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Twine seal at tele fork slider/oilseal holder

Posted: Tue Feb 12, 2013 1:35 pm
by Roderick.Bradley
Anyone know the size of twine used as a seal at the junction of the oil seal holder and the front fork slider.

It is not specified in any workshop mauals that I've got which is more than a few. I did come across it 0nce reading a Sqaure 4 Manual for sale at an Autojumble but I didn't buy the Manual as I don't have a Sq.4. I think No. 3 was specified but it could have been No.2. Looking at a used, original example from the bike I am working on, I think it's got to be sisal rather than cotton.

I have often found it difficult to seal this particular joint. There is no substitute that I know of for the correct twine & gasket goo. I've tried plumber's tape on the threads but not bery sucessfully.

Posted: Tue Feb 12, 2013 1:55 pm
by pete.collings
I have just used silicone rubber to seal the joint, but allowed it to set before screwing the oil seal holder down into position, so that there is a solid but flexible seal at the junction of the slider and seal holder. Any excess that is squeezed out can be simply rubbed away.

Posted: Tue Feb 12, 2013 7:13 pm
by keith.hodgenia
Cammy Velo's use this method to seal the cam drive tube. perhaps you could try Grove Services. Keith.

Re: Twine seal at tele fork slider/oilseal holder

Posted: Wed Feb 13, 2013 12:20 am
by Richard Kal
I used to use twine, but now find (plumbers) teflon tape easier to install, and very effective.

Posted: Wed Feb 13, 2013 1:39 am
by nevhunter
I use cotton wrapped in the correct direction. Slightly thicker than normal is the go. It is also common to have a single strand in the silastic when putting crankcase halves together. Nev

Re: Twine seal at tele fork slider/oilseal holder

Posted: Wed Feb 13, 2013 11:38 am
by malcolm.johnson
PTFE tape is good, using a lot more than you might expect, wound in the direction of tightening on both threads and the recess below. Even better is to twist the PTFE tape into a thick "twine" and use this as you would ordinary twine, but also smear the threads generously with a putty like substance called "Plumbers Mate" (ordiary putty would work just as well, but it does set, whereas "Plumbers Mate" does not). It is used when installing bath and sink wastes etc to make the threads water tight. Make yourself a proper oil seal holder tool from a piece of scaffold tube, ground to leave 2 tongues and drilled to take a tommy bar at a suitable length away. Once tightened cut excess tape and/or wipe excess putty away. Malcolm.

Posted: Wed Feb 13, 2013 7:19 pm
by Danny.Lee
when I was a gas fitter in the late 60's we used hemp pulled off a hank, like loose hair rather than string. Used with common plumbers jointing compound it worked well on tapered(BSP) threads holding water, but was less successfull on parallel threads, they usually needed a flange or locknut to close onto.

The bathroom waste is not a good model, uses parallel threads but holds no real pressure in use.

The fork leg threads are parallel and fine thread. I would now use PTFE wound clockwise to tighten with the seal holder, but as the threads are so fine I would only use maybe three turns, if you over do it you could end up cross threaded.Put a thin smear of silicone over the tape that will fix just about anything unless the thread is distorted.

a good home made tool is well worth having, the actual tool is available from Drags for about twenty quid plus the usual. If you dont have one you end up with pipe gripper marks on the seal holder ( like mine) and also run the risk of a distorted fork leg also like mine....I should send this note to the previous owner..

Posted: Wed Feb 13, 2013 7:50 pm
by nevhunter
My view is the threads are fine and NOT tapered so fitting tape between them is not a good principle. There is a relief above the top thread where there is room for cotton to be wound so the whole thing doesn't require a lot of tightening. This only happens in the last few turns unless there is too much cotton there, so no need for stillsons etc or gripping things in a vice. Nev

Posted: Wed Feb 13, 2013 11:17 pm
by marcus whatling
Hi Rod just put some forks back together, 49 KH500 same forks, Used PTFE tape they haven't leaked yet !

Posted: Tue Feb 19, 2013 12:53 am
by stu.sharratt
Just stripped my forks today & was wondering if the piece of hemp / jute twine was meant to be there until I saw this thread.
On the subject of seal holder removal tools, I made a nice one out of a section of scrap 41mm fork stancion I had lying around, for speed I then ran two short beads of weld down opposite sides & used stilsons working against the weld for extra purchase. They were f tight !
Moral of the story is never throw away bits of tubing , there can be a silver lining to a wrecked front end !