HOW TO: Forks Seals, Bushes and Oil

[John Silva]

Originally posted by pointer2null on 07/06/2009


Firstly, this is a guide. I accept no responsibility for any mistakes or omissions. If you break it or injure yourself then that’s your problem.

If you're using this guide to change fork oil, only follow the drain, clean and refill parts of the process.

Tools needed: You will need the usual set of spanners, sockets, Allen keys/sockets, torque wrench, hammer and screwdrivers.

Special tools:
You will need something to drive in the new fork seals. On the occasions I have done this I have used a plastic tube of the right dimensions and a brass pipe fitting that also happened to the correct size. You will need something that will fit over the fork inner without scratching it. The fork inner is approx 41 mm diameters so a plastic tube with an inner diameter of 42mm would suffice. The outer diameter must be small enough to fit into the top of the fork lower. The fork lower internal diameter is approx 53mm so you tube should have an outer diameter of approx 52mm. The tube should be at least 0.5 meters long if possible so you can place it over the upper fork tube and tap it with a hammer to drive the seal in. If it is not long enough you can still use it but you will have to tap around it to drive the seal in evenly.

Parts:
You will definitely need new fork seals and fork oil.
You may need new dust seals (depending on the condition of the old one - if they are ok they can be reused).
You may also need new seal retaining clips if the old ones are corroded - these are not expensive so it may be a good idea to replace them regardless.
Bushes if you intend to replace these as well.


Although this is possible with the front fairing & headlamp assembly in place it is easier to remove it first.

[smg id=12[/img]

After removing the fairing etc, remove the front wheel. Take care not to damage the speedo sender unit (1) or loose the inner rotor part. Tie the front calipers (2) to the handlebars so that the brake pipes are not under stress or damaged (2).

[smg id=23[/img]

Work on one fork at a time; do not mix components between forks.

Loosen the top clamp bolt on the fork you are working on (1). When this is loose also loosen, but do not remove, the cap bolt on the fork (2). The image below is a MK2 Fazer; the MK1 does not have the preload adjuster.

[smg id=33[/img]

A couple of turns is enough.

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Next loosen the lower clamp bolt. In the image below the hex clamp bolt has been completely removed, you only need to loosen it (we removed it for another reason not connected with the fork seals*)

[smg id=35[/img]

When this is released the fork will slide down so be prepared to catch it.

[smg id=36[/img]

Try and loosen the damper retaining bolt located in the bottom of the fork.

[smg id=37[/img]

Sometimes you will be lucky, sometimes you won't. Often it won't loosen because the damper assembly inside the fork is turning. If it won't loosen continue and we will remove it later.

Next the cap bolt can be completely undone.
IT IS UNDER SPRING LOADING SO WILL SHOOT OFF IF YOU ARE NOT CAREFUL!

You will need to keep hold of the top fork tube as when the spring tension is released it will try to slide down into the fork lower - we are not ready for this yet.

Tip out the old fork oil and be prepared to catch (in this order), a solid washer spacer, a hollow tube spacer, a normal washer spacer and finally the spring.

[smg id=38[/img]

Note which way the spring comes out - the closer coils are at the top of the fork.

[smg id=39[/img]

Here is everything you should have:

[smg id=13[/img]


1 Cap bolt (MK1)/preload tensioner(MK2)
2 Solid washer spacer
3 Hollow tube spacer
4 Normal washer spacer
5 Spring

Wipe them off and put them out of the way.

Holding the fork upside down, pump it a few times to remove the last of the oil.

DO NOT LET THE FORK BOTTOM OUT OR IT WILL JAM!

If it does jam then you may be able to release it by pulling it hard, however since you and the fork are probably both covered in oil this isn't easy. If you cannot release the fork, partially refit it into the bike and tighten the lower clamp bolt. Using a piece of wood to prevent damage, tap the fork lower around the dust seal until it unsticks.

If you wish to wash out the fork, now is a good time. We used diesel and I have used paraffin before. Pour a small amount into the fork and pump it a few times then drain. Repeat till you think you've got most of the gunge out. DON'T bottom the fork out! 

Next loosen the damper assembly nut located in the bottom of the fork. If you managed to loosen it earlier this should be quite a simple stage, if not then this is difficult as the damper assembly will most likely rotate in the fork itself.

You will need to find something to put inside the fork to try and jam the damper assembly - a broom handle or a piece of wood with a tapered end works best.

Upend the fork and place it over your pole, force the fork lower down so that the pole grips the parts inside and then try and release the bolt. Be prepared to swear a bit and just keep trying. It took us 15 minutes to release one, and the other just 30 seconds.

