Fork seal question(s).

I just rebuilt my forks a few days ago (Thanks Chacal for the parts!) and the biggest piece of advice I can give you is print out the assembly diagram for them and have it sitting in front of you on your work bench. The entire job is straight forward, however, time consuming. It took me about 2 hours to do one fork, and then another 1.5 hours to do the other.

Take your time and make sure you assemble everything in the right order. When I rebuilt the first one, I noticed that I forgot to put in the taper spindle (xj 700n) and had to disassemble the entire thing to put it back in there. I am not sure of the similarities between the xj700 and the 900, but if you need any help along the way let me know.

 

Well, after getting my first one completely apart, I was a bit lost. There were several parts listed in the Haynes manual I didn't remember seeing. So, I decided to take the second one apart and put the parts for the first one in order piece-by-piece as I went along.

What I found was: Haynes' breakdown of XJ750RJ forks does NOT match my forks. Specifically, where Haynes shows an O-ring below the oil seal, mine have a cup shaped washer, and the oil lock assembly is pretty much entirely different than what Haynes shows.

The oil lock is where I have a problem, though. In mine there's a conical piece that fits onto the bottom of the damper rod where it pokes through the stanchion. Below that conical piece are a shim and what looks to be a spring shim (either a spring shim or a shim that got bent at some point - like when trying to pull out the stanchion from the lower assembly). Anyway, one of the (spring?) shims is broken. Since that part isn't on my Haynes IPB, I'm not sure what to do next.

So... Help!

Anyone else seen this form of a SECA 750 fork? If so, were the lower pieces spring shims or just shims?



Thanks,
Paul

 

On the XJ900RK it is unnecessary to remove the anti-dive unit from the fork lower to replace the seal. Just leave it on.

Here is the place where you can screw up, and the book warns of this: You use the inner fork tube as a slide hammer to knock the seal and outer bushing loose (make sure the spring clip is removed). When you slide the inner tube back down to hit it again you MUST be gentle and try to avoid bottoming it out. At the bottom is the oil lock mechanism and it is VERY fragile. You don't want to bang on it. Do it the opposite of sex - in slow, out fast and hard.

 

Well, I just double-checked my Haynes book, and it does not warn you about the possibility of damaging the oil lock.

Regardless of whether it was me, or it was already damaged, the damage is done. My question still stands, especially since Chacal does not list oil lock assemblies or parts in his catalog: "are these pieces shims or spring shims?"

Also, I'm guessing that the order in which the parts came out of mine is not the order in which they actually sat in there, and they probably should match the IPB. That would make the cup washer versus O-ring discrepancy the only difference.

Thanks,
Paul

 

SQL.....they are spring shims, and go check out the info here:

http://www.xjbikes.com/Forums/viewtopic ... tml#137702


UPDATED: you are right SQL, one is flat and one is a spring washer....but I'm not sure which one goes in which order within the tube!

 

Hmmm... OK.

In mine, the lower piston ring and the oil lock valve itself seem to be fairly solidly installed (or stuck) in the bottom of the fork leg.

As to the "wave" washer... two of mine are perfectly flat. One's a bit wavy, and the other one's broken. Do you stock them? Or can you suggest replacements?

Thanks,
Paul

 

Hey Paul, unfortunately I'm plum out of those little wave washers......and don't know where to get them.

 

We'll, I guess I'll have to see what I can find at ACE. Worst case, I can make one out of some somewhat thicker spring steel I have here, and grind it thinner.

I'll let you all know how it goes.

Cheers,
Paul

 

Hey SQLGuy. I'm at the exact same point as you in reworking my forks. Have one apart and just ordered my parts from Chacal.

Isn't it nice when you spend an hour scratching your head trying to match the parts that just fell out of your fork to the parts sequence in the manual and then find out the manual is wrong!!! I guess it's one way to get to know your bike inside and out.

 

Yeah, I suppose... though I would have thought my bike already had enough hand-made parts!

By the way, how do those shim washers look in your forks? Are they all wavy, or does each fork have one wavy and one flat?

Two of mine are definitely flat. It seems to me that, if both were wavy, I could replace them with one thicker wave washer; if both were flat, then they probably would have used one shim to start with; and if only one is wavy, then their use of two makes much more sense (as one would act as a spring for the valving of the oil lock, while the other would do part of ensuring a minimum gap between the cone-shaped washer and the bottom of the stanchion).

 

Hey guys...same with me, one spring (wave) washer was broke. You cannot get replacements. You will have to find an old fork and scavenge the sping washer.

Here is what I did:
Bought 2 nylon washers. Used a flat grinder to make them fit perfectly above the oil lock valve (the cone shaped piece). In this fashion, the oil lock assembly never by-passes fork oil. No adverse effect as I have test ridden mine. Possibly a little stiffer on the compression.

