Fork seals help needed

[Lysy]

Hi there . Sorry to trouble you all again. My fork seals started to leak and need replacing, at first I wanted to take the bike to my local garage but then I looked at Honda manual and it does not look like a very difficult thing to do so I thought I could maybe give it a go myself. How big a job is it. Can a normal human being do it (not that I'm saying I'm normal ) or is it a job for super talented motorcycle mechanic? I know what to do with a spanner but I am not motorbike mechanic. Are there any catches or a special tools needed - I've only noticed that seal driver in manual, the rest looked like normal spanners/sockets or am I missing something. Would I really need that seal driver or can something else be used. The thing is bike is my main transport so if it is something that requires super skills I'd rather take it to the garage but on the other hand I don't like paying the money for things that I could do myself. Your advice will be greatly appreciated. Thanks

[popkat]

If you've never done it before and it's your only transport then get someone else who knows how to do it. there maybe someone on here not too far from you who could help out, if not then take it to a bike shop..

It isn't too difficult but you may encounter problems undoing the bottom bolt, also you need to know about the damper rod (damper settings), internal cartridge and air gap.. That lot should tell you if you have the skills and confidence to do it


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[AMCQ46]

before you replace, try cleaning the seals in situ by lifting the dust covers, pushing a business card or thin plastic sheet into the gap between the fork and the seal and dragging it round the circumference to pull out any trapped dirt.

you can also buy a little plastic stick that does the same, but look on youtube and then copy that shape onto a bit of thin plastic container from your recycling bin

[popkat]

Seal mate is the tool, look at link below.






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[Lysy]

Yeah I've got that seal mate. It didn't really make any difference.

[Lysy]

Well maybe I'll let the bike shop do the job this time. The good think is there are good lads there and they always let me watch as they work on my bike so I might learn something new. What kind of money am I looking at here. I know it varies from place to place but what's the average so know if I need to ask for a discount or not . Thanks

[popkat]

Two to two and a half hours I reckon, plus cost of seals and oil..

If you've still got standard fork springs now's the time to fit some better ones, K-tech do a drop in spring, 0.85kg works well for average weight rider with a 140mm air gap and 10 weight oil. After fitting set up so that 5mm of fork is showing above the top yoke.. The bike will sag less with firmer springs so if you don't drop the front you'll be riding higher at the front. set preload to 27-28mm, should be all good then..

http://www.ktechsuspension.com/products ... cats_nid=7


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[Lysy]

Thanks popkat
Iwill look into that

[Cadbury64]

Hi there . Sorry to trouble you all again. My fork seals started to leak and need replacing, at first I wanted to take the bike to my local garage but then I looked at Honda manual and it does not look like a very difficult thing to do so I thought I could maybe give it a go myself. How big a job is it. Can a normal human being do it (not that I'm saying I'm normal ) or is it a job for super talented motorcycle mechanic? I know what to do with a spanner but I am not motorbike mechanic. Are there any catches or a special tools needed - I've only noticed that seal driver in manual, the rest looked like normal spanners/sockets or am I missing something. Would I really need that seal driver or can something else be used. The thing is bike is my main transport so if it is something that requires super skills I'd rather take it to the garage but on the other hand I don't like paying the money for things that I could do myself. Your advice will be greatly appreciated. Thanks

Fork seals are pretty easy to replace and you don't need special tools. Loosen the fork caps before you take the forks out of the bike. Plan on fork oil being squirted/dripped wider than you might expect! You need 1 litre of oil, I usually use 5W but other opinions are available. In addition to new seals, I would suggest replacing the copper washer (90544-283-000 WASHER (8MM)) on the damper bolt (it acts as an oil seal), and if your bike has higher mileage, maybe replacing the bushings as well (51415-MM8-003 BUSH, SLIDER, 51414-MN5-003 BUSH, GUIDE). The suggestions for 0.85kg/mm fork springs are correct as well, and if you go down that path you might need different length spacers (e.g. 32mm OD PVC pipe). Blue Loctite is recommended for the damper rod bolts on reassembly.

The one place where you might have difficulty is getting the hex head bolts out of the bottom of the fork leg. If they don't come out cleanly you may need an air impact driver to break them loose. If these give you any grief, head to the bike shop. To avoid future issues, I run a tap and die through the parts once apart so they will screw back together nicely.

