How To Perform A Lower Leg Service | Mountain Bike Suspension Fork Service

keeping your suspension forks well lubricated and clean is the key to both longevity of performance and of course making sure they feel really good and slick on that small bump stuff here's how you do it [Music] now the idea behind a fork lower leg service is to make sure that the telescopic action continues as it should do now think what's happening you've got the lower part of the fork and it slides over the upper part of the fork as soon as there's any friction or debris or dirt and muck in there it's not going to be doing its job properly so the bottom of each fork on the inside you have what's called a bath and you have a small amount of fluid here it helps the sliding action over time that can get it can get gunked up from stuff that's ingested into the fork and of course it can dry up as well so it's really important to make sure you do this from time to time now most fork manufacturers will recommend you do this sort of service approximately every 50 hours of riding although i wouldn't pay too much attention to that because it depends wildly on where you ride if you ride somewhere extremely dusty your forks are certainly going to dry out quicker likewise if you ride somewhere extremely wet they're just going to ingest more stuff that can contaminate any moisture any oil even that's on the inside there so it's kind of up to you to monitor that just use the 50 hours as a bit of a guideline now i'm using a fox 36 here but the principle is pretty much the same for any modern suspension fork now the only major differences between them and the way they sort of disassemble is the fact that on fox forks for example you have foot nuts on these so you need a socket set to undo these whereas on a rockshox fork you have allen bolts i think you have a four or five mil on the bottom there so it's just slightly different in the way you take them apart but the same principle so you'll just need to check this with the brand that you're working on and then of course there's the oil on the inside you'll have different oils that you need for both the damper leg and the air leg and it will be different oil weights and different amounts so you just need to check that for your specific manufacturer i'm just gonna put a link in the description underneath for both fox and rockshox because i have charts for all their forks for all years on there so super easy to find out what you want i've got my oils ready here okay so tools for the job this will vary dependent on your particular forks i'm just going to list what i'm going to be using today for my fox 36 some rubber nitrile gloves you can use latex or anything like that they're good because the fact protects your hands from the oil but also means you can actually grip the things as well because you're going to get a bit messy doing this job you're going to need a mallet with either a soft plastic or rubber ending on it or even a wooden mallet that would do no problem something you can use as a pick obviously a pick is the best thing for that purpose depending on your fork you're going to need a tiny allen key i need a two millimeter for this one to remove the rebound dial on the bottom of the fork there depending how advanced you're gonna go with this you might want some replacement of foam rings uh they look a little bit like calamari but don't be tempted to eat these things and you could replace the seals in them although i wouldn't recommend doing this without the tooling for this i'll explain this when we get to that stage you'll need a couple of different syringes to put the oil inside the forks you'll need a shock pump for this fork i'm going to need some sockets i need a 32 mm socket for the air chamber there and i need a 10 and a 15 to remove the lower legs now if your fork for example is a step cast option there's one more thing you're going to need and this might put you off doing this at home because of the fact the foot nuts are actually here you need this specific tool to allow you to reach in there to actually release them so if that's the case with your fork you might be better off getting them serviced at your local bike shop just because the fact that tooling is quite expensive and lastly you're going to need some lubricants and things to clean them with so i'm going to use disc brake cleaner but you can use just regular isopropyl alcohol to make sure there's no sort of residue on the forks as such you'll need different oils for your fork i need 20 weight in these particular forks and five weights so five goes on the damper leg 20 weight goes on the air leg and you'll need some suspension grease there's loads of different options on the market and essentially it's just a small amount just to rub around the inside of the seals okay and the last thing you're going to need is something to catch that oil in now you could use an old takeaway container you could use some old mugs i'm using our trusty park tool tray here and you'll obviously need to recycle that or discard that correctly afterwards now you need to a little bit of prep before you get started so if you have a work stand at home it will definitely make this process easier now i've decided to take the fork off the bike it's much easier to do it this way and it's easier to show you but you don't have to do this you can do this on the bike as well so if that puts you off just do it on the bike i'm using our work stand here i've just put behind the counter here so i can mount