[smg id=14[/img]


When the bolt is released, slide out the damper assembly.

The images below show you what you are trying to do.

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[smg id=16[/img]


You should now have all the following bits from inside the fork:

[smg id=17[/img]


Next pries off the dust seal to reveal the fork seal and retaining clip

[smg id=18[/img]


[smg id=19[/img]


Depending on how bad the dust seal was there may be a fair amount of gunk in here.

Next pries out the fork seal retaining clip. If you are not planning to replace it, take care not to damage it.

[smg id=20[/img]


There are 3 points you can use the get the clip out - the two by the open ends are best if you can identify which they are.

[smg id=21[/img]


[smg id=22[/img]


If the clip is badly damaged or corroded it must be replaced.

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Hold the fork lower in one hand and the fork upper in the other and give it a good yank. This will pull the upper out of the lower and remove the old fork seal.

[smg id=25[/img]


1 - upper fork bush
2 - washer
3 - old fork seal

Remove and discard the old seal.

Clean up the fork upper and lower and flush out any gunk.

At this point if you are going to replace the fork bushes, pry off the old ones and fit the new. They are not continuous, but have a split so should come off easily.

[smg id=26[/img]


Now take a new seal and rub a small amount of oil around the inner edge. Carefully fit the new seal over the top of the fork. Be careful to get it the right way round. The 'open' side faces inside the fork and the closed side faces outwards.


'Open' side which faces inwards/down

[smg id=27[/img]


'Closed' side which faces outwards/up

[smg id=28[/img]


Refit the fork inner into the outer. The bush may or may not slip in easily. If it won’t go in all the way don't worry as it will be pushed in when we drive the seal in.

Using you seal driver tool hammer the seal home.

[smg id=29[/img]


[smg id=30[/img]


When the seal is fully seated you will be able to see the retaining clip groove all around the fork lower.

[smg id=31[/img]


Refit the retaining ring and the dust seal.

Next refit the damper assembly - make sure the rebound spring does not come off in the process. We found (as in the pics above) that it was easier to insert the damper assembly from below. Insert the retaining bolt and tighten it to the correct torque.

Next refill the fork with the correct amount of fork oil as specified in the manual. The manual specifies 10W fork oil, but many Fazer owners (myself included) use 15W as it makes the front forks less bouncy.

The fork inner must be fully inserted into the fork lower to do this - remember the risk of getting it jammed so DO THIS VERY CAREFULLY!

Fill the fork with slightly less oil than required (440ml instead of 475 as needed). Pump it a few times to remove any air trapped around the damper assembly. Do not pull the fork inner out by more that 130mm or you will cause more air to enter. Leave the fork for about 10 mins to let any air bubbles rise. Measure the air gap and add oil as needed. Keep repeating until you have got the correct air gap.

To get the correct air gap you can either use a rod or micrometer depth gauge and carefully fill the fork until the oil just touches your measuring rod, or you can make up a tool like I did.

[smg id=32[/img]


The rigid (bit of old metal brake pipe or hollow car aerial) tube is set to the correct air gap, the fork is slightly overfilled with fork oil and then the tube is inserted. The suction bulb is then used to suck out the excess oil.

When you have the correct amount of oil in the fork, pull the fork inner up (no need to worry about air now) and insert the spring and spacers making sure you get them in the right order. Refit the fork cap bolt- this is a little tricky as you have to depress the fork spring at the same time.

Refit the fork into the bike, making sure the top of the fork is just level with the top of the top yoke, and tighten the lower clamp bolt. Before tightening the top clam bolt, correctly tighten the fork cap nut. Now tighten the top clamp bolt.

Repeat for the second fork.

Refit the front wheel - take extra care to make sure the two lugs on the inner part of the Speedo sender unit are correctly located or they will snap off.

Refit brakes and fairing.

(* The owner of this bike sheared the other so we removed this one to measure it. )  :rollin

[John Silva]

Originally posted by limax2 on 20/10/2009


As you point out removing the damper tube screw can sometimes (often!) be frustrating, not aided by loctite being used on assembly. The official Yam tool for the job is a steel spike thing which seems a bit crude. What follows are details of a simple tool I have made that making this part of the job very easy. It can also be used to hold the damper tube when assembling and tightening the screw, as it is easily removed when done.

[smg id=48[/img]

These are the bits of the tool.


[smg id=49[/img]

This is the tool ready for use.
It is inserted down the fork leg so the slotted end, left in picture, slides into the damper tube. The small nut near the right hand end is then tightened to expand the slotted end and grip the damper tube. The right hand end in the picture is still sticking out of the fork leg and can be gripped in a vice or mole grips and the offending screw undone with great satisfaction and no cursing. 
You then back off the small nut and a light tap on the end of the rod (domed nut in picture) releases the grip.

