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Carbon fibre rod for gearshift mechanism?
TimC - 20/10/13 at 04:28 PM

I'm thinking of using 8mm pultruded carbon rod and bonded-on fittings for my gear-change mechanism.

Does anyone have any experience or advice?

liam.mccaffrey - 20/10/13 at 04:59 PM

What would the benefit be Tim, weight?

steved - 20/10/13 at 06:12 PM

they take a lot of abuse ,cant see it working and the weight saving over alloy rods wont be much ,though no harm in trying

TimC - 20/10/13 at 06:32 PM

Maybe, but also no welding and painting - potentially something that I can do in the house one evening.

steved - 20/10/13 at 06:41 PM

you shouldnt need to weld the alloy rods just tap the ends and screw in rosejoint ,simples
i just cant see carbon working with bonded ends ,very happy to be proved wrong though

[Edited on 20/10/13 by steved]

TimC - 20/10/13 at 07:01 PM

quote:
Originally posted by steved
you shouldnt need to weld the alloy rods just tap the ends and screw in rosejoint ,simples
i just cant see carbon working with bonded ends ,very happy to be proved wrong though

[Edited on 20/10/13 by steved]


Maybe - I'm using some serious adhesive - This stuff will happily stick steel to GRP

I may give it a go - if it breaks on the shake-down, so be it.

Thatcher - 20/10/13 at 08:00 PM

I plan to do the very same thing with some 10mm UD or uni directional carbon fibre tube and make a collar out of ally for the gbox lever and bond it together with Loctite's C2 heat cure adhesive but not for a while yet. Check out my pre preg carbon fibre gear knob post to see some pics.

Duncan36 - 20/10/13 at 08:55 PM

Tim you'll have to make sure the carbon is high temp. We had problems with the pushrods on a Jordan as the originals weren't made with high temp resin and one failed due to the heat.

twybrow - 20/10/13 at 11:25 PM

No issue with this at all. The only concern is you get you fittings on the end to be a snug fit, and your bond line wel defined with a decent adhesive. The downside of using a pultruded rod is that as a solid lump of carbon and epoxy, they are not the most efficient structure - ie with the same amount of resin and fibre, you could make a far stiffer rod if it were hollow (I am assuming here you are using a solid rod, as opposed to a tube?).

Strangley enough I was playing with some of this yesterday, to clean resin out from inside a pipe. We make the stuff in 5-15km rolls to use as the main load bearing structure within high voltage overhead power lines. It is VERY good in tension, and when constrained in a sleeve, it can take a huge compression load too (buckling is your enemy).

Autoflock Motorsport - 21/10/13 at 07:48 AM

you could still tap and thread the ends combined with 3m 8115 panel bond, it will go no where. Does the shape have to be tube? why not make a bespoke part which is suited to the exact needs?