Replacing Fork Seals on an XJ600

[anon]

YAMAHA DIVERSION CLUB
TECHNICAL LIBRARY
ARTICLE 03/05 - REPLACING FORK SEALS ON AN XJ600S
Written by Trevor James July 2003
This procedure was performed on a 1994 XJ600S. Later models have twin front disc brakes and an oil cooler (which may or may not get in the way), and some of the specifications are a little different. Also, some of the torque wrench settings are different.

Things you will need:

Haynes manual (preferable but not essential)
Replacement fluid seals and dust seals
Non-permanent thread locking fluid (e.g. Loctite)
1 litre fork oil
A piece of plastic drain pipe
Car jack and bits of wood

Tools:
8, 12, 14, 19, and 24mm Sockets (and/or ring spanners). Hex sockets are preferred, as they offer a better fit.
6 and 8mm allen keys
Pliers
Flat-end punch and small hammer/mallet
Small flat-blade screwdriver

Before tackling this job, read through and be certain that you are confident and capable of doing it. Otherwise, take the bike to your local bike workshop. You could remove the forks and just take them to have the seals replaced, which will save you quite a bit in labour charges. I did this first time I needed one doing. It cost me £30 to replace one seal and change the oil in both forks.



Start - bike on centre stand


Block of wood on jack, then jack up so front wheel is off the floor. Support also with piece of wood under frame.


Remove bolt holding brake pipe in place (8mm)


Remove 2 12mm bolts holding caliper (spanner's on one, I'm pointing to the other)


Support brake caliper(s) - I hung mine from the frame on a piece of wire. Also disconnect speedometer cable from the wheel hub.


Undo 6mm allen axle pinch bolts (later models have one instead of two, and the axle is threaded from the opposite side)


Unscrew and remove wheel spindle (19mm) whilst supporting the wheel.


Front wheel removed - next undo 4 8mm bolts supporting mudguard and remove it.


Loosen (but do not remove) 19mm fork cap bolts each side


Loosen top fork clamp (6mm allen screw)


Loosen lower fork clamp bolt (14mm) whilst supporting fork leg


Lower fork leg from clamps (then repeat for other side)



Remove fork cap (be careful doing this, as it is under a lot of spring pressure), spacer, spring seat and spring, then drain oil. Fork is then ready for disassembly. You'll need one of these, or something similar. It's a bolt with a 24mm head, to which a nut has been secured using a roll-pin. This is used to hold the damper rod inside the fork whilst undoing the 8mm allen bolt at the bottom of the fork leg. You'll need an extension bar, as it's quite a long way down the tube.



After undoing the bolt and removing the damper rod and spring, remove the dust seal and spring clip covering the fork seal, then slide the two parts of the fork leg apart (use a slide-hammer type action - should only take a couple of pulls).
Showing the fork components. At the top is the damper rod and the 8mm allen bolt. In the middle is the outer fork leg, and at the bottom the inner fork tube with seal, washer and bronze bushing still attached. Not shown is the plastic oil lock piece from the bottom of the damper rod - this was still inside the outer tube.



Clean and dry all components and inspect for wear. If the bronze bushings are worn, they will need to be replaced. To reassemble, apply some thread-lock to the 8mm allen bolt, then slide the damper rod (with its spring) down the inner fork tube, then put the oil lock piece over the end. Slide the inner tube into the outer and fasten with the 8mm allen bolt to 22ft-lb torque. Hold the damper rod the same way you did when you loosened it, using the 24mm tool. The piece of plastic drain pipe is used to drive the bronze bushing into place. I just slid it down the tube repeatedly until the bushing was home.



After the bronze bushing is in place, fit the washer, then oil the new seal inside and out with fresh fork oil and slide it down the tube.
Drive it partially home using the drain pipe.
Unfortunately, the pipe is such a close fit on the tube that it actually contacts on the seal face, so don't drive it all the way home using this.
Either find another piece of tube of a slightly wider diameter, or very carefully punch the seal home the rest of the way using a flat-faced punch about 6mm diameter.
Be very careful not to distort the seal when doing this.
Fit the spring clip and dust cover, then the fork is ready to reassemble into the bike.
After mounting the fork back in the clamps (flush with the top yoke), slide the spring back in (close-wound coils to top), then fill with oil (in my case, 379ml, but later models are different). Standard is 10w oil, but I used 15w, just to see if it improved the feel of the front end (it did!)

Fit the spring seat (washer), then the spacer, then the cap bolt. Be VERY careful fitting the cap bolt. You have to apply quite a bit of pressure against the spring, and it's really easy to cross-thread the cap bolt (as they seem to be about as hard as cheese).

The rest of the reassembly is a reversal of the disassembly sequence. It is advisable to use a bit of copper grease on the bolts before fitting them (except on the damper rod bolt!), to aid any later disassembly.

Torque setting are:

Fork caps - 17ft-lb
Top clamp bolts - 17 ft-lb
Bottom clamp bolts - 27ft-lb
Wheel spindle - 43ft-lb
Wheel spindle pinch bolts - 14ft-lb
Brake caliper mounting bolts - 25ft-lb


The author will not be held responsible for any loss or damage arising out of the use of this document. It is your responsibility to make sure that you have the facilities and the capability to complete the job safely.

[jockyT]

Great article but can I suggest something:

Loosen the upper triple clamp bolt before loosening the cap nut (which is soft alloy) - this takes the pressure off the cap nut threads and makes undoing easier.

