Tag Archives: Fork repair

Fork servicing part 4, alternative parts & tools.

Oh no…not more fork stuff from this clown! Yes but there is nothing more about working on them. This is about the parts used in them and what we can use from other models and other manufacturers. I also have a few tips on tools…lets take a look…

First of all, here are some dimensions that might come in handy if you are researching fork info for this bike. The inner tube is 35mm in diameter, this is the inner measurement for the oil and dust seal. The outside diameter of the oil seal is 48mm. The dust seal has an outer diameter of 48.5mm I presume to help with the interference fit in the fork because of its smaller thickness compared to the oil seal.

Some of the other Yamaha models that use the same seal are; YZ100 ’80-’81, DT125 ’82-’83, IT125 ’81, XT125 ’82-’83, RT180 ’90-’93, XT200 ’83, RD250 ’78-’79, RD250 ’76-’79, TZ250 C-D-E, XT250 ’80-’83, RD400, XS400, SR500, XJ500, XS500, XV535 ’88-’92, TZ750 (!!!). Some alternate Yamaha part numbers for the oil seal are; 10V-23145-00, 38W-23145-00, 1UA-23145-00, 29L-23145-00. Don’t quote me on all this, it’s just what I have found while cross referencing stuff. There is no way I can confirm this 100% because I don’t own or have serviced all these bikes. What I do know is that the YZ100 does fit.

As for after-market suppliers, some don’t even have a listing for the AG200 but you can go on the dimensions – Fork oil seal 35x48x10.5mm (35x48x11mm is also fine) ARI has a listing as ARI.003T, Vesrah – AR-3506, Emgo 19-90134 and Allballs 35-1011. The dust seal is a bit more complex because some hang up over the fork tube so it’s hard to say what their correct height is. The factory dust seals measurements are 35×48.5x5mm. ARI do a listing of ARI.049 but I notice the thickness is larger (8mm) but this may be because the design is different like the Pyramid Parts seal that I have tried and discuss below. Allballs do a kit listed as AB55108. I have never ordered any of these parts or kits except for the genuine parts and Pyramid, so do some research of your own if you’re going to go your own way.

Fork seal kitI have checked a lot of the after-market companies and their listings and have found a supplier called Pyramid Parts that sell a kit that is quite good quality. Their product code is F&D 013 & 066. They don’t have any listings for an AG200 but, as stated above, I do know that the 1981 YZ100H has the same fork seal dimensions as the AG200. I have purchased a few of the dust/oil seal kits and they work well. In fact, I think they are better than the genuine items. I haven’t had them running for extended periods as yet but the oil seal has a tension spring on the upper and lower lips while the dust seal has multiple lips that should work much better than the original.

Dust seals compThe only hitch is that your fork boots may hang up on the top of the dust seal when you lower the boot down on it. I have installed two sets of these seals so far and this only happened on one installation and only on one leg. I still managed to get the boot down OK and fastened the lower section of the boot with a cable tie. I suspect it was just the boot in this situation (it was a bit wonky). You can see in the photo here that the after-market dust seal on the left sits up higher on top of the fork, while the original dust seal on the right sits down in the outer fork housing flush with the top.

The YZ100H were shipped from Yamaha with fork boots but maybe it was a different design to the AG with more room at the lower section of the boot? Or maybe its just a oddity of the the after market? It is a much better dust seal than the genuine AG item, to the point where you could run the forks without the boots if they are damaged. So this kit is good for a few reasons – if your boots are wrecked, leave them off and just use this superior dust seal. If your boots are OK then you have the protection of them AND a better dust seal – you cant loose.

Fork seal kit#2Pyramid Parts has a shop on ebay Australia that sells these seals at $25.00 for a kit. It’s cheap and even comes with a little tube of assembly lube which is cool. Just be aware though, his feedback is poor because he is sloooow! You will be waiting for two weeks to get anything out of him but that is my experience of anything out of New Zealand. You can’t rush these Kiwis! 🙂 He says it’s Australian stock but from the mirth of his feedback I find it might be stretching the truth a bit. But who cares? You want stuff cheaper then something usually gives, in this case it’s the delivery time. Maybe I should do a bulk purchase from the company via their website and sell them myself? let me know what you AG200 owners think about this and I may start my own AG-only parts thing up.