The dust seals and circlip will come out easy, but driving the old seal out can take some effort; just keep extending the fork hard to hammer it out. Once apart, look at the bushings and check whether they still have nice grey teflon coating or if it has been worn through to copper, if so get some replacements.

Take a close look at the length of the fork staunchion where the seal slides, it may have a stone nick/burr that caused your old seal to leak. If so take a fine file and take off any high spots and polish with 1200 grit sand paper.

In place of a fork seal driver, get yourself a length (I'd guess 600mm or so) of PVC pipe that will only just fit over the fork tube, make sure it has a straight, clean end. Clean the area where the new seal will sit carefully (and in fact clean all of the fork innards carefully, e.g. brake cleaner) and make sure the new seal goes on the right way up. If you slip a thin plastic bag over the fork tube end that will protect the new seal from being cut as you slide it onto the tube. Once the new seal is settled into place, slide the old seal down the tube, then the PVC pipe, and gently tap the new seal into place. You'll know when it is properly seated by the sound. The old seal protects the new seal from any driving damage. A little red rubber grease on the oil seal and dust seal won't go astray.

Once the damper rod is bolted back in place, fill the fork most of the way with oil, then prime the cartridge to expel air. I use a 100mm bolt with the same thread size as the damper rod and connect it to the damper rod with the locknut. This allows me to reach into the assembled fork and pump the cartridge up and down to prime it. Do the same with the whole fork leg to get air out from between the bushes. Once all the air is out, fully compress the leg and set the final oil level. I use 120mm from the top of the leg.

If you choose to do this yourself and are unsure at any point, ask away.

[popkat]

Hi there . Sorry to trouble you all again. My fork seals started to leak and need replacing, at first I wanted to take the bike to my local garage but then I looked at Honda manual and it does not look like a very difficult thing to do so I thought I could maybe give it a go myself. How big a job is it. Can a normal human being do it (not that I'm saying I'm normal ) or is it a job for super talented motorcycle mechanic? I know what to do with a spanner but I am not motorbike mechanic. Are there any catches or a special tools needed - I've only noticed that seal driver in manual, the rest looked like normal spanners/sockets or am I missing something. Would I really need that seal driver or can something else be used. The thing is bike is my main transport so if it is something that requires super skills I'd rather take it to the garage but on the other hand I don't like paying the money for things that I could do myself. Your advice will be greatly appreciated. Thanks

Fork seals are pretty easy to replace and you don't need special tools. Loosen the fork caps before you take the forks out of the bike. Plan on fork oil being squirted/dripped wider than you might expect! You need 1 litre of oil, I usually use 5W but other opinions are available. In addition to new seals, I would suggest replacing the copper washer (90544-283-000 WASHER (8MM)) on the damper bolt (it acts as an oil seal), and if your bike has higher mileage, maybe replacing the bushings as well (51415-MM8-003 BUSH, SLIDER, 51414-MN5-003 BUSH, GUIDE). The suggestions for 0.85kg/mm fork springs are correct as well, and if you go down that path you might need different length spacers (e.g. 32mm OD PVC pipe). Blue Loctite is recommended for the damper rod bolts on reassembly.

The one place where you might have difficulty is getting the hex head bolts out of the bottom of the fork leg. If they don't come out cleanly you may need an air impact driver to break them loose. If these give you any grief, head to the bike shop. To avoid future issues, I run a tap and die through the parts once apart so they will screw back together nicely.

The dust seals and circlip will come out easy, but driving the old seal out can take some effort; just keep extending the fork hard to hammer it out. Once apart, look at the bushings and check whether they still have nice grey teflon coating or if it has been worn through to copper, if so get some replacements.

Take a close look at the length of the fork staunchion where the seal slides, it may have a stone nick/burr that caused your old seal to leak. If so take a fine file and take off any high spots and polish with 1200 grit sand paper.

In place of a fork seal driver, get yourself a length (I'd guess 600mm or so) of PVC pipe that will only just fit over the fork tube, make sure it has a straight, clean end. Clean the area where the new seal will sit carefully (and in fact clean all of the fork innards carefully, e.g. brake cleaner) and make sure the new seal goes on the right way up. If you slip a thin plastic bag over the fork tube end that will protect the new seal from being cut as you slide it onto the tube. Once the new seal is settled into place, slide the old seal down the tube, then the PVC pipe, and gently tap the new seal into place. You'll know when it is properly seated by the sound. The old seal protects the new seal from any driving damage. A little red rubber grease on the oil seal and dust seal won't go astray.

