33mm Ceriani Fork caps stripping . . .help?

[penton117]

Hi fellow Poggers,

Can anyone ofer some advice or at least new curse words to use? This is the second bike in a row on which the aluminum fork caps are stripping out. Both on 35mm Ceriani forks. Is this common? If so, what is a common fix? Has anyone ever used a steel replacement and why were soft aluminum caps used to screw into hardened steel forks? Any help or at least a line on a new pair of caps would be appreciated.

Thanks,


Don

 

[Rocket]

Don
I assume the forks are the newer style 35mm 74-76.  The tube has a taper that is pulled up into the upper triple clamp, do you have the lower pinch bolts loose when you are tightening the caps?  I don't know what the torque would be for the caps, but I would guess it to be around 10-15 ftlbs.
Rocket

 

[peter]

Are they striping out when you tighten them down or when you are trying to get the cap started? I had experienced the same problem when trying to start the end cap. I dressed the damaged threads on the endcap with a small triangular file. To keep it straight when screwing it into the tube, I grabbed the tube with my left hand and used my thumb to push down on the cap. That gave me enough control to get five or six turns on it before i relived the pressure on the cap. Hope that makes enough sense to be of help
-->pd

Edited by - peter on 08/10/2002  9:53:41 PM

[penton117]

Hi Peter,

The caps are stripping when starting them. It looks like the female thread in the fork is a bit boogered up. That's going to take one big tap! Is there any other way to clean up an inside thread like that?

 

[rob w]

Hi Don, I have done this a few times when I had a situation like yours. You can use a knife. The hardness of the steel in a good knife blade is harder than the fork tube material. The tip of the blade should be narrower than the width of a thread. Steady (rest) the blade on the top edge of the tube and follow through the good part of the thread until you find the rough area, you just have to carve off the high spot, it will take a few passes with the right amount of pressure. If you are left with a little burr, hit it a couple of strokes with some emery cloth, and install with some grease. Another way- If the thread that is bad happens to be at the very beginning (top) you can use a die grinder and eliminate the bad beginning, but I would'nt recommend that operation, because you have to be brilliant with thee ol'grinder. Hope all goes well. Bob.

 

[peter]

hi don,
 i just had to get a new file for that actually. My local NAPA store was able to order it, and a larger one might keep it in stock. The file has four sides, each side has ridges for "chasing" a different thread count (1, 1.5, 2 ect). you could see if they have one that will match your threads. -pd

 

[john durrill]

Don ,
 if you are still having trouble straighting out the threads in the fork tubes , this is something that has worked for me in odd situations like that.
 get a tap . any size the right thread. I think the caps are 1mm per mm so a 6 x1mm tap would do. and 8 or 10 would be better but they are rare. use the tap in a sliding motion . Press it against the wall of the tube and use some of the good threads to align it.  work it side to side, the tap is so hard it will cut and move metal. it takes some time but will usually fix any thread but one that is a total loss.
John

 

[penton117]

Hi Guys,

Thanks for all the good ideas. I finally ot it going. I bought a thread chaser file from McMaster-Carr @ $19.00 It is a very handy file for internal and external threads. It just takes some time, doing it like John says, by using the good threads at the bottom as a guide. Anyway thanks again to everyone.