Helicoil repair for crank pedal thread?

Discuss light weight issues concerning road bikes & parts.
bm0p700f
in the industry
Posts: 3557
Joined: Sat May 12, 2012 7:25 pm
Location: Glermsford, Suffolk U.K
Contact:

by bm0p700f

Surely if the aluminium insert is bonded in it can be re bonded as well. If it is the treads that are damaged the heliccoiling is easy strangely many shops in the U.K don't do it.

austke
Posts: 204
Joined: Mon Jan 16, 2012 7:03 am
Location: Queensland Australia

by austke

Is it possible for a Carbon experienced member to maybe remove the aluminium thread and then rebond it back in place. Maybe its not much cheaper than a new arm, but it may it is?
Thisisatest is correct about helicoils, all the ones I have used are steel, and therefore I would also assume to be stronger than standard alloy thread.

Oops, bm0p700f, beat me to it. :)
2013 Giant TCR Advanced SL 0, 6.92kg
2013 Giant Defy Composite 2 M, 8.5kg - Wife's
Azzurro Torino 8.55g
Fuji 650 10.8kg
Miele Lupa Triple Tandem 38,89kg

wally318
Posts: 475
Joined: Fri Feb 21, 2003 1:00 am

by wally318

Rebonding of the aluminum in the carbon crank arm is probably not possible.
Usually the carbon crank arms encapsulate an aluminum plug at the pedal end and depending on the design at the crank spindle end as well. So if you can imagine that if both sides of the
internal bond contact has let go. When you unthread the pedal spindle, if it's even possible.
You will have an alum. part that can slide up and down the crank arm. There will not be room
to get new adhesive on the sides of the part properly.
If the pedal thread insert were a T shape in which only 1 side is bonded, it wouldn't last
long under the pedaling forces.
AEROLITUS-defender of the faith

fdegrove
Tubbie Guru
Posts: 5851
Joined: Tue May 03, 2005 2:20 am
Location: Belgium

by fdegrove

Hi,

If so, it is the aluminum threaded part that is loose in the carbon arm, no (simple, convenient, cost effective) fix for that.


If the insert is round and just epoxied to the crank arm then it can be fixed provided you can remove it first.
Problem is that we don't know how it is attached to the arm nor what shape it has.

I had a similar problem with an older Campa carbon crank one that had the pedal spindle bonded to the insert (Ti to steel IIRC). Forcing the pedal spindle in the wrong direction dislodge the insert and eventally the pedal as well.
After that I epoxied the insert back into the arm and never had any problem with it since.

Since it seems to move a bit I suggest for Tinea to try and see if he can make it move around its own axis. If so then it can be solved.

Cheers, ;)
Last edited by fdegrove on Mon Dec 31, 2012 2:35 am, edited 1 time in total.
Being a snob is an expensive hobby.

austke
Posts: 204
Joined: Mon Jan 16, 2012 7:03 am
Location: Queensland Australia

by austke

Fedegrove is right, I think it could be rebonded. My hunch is that it would be best to remove the round? spindle thread? from the crank arm, and after cleaning and reabrasiving? not really a word, :lol: ( but remaking an abrasive surface to rebond to, within the crankarm and on the alloy spindle thread) you should be able to make enough room within it to get a strong enough bonding, to make it work. :thumbup: Best of luck.
I believe there are certainly some very smart people on this forum, who are more than competent to help you out, Tinea.

Cheers
Austke
2013 Giant TCR Advanced SL 0, 6.92kg
2013 Giant Defy Composite 2 M, 8.5kg - Wife's
Azzurro Torino 8.55g
Fuji 650 10.8kg
Miele Lupa Triple Tandem 38,89kg

User avatar
thencameyou
Posts: 303
Joined: Thu Jul 02, 2009 11:27 am
Location: Nu Zild

by thencameyou

Tinea Pedis wrote:it was drive side, I doubt the regular S900 has a mount for the SRM spider.


I was surprised too, but the spline pattern is exactly the same for the removable spider they come with and the SRM spider. I have switched arms over on an SRM myself.

DartanianX
Posts: 500
Joined: Sun Nov 13, 2011 6:00 am

by DartanianX

What type of SRM was this?

It happened to my FSA K-Force one this year. They replaced it on warranty. I think the trick is to run pedal washers from what I've been told. Better safe than sorry.

I think you can pick up a new K-Force NDS crank arm between $200 - $300 NZD.

User avatar
Tinea Pedis
Posts: 8445
Joined: Sat Mar 14, 2009 6:08 am
Location: Geelong
Contact:

by Tinea Pedis

SRAM.

Pedal washers were on as well.

Post Reply
  • Similar Topics
    Replies
    Views
    Last post