Fork circlipIf your forks are full of water, which is pretty common, then the oil seal retainer clip will be in pretty poor condition and I strongly recommend replacing it. Any old garden variety bearing shop should have, or can order in, some internal circlips to do the job. Just ask for 1.75mm thick by 52mm internal circlip. Make sure they are seated correctly in the groove and they will do the job fine. You can get stainless ones too ($$$) but if you maintain your forks you shouldn’t get moisture past the dust seal. You will need to update your tools, a proper set of circlip pliers will be needed of course.

What about fork oil? Fork oil is hideously expensive for what it is. I pay well over $20 for 500ml. It’s too much I reckon. I have read around the web that a lot of people use Auto Transmission Fluid. Never tried it myself but I can understand why people would. I will stick with the proper stuff with my bikes but I can’t see how ATF would hurt on our more lowly steeds. It is just hydraulic fluid after all. The AG needs 15wt oil and I’m not sure of the viscosity of ATF, some say between 7.5 to 10wt so you may find the forks a bit quicker on the rebound action but what the heck…my view is that use proper fork oil if you can but if its a 100km trip to get it and/or you have a heap of ATF hanging around your workshop then give it a go.

Alternate oil seal driver!While we are on to alternate parts, here’s an alternative oil seal driver! The cam-chain side camshaft bearing in the AG200 is an alloy bush which I chuck out in favour of a roller bearing. It fits very neatly on top of the oil seal and does a good job of getting the seal in even. I will document this mod in an up-coming post so you too can get your very own, genuine Yamaha fork seal driver!

In my fork repair posts I also noted that you need to weld a 19mm bolt into a socket, well Fork damper holderthere is a cheaper way of getting that tool into your AG200 toolkit; just weld a 19mm bolt into a piece of pipe or on the end of piece of steel bar – what ever you have lying around really. Weld another piece of pipe or bar at 90° on the other end to make a big long T-bar tool (check out the “damper rod T-Bar tool” in the Yamaha service manual). Many moons ago I did this to get the forks apart on a road bike and it worked a treat so it will do the job for the AG. The bolt into the socket tool mod isn’t that expensive, but acquiring the 1/2″ extension and T-handle can add up. Just make sure the length from the bolt end to T-handle is around 55cm or longer to reach into the fork properly.

So there you have it…I don’t think there needs to be any more info on AG200 fork maintenance. We are done.

Cheers

AGman

Fork servicing, part 3 – re-assembly.

This is the last part – I promise! Time to re-assemble the forks and get them working the way the Yamaha engineers intended. Which is nothing special I might add, but at least they soak up a few bumps without banging and leaving oil all over the place!

Fork parts2So what do we need? Tools were covered in Part 2, but the new parts were not. I will be doing a post on after-market seal options in the future but we will assume genuine Yamaha parts at this stage. Oil Seal: 1T3-23145-00, Dust Seal: 4G0-23144-01 and if required, Retaining Clip: 4A1-23156-00, 600ml of 15Wt fork oil (1 litre bottle is what you need). If you shop around I’d say the job should be done for not much over $50AU. If you use after-market parts (or shop from the US) you could knock $20 or more off that cost.

Insert tubeNow that the inner and outer tubes are nice and clean, stick the outer tube horizontally in the vice and slide the inner tube into it. Slide the tube in and out to make sure there is no binding and use your eye (line the inner tube up with the edge of your bench) to rotate the inner tube to see if there is any misalignment, and therefore see if the inner tube is bent. Remove the inner tube if you’re happy with the fork operation.

Inner tube wearIn my last post I showed a picture of the lower section of the inner fork tube where the inner tube bush should go. While we have the two fork sections apart, give this section a close inspection. This area is usually quite worn to the point where the chrome has worn off the leg. No one is going to spring for a new inner tube though right? So either nick or mark the top of the tube where it lines up with the wear so you can reassemble the tube in the triple clamps 90 degrees so you are on some fresh chrome.

Sound dodgy? Well, it is but the inner tube is pricey from Yamaha, to the point that it might be worth more than the bike. Re-chroming is also an option, I guess it all depends on what sort of maintenance/restoration you intend doing.

Cleaning inner tubeUse a piece of 2000 wet and dry paper lubricated with fluid (kero, diesel or non-water based wash fluid) to run up and down the chrome of the inner tube. You will feel imperfections that you can’t see. It will clean up the chrome and make work much easier for the seals. Also clean up the inside of the top of the inner tube where the fork cap screws in. This is where the o’ring for the cap seals the fork – clean is good.

