Our guide to
Servicing your forks. A step-by-step guide from the guys at Black & White Bikes.
Hello and welcome to our new workshop section. Each month we’ll be getting down and dirty, ticking off the servicing jobs you want to know about in a step-by-step manner
If you’re not taking care of your pogos, how do you expect them to be taking care of you? This month, we delve in deep with the darkest art of them all. With the help of our friends down at Black & White Bikes, we see what the best process is for servicing your forks. Take it away, chaps. 1 Get the bike on a sensible stand
The very first thing to do is get your machine on a stand that’s fit for purpose. You can’t use a fork stand as you need to be dropping the forks out, so my recommendation is either an Abba Sky Lift (like the one I use) or a front stand that goes into the triple clamps. I’ve seen people do all sorts, including bungee-ing their bikes to the roof of their garage, but just make sure the bike is secure.
Measure the dropthrough 2 of the forks
Always make sure you measure the drop-through between the forks and the top yoke, as it needs to be identical when putting it back together. This particular Fireblade comes in at 2mm (and there is actually a spring clip under the clip-on that makes it foolproof on this bike), but it will vary from bike to bike so you need to measure and record the amount of fork poking over the top of the yoke.
Note the settings 3 and prepare the forks
Just as important as measuring the drop-through, is measuring the settings that go with it. This means measuring the compression, rebound and preload values for each fork and writing them down. Record the setting for compression and rebound as clicks or turns from fully in and preload from fully out. There can also be preload rings showing on the adjuster to make it easy in some cases. Once this is done, wind each adjuster completely out and take all of the preload off. I like to wrap tape around the preload adjuster here to keep the forks looking nice, although if it’s already been battered (like a race bike will) then don’t worry too much.
4 Drop the wheel out
Now the forks are prepared and ready to go, it’s time to get
the wheel out. Do the usual here: Caliper bolts off and calipers up on bungee cords, pinch bolts out, axle out and place the wheel somewhere safe.
5 Lose the mudguard
Now the wheel is out, it’s time to take the mudguard off. Watch the brake lines here as they might be attached, but it should only be a few bolts for full removal.
6 Loosen the fork
If you’re using standard bars they’ll have a fixed position, but it’s always worth taking a measurement and photo of the bars so you know their exact location. Gently undo the bolt on the top yoke, followed by the clip-on bolts. Using a nylon spanner (so not to damage the forks) loosen the top of the fork and brake the seal while it’s still in the bike, before loosening the bottom clamp bolts.
7 Drop the fork through
Now you should be able to gently ease the fork out the bottom, but remember to only do one at a time as it makes the job a lot less confusing and removes any risk of mixing parts up.
8 Clamp in and release the cap
Now you have your standalone fork leg, use a clamp to secure it, preferably set up on a nice, clean work bench. This is where things start to get tasty, so be careful. Release the cap completely on top, being careful not to spill anything, and the outer tube can be slid down to reveal the plastic spacer.
9 Pull the collar down
Now we need to compress the spring to gain access to the lock nut. There is a manual kit available from K-tech, but you will need the help of a mate to pull the tool down as you slide the tool under the lock nut. I’ve got a special fork compressor to let me get the job done on my own (as I don’t have any friends). With that in place I can get some spanners in there and undo the lock nut. You may need a special thin spanner to squeeze into the limited space available.
10 Loosen the top unit and get it out
The cap can then be unscrewed and removed. Watch out for the rebound damping adjuster that lives inside the damper rod, as sometimes it’s attached to the cap, like it is here. Time for another special tool from K-tech now, a damper rod extension to prevent you losing the damper rod into the depths of the fork. You can now remove the spacer, washers and the spring, but watch out as it’s going to get messy from now on and oil will be dripping off the spring as you pull it out.
11 Undo the bottom bolt
For most types of fork there’s a bolt in the bottom of the forks, which needs to be loosened off and removed in order to get the cartridge out the top. Now this is an important step and it can be where things start to go wrong if you’re unlucky and/or don’t have a cartridge holding tool. The bolt should be held with thread-lock so it can be cracked off, but then it just spins (because the cartridge is spinning inside, too). So if you have the right tool, slide that in from the other end, which stops the cartridge from turning and so you can then fully remove the bolt. If you’re lucky, there’s not too much thread-lock and the bolt comes straight out. There is another method where this is the first job you do, before you take the top cap off. The force of the spring pushing
against the cartridge is enough to prevent it from turning and the bolt will come out (hopefully!). Once that bolt is out there will be oil absolutely everywhere, but hopefully mostly in the catch tray you put underneath. You did put a catch tray underneath, didn’t you? With all the oil out of the way, just check to see if the sealing washer came out with the bolt, or if its stuck in the recess in the fork. It needs to be out the way and in the bin, and replaced with a spanking new one.
12 Pull the cartridge out
With that bolt out then the cartridge can be pulled out of the top of the fork and put to one side.
13 Separate the seals
By now all the oil should be out of the fork, so it’s time to separate the fork tube and stanchion. First up will be the dust seal, which will prise off easily using a thin nylon tool to gently work it off. Take care not to damage the chrome here as you then remove the retaining clip. That’s the clip that holds the fork seal in place and with that out the way, we can use the two tubes in a slide hammer action to force the seal out and separate the fork. You are banging the bushes up against the fork seal in order to knock it out. Warming the area with a hairdryer or hot-air gun could help if it’s a bit tight. Once apart, you can strip the seals and bushes off the stanchion. First off is the slide bush, which will need to be prised open and then popped out of its groove. Then the guide bush slides off, easily followed by a washer, the fork seal, the retaining clip and finally the dust seal. You might have a posh travel indicator or a not so posh cable tie right at the bottom. Remember the order in which they’ve been removed, and if it helps, place them on the workbench in the order you took them off.
