Disclamer: this is just how I do it, it doesn't means that there isn't a better way of doing it; follow this guide at your own risk as suspension is a critical part, doing a poor job as to DIY on your bike may result in death or major disappointment at yourself. If any information I have provided is not true or misleading, please message me and I will correct/amend. This guide is only to provide information given that you already have basic knowledge of repairing your bike; if you are unsure, ASK FOR HELP, many people are very nice here and will help or better yet if you are rich enough, ask your mechanic. Showa BPF is on 12-19 base model, and all the parts shares across including fork seals and internals With all that out of the way here is how the fork looks like the whole assembly is hold on by 2 bolt, fork cap bolt and the inner bolt which sit between the damper valves and spring(big silver collar looking thing). Like cartage forks, its hard to take apart without the tight tools. Or in this case the inner bolt is almost impossible to take apart without a special holder unless you put the front axle in while undoing it. Its important to keep the work area clean and have to clean towel around. I don't have fancy tools and good working area like I have back home home so I had to improvised so pardon my B&Q bucket etc and also bit poor camera phone picture (sorry but my DSLR is NOT going near fork oil) Disclaimer: none of the item listed below is sponsored. Let get to it: you will need: - 1L of fork oil (about 500ml per leg); for first timer get 1.5L so you will have some spare and some to rinse out the oil stuff (stock weight is 10w) - SHOWA BPF 43mm tool (35mm hex, you will need a crow spanner adapter if its haven’t got an adapter to your torque wrench) - cheapest I found in UK https://www.reactivesuspension.com/product-section.php?subcategory_id=10 - 45mm socket/spanner for fork cap - torque wrench - breaker bar - socket set - paddock headstock stand (23mm pin) or something to lift the front end up (I had seen some creative getto way over the years. - Usual tool kit, esp a good 10ml closed end spanner You will not need to touch the valve assembly at all for oil change, spring change or seal/bushing change but this is how it looks like: There is two rod inside the fork caps moving them which adjust your compression (screw on top set load on the outer plastic collar/valve assembly) and rebound(TEN)(screw on top set internal valve) What I did: 1) put the bike on paddock stand, fork yoke stand and remove front wheel, mudguard. remove the chin curtain on the bottom of the headlight. 2) put the front axle back in and do up the pinch bolt 3) use bungee or something to hold the brakes up 4) undo top yoke pinch bolt, and handlebar pinch bolt (be sure to put something under the bars to protect paint job, trust me) 5) undo fork cap, both side 6)use something to lift the front up to expose the bolt that hold down the spring 7) turn handlebars to the left all the way, insert tool and undo the nut both side 8) lower the fork lowers, and thread the cap in a touch by hand 9)remove lower pinch bolt on the lower fork clamp and remove fork 10) unscrew the top cap and remove the damper 11) and you can tip it all out in a oil bucket (pardon my foot) The below steps are for fork oil seal/bushings/dust seal change only (12-27) 12)remove dust seal with tape wrapped flat head screw driver 13)Remove the oil seal retainer (under the fork seal) 14) hold the legs in one hand, top tube in the other, slide it apart with some impact. I didn’t manage to take picture as forks are in my hands but use it like a slide hammer to knock the oil seal out. 15) remove bushings, seal spacer, old oil seal, oil seal retainer and dust seal. 16) electric tape the holes and risen edges 17) lube up dust seals and put onto sanctions 18) put retainer run onto sanctions 19) use a small plastic bag (I used one of them air pocket shipping packaging and cut both ends) onto open end of sanctions 20) lube up the inside of oil seals and slide onto the plastic bag 21) the top part of the sanctions are machined and not smooth, don’t push the seal down but slide the plastic bag down with the seal instead, pushing the seal down the machined part is like putting it though a cheese grater, once you get to the smooth part then you can slide the seal out of the bag 22) put the metal washer on (groove face upwards/towards fork upper) 23) remove tape, install lower and upper bushing 24) clean fork upper and slide it back on 25) use fork seals driver to drive fork seals into upper 26)put retainer clip back on 27) seat dust seal back on At this point do no extend fork legs too much to prevent seals being cut by sharp edges on top of sanctions hit word limit here
28) clean all internals that come out, there will be lots of particles sitting in springs and plastic collors. 29) insert white plastic collar (white) Warning MAKE SURE ITS INSTALLED IN CORRECT WAY OTHERWISE IT WILL REQUIRE SPECIAL TOOL TO GET OUT IF IT SEATED IN PROPERLY – don’t ask why 30) insert spring (stock spring is non-directional) 31) insert upper collar (black) 32) insert valve/topcap unit and screw in by hand all the way 33) put outer all the way down(fully compressed) pour fork oil in and set oil height with tool (stock fork height is 84mm) 34) hand tight the fork cap, pump the forks until it feels like there is no air in the damper and check fork oil height again(air gap) 35) Do the other fork 36) reinstall the forks back on the bike with the spindle, tighten lower triple clamp 37) lift the forks up again 38) turn the steering full right, tighten the lower collar with the tool and torque wrench (90Nm) 39) Tighten fork caps (35Nm) 40) remove the front wheel spindle and fork one last time and reinstall: Put the snap ring back on outside of the fork upper, slide the fork all the way up, the stopper ring should stop at the clip ons leaving pre-set fork clamping height. At this point you should also line up the fork cap so writing is facing you when you are sitting on the bike like this (Post edit picture) 41) tighten upper fork clamp(lower: 27Nm; top & clip on22Nm) reinstall mudguard and wheels and brakes etc. So that is, to do a proper job first time you are look at about 5ish hours, then after it’s a 2-3hour job. If you are planning to do it message me and I can send you a PDF of the fork section of service manual so you can have a read through before doing so.(basically the same as what i wrote with less picture and need more special tool to hold fork leg) Good luck
