Red crank loose pedal insert repair (DIY) step by step
Moderator: robbosmans
- josemari220
- Posts: 12
- Joined: Sat Nov 05, 2011 9:52 pm
Hello everybody.
Sadly i am another victim of the carbon crank pedal insert loose. MIne are Sram Red. Not so usual like FSA, but the same consequence. Many post asking for solutions or repairs, but seems that almost nobody do it. Some of them tried to put some glue through holes, but nobody tried to do a real repair, so I have done it. Looking for practice more than do a real repair. This is my first attempt with carbon fiber, so I don´t mind which will be the final results.
So here you have the proccess with some pics to see real step by step.
First is to discover the pedal insert. You can do it easilly with a grinder. I opened a window in the front face.
Then the insert can be taken out to clean the old epoxi and carbon residues.
Because of the unbonded, the insert is a bit loose, so it is necesary to add a thin layer of carbon where it sits to fill the gap. The good thing is that the inside of the arm has a shape where the insert sits perfectly, so is in no possible to vary the position, angle, lenght, etc.
To avoid epoxy goes to the pedal thread, I put thick grease in it, and cover both holes with a rouded piece of adhesive tape, just to cover the hole.
With the insert out, you can see the hollow inside of the arm. Hi-tech.
I designed some pieces with paper, with the shapes of carbon to do the layers. It is necesry to
wrap in differents directions, and it is complicated because the rouded shape of the arm end.
I also cut an small piece of poliuretane foam to fill an smal gap between the insert and the arm. The carbon must to be pressed, and, if is nothing under it, the carbon will fall into the hole and it will be not well compacted.
I have done the work with carbon cloth and epoxi resin bought in ebay.
Epoxy comes in two parts, so it is necessary to mix them in the right percentage.
Apply the carbon pieces and soak with epoxi. It is not easy because they tend to loose the
position when you try to add the next piece in other direction.
When you have put enough layers, it is necessary to give pressure to the carbon-epoxi to force
the excess of epoxy to go out and achieve the carbon ends up very tight and with no air inside. There are some ways. This is a DIY, so i have used a tyre inner tube, opened along the middle. I gives you a wide, flat and elastic, rubber, that wrapping it, gives homogeeous pressure, and works very well.
First you need to wrap with carbon with some porous plastic. I have done with food film, holed with
an small nail.
Then you need to put a layer that absorve the excess of epoxy. A piece of an old trouser do the work fine too.
Stretch and wrap the inner tube trying not to move the added carbon layers. Before give pressure, all is very loose.
This is the final look after wrapping.
Sadly i am another victim of the carbon crank pedal insert loose. MIne are Sram Red. Not so usual like FSA, but the same consequence. Many post asking for solutions or repairs, but seems that almost nobody do it. Some of them tried to put some glue through holes, but nobody tried to do a real repair, so I have done it. Looking for practice more than do a real repair. This is my first attempt with carbon fiber, so I don´t mind which will be the final results.
So here you have the proccess with some pics to see real step by step.
First is to discover the pedal insert. You can do it easilly with a grinder. I opened a window in the front face.
Then the insert can be taken out to clean the old epoxi and carbon residues.
Because of the unbonded, the insert is a bit loose, so it is necesary to add a thin layer of carbon where it sits to fill the gap. The good thing is that the inside of the arm has a shape where the insert sits perfectly, so is in no possible to vary the position, angle, lenght, etc.
To avoid epoxy goes to the pedal thread, I put thick grease in it, and cover both holes with a rouded piece of adhesive tape, just to cover the hole.
With the insert out, you can see the hollow inside of the arm. Hi-tech.
I designed some pieces with paper, with the shapes of carbon to do the layers. It is necesry to
wrap in differents directions, and it is complicated because the rouded shape of the arm end.
I also cut an small piece of poliuretane foam to fill an smal gap between the insert and the arm. The carbon must to be pressed, and, if is nothing under it, the carbon will fall into the hole and it will be not well compacted.
I have done the work with carbon cloth and epoxi resin bought in ebay.
Epoxy comes in two parts, so it is necessary to mix them in the right percentage.
Apply the carbon pieces and soak with epoxi. It is not easy because they tend to loose the
position when you try to add the next piece in other direction.
When you have put enough layers, it is necessary to give pressure to the carbon-epoxi to force
the excess of epoxy to go out and achieve the carbon ends up very tight and with no air inside. There are some ways. This is a DIY, so i have used a tyre inner tube, opened along the middle. I gives you a wide, flat and elastic, rubber, that wrapping it, gives homogeeous pressure, and works very well.
First you need to wrap with carbon with some porous plastic. I have done with food film, holed with
an small nail.
Then you need to put a layer that absorve the excess of epoxy. A piece of an old trouser do the work fine too.
Stretch and wrap the inner tube trying not to move the added carbon layers. Before give pressure, all is very loose.
This is the final look after wrapping.
Last edited by josemari220 on Tue Sep 13, 2016 4:11 pm, edited 2 times in total.
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Of course it is your crank, and your health at risk if a pedal fails, but I would highly recommend against do-it-yourself crank repairs like this unless you are really confident of your experience in stress analysis and carbon fiber repair.
Most commercial carbon fiber bonding is done at high pressure and high temperature.
Surface prep is also critical, and just the tiniest bit of grease on the bonding surface can ruin the whole thing.
Please be careful.
Most commercial carbon fiber bonding is done at high pressure and high temperature.