Most corrosion on the inner tubes will be above the area where the inner and outer tubes move, in other words between where the triple clamps hold the forks. It is very common for this to happen on the AG200 and is one reason why I like to assemble the new seals in the outer tube before inserting the inner tube. It prevents damage to the seal by lowering it down over the rusty inner tube. This is contrary  to most other methods of fork assembly but I think that a little bit of attention to inserting the seals takes away all these other issues for medium to long term durability of the seal.

Of course another reason is you don’t need a fork seal driver. I have one and can do it this way but since the AG200 doesn’t have a inner leg bush, it all goes together quite nicely and you can insert the seals before assembling the two tubes and not have to worry about damage. It just means you have to be more vigilant while installing the oil seal.

Give your inner tube another clean-up to remove the grit from the wet and dry paper. Give the inside of the outer tube a blast with carby or brake cleaner (careful of paintwork) to make sure it’s all clean.Oil seal instal Place the outer tube in your vice, use some rubber grease (normal grease is OK) to lubricate the outside of the seal. Apply a bit to the mating surface in the outer tube as well. Make sure the seal is installed the correct way up (lip spring facing the bottom of the leg)

Install oil sealNow comes the tricky part, the oil seal MUST be driven in parallel to the outer tube. It must be even as possible without one side of the seal hanging up as it goes down. You only really get one chance to do this right, if you have to pull the seal back up you will wreck it. Patience and being observant will win the day. Use the old seal on top of the new one and drive the new seal down with a hammer. Oil seal inTake one tap and observe what the seal is doing and try and correct any unevenness as it goes in. When you see the groove in the outer leg for the retaining clip, you are close. The seal needs to be even all the way round and the clip needs to be able to go in, when this is achieved you are done. Install the clip, put some lube on the dust seal lip and install the dust seal. You should be able to do this by hand. This is a good time to get some grease on the oil seal lip as well.

Install damper rodIf you have got this far then most of the work is done. Use some 15Wt. oil to lubricate the damper rod piston and slide it, with the small rebound spring, down the inner tube so the rod slides out the end. Install the spring, washer, spacer and end cap. No need to screw the end cap up too far yet because it’s all coming apart again in a minute. Damper rod installedPlace some oil on the end of the damper rod where the collet fits on the end, fit the collet and use some fork oil to lube the damper rod and the outer tube bush below the oil seal. The inner tube can then be carefully installed into the outer tube.

Fit colletLooking into the damper rod bolt hole at the bottom of the outer tube, use your pick or a fine screwdriver to align the damper rod with the hole as you push the inner tube down the outer tube. Now the damper rod bolt can be inserted and done up. Aligning damper rodBecause there is no oil in the assembly, you will find that compressing the fork to put pressure on the damper rod to stop it turning, will work much better than when we pulled it apart – no oil = more friction. The Yamaha manual specifies 30Nm torque for the damper rod bolt so if Instal damper rod boltyou have a torque wrench you can put it to good use here. If not…don’t do it up too tight, 30 Nm isn’t a lot and I use a small amount of weak thread locker on the threads of this bolt.

Remove the top cap, spacer, washer and spring and check the operation of the fork assembly for smooth and correct operation. Oil fillIf all is OK place the fork assembly vertically in the vice. Measure out 294ml 15Wt. fork oil and pour it into the fork assembly. I pump the fork up to the top of its travel to the bottom 10 times to pump all of the air out of the system. I then go and have a latte while the air rises out of the oil. You don’t have to do this of course but I love my coffee!

oil measureI then use my oil height tool (117mm from the top of the inner tube to the oil level, fork tube collapsed) to suck out any excess oil. The height of the oil is more important than the volume but you don’t have to get too particular, especially if you don’t have the tools required. Actually I have all the tools that the manual and the experts on Youtube use, but I was also bought up on a farm where we had to make do with nothing. The AG200 can be worked on with minimal special tools and I try to give tips in avoiding them when I can. I realise that most people with these bikes are on a budget, I understand because I was too.

Spring pitch#1Extend the fork up to its full height, install the spring and make sure the tighter pitch section is at the top. Drop in the washer, spacer and then lube the o’ring on the top cap and screw it in to the fork. We are finished! All that needs to be done is to tighten up the top cap (23Nm) and can be done in reverse of the Part 1 procedure to undo them. I suggest spraying some chain lube or similar into the hex section of the fork cap before putting the plastic cover back on. Water seems to find its way in under this cap and it will rust pretty bad if you don’t protect it.

The installation is pretty much the reverse of Part 1 taking note that the top pinch bolt (1 x 14mm bolt & 17mm nut)  is set to 34 Nm, while the lower pinch bolts (2 x 12mm) are set to 23Nm. Also take note of the nick or mark that I advised to put at the top of the inner tube as discuss earlier in the blog. As mentioned, if you rotate this mark 90 degrees you wont be running on the section without hard chrome.