------------------------------------------------------------------------------------------------------------------------------------------------------ How to find ideal fork setting(from my other reply) After servicing you will find your fork setting will need adjusting at least a little, here is from me the other reply of how I found fork setting on road on road bike: Some quick tips on finding right setup following oil change(yes it change setting even with just oil change) in short, assuming you are not going to change spring and for road riding 1) put fork/shock to factory setting for compression and rebound 2) set static sag: https://www.cycleworld.com/sport-rider/ask-geek-set-your-static-sag/ 3) bring a screw driver with you and go for ride, dial in forks first before moving on to shock(8/10 people would be fine with stock rear shock setting if rear sag is right) 4) find a very quiet road and do some hard braking, say 70(for legal sake)-20mph if the forks dive too much then increase compression (harder) if front is solid then decrease the compression (softer), you are look at a consistence dive loading the front end under hard braking, i judge this by how heavy i feel on my wrists too much compression will decrease your forks small bump sensitivity, i'd go as little as possible for fork compression 5) if the front end come up too quickly after hard braking then increase rebound (harder); too slow then decrease(softer)- very unlikely (go with 1/2 a turn at a time, make frequent stop to adjust, when you are close then go 1/4 turn and 1/8 turn to fine tune) 6) on bumpy roads if its bouncing you up and down around then increase rebound for suspension to return to full travel slower (harder), if the front end come up too slowly after a bump then decrease rebound(softer) This should get you close to 70-80% of ideal setup for road on stock suspension 7) for advance riding/ tight hard twisty road or track (trail brake situation) then follow the following troubleshoot guide 8) verify travel used (by dust on sanction or cable tie method- do not tie it in hard and remove after you finish your setup, it will kill dust seals) increase/decrease preload with account for compression and rebound until you use almost full travel, i would say if you are not wheeling and slamming front down a lot then 20-25mm unused travel is good for road (more if you like to stunt and use your blade rallying), I tend to aim for about 10-15mm with adjustment of fork oil level to get a more linear feel at then end of the stroke Be aware oil age, oil weight, oil brands even, temperature, road surface, tyre pressure (suspension work only when bike is upright and low lean) will change handling you will know when you get close as you will feel that the bike grips far better in corners, the ride is more comfortable and you can run higher tyre pressure to make the bike turn quicker and your tyre will also last longer. for example on road i am running 33-36psi F/39-42 psi R on stock tyre size, bike turn plenty quick enough with stable corner transition (going to 190/55 will have to have lower pressure), my rear tyre last 6-8000 miles on road, 2 rear to a front. Not to say you would have the same because we are all different in weight and riding style but simply just stating with good suspension setup, you won't rely on tyres to do most of the job therefore you will have better tyre life and can run higher pressure for better lean-ability. This is just how i do it so like any advice on internet do at your own risk, please let me know if i got anything wrong or if its a better way; or if you are a pro and how you do it. always up for learning more
Great write up. I've just lifted the cap off one of mine to find an air gap of only 55mm. The oil looks a fairly clean green. I'm wondering if I just need to set the correct air gap and get it set up for the road.
In short term I would just set the air gap and see if it improve handling; too much oil will affect the forks behavior towards the end of travel. Your forks is a sealed unit and having less air gap typically increase internal pressure pressing onto the oil and might pop the oil seal out in extreme case; experiment with it, I had to increase air gap because I don’t weight much to get a more linear feel near the end of the travel. (And I am too cheap to change spring knowing that I am close to the ideal spring weight already) All of your worn stuff would sit at the bottom of the spring around the plastic collar/preload adjuster. The design of BPF is cleaver by giving it more of a chance for dirty stuff to sink down (not that it will make a difference when the oil heat up from working your compression and rebound) The oil in pic is 1500miles old and I change it because of shitty pyramid seals (8quid a pair job) weeped after some dirt got in and I am planning euro trip next month; also put 7.5w oil in to try as well. Good luck
10W oil arrived this morning, so I set on with swapping the oil over for the sake of £15. Takes a lot of pumping as only a couple of hundred ml poured out, but just over 450ml came out with a bit of pumping. Left it hanging off the back of my other bike in the end to let the oil drain out before refilling to 84mm from the top. I'm glad I did this as the oil wasn't as clear as first thought. It's all back together now awaiting the return of my wheels next week, then I'l take it to get the suspension set up for me on the road.
should there be a step 24.5 drive the bushing in? This is the bit I really struggled with - anyone got any tips?
I sorted this by putting the old bushes back in (I checked them carefully and there is no visible wear) - it turns out all balls racing inner bushes are 0.2mm bigger in diameter than the originals - originals can be pushed home with just fingers and feel really snug with no play - the all balls racing bushes I had to hammer home with the seal driver
Great write-up and advice, thanks. I did mine last weekend. 4 year old bike with 30k km on it, i guess it was the first time the forks had been opened, oil was pretty black. I bought the new O-rings as per manual recommendation, but could not find where the smaller-sized one went, as shown in the diagram.