14 Clean!
This is the most important part! If your forks have never been serviced, or at least not serviced in a while, you’ll notice that there will be a load of gunk in the oil. It’s imperative to get rid of all the crap out of the fork. If you need to, you can remove the compression adjuster on the bottom of the fork with a spanner or special tool, and that helps clean the nooks and crannies. Use brake cleaner here and a lint-free cloth, to make sure you don’t get fibres in your nice clean forks. Clean each element individually as well, one at a time and be careful not to mix the parts up. Completely clean the internals here of the fork leg and pay special attention to the cartridge to make sure you get all the old oil out from inside.
15 Re-apply first seals
Now everything should be cleaned, dried and laid out nicely in the correct order, so it’s time for the re-assembly. It’s wise to protect the top of the fork leg here with some tape on the top and over the holes, as otherwise it could be incredibl easy to damage the new fork seals. Dab a bit of fork oil as lube over the top and some red rubber grease on the dust seal, and stick that on first. Then, the retaining clip goes and the fork seal (making sure it’s the right way round), followed by the larger
washer (which also has a right way round) and the guide bush. Lastly, clip a new slide bush on the end of the stanchion. Now to put everything back together.
16 Lower the fork in
This step takes some real ingenuity, so take your time and don’t rush, and the process can alter hugely between different forks – don’t forget, this is a ’08 Fireblade system we’re doing here. Gently secure the outer sleeve in the vice and lower the fork leg in – here it helps to either use a lump of wood (as you can see in the photo) or an extra pair of hands. Work far out down the fork leg so if you damage the chrome it’s not on a section that’s swept by the seals and bushes, and gently ease in. Here you can use a cable tie on the fork to stop the washer falling down, as you just want to gently tap the guide bush in place. Pop the cable tie off now, let the washer fall into place and then drive the seal down with a fork seal driver and reasonable force. Again, the right tool here makes a world of difference.
17 Retainer clip and final seals
Next up is to get the retainer clip in, which can be a bit of a pain in the neck. Slide it in and push it down until it clicks – although the annoying thing is, sometimes it doesn’t quite click, so it needs to be pulled out and pushed back in. Pop the dust seal back on to finish that job.
18 Insert the cartridge
Now the fork will look more like a complete unit, it’s time to insert the cartridge back in. Stick it in, but not too tight, and once that’s done it’s time to tighten the bolt at the bottom with the new crush washer. Use a dab of thread-lock to secure it and check torque settings – it should be around 25-30Nm, although this one is a bit more at 34Nm.
19 Fill the oil and set the air gap
This is where a lot of people tend to make mistakes, so the best thing to do is read your manual and see what the air gap is – this one, for example, is 93mm. It’s not so critical for the first attempt to be precise with the amount of oil going in, so put in about the right amount to fill it up – for this it’s about 517cl. Make sure your compression adjuster is fully wound out and use the damper rod pull-up tool to force oil into the cartridge by pumping it up and down a few times. You should be able to feel it stiffen up as air bubbles move out and the oil flows around. Using an air gap measurement tool, set the required amount – this one will be 97mm, as I have to allow an extra 4mm for the travel
indicator at the bottom of the fork leg. Use the tool to measure the gap, stick the cap on and fully compress the fork a few times to check everything works nicely and make sure that oil is completely filling the cartridge inside. Once done, re-insert the fork into the vice and remove the cap, measuring the gap once again, as it could fluctuate up to 10 or 20mm when everything is flowing around. Measure it once again to 97mm and repeat. Usually twice or three times is enough to get the right value.
20 Insert the spring and final spacers
Now you have the air gap set correctly, take the cap off once again and insert the spring, washer and preload spacer. Then we need to compress the fork again in the compression tool so that we can correctly set the top cap. This is important and you really need to check the manual to make sure that you get the setting correct, otherwise its dead easy to screw up your rebound damping. This bike wants 10.9mm of thread showing above the lock nut, so that’s quite easy. Another way is to turn the rebound adjuster to it fully IN position and replace the cap until you feel it lightly seat. Whatever you do, don’t force it any further and then tighten the lock nut. With the cap secured you can remove the fork from the compression tool and slide the outer up to the cap and screw it back on. Everyone likes to have a bounce on it at this point, just to check it is all working ok. You can even play around with adjuster settings now and see how they affect the fork, but remember to set them to the settings you wrote down at the start.
21 Stick the fork back in the bike
Now you have a completely serviced fork, carefully re-insert into the bike. Go through the bottom, through the yokes and up to the measured length at the top yoke. Tighten everything up on the spot right there, and use your manual to find the exact torque settings. With the lower yoke tightened up correctly while the top yoke is still loose, it’s a good chance to just check that the fork cap is done up tight.
22 Repeat!
Yay! You’re half-way done. Now’s the time to have a cuppa, before going back to step six and repeating all of it, but this time on the other fork leg. Take your time and be patient.
23 Enter settings
Now you should have both forks serviced, ready to roll and like brand new. Using your set up sheet where you recorded your settings initially, put them all back in identical to before.
24 Insert wheel and mudguard
Your forks should be back in safe and sound. Stick your wheel back in, calipers on, get the mudguard back on and you’re ready to go!