XJ900 Continuing to put up a fight - fork disassembly

Working on the forks on my '83 900 today. Got them pulled off and drained, now I'm working on disassembly. But I'm having trouble getting the bottom retaining bolt out for the damper rod. I can get it to turn, but it won't crack loose and just spins the whole rod. Usually, an impact will pop them loose even without anything holding the rod, but no such luck here.

I have a collection of tools that I've used in the past to hold the damper rod on various bikes, but none of them seem to fit the ones on the 900. I only have hex sockets up to 19mm, and my 3/4" homemade tool is too big.

If I had to guess, I'd say it's probably a 22mm? Can anyone confirm?

Also, has anyone tried something like this? Will it work? Seems like it should, and it would give me a few more options in the future. Plus, they're pretty cheap.

 

I have one of those things that I used for XJ700s, which are 22mm. I don't know about the XJ900s, but I don't know why it wouldn't work if they are 22mm.

On mine, I have ground down the 17mm section a little bit in order to give the the 22mm section more bite. I can't recall how necessary or unnecessary this was, but just FYI.

 

Thanks Dan. For $8 it's worth a shot.

 

While I'm waiting on the tool, I decided to pull apart the anti-dives. Ugh. Not pretty.

To start, the adjustment screws were cranked in tight. Had a hard time cracking them loose. Is that normal? Fortunately, they finally succumbed without any damage.

Then one of the bolts holding the body together decided it was happier where it was and refused to follow the hex wrench. EZ-out to the rescue. For a while I wasn't sure which would give up first...the extractor or the bolt. The extractor won.



Once open, much nastiness ensued. Some sort of grit built up in this one. Actually, looks like it was eating away at the diaphragm, or at least permanently deformed it. The diaphragms are seriously stuck too. I don't think I can get them off without damage. Guess I'll be talking to Len again...

Any reason I shouldn't chuck the whole thing in to the ultrasonic bathtub?

 

Got everything apart and cleaned up...well, almost everything. The thing that is giving me the most fits is the little cotter pin on the adjustment screw. One of them was rusted in place and it broke off when I tried to pull it. Tried to pull the other way and that side broke off too. Not enough sticking out to get ahold of, so I just ground it flush so I could go ahead and remove the screw figuring I can press it out with something when I have it on the bench. That has turned out to be easier said than done. Really hard to hold the screw securely, and I don't have any sort of punch that small. Tried nails, no luck. Hole is smaller than any drill bits I have. It's kinda pissin' me off.

At least it's not super critical. The only purpose is to keep somebody from screwing it in too far when it's on the bike. Worst case I just reassemble as is and remember not to turn it too far.

Also mangled up the spring clips that hold the big spring in place. Those things are about as stiff as a paper clip, and probably a smaller diameter. Over the years they indented themselves into the plastic seat making them even harder to get out. In hindsight, I probably should have just left them in place. There isn't really anything under them that's a wear item. But I couldn't bear the thought of leaving crud down in there.

Hope Len has all the parts I need. If not, I guess I'll be installing the block off.

 

Yep, I had to grind it down too. The issue is that the 17mm hex is too wide to fit the inner diameter of the damper rod. I basically just chucked it in a drill and ground the flats off and that worked. No big loss since I have other 17mm hex sockets if I need them.



In hindsight, I'd probably recommend something more like this for a few $ more. Although my choice had more to do with which one had next day 6am delivery than cost.



Man, those bolts were tight!

 

Ok, next issue. I've searched for tutorials here and haven't found any that show the answer, nor do I see anything about it in the manual.

Inside the lower end of the inner tube are some "parts" that are free to spin around. I think in the exploded view it might be what is labeled "cylinder complete", but it's not very clear so it's hard to tell. Feels like there are multiple pieces in there. I can wiggle them around and spin them with my finger.

At any rate, I can't figure out how to get it out. Any ideas?

I've got it pretty well cleaned up, so I could just put it all back together, but I'd like to be able to inspect whatever those parts are in there.

 

When I do forks, that lower bolt is the first thing that I loosen. Get a good impact electric drill or air impact with a very good Allen head and just pot them loose. Even taking them out first will only make a mess and will not hurt anything. I have had to drill a number of them out of forks before I started taking them out first before removing the top of the fork. Just a thought.

 

I got the bolts out fine. Just took a little muscle once I had the right damper holding tool. It's the other doo-dads in the bottom of the inner tube (red arrow in pic above) I am unsure about.

 

I'm not sure that the bottom of the inner tube can be dis-assembled....it think there is a "plug" that is press-fitted in place during manufacture of the tube that contains a floating "bearing" of sorts for the shaft of the damper rod........but, I'm just speculating here, as I've never taken a tube apart.........

BTW, the lower bolt (that holds the damper rod in place) is loctited in place, which is why they are such a beast to get out.

 

I think you are probably correct. I sure don't see any way it can come apart. There is a little slot in the inner ring which will halfway line up with the oil port on the side of the tube if you rotate it just the right way. It looks like you could in theory insert something in there to pry, but I'm too chicken to try for fear of damaging something.

