Thumper Club Forum
Technical => Bike Problems/Questions => Topic started by: xbally on August 28, 2025, 06:47:29 PM
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Not on one of my thumpers, but on my GPZ500S.
I'm rebuilding a fork leg after replacement of a leaking seal without the special tool which stops the damper rod turning as you tighten up the allen bolt on the underside of the fork leg through the stanchion.
I can't get the bolt d in how much I try.
Any tips please?
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I have never done a Kawasaki, but I looked on the exploded view on Fowlers website. This looks remarkably like the Yamaha SRX forks. I'm sure there are detail differences! I had to make a tool to hold the damper rod, I think it's about 22mm A/F on the end of a longish piece of bar(without looking and measuring it!). Is this a similar size for yours? If so you are welcome to borrow it. (I'm in Telford). They are a bit of if faff to rebuild even with the correct tool. Failing that there's always YouTube, which seems to be the "go-to place" now.
Ian 👍
i=vS_7Q8-70Mg4vZIK
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Morning, just a quick word afore going for a canter! ::)
The SRX twin shock and Monoshock use the same method of holding the damper tube, using a large hex head on the end of a rod, with a "T" handle.
The hex sizes are different, so you cannot use the twin shock on the monoshock damper rods. I haven't looked at the Fowlers website to see if the hex head size for the GPZ500 is quoted. I am happy to post dimensions for the two tools that I have, both home made, using large HT bolts, welded onto lengths of bar, with a "T" handle.
Toodle loo, Bill
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Thank you.
Yes mine's the same as the Youtube video.
Here are pics of what I've been trying to use todate.
The problem is the damper road part I'm trying to hold is round.
I've tried hammering the socket in the photos into the damper road with my soft faced mallet but I still can't get the allen screw started on the bottom of the damper rod through the hole in the fork leg bottom.
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more pics
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and again
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Have you tried using a piece of tapered hardwood (whittled down to the appropriate size)instead of your socket. I have managed to get away using this method before now. 🙄
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Thanks again Ian, and for the offer of the tool-I'm unsure whether it would be suitable but would be more than happy to have a ride or drive over as it's not far and a nice run.
The deep socket I tried to use was only a 10mm.
I've heard the "shoving a broom handle down the stanchion dodge" but never tried wood, although I may have a go.
When I used to work on Kawasaki triples a friend gave me 2 long bolts with a cut off nut welded together but I don't think I ever used it and it was probably lost in a house move along with a few of my other tools and bits and bobs.
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Come to think of it, now it’s been mentioned. The broom handle was the dodge I used years ago when I put some new Hagon springs into my xbr cafe racer. Best of luck Martin.
It seems the the word “suspension” is the curse of your life at the moment 🙄
Cheers… Michael
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Come to think of it, now it’s been mentioned. The broom handle was the dodge I used years ago when I put some new Hagon springs into my xbr cafe racer. Best of luck Martin.
It seems the the word “suspension” is the curse of your life at the moment 🙄
Cheers… Michael
Thanks for that Michael.... :(
Looks as though I'll be keeping you all in suspense for some time................
Hopefully NOT though.
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Coming to this a bit late (and I know nothing about these forks) but the inner diameter part shown in your first photo looks as if it's parting company with the outer. This may be how it's made.....
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I think that's just how it appears in the photo Ian.
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Just a thought re hexagon - I'm assuming that it's an internal hexagon like an allen screw. My local steel supplier does a range of stainless and mild steel hexagons and it may be worth buying a length of that if you know the dimensions.
https://www.rapidmetals.co.uk/product/en1a-230m07-hexagon-13mm/
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https://www.rapidmetals.co.uk/product/en1a-230m07-hexagon-13mm/
Handy link Ian, thanks for posting. Not I need any hex bar at the moment, but who knows I may in the near future 👍
Cheers …Michael
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Come to think of it, now it’s been mentioned. The broom handle was the dodge I used years ago when I put some new Hagon springs into my xbr cafe racer. Best of luck Martin.
It seems the the word “suspension” is the curse of your life at the moment 🙄
Cheers… Michael
Broom handle ya say? That wooden work. Shirley.
😁😁😁
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Thanks...but unfortunately the inner surface of the upper part of the damper rod is circular not hex shaped-hence my problem.
I've just shoved a broom handle up into it but first attempts to wind in the allen bolt from the bottom of the fork leg have failed.........
I'm beginning to wonder if I'm missing something here...
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I've just shoved a broom handle up into it
Ooo err…….more tea vicar 😜
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Hi Martin. I assume the screw goes into the female thread just loose on the bench? Just to prove the threads are ok?
It's a long while since I've stripped a fork leg down , but I'm pretty sure I've only ever used a broom handle or similar. I ran a gpz500 for several years but the fork seals never gave issue. Last bike I stripped the fork leg would have been an fzr 1000. I remember it being straightforward but can't recall exactly what I did...
