BaGearA Posted November 12, 2016 Posted November 12, 2016 Long story short , rebuilt a fork and found a leak into the steerer ( suspect cross threading of topcap ) its a carbon steerer so only way out its through the top ( already tested with water , that is indeed where the leak is) so I want to try to pour some type of sealent/epoxy/ foam down the steerer to seal it. I just need ideas on what to use that will handle pressures upwards of 12 bar. I'm going to to put the fork in a saker as I pour it in to avoid air bubbles as far as I go. *************** I HAVE CONSENT FROM THE PERSON TO TRY DO IT Any help greatly appreciated , this fork is in way to good condition to throw away.
JXV Posted November 12, 2016 Posted November 12, 2016 pics....to understand better. Why not fix the problem at source....i.e. the cross threaded bit Sent from my SM-G935F using Tapatalk
BaGearA Posted November 12, 2016 Author Posted November 12, 2016 Will post a few shortly The reason I think trying to do a repair on the threads won't work is once you screw in the topcap again it will probably just chip/cut away at any bondwork I have done there , I had to feel for the whole with a tiny screwdriver ....its so small i can't get detailed photos of it **There is absolutely no air leaking out form the topcap or valve which is why I also think its better to attack it form the way that the air is leaking
bikebloke Posted November 12, 2016 Posted November 12, 2016 liquid epoxy or some similar seems like a great solution to me also I think you on the right track possibly a liquid resin with a hardener ? fibre glass resin maybe but that maybe too brittle ?
DJR Posted November 12, 2016 Posted November 12, 2016 I know nothing about fork repairs, but I work with bonding epoxies / plastics / acrylics / ceramics and metals all day long. I don't think any filler foam will be strong and solid enough. I would go the epoxy route. So, consider my advice as very general: 1. You have to make sure you get the surface you want to bond the epoxy to ABSOLUTELY clean of ALL residues and of especially anything OILY. That means degreaser, several times, rinse and again. Then clean it again with something like 90% alcohol to get rid of the degreaser. 2. You have to get it absolutely DRY. Extensively blow compressed air, maybe even leave it in a hot place for a few hours. 3. Get the right epoxy for the application. They are NOT all equal. You will have to ask someone else advice on this, because the things I work with will not be good for your application. The strongest thing I've ever come across is Epidermix 372, it is meant for gluing together concrete and boats. But I think it may not be flowable enough to get it down the steerer tube as it it quite stiff. 4. Using a vibrator to pour the epoxy is a great idea. Do the same when mixing the epoxy. Vibrate the living daylights out of it before you pour it to get as many of the air bubbles out as possible. Use a flat spatula to mix it with and make a "plastering" movement (like spreading butter) in stead of a "stirring" movement. That will incorporate less air into the epoxy. 5. Make sure of the working time once you start mixing, it will be influenced by temperature. If you can, slow it down by doing it in a cold air conditioned room. Be careful of cooling the fork and the epoxy too much (like in a fridge) because then it will attract water condensation while you are working and that is not good. So, cold dry air conditioned room will give you more time to work. 6. Pouring down a long narrow tube is tricky because you tend to catch air bubbles in the deepest corners. You can prevent this by putting a long straw down the tube and pouring down next to it. Air can then escape up the straw. Remove straw carefully afterwards and shake some more. Good luck and let us know what the outcome is!
BaGearA Posted November 12, 2016 Author Posted November 12, 2016 I think that you might need new sealsI found the leak after a complete overhaul , every o-ring /washer /dustwipe/ and all oil was replaced. When submerged the bubbles ONLY come out of the steerer , so seals are not the problem. liquid epoxy or some similar seems like a great solution to me also I think you on the right track possibly a liquid resin with a hardener ? fibre glass resin maybe but that maybe too brittle ?I have some industrial clear coat and hardener with me form a earlier project , I'm just not sure if it will take the pressure. Hoping to find some kind of sealent or foam and then throw the clear coat on top of that for some insurance. Anyone thing the cleat coat will be strong enough on its own?
BaGearA Posted November 12, 2016 Author Posted November 12, 2016 I know nothing about fork repairs, but I work with bonding epoxies / plastics / acrylics / ceramics and metals all day long. I don't think any filler foam will be strong and solid enough. So, consider my advice as very general: 1. You have to make sure you get the surface you want to bond the epoxy to ABSOLUTELY clean of ALL residues and of especially anything OILY. That means degreaser, several times, rinse and again. Then clean it again with something like 90% alcohol to get rid of the degreaser. 2. You have to get it absolutely DRY. Extensively blow compressed air, maybe even leave it in a hot place for a few hours. 3. Get the right epoxy for the application. They are NOT all equal. You will have to ask someone else advice on this, because the things I work with will not be good for your application. The strongest thing I've ever come across is Epidermix 372, it is meant for gluing together concrete and boats. But I think it may not be flowable enough to get it down the steerer tube as it it quite stiff. 4. Using a vibrator to pour the epoxy is a great idea. Do the same when mixing the epoxy. Vibrate the living daylights out of it before you pour it to get as many of the air bubbles out as possible. Use a flat spatula to mix it with and make a "plastering" movement (like spreading butter) in stead of a "stirring" movement. That will incorporate less air into the epoxy. 5. Make sure of the working time once you start mixing, it will be influenced by temperature. If you can, slow it down by doing it in a cold air conditioned room. Be careful of cooling the fork and the epoxy too much (like in a fridge) because then it will attract water condensation while you are working and that is not good. So, cold dry air conditioned room will give you more time to work. 6. Pouring down a long narrow tube is tricky because you tend to catch air bubbles in the deepest corners. You can prevent this by putting a long straw down the tube and pouring down next to it. Air can then escape up the straw. Remove straw carefully afterwards and shake some more. Good luck and let us know what the outcome is! Cool , this sounds like the best solution so far
PeterF Posted November 12, 2016 Posted November 12, 2016 Can't you get the epoxy in from the bottom of the steerer tube?
JA-Q001 Posted November 12, 2016 Posted November 12, 2016 Ok wait before epoxy-ing anything. Is the air from the air chamber leaking, is there a physical air loss that you notice over time? If yes, then epoxy anywhere will not help. The metal tube creates a sealed unit. The no seal is created on the carbon. The only way to stop the air leak is by fixing the seals. The fact that water seeps through from the steerer to the stanction means that their is a crack in the carbon, than may get worse or may do nothing.
Formallyknownas Posted November 12, 2016 Posted November 12, 2016 Laaitie, I'm impressed. Good luck with the repair dude. Keep the people posted with your progression. Kekeke.
BaGearA Posted November 12, 2016 Author Posted November 12, 2016 Can't you get the epoxy in from the bottom of the steerer tube?Its a carbon crown so no hole at the bottom
BaGearA Posted November 12, 2016 Author Posted November 12, 2016 Ok wait before epoxy-ing anything. Is the air from the air chamber leaking, is there a physical air loss that you notice over time? If yes, then epoxy anywhere will not help. The metal tube creates a sealed unit. The no seal is created on the carbon. The only way to stop the air leak is by fixing the seals. The fact that water seeps through from the steerer to the stanction means that their is a crack in the carbon, than may get worse or may do nothing.no leaks anywhere on the air chambers , and as i said it has brand new seals EVERYWHERE.
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