Also take care aligning the speedo drive up when installing the wheel. If you don’t align it properly, you will bend the speedo drive tabs and it can jam and destroy the whole speedo drive assembly. Have seen this many times.

So there you go, all done! Fresh new forks working as they should. Now get that bike back together and enjoy your handy work…

Cheers

AGman

Fork servicing, part 2 – disassembly.

Welcome to part 2! This is the nitty gritty of AG200 fork servicing. It’s the bit where you have to have your wits about you because if you rush it, you can easily stuff it up! We don’t want that so PAY ATTENTION! I don’t want you turning a perfectly good set of forks into an oil pump! Seriously, its not that difficult and I will explain why I do the things I do and why you need to pay attention in certain areas that could end in tears if you don’t.

So what tools will we need? 6mm Allen key, the 19mm hex/Allen key special tool we discussed in part 1 (and a T handle and extension if things don’t work out), tyre lever, pick or something pointy, a wire brush, a sturdy bench vice with protective jaws make it all a lot easier too. In fact I can’t imagine doing this job without it. Facilities to give all the fork components a good clean up is nice – a parts washer is perfect but a bucket with some solvent and a stiff brush will do the job too. A can of carby or brake cleaner comes in real handy as will a lot of rags.

Damper rod boltOK, first thing to do is place the outer tube in the vice horizontally and give the bottom of the fork leg a jolly good clean up. Grab your pick or other fine tool and clean all the crud out of the 6mm Allen bolt (damper rod bolt) at the bottom of the leg. Make sure you clean all the crud you can between the circumference of the bolt and the outer tube, compressed air is good if you have it at hand. If there is a lot corrosion on the bottom of the aluminium outer tube then you may need to hit it with a wire brush and some CRC/WD.

You can now stick your 6mm Allen key into the damper rod bolt and try and release it. IfDamper rod release you have been watching YouTube videos on dismantling conventional forks, you will know that there may now be some issues. Once the damper rod bolt comes loose, it may just turn the whole damper rod assembly inside the fork leg preventing it from unscrewing. So what do we do now? Well the manual says we can use the special damper rod holder tool to hold the damper rod but I just compress the fork leg a bit (see pic below) and the spring will put more pressure on the damper rod and hold it while you undo the bolt.

Damper rod hold2For me this works nine times out of ten. For the other times is when you will need the special 19mm tool with a 1/2″ extension and slide it down (after removing the cap, draining the oil, removing the spring and spacers) the inner tube to hold the damper rod. I find that if a fork is in really bad condition, there will have been water in the tube for a very long time and the damper rod components will have rusted and will need some extra love to get them all apart.

Damper bolt removeSo assuming the damper rod bolt came out OK, you should turn it so you can undo it with your fingers but not all the way out. Remove the fork from the vice and place the fork over a container and remove the bolt, watch out for the copper washer under the bolt. Have plenty of rags on hand in-case they are needed. After the initial oil has drained, slowly pump the fork to remove as much oil as possible.oil drain Be aware that the fork will now separate so be really careful when extending the inner and outer tubes apart, especially if you don’t plan to replace the seals.

When you think the majority of the oil has drained you can now gently separate the two fork components. It’s probably best if you do this procedure back in the vice with the outer leg mounted horizontally, be gentle with the seals if you aren’t replacing them. The outer tube is in the vice and the inner tube will look like at left.Inner tube If watching the above mentioned YouTube vids, you would of looked on in horror as people use their lovely front suspension components as a slide hammer, bashing them apart! Well luckily you don’t have to do this with the AG200 fork because there is no inner tube bush to hang up on the outer tube bush as they come apart.

Remove fork capNow we have two separate components. Put the outer tube aside (beware the damper rod collet or oil lock piece – see below) and we can divert our attention to the inner tube. Undo the top cap (you did loosen it per the instructions in part 1 right?) of the inner tube and remove the spacer, washer and spring. Keep some rags handy as you remove these components because there will usually be some oil left in the inner tube. The damper rod will now be free to slide out the top of the tube as well depending on whether the oil lock piece stayed on the damper rod or stayed in the the outer leg when separated.

Damper rod colletThe photo at left shows the components talked about above. 1 is the inner tube. 2 Shows where the inner tube bush usually goes on conventional forks! 3 is the damper rod and 4 is the pesky collet that can get corroded.

