OzVMX Forum
Clubroom => Tech Talk => Topic started by: mainline on January 02, 2008, 11:13:58 pm
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G'day,
my first question of many - is it within the capabilities of a backyard mechanic to replace fork seals in a 79 YZ. I don't have a workshop manual yet so I'm not sure what I'm up against. I'm of the pull it apart-have a look- put it back together- school of mechanics.
My previous mechanical experience is limited to top-end jobs and changing fork oil height/weight etc.
Any how-to's would be great, cause I'd like to learn, or if you think it's safer to drop them at the shop let me know.
cheers
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Yeah mainline, its not a hard job. Before you undo the bolts in the triple clamps, loosen the fork cap half a turn so when the forks are out of the triples you can hold them in your hand and undo the fork cap. Watch that you dont lose the preload spacer and washer/locator when the spring pops up, remove the spring and then drain the oil. Remove any dust seals and the circlip so its just the oil seal left in the fork leg. Now the hard part comes. You need a tool like this, I made this and it is 510mm long and the nut is a 24mm.
(http://i45.photobucket.com/albums/f65/djracingyz/ideas006.jpg)
(http://i45.photobucket.com/albums/f65/djracingyz/ideas004.jpg)
That tool goes down the centre of the fork leg to hold the damper rod while you take an 8mm allen key to the bottom of the fork tube and undo the allen key bolt. Once that is out, just hold the fork slider and the fork leg and pull then apart, you may need to really pull them apart hard and fast a few times until they pop apart. Clean everything up and then rebuild them keeping everything in the right order.
A tip on replacing the fork seals is; place the plastic bag they come in over the fork slider and oil up the inside of the oil seal, slide the oil seal over the plastic bag down on to the slider. It helps prevent nicking the oil seal on the top of the fork sliders. ;) :) Have fun :), :oDisclaimer; this is just a quick general discription of how its done, at no time do I or my TOOL take responsiblity for oil stains, broken nails and bad language ;D ;D ;D
Hope this helps Mainline
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thanks for that, I'm sure there will still be a certain amount of swearing though. I'm sure the problem is my shitty internet connection, but I can't see the pics you've posted?
Broadband was due to be connected yesterday, so fingers crossed for today. Thanks again.
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Hey DJ does this fit 43mm forks also ,as most times i get away just using the rattlegun but i will make a tool up if it does both as i have a few to do .
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got broadband connected now, and can see the pics. Cheers. The only problem I've got now is that I've been quoted a couple of hundred bucks for the dust caps for these forks!!! The oils seals themselves only cost $19 a pair!
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G'day DJ do you think that tool you made will fit the forks on a DT1 is it the same set up. jimson
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you could also use a rattle gun and a allen socket to remove the base fork bolt always worked for me
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Caps999 the reason I made the tool was because the rattle gun didnt work, the dampen rod kept spinning so I made the tool up. Its been very handy, the nut welded to the end has been ground flat to remove most of the tapered edges.
As for DT1 or 43mm forks I'm not sure if it will fit. But I do know it works on 36mm and 38mm yammie forks. The length of the tool would work for all of the forks and the reason why the handle is bent is because I used it as a prying bar(stupid thing to do). I have made a couple of tools now including a clutch basket holder, two different stator pullers and I want to make a 2-stroke leak down tester.
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i used the rattle gun to undo the bottom of my 43mm fork legs on the yz too caps999....but i must take my hate off to djracing for makin his own tools...to undo his forks great stuff...good thinkin mate...one question ....when you put the forks back together did you put any locktite on the bottom bolt on the base of the fork when you tightened them back up.....cheers.. 8)
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Andrew, it just depends on how scary a ride I want to weather I put loctite on the bottom allen key bolt. ;D ;D :o. I dont like scary ;) so yeah loctite goes on and for most bolts on the bike I use a small bit of loctite. Ya know how these things vibrate and there is nothing worse than loosing stuff off ya bike or ya day is spent pushing a bike back to the pits because of a bolt.
