Thumper Club Forum
Technical => Bike Problems/Questions => Topic started by: pete on September 20, 2010, 03:11:49 PM
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Hello to all you thumper lovers.A bit miffed on the forks.When changing the front tyre after a puncture i noticed a leak from under the right fork, the bolt inside the bottom of the leg.The forks bottom out on sharp bumps and are a bit squidgy?I am going to change the front tyre and tackle the bolt at the same time.Is there a easy way to bleed the forks as i am thinking if i release the top nut it will shoot off to some obscure place.I don't really want to remove the forks if i can help it.No one i have asked have ever undone the top nut on their forks before. I draw from your wealth of knowledge and stand by with a keen eye for flying objects.
Regards to all,Pete.
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Hi Pete.
To change the seal , you need to remove the leg from the yokes.
Loosen the top nut while the forks are still in the yokes.
Then remove the leg, after slackening upper & lower yokes.
And then removing the front mudguard.
Carefully remove the top nut, better with a socket , keeping pressure onto the nut.
Turn the fork upside down remove all of the parts & place down in the order & position they came out !
then pump the leg in & out to remove the oil, into a suitable drum.
I then wash everything in a parts washer.
The allen bolt underneath is best removed with an air gun & suitable socket drive for allen ....
Remove the dust seal & the wire clip that holds the seal in.
Then when the bolt / copper washer has been removed, grab the fork tube & the lower & pull apart in a quick jerky movement.
They will eventually part.
Slide the seal off & the metal washer.
If placing the lowers into a vice for reassembly , ensure that you have plenty of packing to prevent damage.
NEVER , NEVER place the chrome sliders into a vice , I have some here that have been DAMAGED by this.
Clean everything again, inside the lowers to remove any sludge.
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Reassembly.
Everything Clean.
Hold the slider ontop of your shoulder.
Using a small flat screwdriver gently ease the metal bush back into the holder on the lower.
You will feel it click, do one side then the next so it goes in equally.
Then the washer, then seal, again ease it in carefully with a drift / screwdriver.
You DONT want to damage the slider , a few winds of insulation tape around the slider can save you damaging it.
Make sure the seal is 'Home', then fit the clip ring , a smear of grease on top & then the dust seal.
Refit the allen & washer underneath.
all the internals in the order they came out, refil with 285 ml medium grade fork oil, screw the top nut on .
Refit to bike, & then tighten the top nut while the top yoke has been tightened.
No point doing just one side, sods law , the other will start leaking..
ALSO.
If the bike has been standing for a bit , try moving the forks up & down for a while as sometimes the forks will re-seal themself !
It CAN be done, just take your time , & if you are not confident , take to a REPUTABLE workshop....
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Cheers Fuzz,very comprehensive and spot on.The fork seals have no leaks just the bolt on the bottom of right fork.I just want to bleed and refill the legs without dismantling.Just wondering if this was possible?My idea was to undo the the small bleed nut pump the oil out by bouncing up and down,when empty undo the nut and refill to the spec.Never that easy is it.May have to take the forks off and ask a REPUTABLE bike fixer to sort them.I have no work shop,just my drive and a handful of half decent spanners...etc.There are some forks on eBay but say they need servicing.Back to square one.
Thanks for your thoughts,Pete.
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Do both , so that they are the same !
A handy thing is a large syringe available on ebay , they have ml measurements on them ....used for Vets
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If you can find a bit of old scaffolding pipe it makes a perfect slide hammer for driving the new seals home - internal diameter is just big enough to slide down the fork leg and the external is just the same as the seal.
If you just want to change the oil, there are drain plugs on each fork leg make sure you pump the bike up and down to get all the old oil out - be warned the oil WILL shoot out sideways about 6' !!. To refill remove the top nuts, preferably with a socket spanner the nut will probably 'pop up' a little bit but it shouldn't be under enough pressure to shoot right off -WARNING when you do this cover the tank with an old anorak/fleecy/ old blanket as it's very easy to chip the paint when if you don't catch the nut....trust me I know this... :-[
Top up with 283cc / 9.8 oz of ATF ( Automatic Transmission Fluid - available from garage for automatic car gearboxes - it's usually red).
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Do both , so that they are the same !
A handy thing is a large syringe available on ebay , they have ml measurements on them ....used for Vets
You can buy (sorry) these big syringes from any agricultural mechants.
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Ahhhhh!...Cheers Steve.Just what i wanted to hear,it is possible to do a quick bleed and top up without a strip down. ;D Going to go for that after fitting a new tyre and tightening the fork bolt.
Thanks for all the replies, Pete.
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Oh, and remember to use ATF, not fork oil.
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Maybe these have a dual use?
http://cgi.ebay.co.uk/1000cc-Large-Glass-Enema-Colonic-Irrigation-Syringe-/320582785284?pt=LH_DefaultDomain_0&hash=item4aa4391904
Why would you want 2 pints of anything up your @rse? :o :o :o ??? ??? ???
If i did i'd find a way of not spending £180.00 to get it up there!!!!!!