[smg id=50[/img]

Tool in damper tube.

If you fancy making one here are some details. All shown in millimetres. The only fairly important dimension is the 18.40 diameter that goes into the damper tube, which has a bore of 18.50 diameter. All the rest can be altered to suit the material available.

[smg id=51[/img]

This is the gripping end showing the tapered bit that does the expanding of the slotted tube. The threaded rod is M8, the type you can get from B&Q etc.

[smg id=52[/img]

[smg id=53[/img]

This was made from some tube I had which I think might have been electrical conduit at some time, not sure.
This tube needs to be at least 500mm long so that it protrudes out of the stanchion when inserted into the damper tube. I have welded a large nut on the right hand end, but it's not necessary as a vice or mole grips on the end will do fine.

Of course if you live within striking distance of Chorley in Lancashire you won't need to make one because you can borrow mine. 

I made the expander wedge from a piece of mild steel bar, but aluminium etc. or even hard wood would probably do. Instead of threading it it could be fastened to the screwed rod with a nut at the back. The flats on it are not necessary; I just put them there for holding whilst tightening the lock-nut. All very easy on a lathe, but a bit more difficult without one. If you want an expander wedge as per the drawing let me know and I'll send you one, post man permitting!
A couple of thing I forgot to mention.
1) In use don't tighten the top nut too tight because the shallow taper exerts a very strong outward gripping force on the damper tube.
2) The small 1.5mm dia hole at the top end of the damper tube sometimes has a burr on the inside, so best to check that it doesn't end up partly blocking the hole.

[snapper]

it might just be me but none of the pictures work

its not important at the moment i was looking for future refferance as i have to replace my dust seals soon

[Farjo]

Fixed. Thanks snapper

[Fazerider]

Is there a restriction on the number of pictures a post.. or thread..  can have? 'Cos it looks as though later ones are missing and have been replaced by an error message.

[BIG MAC]

I cant see the later pics just a lot of 'limit reached' stuff?

[willmckeand]

Hi guys, I've put 475cc/ml of oil in the fork with the spring etc out of it, and that amount of oil is no way near enough?


I's about 280mm down from the top with 500ml in, whereas my Haynes manual says it should be 121mm from the top!


If I put any more in I won't have enough for the other fork, and while I could buy more I think I must be missing something that's making my level so low.


Any suggestions greatly appreciated!


Will

[keratos]

all I can see is [limit reached] error . also this is a good image supported tutorial but please can i propose some additions to help us; where there has been a level of working-knowledge or assumption , some additional images would help:..

1. image showing the black and decker workbench with the bottom of the fork, what is it we are looking at/for here? a red circle and text would help
2. DO NOT LET THE FORK BOTTOM OUT ... what does this mean and what do we do to prevent it - pics please - what does "good" and "bad" look like?
3. Loosening/removing damper assembly and stubborn bolts - example pics please
4. ..from here on in the tutorial is not easy to follow  as there are just "[limited reached]" errors littered through the text and I wouldnt attempt this job without guidance - please can we sort out the errors

thank you in advance for what would be a most excellent tutorial

[pointer2null]

original site still has the piccies




http://fazerowners.yuku.com/topic/23188/...es-and-Oil

[red98]

Yeh...I did see that.great guide,...iam doing something silly but I just cant see it.....driving me mad...

[pointer2null]

1. image showing the black and decker workbench with the bottom of the fork, what is it we are looking at/for here? a red circle and text would help


As in the original the text says: "[size=78%]Try and loosen the damper retaining bolt located in the bottom of the fork. [/size][/size][size=78%]  You can see in the picture the top of a hex nut in the bottom of the fork.[/size]




2. DO NOT LET THE FORK BOTTOM OUT ... what does this mean and what do we do to prevent it - pics please - what does "good" and "bad" look like?


This means when you compress the fork (push inner into bottom) do not force it right to the bottom "bottom out" as it will stick. If it does you have to pull it out which can be tricky as it's all covered in oil by then.
3. Loosening/removing damper assembly and stubborn bolts - example pics please


what does a pic of a stubborn bolt look like?
4. ..from here on in the tutorial is not easy to follow  as there are just "[limited reached]" errors littered through the text and I wouldnt attempt this job without guidance - please can we sort out the errors

see link to old site with pics

[keratos]

thanks!  :\ I'll write a n00b HOWTO when I get round to it as I sense no appetite to change the thorough excellent yet - to me at least - difficult to follow guide . I'll do a complementary article in due course. Dont shoot me down foccers - if I find it less straight forward then there is a reasonable expectation that others will too. Its a great guide, but could do with simplifying for less experienced and confident chaps like myself just to explain how to replace fork oil  - simplez. Electrics is my forte , not mechanical.