I find if the forks had water in them and there was a bit of corrosion, the collet may stick to the damper rod and might need a bit of persuasion to come off. Once free from the damper rod you can turn the whole inner tube upside down and the rod and the small rebound spring should slide out of the tube. AllAll components these inner tube component need to be thoroughly cleaned and any corrosion removed. Pay attention to the thread on the inner tube where the cap screws in. Make sure any corrosion leading up to the threads is removed with wet & dry.

Now lets turn our attention back to the outer tube. Give it a bit of a scrub up but there is no need to get too fussy because there is still work to be done here. I prefer to do all the work on the seals while the two tubes are separated. Why? Because nothing will go near the delicate chrome surface of the inner tube if you work this way. If you fumble removing the dust seal or retaining clip and gouge the chrome on the inner tube, then you have stuffed it! It will never stop leaking oil or it will damage new seals that you will install. Even if you put it all back together and it works OK you have created an area for corrosion to set in. Get the two tubes apart and away from each other and this wont be a problem.

Another reason why I do the fork seals the way I do is because 80% of AG200s I have seen have rust and pits on the chrome fork leg between the upper and lower headstem clamps. So if you do the seals like they show you on the Youtube videos, you will have to slide the new oil and dust seal down over all this dodgy chrome. In the next part I show you how to clean up the legs but damaged chrome is damaged chrome. It WILL hurt your seals as you slide them down over this damage. If the AG200 forks had an inner tube bush, my procedure would be harder to pull off but it doesn’t so we are on easy street. The only thing we have to watch is getting the oil seals in even and square. We just need to be more careful when we do this job…but I digress…

Dust sealPlace the outer tube in the vice as low as it will go to reduce the force placed on your bench and vice. Grab your tyre lever and use it to lever out the dust seal. I use a piece of rubber under the lever to protect the top of the outer tube. Your thinking why use a tyre lever right? Why not just use a screwdriver? While removing this top dust seal (which will be easy compared to the oil seal under it) be really careful you don’t scratch the aluminium on the inside of the outer tube. A tyre lever will have less chance of damaging this area as opposed to the sharp corners of a flat screwdriver. It’s probably not so important where the dust seal fits, but it is critical for where the oil seal fits.

Outer tubeUnderneath the dust seal is the oil seal retaining clip. See the pic. at left where 1. is the clip, 2. is the oil seal and 3 is the outer tube bush discussed bellow. I suggest that you leave off purchasing parts for the forks until you have it all apart to see what is actually damaged. If the forks are old and the fork seals have failed then there will probably be dirt and corrosion between the dust seal and the oil seal. If the clip is rusty, replace it.Retaining clip Be careful removing it, place a rag over the top of the tube as you lever it out blind. There are two reasons for this; the first one is obvious; the clip can fly out and take out an eye. The other reason is not so obvious. If the seals have failed and there is oil, dirt and rust in there, the spring can flick back into its slot and not come out but in the process of springing back home it propels rubbish out and into your face. Don’t ask me how I know this!

Oil sealSo the dust seal and the retaining clip is out, now it’s time for the tough one – the oil seal! It’s not that tough really but you just have to be careful not to damage the surface that the seal is pressed into. This part of the fork is under pressure so anywhere the pressure can escape it will. You damage this surface and medium under pressure will escape past the seal. Because it is further in the tube it makes the tyre lever a bit more awkward to do but take your time and it will come out. Removing as much of the crud above the seal will help as well.

Once the oil seal is removed, clean this area to as close to perfection as you can. Use grade #2000 wet and dry paper to clean up the area where the seals press in. Use your pick to clean out the retaining clip groove. Be careful of the bush just (see above) below where the oil seal was, and try not to nick or scratch the anti-friction coating on it. Of course, if the bush is really worn you will need to replace it but surprisingly, it’s quite rare for it to fail.

SludgeTake a good look at the inside of the outer tube and there may be an accumulation of black sludge at the bottom. This is where brake cleaner can come in handy for cleaning this up. Get it as clean as you can and jam a rag down there to clean out the residue. Give the whole outer leg a good clean up and look over, throw away the dust seals and retaining clips if they are damaged but hang onto the old oil seals for now because we will use them to drive in the new seals. Just give them a bit of a clean so you don’t put crud all over your nice new seals and clean components.

So everything should be cleaned and ready to go back together, soooo this ends Part 2. It just got too long! I bet you didn’t think it would be over 3500 words to describe this procedure? Cant wait for the engine rebuild eh? 🙂

Cheers

AGman