Second option:
I bought spring washers from Seastrom Mfg 800-634-2356 part # 5804-326-2 for $12.66. These washers are just about the correct diameters. Problem, almost 2x the thickness which means they need more pressure to compress. This will change the closing of the oil lock valve. Don't know how they will work. Next time I open the forks I will try them.

UNLESS someone sends me one good original spring washer!! Then I'll have a set and will put it back to stock.

 

I carefully removed the washers, noting the order that they lay inside the aluminum casting that rests at the bottom of the bottom tube. There are two washers, one wavy and sits in the bottom, or first into the aluminum casting. Next is the flat washer. See pic below.

Also, Apparently, the fork tool that everyone makes or buys won't work in our 750 Seca forks because the top of the damper tube is round and not hex to accept the spark plug socket end or tool. I'm lucky I read the note on the XJCD's suggesting to break free to retaining bolt before removing the forks. Mine broke free with no problem. I removed them to drain the oil prior to fork removal. I'm hoping that I will be able to tighten the bolt with no positive way to hole the damper tube from spinning. I'll probably make a wooden dowel to press onto the top of the damper while tightening the retaining bolt.

 

Excellent information. That's exactly what I needed to know. Thanks Carl!

I stopped by ACE, but came up empty-handed... nothing even close.

So, plan B will be first to make a small shellac face plate for my mini-lathe, then to shellac some .25mm spring steel sheet to it. I'll use the lathe to cut the ID and OD, and maybe to face off the "extra" .1mm of thickness. Probably finish up with a fine diamond sharpening stone. Should know how well this plan works out later today.

Len, if you want to get a set made, Misumi was mentioned on one of the machining forums as a good supplier for small-quanity custom shims and wave washers along the lines of what's needed here.

Cheers,
Paul

 

Carl, way to go, thanks!

Paul, I'll look into it. I know that those wave washers are almost always deformed or broken, and so it's a part that needs to be made.

 

Well hopefully I don't have those same problems when I work on my forks. I ordered my parts from Chacal and hopefully I will be able to start in the next few weeks. The weather is getting better here and I am ready to ride.

Thanks everyone for your help and I'm sure I will need some assistance in the future.

 

Success! I think/hope anyway...

It took three tries, and I had to make a couple of different new tools for the lathe, but I managed to make a fair copy of the broken wave washer.

The forks are now back together and I'll install them either tonight or tomorrow night. I used a piece of 1 1/2" PVC for the bush and seal driver (had to taper one end a bit with the bench grinder to make a good fit). It worked well, and seating the bushes and seals was actually pretty easy.

Cheers,
Paul

 

leoks,

I might suggest also looking on YouTube. I didn't find my exact forks there but there were lots of videos of fork replacements for different motorcycles. By watching enough of them, I was able to find enough variations to cover most of the features of my forks.

It gave me a good sense of what to do. Didn't hurt that I also had some help from bill.

 

SQLGuy, Wow, you don't mess around. I've always wanted one of those mini lathes. Congratulations on making the spring washer. It looks great.

 

When I rebuilt the forks on the XJ750E-II I found that the previous owner had lost some of these Lock Valve "shim washers". After some investigation I found that the Yamaha Venture had the same arrangement and I ordered the genuine Yamaha parts using the Venture part numbers.

 

Kiwi, I think the 750E-II uses the same forks as the XJ900 models? And those shims are not the same as the XJ750 Seca model shims........although they are VERY similar.

The 750 Seca shims have the following specs:

ID: 15.55mm
OD: 20.85mm
Thickness: 0.14mm
amount of bow, resting: 1.60mm


The 900RK Seca shims have the following specs:

ID: 16.15mm
OD: 20.85mm
Thickness: 0.21mm
amount of bow, resting: 1.25mm



So the 900 shims have the same OD, but a bigger ID (which shouldn't matter, that means for sure they will fit over the 750 Seca damper rod shaft), but they are 50% thicker than the 750 Seca shim, and have less "bow" or height to them in their un-loaded state.

NOW, these are certainly very thin shims, and can't exert a whole bunch of pressure (control) to begin with, BUT.......perhaps not much pressure, or, very precise control IS needed in these contraptions. And although my "spring rate calculation" formulas and knowledge is really, REALLY rusty, I do recall that the thickness of the wire (or in this case, the shim stock) is a huge determinent of the final spring rate, and I just don't know what (if any) effect using a different tension spring is going to have on the functioning of the forks (good, bad, or down-right scary-ugly),


By chance, you wouldn't happen to remember what YEAR and MODEL of Venture used those style shims, do you?