Once the damper rod is bolted back in place, fill the fork most of the way with oil, then prime the cartridge to expel air. I use a 100mm bolt with the same thread size as the damper rod and connect it to the damper rod with the locknut. This allows me to reach into the assembled fork and pump the cartridge up and down to prime it. Do the same with the whole fork leg to get air out from between the bushes. Once all the air is out, fully compress the leg and set the final oil level. I use 120mm from the top of the leg.

If you choose to do this yourself and are unsure at any point, ask away.

Don't pull the forks apart hard to hammer them out, that's the quickest way to get them stuck as the bottom bush tries to pull through the top one tearing off the coating, your in for a heap of grief doing it like that... Pull the fork gently, yes you are using a slide hammer action but you want the bottom bush to tap out the top one, if it's not moving then apply some heat to the fork at the seal area, warning you might blister your fork paint. Unfortunately sometimes they are very stubborn if this is the case you will be needing new bushes.



Wind the rebound damping all the way in before starting, loosen locknut and unscrew fork top, when putting back together screw top cap back on, when it gently reaches a stop bring the locknut up to it then tighten it up. once fork is fully back together reset your rebound damping...



120mm air gap seems too much oil, you risk blowing a seal or possibly hydraulic locking.. the level of fork oil effects the last third of the fork travel, I'm not aware that I've ever bottomed mine out or had any hard braking problems with a 140mm air gap, I don't think any more oil is needed..


It's not a difficult job but I suggested above to take it to a shop as it was the OP's main transport, if you've never done it before you need to allow time for things to go wrong (which they can) rather than screwing up your transport.


The K tech springs are the correct length, no need to mess with new spacers, just drop in and use original spacers.


.

[Cadbury64]

Some good points there Popkat. I did have to resort to handing my forks to the nice men at Botany Honda to separate as when I bought my VTR, the dust seals were nearly in pieces and water had leaked past, causing corrosion further down. (I was also trying to work one handed as I had carpal tunnel surgery that week!) They used heat as described, but still had to hammer the forks very hard to separate them. The bushes were OK with this, I bow to your superior experience but I can't see how one could ever slide over the other as when they are in place there is very little clearance between their ends. I have personally fully disassembled forks in four of my bikes over the years, but mine tend to live pampered, garaged lives that may be different from a bike that gets used year round commuting in bad weather on salted roads.

There is no risk of hydraulic lock or blowing a seal with higher oil levels. You are looking at an air gap of 120mm with the fork fully compressed, so when that is extended to the full travel the air gap will be 229mm. If I ignore the volume taken up by the spring, when fully compressed the pressure in the fork top will reach 192 kPa with this oil height vs 179 kPa with 140 mm; in psi terms that is a difference of 2 psi. Back in the day of using air pressure in addition to fork springs, I recall 15 psi was the maximum pressure of an extended VF750F fork. For reference, the specified air gap in a VFR800F 2002 model is 100mm. I use the smaller air gap on the VTR as I run straight-rate springs and wanted a bit more progression near the end of the stroke.

On the damper rod reassembly I would suggest screwing the needle fully in, winding the fork cap onto the damper rod until the needle lightly bottoms, and then backing the needle out one turn before tightening the lock-nut. I think if you leave the needle fully in when you do up the lock-nut you risk damaging the needle tip as everything pulls tight.

[darkember]

Sounds all too painful. Utube video would be handy all that type is giving me a headache

[Lysy]

Great write ups. Thanks guys. When I finally get back home this Saturday morning I'll try to loosen a bit bottom hex head bolts. If they go I'll order new seals etc and then I'll give it a go following weekend if not I'll let my bike shop do it.. What could possibly go wrong? . Worse case scenario : missus will have to give me a lift to work on Monday morning and then pick me up on Friday. She might not be very happy as I normally start at 1am on Mondays but I'm sure she will do it for me. I hope ...........

[bigtwinthing]

Great write ups. Thanks guys. When I finally get back home this Saturday morning I'll try to loosen a bit bottom hex head bolts. If they go I'll order new seals etc and then I'll give it a go following weekend if not I'll let my bike shop do it.. What could possibly go wrong? . Worse case scenario : missus will have to give me a lift to work on Monday morning and then pick me up on Friday. She might not be very happy as I normally start at 1am on Mondays but I'm sure she will do it for me. I hope ...........

both have a good "forking"

[Lysy]

both have a good "forking" [/quote]



Cheee mate