[red98]

Having just done this job, and re read the guide , its a good guide and in my opinion....yes I did struggle when the fork tube jammed in the lower, but the guide did mention it...what I could'nt understand is why it should do it....all sorted now...as with any guide or manual you do need a bit of knowledge to start with......really pi**es me of when people knock haynes and the like, yes they have made some mistakes in the many years they have been going but who has'nt..........cheers for a well written guide  :thumbup

[keratos]

Having just done this job, and re read the guide , its a good guide and in my opinion....yes I did struggle when the fork tube jammed in the lower, but the guide did mention it...what I could'nt understand is why it should do it....all sorted now...as with any guide or manual you do need a bit of knowledge to start with......really pi**es me of when people knock haynes and the like, yes they have made some mistakes in the many years they have been going but who has'nt..........cheers for a well written guide  :thumbup

jolly good for you - btw , who's knocking Haynes?? I have stacks of them and helpful they are too but sometimes you need these forums to get that little extra detail where perhaps there is a bit of assumption by the Haynes experts and contributors . This is an excellent guide and we should be grateful of the time taken to capture and share the work undertaken. All I am saying is that for me, and other first-timers, a little more help around the assumptions or perceived "simple bits" would be helpful - like I said, one mans forte is another's woe.

[Jamieg285]

I've just done this job, using this guide for reference.  (3hrs for the 1st leg, 1hr for the 2nd)


I'd like to add a couple of snippets of info that caught me out.


1. After pulling the inner from the outer, I had more bits that were listed - the normal bush, washer and seal, but also a white-ish, top hat shaped piece of plastic with a spring in it.  I couldn't see any reference to this and couldn't work out where it went.  After much trial and error, I found it went into the outer fork, before the inner.  On the picture of the removed inner (visible on the yuku page) you can see the end of it stuck into the inner (left side).  It seemed to tight to fit there on mine, but I confirmed from the other fork, that is where it goes.


2. Halfway through the strip down, I found a copper washer on the floor and wasn't sure where it came from.  It wasn't until the 2nd fork that I discovered that it went on the damper bolt, on the underside of the fork.

[Chris]

Great guide 


Just done my fork seals and the guide really helped.


One of my damper rod bolts had a rounded off head so I had to hammer in a triple square bit to grip it and get it out. I obviously then needed to get a new bolt. I thought I'd post up the part numbers in case anyone else has the same problem.


Damper rod bolt part number: 3D8 23181 00
Copper crush washer for damper rod bolt: 509 23158 L0


Hope that's useful to anyone else with the trouble I had with mine.


Chris

[Qutuz]

hi, thank you for the above tutorial, a fantastic resource for all. i followed it yesterday to replace my blown fork seals, FZS600 1999


there is something significant the tutorial does not mention which gave me a real headache for a few hours, im not sure it is due to the fact the one in the tutorial is a slightly newer foxeye model.


there is a small white plastic spring loaded tube called a spindle taper(alluded to by Jamieg285) which sits right at the bottom of the lower/outer of the fork, this has a habit of jamming into the inner/upper fork, if this happens you cannot refit all the internal parts as it becomes impossible to close the cap bolt.


you have to drop the spindle taper into the bottom/outer fork first and foremost, then to add the bottom damper retaining bolt you need drop the damper unit into the upper/outer fork and slowly lower it in without bottoming out and not catching the spindle taper, torque to required amount, you can then add all the spring/spacer etc before adding new oil and top cap.


as i mentioned you cannot let the let the inner/upper fork drop all the way down whilst fastening the bottom damper bolt as it will catch the spindle taper making assembly impossible, hope this helps.

[mcr1957]

Help! 
I've tried to follow the instructions and ended up jamming both fork legs on my 02 FZS 600.  I suspect that the action of pressing a broom handle up the fork inner helps to hold the damper in place (to undo the screw), but also forces the white plastic spigot where it shouldnt be.  So could someone confirm: should it be embedded in the end of the fork inner?
Thanks.

[BBROWN1664]

it you turn the tube upside down and, using the broom handle, insert the damper rod into the tube, once it it out the (now) top end, put the spigot on the end. Then put the fork slider on. Pushing down on the slider onto the broom will allow you to tighten up the bottom (now top) bolt.
Now turn the fork the right way up and tap the upper bush etc into place before refitting the spring.