hi jose, amazing work. was thinking whether you can carry out repairs for me. im facing the exact same problem on my FSA crankset.josemari220 wrote: ↑Sun Sep 04, 2016 4:45 pmHello 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.
1 red crank insert view comp.JPG
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.
2 red crank insert out comp.JPG
With the insert out, you can see the hollow inside of the arm. Hi-tech.
3 red crank insert hollow arm comp.JPG
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.
4 red crank planning carbon pieces comp.JPG
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.
5 epoxi mix comp.JPG
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.
6 apply carbon layer and epoxi mix comp.JPG
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.
7 holed film wrap comp.JPG
Then you need to put a layer that absorve the excess of epoxy. A piece of an old trouser do the work fine too.
8 cloth wrap comp.JPG
Stretch and wrap the inner tube trying not to move the added carbon layers. Before give pressure, all is very loose.
9 stretched rubber wrap comp.JPG
This is the final look after wrapping.
10 stretched rubber fully wrapped comp.JPG
thanks.
ray