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Hi Andrew.
Yes there's nothing wrong with the threads. They run easily into each other on the bench before trying to re-assemble the forks.
I'm no fork expert. I usually get my mate to do any work like this but I thought I would give it a try as I have more time on my hands.
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Aye Martin,
As you have the the damper rod dismantled out of the fork slider, not still stuck inside the fork slider, now is the time to modify the damper rod.
I would find the point of maximum diameter of the cupped end of the damper rod, measure 1.5mm or 2mm either side and cut a slot using a hacksaw to the 3mm or 4mm width, as per the attached image.
I do not know what the OD of the cup is, but I would then get some steel tubing of a diameter similar to the cup and sufficient length, so that you can grip it, whilst the damper rod is at the bottom of the stanchion. Manufacture a twin pronged key from the tube, to fit in the slot in the cup that you have cut. You could also use a robust, long shanked, wide bladed screwdriver, if you have one?
Suzuki and Marzocchi use this slotted method for retaining the damper rod, rather than hex internal machining of the damper rod cup, as used in the Yamaha forks. I manufactured a key from gas pipe, so that I could dismantle a pair of Hyabusa forks, to renew the seals and bushes.
I have used the broom handle method, but have always found it "iccky" at best, and just bl**dy infruriating in most cases and I have modified them accordingly.
Don't forget a wee dot of nut lock on the hex cap scew when assembling, along with an annealed copper washer beneath it's head, if fitted, as they are on Marzocchi forks.
Hope this helps.
This link to a special tool site may also prove useful to all Thumpeteers:Bikers_tool_box_special_tools (https://www.bikerstoolbox.co.uk/)
Within the above linked site, there is a selection of tools specifically designed to hold Kawazaki's offending damper rods that you may prefer to purchase, rather than my home work around: Bikers_tool_box_Suspension_tools (https://www.bikerstoolbox.co.uk/collections/chassis-suspension)
Good health, Bill
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Hi Andrew.
Yes there's nothing wrong with the threads. They run easily into each other on the bench before trying to re-assemble the forks.
I'm no fork expert. I usually get my mate to do any work like this but I thought I would give it a try as I have more time on my hands.
Is the problem you're having to do with the damper tube spinning when you try to screw the allen bolt in, or one of locating the respective components?
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Thanks for the further inputs Bill and Andrew.
That's certainly a good selection of tools including how to make your own :)
Food for thought...........
Andrew as far as I can see the difficulty I've got is twofold : yes the damper rod seems to be spinning AND I seem to have a problem aligning the damper rod and the allen screw.
I'm grateful to Bill for his comments on how tricky this is without the right tools-as my confidence in the workshop (never much) has taken a bit of a bashing with my poor efforts to resolve it.
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Thanks for the further inputs Bill and Andrew.
That's certainly a good selection of tools including how to make your own :)
Food for thought...........
Andrew as far as I can see the difficulty I've got is twofold : yes the damper rod seems to be spinning AND I seem to have a problem aligning the damper rod and the allen screw.
I'm grateful to Bill for his comments on how tricky this is without the right tools-as my confidence in the workshop (never much) has taken a bit of a bashing with my poor efforts to resolve it.
Is the Allen bolt a metric course or fine thread?
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They're a great supplier, no minimum order - in fact I'm sometimes a bit embarrassed to pick up a couple of quid's worth - and just round the corener for me so no delivery charges.
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I've no more experience of fork leg strip down than your average home mechanic, so I'm thinking of ways I might approach the issue.
How about putting a length of threaded bar into the thread then assembling the fork, including spring. Remove the threaded bar and see if the pressure of the fork spring force is enough to allow the Allen bolt to tighten up without spinning.
Even if it doesn't quite work, at least the bar is a way of ensuring everything is located, while you wedge in the wooden pole.
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Morning Martin,
As Marvin Gaye and Tammy Terrell said, "It takes two, baby, it takes two, to make a dream come true." ;)
Well, it might do in your case Martin. If you cannot rigidly hold the damper rod, you will always be chasing the threaded lower end around the larger bore of the fork slider. An extra pair of hands can be very useful. ;) In my experience a standard/coarse metric thread, or a 1.25mm pitch thread, is used for the bolt holding the damper rod to the fork slider, not the fine metric thread, with a 1mm pitch thread. This may vary from manufacturer to manufacturer, annoyingly Fowlers don't show the size or thread of the cap screw in their parts diagram of the assembly, or the material of the sealing washer beneath the cap screw head. If it is aluminium alloy, I would replace it with an annealed copper washer. Fowlers have no replacement washers in stock and want £3-86 + P&P for one! :o
I use a Black & Decker "Workmate", to hold the fork stanchion upright, with the damper rod assembled, oiled, with whatever fork oil/ATF you intend to use (I prefer ATF, as it has a known viscosity, non of the oil weight marketing smoke screen), now is the time to secure the damper rod, with whatever tool you are using and ensure that the threaded end is centralised. Now slide the assembled fork slider, again well lubricated, up the fork stanchion and align the bolt, with its annealed copper/fibre washer, wee dab of nut lock, with the thread in the damper rod, with a wee wiggle and I turn the cap screw in the reverse direction, so that you can feel that it is centralised in the threaded hole of the damper rod, before turning it to tighten. It should be finger tight and I then tighten it up using 9Nm of torque. The cap screw needs to be nipped up, but not have its neck wrung!