But for scary shit ask the newest member of the forum what its like to be blasting around a 50 acre paddock on a YZ400F, pulling wheel stands and sliding everywhere, and then stop to have a chat to the other riders. He shut the bike off, chatted for about 2mins(didnt even get off the bike) and then went to kick start her again and as he did noticed the the front wheel was wobbly, got off the bike and wiggled the front wheel and found the axle had sheered in half. scary shit :o
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Alrighty, got the forks half apart (except for the aformentioned hard bit). I've made up my version of your Damper Rod Tool (TM) but because I'm an idiot and I've never had a fork completely to bits before I'm not sure how it does the job. Is the top of the damper rod threaded, and is that how I use to tool to hold it while I undo the allen key? Or is there something I'm missing?
Also, the measurement for the nut you show relates to an M16 nut?
Cheers
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The nut on the end of the tool becomes a male locking device on the top of the damper rod. The damper rod has a female end same shape as the 16mm nut. Just poke the tool down the fork tube, turn it until it locks in place and then start undoing the allen key bolt while holding the tool to stop the damper rod turning.
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cool, thought that might be the case (after I tacked the nut in place on the inside!!!) luckily I made it slightly longer so I'll just cut him off and start again.
Cheers
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Sorry, just re-read your last post (properly this time). I was thinking there was a thread on top of the damper rod.
The problem is that, looking down the fork tube (with a light) I can't see a female hex that the tool is supposed to lock into. Is there something else under the spring that I was supposed to fish out first?
thanks again.
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Are you sure they are YZ125F forks?
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I'm 99% sure, they certainly look like the ones in the parts diagrams and the brochure copy I've seen. Looking at the exploded view of the parts diagram there seems to be a component called a sub-spring which sits above the rod and below the main spring. The diagram is a bit blurry but I think that's what I see as I look down the fork tube. When I pull the upper and lower legs apart (excuse the pun) there does seem to be a spring type tension there.
If I could figure out how to post the pic I would. The Yamaha America parts website has the pic http://www.yamaha-motor.com/sport/parts/home.aspx
What do you think?
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The small topping out spring should be under the top of the damper rod. once you have taken the long spring out of the forks all you should see down them is the top of the damper rod. ??
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Stopped in at the Yamaha dealer on the way home yesterday, and asked the helpful guy at the parts counter what they used. Would you believe a freakin' broomstick!! He said just jam it in there and hold it tight while you undo the bolt.
Got home last night, grabbed my handy broken broomstick (which now has 1001 uses) pushed the fork upside down onto it and leant on it a bit and the bolt came out with absolutely zero effort!!
So there you have it, a magic broomstick.
Thanks for your help though DJRacing, it's been much appreciated.
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modify your made up tool for reassembly, you dont want to get any timber contamination in the forks when you put it back together.
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So has anyone worked out if this jigger fits the 43mm forks yet - or am I going to be the guinea pig ???
I know the length is way more for the 250H - like nearly 800 mm
24mm or not 24 mm that is the question ::)
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Try a Holden bottle jack handle ......nice and long and easily modified ;)
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Had a quick squiz at the Yamaha parts catalog for your forks, and they do seem to have a spindle on top of the damper rod similar to mine. Have you given the Magic Broomhandle Fork Tool (tm) a go yet?
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Yeah,
I had a look at those too. Unfortunately Mr Yamaha keeps changing the part number. I have a selection of nuts from work on had. I will start with 24mm and see what happens. Just a tack weld should do it initially until I'm sure of the size. I will let you know how i get on.
Cheers
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For those with 43mm forks YZ250H style the nut on the bottom is 30mm not 24mm.
Hope this helps someone else. Made up the tool yesterday - worked like a charm. Thanks DJ. A great tip. ;)
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YZ250H, no problem, sorry I never got to try my one out on a set of 43mm forks, but I havnt had to rebuild any lately and I have been busy with other bikes but I'm glad you liked the tool. I should post up a clutch basket holder for you to copy. Have you got an old set of vice grips?? They make great adjustable clutch basket holders, a couple of bits of steel welded on in the right place and bobs your uncle, a tool for all clutches. ;D
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I have a few different size forks.
So I use a 3/8" T-Bar and a long extension.
The 19mm is a standard Dowidat socket.
The 24mm bolt was welded to a 15mm socket.
But now I have a press I prefer to force the bolt and socket together like with the
22mm bolt pressed into the 13mm socket and the
30mm bolt pressed into the 19mm socket.
(http://www.spitfire.com.au/~mboddy/fork_tools.jpg)
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Very Clever idea.
we should start a seperate thread in Resto Tips with all the special tools (complete with tips) we have made to do things over the years.