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Hi Pete
If you're leak is coming from the allen bolt that screws up the very bottom of the fork leg it'll be the copper washer that's the culprit. You need to take the allen bolt out with the top nut fitted as it needs the spring tension to stop it spinning the gubbins around inside the fork leg. If you drain the goo out first you can just pop the allen bolt out, shove a new washer on it then pop it back in.
Them top nuts can come out with a fair bit of gusto, particularly if someone's put a spacer under 'em. When I rebuilt my CB900 I fired one right across the garage with a socket still attached to it :o
Dave B
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Oh, and remember to use ATF, not fork oil.
Why is that ???
ATF is formulated for transmissions.
Fork oil is formulated for forks.
What is the viscosity of ATF compared to 5W or 7.5W fork oil? It really is important as with non-adjustable forks the only way to "tune" the damping without messing with metalwork is to change the weight and/or the level of oil in the forks..
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Honda specifies ATF for the forks. And it's way cheaper than fork oil. Buy the stuff for Toyotas and the like, ordinary ATF. Because it's relatively cheap, you can afford to pump out the old oil, fill it with new and pump that out to clean out the rubbish in there.
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Perhaps in the 80's ATF was as good as it got.. I'll stick with fork oil, 12€ a year isn´t too much to pay.
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You may be disappointed. I tried that - thought I was smart - and regretted it. ATF's the goods.
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Seems that ATF is very roughy equivalent to 10W.
Honda recommend 7,5W in mine but I use 5W with less airgap: responsive with less dive under braking
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Does anyone know where i can get a replacement copper washer and what size it is? Don't want to have to do the job twice just to size it up. :P
Cheers,Pete.
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8mm
According to the part catalogue it should be Part No 90544 283 000
Available from David Silver Spares at 45p each
http://www.davidsilverspares.co.uk/parts/by-part-number/partnumber_9421/ (http://www.davidsilverspares.co.uk/parts/by-part-number/partnumber_9421/)
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Thats done the job for me.As proved once again..this site has many people willing to give their knowledge and time for a great many thankful in need of advice bikers.With the odd joke thrown in of course. ;)
Thanks for all the help, Pete. ;D
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No prob mate!
if you need the workshop/parts manuals and a load of other XBR/GB stuff on CD PM me you're address.
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Thanks Steve,i have a download manual as a desk top.That does me usually.But now and then we all need a little advice on things we are not certain of.A very kind offer for the tech stuff.
Hoping the weather holds,Pete.
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Hi Steve, could you just check the link to the washer you sent me as the part numbers and size did not seem to match.Just double checking as i do not normally order parts like this and want to be sure,not questioning your knowledge but doesn't say 8mm fork washer.Just me i guess. ???
Regards,Pete.
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Hi Pete
The part number I have is 90544-283-000. It's listed as 'Washer SPL. 8mm' on www.cmsnl.com.
Regards,
Dave B
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Yep, that is the part no for the washer that fits on the allen bolt in the bottom of the fork leg. If you phone Dave Silver's you can ask them to check, I've always found them very helpful.
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Oval screw is what your last quote come up with?Copy and pasted pigafettas number onto Dave silvers parts list and HEY....BINGO! 45p washer with £1.95 delivery...weighing in at 12kg got myself a bleedin bargain i hope. Just rambling , If it does the job i thank all for the help i received.Computers can be a real source of fun for us Mensa uninitiated. ;)
Sixpence non the richer,Pete.
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12 kg ??????
How many have you ordered ????? ;D ;D ;D ;)
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12 kg ??????
How many have you ordered ????? ;D ;D ;D ;)
Aha! he's an XBR stock hoarder like me! :D
GC
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So, resurrecting an ancient topic. But a related reply is allowed to do that.
I'm in the deep here. I can't get the bottom bolt of the fork off. I can spin it both ways, but it won't come undone. I got the other one off and looked into the design - the bottom bolt is attatched to the piston and the piston is attatched to... wait - nothing?!
I can see the repair manuals advice to keep the spring tensioned while undoing the bolt because apparently the only thing holding the piston in place is the tension of the spring? So now I'm spinning the bolt AND the piston when trying to undo the bolt..
So... the fork leg is useless now since it's leaking and I can't remove the bolt to replace the copper washer. If you have an answer, I'd be one happy camper.
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What you may need to do is find someone with an air (or electric) impact gun and get them to try undoing the bolt with the (complete) fork upside down and compressed as much as you can manage.
There's probably a Honda special tool to stop the damper turning but the above method has always worked for me (admittedly with someone more qualified using the gun).
GC
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Hi all, just to confirm a few points on how it went on the forks. Luckily the bolts came straight out and the washers straight on no problems since.I undone the bottom bolts then the same with the top nuts. To my suprise and probably not good, there was no resistance against the caps and all just stayed in place.After draining the legs and replacing the bottom bolts i used castrol ATF oil ( TQ D111) from the local car shop to refill (£8.99 for 1 ltr). Top nuts back on and gave it a test ride up and down the road.It seemed a bit soft still so added an extra 50ml to each fork.This was probably due to the springs being a bit worn i would guess and compensating with a bit more oil. In the back of my mind i was hoping it wouldn't cause a seal leak from too much pressure from the extra oil,but, all is good.
hope you sort it soon, Pete.