I dunked the end of the tube in the ultrasonic for a while and that cleaned it up pretty good, so I think I'll just leave well enough alone and put it all back together. I plan to fill and flush with some cheap fork oil before putting in the good stuff so hopefully that will wash out any gunk I might have missed.

 

Working on reassembly of the anti-dives now...

Is there some secret to getting the retainer ring in place when reinstalling the seal on top of the big spring? I tried using a socket to compress the spring/seal/clip hoping the clip would pop into the groove, but the pressure from the socket prevents the ring from expanding into the groove. I finally got one of them to go in by using a smaller socket that fits inside the ring, but I'm not happy with it. I'm not confident the retainer ring is fully seated. Hoping somebody knows a better technique before I attempt the second one.

 

If I recall correctly, a strong flashlight and a small flat-bladed screwdriver (or a pick) maneuvered in from the side (thru one of the passage holes) while someone else / something else is holding the housing and compressing the big spring. For sure it's a real pain in the butt to do.

 

That ended up being the ticket. Sort of. The general idea anyway. On the first one I was struggling because my bench vice doesn't open up far enough to have it hold the socket and I couldn't apply pressure and pop the spring at the same time. But then I remembered I have a woodworking vice in the shop downstairs that opens up plenty wide.

I used a 9mm socket with an extension centered inside the spring clip, then clamped the whole thing in the vice and put enough pressure to move the seal past the slot for the clip. Took a lot of fiddling to get everything lined up and get the spring in place. In the end the best tool ended up being a cheap screwdriver with a bent tip.

I was going to post some pictures of the setup, but for some reason it's not letting me insert them anymore. They show up for a brief moment, then disappear. Strange.

 

Never get rid of old tools.....they're always useful for some type of work!

 

Ok, so I had a "duh" moment the other day and realized that there is a much easier way to get that little wire spring for the seal in the main body in and out...

Just get an M6x45mm or longer bolt, and a washer with 12-12.5mmOD, or better yet this tool that I uploaded to the 3D printing section.
https://xjbikes.com/forums/threads/xj-900-seca-anti-dive-wire-clip-removal-aide.132895/

All you have to do is thread the bolt down through the adjuster hole with the washer and/or 3D printed tool in place, then tighten it down to compress the spring enough to take the pressure off the wire clip. It leaves easy access to get the clip in and out.

I wish I had thought of it sooner!

 

Wanted to confirm which way the washers go on the damper rod...

The Haynes manual doesn't have any pictures showing the washers but says they go on BEFORE the "seat" (aluminum thing) as in the first picture.
The manual found online (not sure it's origin) also shows the washers before the seat, but it also shows them out of order, and they show the seat backwards, so do I trust it?

The reason I ask though is I am 99% sure when I dumped the guts out of the fork, the washers were AFTER the seat as shown in the 2nd pic. They were stuck in the recess, and it seems unlikely they would just happen to fall there.

When I did the first one, I put it back together like the first pic, but now I am having doubts on the 2nd one because of the way they came out.

The forks were sludged up enough that I doubt anyone has had them apart before. But 42 years is a long time, so maybe somebody put it back together wrong a long time ago?

 

Not sure if it helps but the 750 Seca forks appear to be like the first figure as seen on page 2 of this thread

https://xjbikes.com/forums/threads/doing-the-750-secas-forks-rebuild-now-a-how-to.18730/

I don't know that I have ever read what the washers function are, which if we knew might make more sense on the stack up

Maybe Len or another 900 owner will weigh in

Or this from the parts catalog

https://www.xjbikes.com/forums/thre...-k-steering-and-suspension.44635/#post-395035

"Order of assembly of 1984 XJ750RL, XJ750P (37H model, and XJ900RK/RL Seca oil lock valve assembly components onto damper rod:
NOTE: the Yamaha factory service manual has an incorrect written description and an incorrect image showing the assembly order of the “oil lock valve” components onto the damper rod, showing the two wave washers being adjacent to each other. The correct assembly sequence --- as shown below --- is for the wave washers to be separated by the flat shim washer:
TOP (HEAD) OF DAMPER ROD
DAMPER ROD REBOUND SPRING
Above fitted thru bottom of inner/upper (chrome) fork tube.
On thinner, lower end of damper rod:
WAVE WASHER (HCP19355) goes onto the damper rod shaft first
FLAT WASHER (HCP19356) goes onto the damper rod shaft next
WAVE WASHER (HCP19355) goes onto the damper rod shaft third
Finally the TAPER SPINDLE (HCP3085) goes on last."

 

This illustration shows the "taper spindle" with the small end up and the washers on top, so like my first pic above. I am pretty sure that is correct.


Something isn't right though, and I can't figure out what. The manual says you are supposed to line up the oil hole in the damper rod with the lower hole for the anti-dive. On the first fork, it kinda lined up...it was towards the top of the anti-dive hole, but you could see it about half cut off. This one, I can't see the hole in the damper rod at all no matter which way I put the parts in. It's like the damper rod isn't seating all the way down...or the hole is in a different place. Starting to get pretty frustrated with it. I really don't want to have to pull the other one apart again to look at it. It's already filled with oil and everything.

 

Well, you could build the needed tool yourself from some nuts and and a thread rod - this is how I did it.