Surface prep is also critical, and just the tiniest bit of grease on the bonding surface can ruin the whole thing.
Please be careful.
- josemari220
- Posts: 12
- Joined: Sat Nov 05, 2011 9:52 pm
Thanks for your care. I know and i asume the risk. If i thought it could fail in any moment, i will not ride them. There must be pioneers to reach higher summits.
In fact, i think there is more risk to fail before repair, with the insert loose than now.
Time ago, carbon frames were un-repairables, and now lots of them are running. I have seen "professional" repair shops with vacuum or presurized ovens, that finally were a door under stairs with am electric heat radiator in.
This work is for practice and investigation purpose. If it works, perfect. If no, perfect too.
i¨m not encouraging nobody to do this. I only tell you that is possible.
Chapter 2. No possible to add more than 10 pics in 1 post.
The first impressions are fantastic. Very hard and smooth. I let cure one day long. Take off the tube, the cloth and the film is quite easy.
Obviously, it is necessary to sand a little to smooth the surface. The best is there are no big
wrinkles.
I prefer to do the job in some stages, to have more control in the way it is finishing, so, I have to put more layers to give thickness and a better leveled surface.
Finally need to open the pedal hole. A drill in the centre and then with care, and a dremmel, sand the carbon arround the hole where the pedal sits with a washer.
This is the final look.
Rear view
A final epoxy coat to the exposed carbon, to hard protection and give a glosy finish.
I have tested them uphill hard sprinting and they work as new, so, I´m happy. Will see in long therm use.
this is weight weenies, so I have checked them and they are now 7gr heavier. Doing the work with calm, doing the transitions between old and new carbon more progressive, and the finishing will be like new and no weight adds.
I hope somebody will be find all my efforts usefull.
Thanks for watching, and sorry for my low quality English.
Updated info. Today a long ride with steps, sprinting at full power with no issues. the feeling is to ride a like new crankset. Now I´ll take them off , and save them for spare, and ride the new one I bought after notice the problem. they are under warranty, so I have 2 years to stress them.
In fact, i think there is more risk to fail before repair, with the insert loose than now.
Time ago, carbon frames were un-repairables, and now lots of them are running. I have seen "professional" repair shops with vacuum or presurized ovens, that finally were a door under stairs with am electric heat radiator in.
This work is for practice and investigation purpose. If it works, perfect. If no, perfect too.
i¨m not encouraging nobody to do this. I only tell you that is possible.
Chapter 2. No possible to add more than 10 pics in 1 post.
The first impressions are fantastic. Very hard and smooth. I let cure one day long. Take off the tube, the cloth and the film is quite easy.
Obviously, it is necessary to sand a little to smooth the surface. The best is there are no big
wrinkles.
I prefer to do the job in some stages, to have more control in the way it is finishing, so, I have to put more layers to give thickness and a better leveled surface.
Finally need to open the pedal hole. A drill in the centre and then with care, and a dremmel, sand the carbon arround the hole where the pedal sits with a washer.
This is the final look.
Rear view
A final epoxy coat to the exposed carbon, to hard protection and give a glosy finish.
I have tested them uphill hard sprinting and they work as new, so, I´m happy. Will see in long therm use.
this is weight weenies, so I have checked them and they are now 7gr heavier. Doing the work with calm, doing the transitions between old and new carbon more progressive, and the finishing will be like new and no weight adds.
I hope somebody will be find all my efforts usefull.
Thanks for watching, and sorry for my low quality English.
Updated info. Today a long ride with steps, sprinting at full power with no issues. the feeling is to ride a like new crankset. Now I´ll take them off , and save them for spare, and ride the new one I bought after notice the problem. they are under warranty, so I have 2 years to stress them.
Last edited by josemari220 on Mon Sep 05, 2016 11:37 pm, edited 1 time in total.
Jose, thanks for this, very interesting!
Do you happen to have pictures of your repair?
Do you happen to have pictures of your repair?
- josemari220
- Posts: 12
- Joined: Sat Nov 05, 2011 9:52 pm
Hello everybody.
This is a long term test conclusion about this carbon crank repair method.
I have repaired another pair of pedal insert loose cranks, right side FSA SL -K, and one Specialized. The owner, a big power biker, have ended the whole cx season with the repaired SL.k with no isues, but finaly fail... the oposite one, the left one, not the repaired, so I have done the same with it, and now, with both repaired, I hope they will last to the end of times.
For weight weenies, this repair have added 8gr to the left crank.
If any of you have this usual problem, look for somebody with the skills. It is posible to repair with full confidence. The cost is less than 20$
This is a long term test conclusion about this carbon crank repair method.
I have repaired another pair of pedal insert loose cranks, right side FSA SL -K, and one Specialized. The owner, a big power biker, have ended the whole cx season with the repaired SL.k with no isues, but finaly fail... the oposite one, the left one, not the repaired, so I have done the same with it, and now, with both repaired, I hope they will last to the end of times.
For weight weenies, this repair have added 8gr to the left crank.
If any of you have this usual problem, look for somebody with the skills. It is posible to repair with full confidence. The cost is less than 20$
good work! always nice to see people repair stuffs instead of just throw it away.
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- wheelbuilder
- Posts: 1199
- Joined: Wed Feb 08, 2017 2:10 am
Nice work! I had a Red crankset warrantied for the same issue. They sent me a new crankset AND an extra set of chainrings! Your repair work is well done!
Never cheer before you know who is winning
Thanks for posting this, inspiring!
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Why? It's a proper repair.