Propellor's threaded rod wheeze, is a good idea, to get everything centralised, before removing the rod and threading in the cap screw.
I assume that you have already got this far and you now need to reverse the process in this video?: Kawasaki_GPZ/EX_500_front_forks_strip_down (https://www.youtube.com/watch?v=djjk_4MgMCE)
"If some bu**er put it together, then I can take it apart and re-assemble it too!" ;)
Good health, Bill
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Thank you again Andrew and Bill................
At least this tread is proving to be of a little interest.
I'll take on board all comments and delve further into this.
As I may have said already I have a spare set of forks and robbed the appropriate one and fitted it to the bike after first having re-sprayed the lower so the one I'm working on although the original fitted to the bike will now become my spare.
I'm intending to use the GPZ as my winter transport as the half fairing keeps off some of the windblast.
This was my winter rebuild project from 2023 /2024 which i bought in pieces so was quite a challenge for me to put it all back together with quite a bit of help and advice .
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Well something strange is going on here! 🤔
Following up on the advice kindly proferred on here, this morning I tried threading a long piece of threaded bar of the appropriate diameter and it wound easily into the bottom of the damper rod.
I then lined up the broom handle down the stanchion to stop it turning and all was well.
But when I removed the threaded bar and tried using the Allen screw it wasn't long enough to go into the bottom of the damper rod.
This could be because I haven't yet driven in the bush or fork seal which presumably will then allow the whole gubbins to drop further into the leg?
Just really seeking views of people who are more knowledgeable than me before I do anything further!
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Well something strange is going on here! 🤔
Following up on the advice kindly proferred on here, this morning I tried threading a long piece of threaded bar of the appropriate diameter and it wound easily into the bottom of the damper rod.
I then lined up the broom handle down the stanchion to stop it turning and all was well.
But when I removed the threaded bar and tried using the Allen screw it wasn't long enough to go into the bottom of the damper rod.
This could be because I haven't yet driven in the bush or fork seal which presumably will then allow the whole gubbins to drop further into the leg?
Just really seeking views of people who are more knowledgeable than me before I do anything further!
No specific knowledge of the gpz500 forks, but I think there might be a recess in the bottom of the fork leg, for the end of the damper rod to sit. I wonder if it's not locating?
I assume this same allen bolt is the one that came out initially?
Don't suppose you have a wrecked old fork leg. Could cut a section out to reveal the internal shape.
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Yes the same allen bolt.
No I don't have a wrecked fork leg-only a good spare pair.
Looking further into this Andrew .I've posted on the US version of the GPZ forum where a lot of UK owners have migrated but no specific answers yet-only reference is to the Yamaha damper rod holding tool.
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If there's a second fork leg still not disassembled maybe you could take a measurement down to the top of the damper rod? It'd need to be a careful measurement. See if the damper rod on the disassembled unit is sat up a bit.
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If there's a second fork leg still not disassembled maybe you could take a measurement down to the top of the damper rod? It'd need to be a careful measurement. See if the damper rod on the disassembled unit is sat up a bit.
Yes, good idea.
These type of Kawasaki forks are a pain to remove the fork caps from. They are retained by a stupid circlip which you have to push the cap down to gain clearance to then fiddle about with to remove the circlip from its groove. This can be troublesome when the forks are off the bike.
Don't ask me how i know you can get smacked in the face by the cap as it flies up under spring pressure.
The best way I've seen is to screw in a puller to release the circlip and then you can safely take off the cap. Trouble is: I don't have a puller and am unsure which size would fit so I use a 3/8 extension bar........
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If there's a second fork leg still not disassembled maybe you could take a measurement down to the top of the damper rod? It'd need to be a careful measurement. See if the damper rod on the disassembled unit is sat up a bit.
Yes, good idea.
These type of Kawasaki forks are a pain to remove the fork caps from. They are retained by a stupid circlip which you have to push the cap down to gain clearance to then fiddle about with to remove the circlip from its groove. This can be troublesome when the forks are off the bike.
Don't ask me how i know you can get smacked in the face by the cap as it flies up under spring pressure.
