJRs are better built, in a number of ways than the Gen2, the suspension lasts longer, no electrical issues, etc. So much for the notion that things/products improve with newer models/designs <_<

 

[Grumpy]

Scooter you should be able to reassemble the fork without the springs and check for slop in the bushings. I recently did this on my new-to-me '03. A piece of white plumbing pipe will be your best friend when replacing the bushings.

 

[Aasland]

At 38k my bushings were shot (Gen II). At 38k by buddie's ST1100 bushings looked brand new.

Maybe it isn't the fork design, but the bushing materials? Fluid? The Gen II's call for that Ohlins liquid gold .. what does the Gen 1 specs call for?

 

[HaulinAshe]

Lower fork tube bushings - No way to tell much about them without disassembly. The wear item is coating/Teflon and only in the thousands-inch range. It requires a visual inspection. Typical wear is noticeable around 25k miles. The forks will continue to operate, be a little sticky, must the most damage is the possible wear to things like the inner fork tube chrome plating or the aluminum lower casting itself.

Reviewing the service intervals, I can't find where the cartridges have ever been replaced. If they have over 200k miles on them, the piston seals/rod bushings/etc. of the fork cartridges themselves are GONE! $150 each for Yami replacements, or ask around for someone who replaced theirs with AK-20s and has their OEM cartridges lying around collecting dust. Be sure to note that Gen-I and Gen-II cartridges are NOT the same.

Seals and bushings for both forks is roughly $100 in parts. I'd be very tempted to pick up some slightly used cartridges, seals and bushings, and tear those forks all the way down for a good maintenance interval. I'd want to know what the condition is of everything. But I tend to be over-cautious.

Like Grumpy said, you can partially re-assemble the forks with fluid and test the dampening. Leave out the springs, spring spacers, and spring washers. Open both Rebound and Compression clickers to something like 14-clicks. Move the fork tube up and down and get a feel for the force required.

Now close both Rebound and Compression clickers to 4-clicks. Move the tube up and down again, noting the required force and smoothness of action. If something doesn't "feel right", something IS wrong and the forks need real attention. Note that both forks should require the same force of movement at identical settings. One fork that dampens differently from the other is a bad thing.

 

[dcarver]

Lower fork tube bushings - No way to tell much about them without disassembly. The wear item is coating/Teflon and only in the thousands-inch range. It requires a visual inspection. Typical wear is noticeable around 25k miles. The forks will continue to operate, be a little sticky, must the most damage is the possible wear to things like the inner fork tube chrome plating or the aluminum lower casting itself.
Reviewing the service intervals, I can't find where the cartridges have ever been replaced. If they have over 200k miles on them, the piston seals/rod bushings/etc. of the fork cartridges themselves are GONE! $150 each for Yami replacements, or ask around for someone who replaced theirs with AK-20s and has their OEM cartridges lying around collecting dust. Be sure to note that Gen-I and Gen-II cartridges are NOT the same.

Seals and bushings for both forks is roughly $100 in parts. I'd be very tempted to pick up some slightly used cartridges, seals and bushings, and tear those forks all the way down for a good maintenance interval. I'd want to know what the condition is of everything. But I tend to be over-cautious.

Like Grumpy said, you can partially re-assemble the forks with fluid and test the dampening. Leave out the springs, spring spacers, and spring washers. Open both Rebound and Compression clickers to something like 14-clicks. Move the fork tube up and down and get a feel for the force required.

Now close both Rebound and Compression clickers to 4-clicks. Move the tube up and down again, noting the required force and smoothness of action. If something doesn't "feel right", something IS wrong and the forks need real attention. Note that both forks should require the same force of movement at identical settings. One fork that dampens differently from the other is a bad thing.

Jeff, how should the 'action' feel when upstroking the dampner rod? Smooth, no pulsations whatsoever or a bit herky-jerky? Hard to definein words. Silky smooth or some 'hesitation' along the stroke?
Regarding GenII bushings - Dave at GP Suspension mentioned that they were designed to keep the inner and outer tubes better aligned, but they don't work as well as the Gen1 single bushing, and they wear quickly. Mine were completely gone, and I mean all the way, after less than 25k. YMMV of course, based upon the type of riding you do (or don't do)!

 

[JR'SFJR]

Only need about $10 worth of special rebuild tools to take a look. I purchased a $7, 2" o.d. tailpipe with .050 thickness walls, 18" long, from Advanced Auto for installing the new bushings. I took a calipier along to measure the wall thickness and they had one pipe that was too thick. Also need a 2" dia. pvc pipe, about 18" long, for installing the seal and a 2" pvc coupler for dust boot install.

The rest of the disassembly is easy. Remove the dust boot, remove the snap ring, put fork in a vice and slide hammer the bushings and seal out all at once with the fork tube.