Weight Weenies

Just noticed my drive side SRM crank pedal thread has, for some unknown reason, come 'loose' (my Speedplay is able to be jiggled, in spite of being securely tightened).

Would a helicoil be a safe and reasonable solution to fix it?

Especially as my odds of being able to find a new drive side SRAM SRM crank arm is looking slim (to say the least!).

Either that, or weld in some new material and redo the threads.

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Tinea Pedis wrote: Would a helicoil be a safe and reasonable solution to fix it?

Helicoils are used in the F15's radar antennas and other military airborne applications, which i presume are exposed to much more stress than your crank arm

Done correctly, it should be more than enough.

Oren

If you don't have any joy, another option is to pick up a SRAM S900/S950 crank, as they are exactly the same arms as the SRM. should be a bit cheaper than buying direct from SRM

OrPe wrote:Done correctly, it should be more than enough.

Excellent.


And 'then...' it was drive side, I doubt the regular S900 has a mount for the SRM spider.

Hey nick, it said done correctly ......

You're screwed:)

Happy new year mate....

In theory it is stronger because you go a size up.
I use a fair few hellicoils were i work i would not hessitate to use them.
Take your time and she'l be right (;

Pedal threads are unusual. No Helicoil made. I read somewhere of a company in France I think making a specific crank thread "helicoil like" repair kit.

Too. Many. Wattz.

Cyclus has a repair kit, can't think of who brings um in the country?.

here you go http://www.amazon.com/Var-Crank-Repair-Pedal-Thread/dp/B004YJ2XNA

now you can set up a crank thread repair business

I was going to say VAR indeed. You beat me to it!

I also feel that assuming you can get a helicoil in the correct fit, that it will be fine. We use them in our trucks from time to time with success, in load bearing applications.
We also still use the correct Locktite, that we would have used, had we done the job with out the helicoil?
Lastly, yes you could fill the crank arm and retap the hole, as a last resort.
Plumbers tape to get a tighter fit may work, but not as confidence inspiring as the first option for me.

Hope this help
Austke


P.S. Happy New Year!!!

Helicoil threads in an aluminum part are stronger than plain aluminum threads. Many, many parts that are screwed/unscrewed on a bike often will have a helicoil from the factory. Cable pinch bolts, front derailleur mount, some mountain shifter and brake clamps...
Yes, pedal thread helicoils are generally available, for both sides.
all that said, I don't think it will help you. To be clear, your crank is a Sram crank with an SRM, right? carbon arms? S975-type? If so, it is the aluminum threaded part that is loose in the carbon arm, no (simple, convenient, cost effective) fix for that.

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

This is my concern, as I think this is what is going to be found.

I think it's the whole structure within the carbon that is loose...

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