the fork on the inside here makes it nice and easy and i'm not going to be able to damage that steera tube because the clamp of course is designed for frame tubes so it's almost perfect for the job if you're going to put it in a vise make sure you use soft jaws on there or some sort of protection around your steering tube when you clamp it uh you don't want to score it or do any sort of damage to it okay so i've set down some shop tail on the work surface and just before get going it's going to get messy so chuck set gloves on now now something to say here is fork manufacturers will tend to recommend that you remove air from the air chamber when you do this process just for safety but something to note when you do this well two things firstly take note of the air pressure that's already in your fork that means when you go to inflate them afterwards you already know what that is you'll get on the trails quicker but secondly it doesn't always work when you're removing the fork because of the fact the basic construction of the fork you have the outer leg you have the inner leg and on the inside of these you have shafts or rods that connect to the bottom of the legs now when you undo the bolts or nuts on the bottom you need to shock these loose to make sure they're not stuck there sometimes when you're undoing this if they're already loose which may be the case on your fork as you undo the nuts or bolts on the bottom you might end up spinning those rods so i find this part of the process is actually better to leave the air in and if you want to remove the air once they're loose that's the time to do it so i'm just going to put this straight into the work stand now that's a pretty good height where it is i'm actually going to start with getting the oil pan underneath so as i said on some forks you'll have allen key bolts on the bottom here and in fact something cool on the rockshox ones is it actually says on them the amount of oil it takes in each side so it's quite cool to note for that so i'm going to start with the 10 mil and just loosen this now whatever style you have at the bottom nuts or bolts don't loosen them fully because you'll need these to just shock the inners loose slightly now before i do the other one you need to remove the little cap on here that you get on the fox forks to protect the rebound adjuster sometimes these get stuck on because they take a bit of a hit yours might have lots of scars from rock strikes if that's the case you might need something like locking pliers or something like that to remove it they can get a bit stuck so use this opportunity to actually clean them and if it feels damaged it might be worth getting a fresh one two mil allen key to remove that rebound adjuster and then just carefully slide that off and put that to the side for safe keeping for later on okay so 15mm socket on this side now now carefully just undo that you don't want your socket to slip so only use good tools if you can for this same principle don't under all the way and you're going to use these sockets or allen keys if you're on rockshox fork just to shock the actual lowers loose that'll hopefully be enough and the same on this side and we'll find out now if that is loose enough because uh it should slide off now note on the bottom here you have washers between the nut and the bottom of the fork they're called crush washers if yours look really mashed up you probably want to get some fresh ones because the fact that that's essentially your oil seal at the bottom there and it's a low pressure unit so it's nothing crazy but you could get an oil leak now at this stage you could be able to slide them off there we go and out comes the oil that's why it's important to be ready with your shop towel and something to drain the oil into we'll just let that cycle down for a second in fact i'm going to remove the fork just from the work stand for a second just to uh make sure it all drains out properly now that oil's in pretty good condition but yours might look uh might be quite black or like muddy and mucky so just pay attention to that because that will probably indicate the conditions of other components on the inside of the fork there okay so as you slide out you'll still get some dripping out the bottom here so just prepare for this and of course you might get some leaking out the top there and just carefully slide them off there we go okay just let those drain out now it's a case of cleaning both the upper and lower legs down now i'm just going to let this drain out and we're going to focus on the upper legs we'll give them a bit of an inspection as well because you want to make sure that your stanchion tubes are nice and smooth there's no sort of scratches and nicks in them now if there is a scratch chances are your fork would probably be all right if it's a major gouge then you might want to get a second opinion on that but if there's any scratches the thing that could be damaging to your forks given that the rubber seal has to pass over them is if they have any burrs on them so it's possible if yours does have a scratch with a burr you can remove that with an extremely fine metal file a bit of metal polish and just polish it out and if necessary you can get repair kits for stanchions just to fill in the void there i've used nail varnish in the past just to do this as a temporary fix but there is a company out there that makes specific products for that so very handy stuff now for cleaning the inside a little bit different obviously you want to