JT

[CD]

You might also be able to use the platic pipe to press the seal into place. Champher out the inside so it doesn't catch the seal lip. Alternatively the solvent weld waste pipe is slightly a couple of mm larger diameter. It might be a better fit for the seal.

[HRHpenfold]

Aug 8, 2008 22:49:28 GMT jockyT said:

Great article but can I suggest something:

Loosen the upper triple clamp bolt before loosening the cap nut (which is soft alloy) - this takes the pressure off the cap nut threads and makes undoing easier.

JT

There should be no pressure on the threads, the top clamp bolt would strip well before exerting a pressure capable of doing this

[skolim]

Thanks for the article - it was very helpful.

Unfortunetley have problem with unscrewing dumper rod. I have prepared special "tool" with 24mm nut (similar to Yours). I inserted it inside fork, but I can't catch the rod to prevent it from spinning
Maybe I got wrong size of the nut? 24mm should be the distance between two flat sides of the nut, or its corners?

Maybe there is difference between XJ models? I've '98 XJ600S which, as far as I know, has wider forks (41mm instead 38mm). Do I need different size of nut to catch the dumper rod?

I would appreciate any help or ideas.

[teejayexc]

Hi Skolim, should be 24 mm according to the haynes manual. Have you got access to a powered ratchet driver to loosen the damper rod bolt? I found that this worked on a Honda I had similar problems with once, just needed that quick sharp turn to loosen it.

[skolim]

I don't have powered ratchet driver:( But I don't know if it would do any good. The allen bolt at the bottom of the fork seems quite loose I can spin it with one finger , but it also spins the dumper rod.
I also tried to unscrew the nut with the spring inserted and top fork cup put on. That would give a little pressure on the dumper rod, but I can hear it spinning when I spin the bottom allen bolt.

My best gues is that something has jammed, or that I can't measure the nut right;)

I have one last idea I think I could use some Kind of plasticine-glue (I don't konow how it is in English) on a steal rod and put it down the fork to stamp any shape of grip there is down there What do You think about that?

PS. I've Haynes manual for XJ 92-99, so it should cover my motorbike, and it does not mention any differences.

[teejayexc]

The rod spun freely on the Honda too, but the action of the powered ratchet just seemed to spin the bolt quick and break the seal.

The mould idea sounds good if you can do it, you would at least have an idea of what shape is down there.

Good luck.

[skolim]

I made It!

I found some information on www.bikersoracle.com/yamahadiversion/forum. Damper rod doesn't have any kind of grip and is just round inside.

So here is a little upgrade to this guide for XJ600 past 1998 (twin front brakes, wider 41mm forks). To remove the damper rod You need other special tool... a wooden dowel ;D It should have about 25mm diameter and should get narrower at one end.

1. Put the narrow end of the dowel down the fork.
2. Tap it few times with the hammer and it should get jammed.
3. Put bottom part of the fork in some kind of handle and loosen bottom 8mm allen bolt.
4. Now grab wooden dowel to prevent damper rod form spinning inside the fork and unscrew allen bolt.
5. Rest of the work is the same as above.

One more important information. From what I found 41mm forks have different oil capacity. They require 463cc, 120mm from oil level to top of tube (with spring, seat and spacer out).

Here are some pics:

Special "tool" ;D


Damper rod with "tool" inserted


Disassembled fork

I hope it is all clear, because my English is not perfect.

[CD]

Aug 13, 2008 11:32:55 GMT HRHpenfold said:

Aug 8, 2008 22:49:28 GMT jockyT said:

Great article but can I suggest something:

Loosen the upper triple clamp bolt before loosening the cap nut (which is soft alloy) - this takes the pressure off the cap nut threads and makes undoing easier.

JT

There should be no pressure on the threads, the top clamp bolt would strip well before exerting a pressure capable of doing this

I always thought this was true, but my fork top plug would not move until the pinch bolt was loosened. The threads were clean and undamaged, but a very close fit. Deffo better with bottom yoke clamp done up tight and the top clamp loose.

[amorti]

You can use the old seal as a soft drift to get the new seal all the way down

A ratchet gun really is magic for removing damper bolts. It doesn't matter if the damper bolt is spinning freely, I have never met one that the rattly gun couldn't get out. I wouldn't put threadlock on this bolt. I have never found one with, but equally never seen one fall out, if anything they seem to tighten in use.

I agree that slacking the pinch bolt really does make a difference to how easy / hard it is to remove the fork cap, and doubly so when refitting. Should or shouldn't? dunno, but it definitely does!

I will be doing mine this weekend, thanks for the tip on the drain pipe. I have never before had a bike with such skinny forks, and so might have not thought of that! Thanks.

On your pre-facelift bike, it has oil drain bolts down the bottom. Yamaha decided these unnecessary on the post facelift bike. The flat face is still there, but the hole is not drilled or tapped.

I would consider drilling and tapping except: a) I might c0ck it up. b) there'll be swarf where it oughtn't be and c) I really don't see me bothering with a fork oil change interval, I doubt the bike has much more than 20k left in it anyway.

[CD]

Grease on the drill and a piece of tube over the drill to stop it going too far in will catch the swarfe. Grease also works with the thread tap. The issue will be getting the hole square with the surface so the sealing washer can seal all the way around.