30-12-10, 08:17 PM
(This post was last modified: 07-01-11, 08:52 PM by John Silva.)
Originally posted by limax2 on 20/10/2009
As you point out removing the damper tube screw can sometimes (often!) be frustrating, not aided by loctite being used on assembly. The official Yam tool for the job is a steel spike thing which seems a bit crude. What follows are details of a simple tool I have made that making this part of the job very easy. It can also be used to hold the damper tube when assembling and tightening the screw, as it is easily removed when done.
[smg id=48[/img]
These are the bits of the tool.
[smg id=49[/img]
This is the tool ready for use.
It is inserted down the fork leg so the slotted end, left in picture, slides into the damper tube. The small nut near the right hand end is then tightened to expand the slotted end and grip the damper tube. The right hand end in the picture is still sticking out of the fork leg and can be gripped in a vice or mole grips and the offending screw undone with great satisfaction and no cursing.
You then back off the small nut and a light tap on the end of the rod (domed nut in picture) releases the grip.
[smg id=50[/img]
Tool in damper tube.
If you fancy making one here are some details. All shown in millimetres. The only fairly important dimension is the 18.40 diameter that goes into the damper tube, which has a bore of 18.50 diameter. All the rest can be altered to suit the material available.
[smg id=51[/img]
This is the gripping end showing the tapered bit that does the expanding of the slotted tube. The threaded rod is M8, the type you can get from B&Q etc.
[smg id=52[/img]
[smg id=53[/img]
This was made from some tube I had which I think might have been electrical conduit at some time, not sure.
This tube needs to be at least 500mm long so that it protrudes out of the stanchion when inserted into the damper tube. I have welded a large nut on the right hand end, but it's not necessary as a vice or mole grips on the end will do fine.
Of course if you live within striking distance of Chorley in Lancashire you won't need to make one because you can borrow mine.
I made the expander wedge from a piece of mild steel bar, but aluminium etc. or even hard wood would probably do. Instead of threading it it could be fastened to the screwed rod with a nut at the back. The flats on it are not necessary; I just put them there for holding whilst tightening the lock-nut. All very easy on a lathe, but a bit more difficult without one. If you want an expander wedge as per the drawing let me know and I'll send you one, post man permitting!
A couple of thing I forgot to mention.
1) In use don't tighten the top nut too tight because the shallow taper exerts a very strong outward gripping force on the damper tube.
2) The small 1.5mm dia hole at the top end of the damper tube sometimes has a burr on the inside, so best to check that it doesn't end up partly blocking the hole.
As you point out removing the damper tube screw can sometimes (often!) be frustrating, not aided by loctite being used on assembly. The official Yam tool for the job is a steel spike thing which seems a bit crude. What follows are details of a simple tool I have made that making this part of the job very easy. It can also be used to hold the damper tube when assembling and tightening the screw, as it is easily removed when done.
[smg id=48[/img]
These are the bits of the tool.
[smg id=49[/img]
This is the tool ready for use.
It is inserted down the fork leg so the slotted end, left in picture, slides into the damper tube. The small nut near the right hand end is then tightened to expand the slotted end and grip the damper tube. The right hand end in the picture is still sticking out of the fork leg and can be gripped in a vice or mole grips and the offending screw undone with great satisfaction and no cursing.
You then back off the small nut and a light tap on the end of the rod (domed nut in picture) releases the grip.
[smg id=50[/img]
Tool in damper tube.
If you fancy making one here are some details. All shown in millimetres. The only fairly important dimension is the 18.40 diameter that goes into the damper tube, which has a bore of 18.50 diameter. All the rest can be altered to suit the material available.
[smg id=51[/img]
This is the gripping end showing the tapered bit that does the expanding of the slotted tube. The threaded rod is M8, the type you can get from B&Q etc.
[smg id=52[/img]
[smg id=53[/img]
This was made from some tube I had which I think might have been electrical conduit at some time, not sure.
This tube needs to be at least 500mm long so that it protrudes out of the stanchion when inserted into the damper tube. I have welded a large nut on the right hand end, but it's not necessary as a vice or mole grips on the end will do fine.
Of course if you live within striking distance of Chorley in Lancashire you won't need to make one because you can borrow mine.
I made the expander wedge from a piece of mild steel bar, but aluminium etc. or even hard wood would probably do. Instead of threading it it could be fastened to the screwed rod with a nut at the back. The flats on it are not necessary; I just put them there for holding whilst tightening the lock-nut. All very easy on a lathe, but a bit more difficult without one. If you want an expander wedge as per the drawing let me know and I'll send you one, post man permitting!
A couple of thing I forgot to mention.
1) In use don't tighten the top nut too tight because the shallow taper exerts a very strong outward gripping force on the damper tube.
2) The small 1.5mm dia hole at the top end of the damper tube sometimes has a burr on the inside, so best to check that it doesn't end up partly blocking the hole.
Biking is about the Journey NOT the Destination...