make sure you clean it around the seals and inspect those for damage i've got a new set of seals here but i'm not going to replace these today because they they don't need it i know they don't but you're looking for any splits perhaps if the seal is perished anything like that if it is damaged you're going to need to replace it now as far as removing them goes you can do this with a ring spanner uh it's not like the correct tool but it will do the job absolutely fine but when it comes to re-seating them it can be a problem if you don't have the setting tool now it's quite a specific tool again just like the step cast tool it's an expensive option so if your seals do need replacing i do recommend you get in touch with someone who has got the correct tool for this although i do know plenty of people that bashed them in using a mallet with a bit of grease i wouldn't recommend it but it is possible if you want to go that way okay so i'm just taking a fresh piece of shop towel here i'm just going to give the upper legs a bit of a wipe down and just give them just generally inspect them make sure there's no sort of wear where there shouldn't be if you're seeing any paint missing here at this stage uh that's signs of a really badly maintained fork and almost certainly you'll have damaged components to it so if that's the case you'll want to get down to your local bike shop we'll get some advice from an independent suspension tuner for that but if like these ones your forks are looking in pretty good condition then you're nearly on the home straight so we're not messing with the damper on the inside today and we're not messing with the air spring on the inside this is literally a lower leg service it's really quite simple now i'm going to move on to cleaning the inside of the lowers now something to to note with this is it's extremely hard to get into the inside don't be tempted to put any sort of uh anything metallic in there because the fact you've got the bushings on which the forks actually slide up and down and they can be damaged quite easily what i tend to do is just flush them through with isopropyl alcohol disc brake cleaner anything like that a bit of water then let them properly dry out you can also stuff down some shop towel in there just to make sure you absorb some of that but before i do that i'm going to remove the foam rings from the inside now the foam rings sit just underneath the seals here and they don't always need replacing it can be quite tricky to get out that's why you need a little fine pick just to get in here now these can be cleaned up quite easily if they're in condition like this so i'm actually going to reuse these rather than fitting some fresh ones in i'm going to save them for when uh get around to winter but have a look at the top of the seal here you can see it's quite a little gunk around there although on the inside it looks pretty good so let's just give this a bit of a clean here before i start putting some isopropyl alcohol so the whole time just being quite delicate with them i'm making sure there's no sort of foreign debris on the inside there and i'm just going to give them a bit of a spray of disc brake cleaner around the inside here this is essentially like isopropyl alcohol and acetone you can use contact cleaner for this i would be tempted to use anything as as hardcore as a degreaser on the inside here and i'm just going to give these a final wipe over then we're going to look at replacing the foam rings on the inside now something to note with the foam rings when you replace them there's two ways that you can do this now to clean these out of course you want to make sure that you've got no old contaminated oil on them so again you can use a degreaser disc brake cleaner something like that making sure that they're actually in pretty good condition now some people actually like to soak these in the same oil that can use on the inside which is a really good way of doing it but you need quite a lot of oil and it can be quite wasteful doing it this way now something i prefer to do is actually put the fresh ones or put the old clean ones in place and actually saturate them with oil using a syringe once they're inside i find i use a little less oil that way and i find it's a little less messy as well as i say these foam rings are actually in really good condition but yours might be absolutely filthy so there's only so much rescuing you can do and they don't cost a lot of money to replace as you can see that one's come up pretty well if you look at it by comparison to one that's come out so i'm gonna continue to clean that one and then we're gonna fit those back in again [Music] okay so we've got our two cleaned rings as you can see by looking at a fresh one i don't look a million miles away so we're going to go ahead and reinstall these now into the fork and just delicately just push them into place make sure they're sitting there nice and neatly and then we'll soak these of oil while they're in situ [Music] okay that's all good and these are essentially just like it's like a trough and it just you saturate these with oil and it just helps the seal pass nice and freely over that slider there in combination with the oil that sits at the bottom it has a bit of a capillary action and just lubricates the slider there okay so time to prep the syringes there with the correct amount of oil so on this fork i have the five weight oil that goes in the damper leg and there's 40 cc in there and it's in this fork it's 10cc of