The best way I've seen is to screw in a puller to release the circlip and then you can safely take off the cap. Trouble is: I don't have a puller and am unsure which size would fit so I use a 3/8 extension bar........
Just think, you'll be an expert on gpz500 forks after all this.
X being the unknown quantity. Spurt being a drip under pressure. 😂😂
(no offence, it's a joke I frequently level at myself) 😁👍
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None taken....As they say in certain circles a GSOH is a very necessary survival tool. It's so easy to offend people these days when that most definitely was NOT your intention. :'(
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Evening Martin. Just wondered if you’d managed to sort out your fork damper issue?
Not that I can shed any light on it but just wondered if you’d Managed get it all sorted
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Hello Michael.
The short answer is no.
There's no urgency as I put one of my spare fork legs on the bike so I can use it.
This particular bike is currently on SORN but I do intend to use it from October and over the winter.
Like you (I think) no luck with my RS250 sale.
To create room for my next project I really need to sell the Rs or the GPZ. Both have now been on eBay twice with no interest whatsoever.
I've been side tracked this week and last in searching out a cheap(if only to buy)new winter project.
I went to see a 250 Super dream but with a 400 engine which needs loads of parts and work. I made a low offer which was rejected so I then found a Honda CB1 400 which was allegedly complete but partially stripped so again I made an offer and guess what the eBay seller hasn't responded.
Sorry for the diatribe but I think this puts my in some sort of perspective.
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Hello Michael.
Like you (I think) no luck with my RS250 sale.
To create room for my next project I really need to sell the Rs or the GPZ. Both have now been on eBay twice with no interest whatsoever.
I then found a Honda CB1 400 which was allegedly complete but partially stripped
Evening Martin. I didn’t get one single enquiry about the RS, and like you I could ideally do with selling it, mainly so I can inject the money into the RS250 tracker winter project really.
A CB1 400 … we have a good mate who has three, two built up and one in pieces (I think🤔 ) He’s built an absolute cracking cafe racer out of one of them. Unfortunately I don’t know how to post pictures up🤦???
Best of luck with finding something 🤞
Cheers, Michael
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Aye Michael, email me an image and I'll try my best! ;)
Bill
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Testing
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Testing
Success. That's a photo of the cafe racer in question with Chris, it's owner and maker, along with Rob (Bill has met) and his Triumph speed 400 also Mick's Triumph street twin.
It's a long time since I've posted photos on here. It's dead simple as long as the file size is right. The best way (as suggested I believe by Iansoady) is to get Photo Editor app and re size it.
Edit: Chris's 400 four sounds absolutely epic through the two open , ahem, silencers.
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Thanks.
The background scenery is even more impressive than the bikes...👍
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Thanks.
The background scenery is even more impressive than the bikes...👍
That's our riding life these days Martin and I'm loving it.
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That's our riding life these days Martin and I'm loving it.
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It's very dramatic Andrew compared to the lovely Worcestershire countryside where I mostly ride these days.
And Michael, my experience of the used bike market recently is that it's very flat which isn't surprising given the poor attitude of most dealers I've come into contact with.
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I find the Worcestershire countryside pretty dramatic but mainly because of the kamikaze drivers......
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I find the Worcestershire countryside pretty dramatic but mainly because of the kamikaze drivers......
I think they're pretty much everywhere now Ian but definitely tend to be worse in urban areas in my experience.
Thankfully I no longer commute when they are at their worse.
I've just returned from a ride on my Interceptor 650 around the Severn Valley and surrounds. No idiots on the road that I travelled on this morning fortunately. :)
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I think they're pretty much everywhere now
Thankfully I no longer commute when they are at their worse.
[/quote]
Now there’s a subject that I’m sure would get plenty of posts up in the “RANT” section.
Idiot, kamikaze drivers
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I seem to have hijacked my own thread...!
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I seem to have hijacked my own thread...!
🤣🤣……..just so long as it makes for interesting or amusing reading Martin. Who cares 👍
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Well ok.
The CB1 400 project didn't get off the ground unfortunately. It seems my offer wasn't enough although communication with the seller wasn't responded to.
I'm going to keep looking.
My Rs250 has another few days to run but I think I may end up keeping it.
I might try to sell the GPZ500 again although previous efforts so far have failed to attract any interest.
I've never known the used bike market to be so dead.
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The time of year certainly doesn’t help either Martin. Now that most people have a “biking season” which usually runs from April until September.
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Not me.
I've been riding mostly throughout the year but have to admit fortunately it's not through choice since the late 1970s.
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Nor me/us. That was ultimately why I bought the RS from Kevin. I fully intend to use it as a winter ride.
That is unless it sells first, which i doubt it will. If it does, the money will immediately go into building the other RS, ready for NEXT winter 😁👍