the 20 weight that goes in the air leg there we go i'm just kind of a little bit more of each of these so i can put some onto the actual foam rings and apply this directly to the ring and it's super porous so it absorbs it really well this might not be the method that works for you but it definitely works for me i don't know quite a few other people that do it the same way because this stuff is really really slippery and it makes it a lot easier to apply it okay so everything is clean and it's inspected and it's time to basically reassemble now it's really important to note that you get the correct oil on the correct oil volumes for your particular fork pretty simple stuff but to put it in basically you need to put the fork back together again and you need to leave a little gap between the foot basically the foot rods at the bottom of the fork there and you squirt it in with the fork inverted so it avoids getting any mess i've seen people put directly into the legs and try and reassemble and half it just comes straight back out again so that's not going to be the best for you and one last thing just before you reassemble these put a smidgen of suspension grease just around the wiper seals uh just underneath you don't need too much in here just a small amount now when it comes to sliding the legs back on you need to be really careful to not damage the seals so just take your time as you do this and you need to try and line them up as best as you can there we go there's one you should find then they slide on nicely now if you've removed any air from your air chamber whilst doing this you may need a bit more air in there just to help extend the bottom of this rod here now as you can see you can see they're both poking at the bottom not about to put the lubricant into them like that so i'm just going to pull them back slightly now i'm going to invert the fork i'm going to do this in the work stand it's got the luxury of using this here so i'm just going to tilt this up very slightly to this angle and then it's a case of the 10 cc's into the air chamber or the bottom of the air leg even that's going in nicely and there's four kids 40 cc's in the damper leg time to slide them home again now you want to make sure that your crush washers are in good condition before we put the fork back together i'm happy with these ones on this particular fork so you almost have to thread these on just in place and then foot nuts go on all the foot bolts depending on what you're using once these are in place i'm actually going to remove my gloves because these gloves are so slippery now i won't be able to use the tooling properly okay we're nearly home and dry uh just got to make sure you do up the foot bolts or foot nuts on your particular fork now something important to say here is it's recommended to use a torque wrench for this i've got one here and i know the newton meters i need is 5.7 for these particular ones it's completely different whatever your particular fork is so i'm going to leave this up to you to make sure you do this right i'm just going to nip these up first but if in doubt and you don't have a torque wrench to hand you don't need to do these very tight 5.7 units isn't very tight so just use caution with these so just dial this in at the bottom here there we go 5.7 there we go that's pretty close to that just by guessing i've seen people hanging off these before there we go so we know it's all good now it's just a case of getting the rebound dial on the bottom to make sure everything lines up now it takes a tiny little two millimeter allen key here uh there isn't actually a torque setting for this so just take care uh it's only a tiny grub screw only it's enough just to hold on don't forget you've got the cover so just to confirm that works no problem and you have your little cover that goes on the bottom here to protect them finger tight is all that's required and there we go you want to just clean the exterior of the fork make sure it's got no sort of oil residue on there cycling through the action a few times clean air residue off the fork stanches at the top there and if you need to reinflate inflate to the pressure that you checked at the beginning and get it back on your bike and go and enjoy it just remember it's all just about taking care of your fork from the amount that you actually ride the bike so the 50 hours is a guideline but you'll know if your fork needs a bit of attention and you'll be amazed how good your fork will feel after doing one of these little mini services it'll feel so good so supple and grippy on the small stuff that's pretty much it it's a similar process for just about every suspension fork out there so hopefully this video has been helpful for you leave us a feedback in the comments underneath if there's any other videos you want us to make here at gmbn tech do let us know and we'll see in the next one see you later

Channel: GMBN Tech

Views: 224,593

Keywords: suspension service, lower leg service, lower leg, suspension, mtb suspension, mountain bike suspension, service, lowers, fork service, mtb fork service, basic service, fox suspension, gmbn tech, mtb tech, bike tech, mountain bike, Bicycle (Product Category), MTB, bicycle, gmbntech, GMBN, Global Mountain Bike Network, mountain biking, Downhill, XC, Cross Country, Enduro, MTB skills, bike skills, mountain bike skills, bike, bike riding, cycling, gmvn, doddy, andrew dodd, Ҙ, ᐶ, 1t, Ң, ፕ16, Ҫ

Id: klJiEzK4YIo

Length: 20min 41sec (1241 seconds)

Published: Sat Jun 12 2021