Corroded alloy.

[Nathan S]

I have an aluminium top triple clamp that's corroded - it has done that weird thing where is kinda like rotting timber - the corrosion is actually quite deep and it lifts up the surface layer of aluminium.

Is this repairable? I'm wondering whether it is possible to TIG weld it to build the material back up, and then grind/sand it back into shape.

On other clamps with similar damage, I've tried simply removing the top layer, but you end up removing a lot of material before you get a remotely decent surface...

Bike won't be raced or ridden hard, FWIW.

And no, I can't find another one (MX125A, before you ask).

[firko]

It sounds like it's rooted Nathan. Is a DT125 triple clamp the same?

[Nathan S]

No, unfortunately.
They're the same as a DT250A item, except that they've got much smaller diameter fork legs.
The DT125 has steel triple clamps top and bottom.

[jhovel]

Building up with a TIG torch is possible - after removing ALL the corrosion right back to sound aluminium,
with the expectation that the clamp is indeed aluminium (and not magnesium or a heat treated alloy).
I know just the person to do that for you - in Bendigo, Central Victoria. But there would be others who can do that for you too.
I would strongly recommend, if at all possible, that you either clamp it to the fork legs (maybe even upside down, if most of the damage is underneath) or make a steel jig from a decent steel plate and a couple of short (even solid) steel pegs of fork leg diameter to clamp it to during welding - to ensure it doesn't get distorted in the process.
Cheers,
Joe

[vandy010]

once the alloy laminates it can be a real pain in the butt to weld properly.
if your going to pay someone to do it, i'd probably trawl yankie ebay and wait for one to turn up as it'd be around the same cost if not cheaper in the long run.
but if it's definately not going to get riden, then a bit of bog and a sand with some paint and who's gonna know.

[Maicojames]

Would that be the same clamp as YZ125A, YZ125B, MX 125 a, B, and C?
You can try salvage in California-Lance at 661-317-2371 .

[vandy010]

same clamp!
 but MX/YZ 'C' is different

[oldfart]

Ream it out - make up a new sleeve drill some holes in the sides  and tig it in place. 

[GMC]

Allthough Aluminium doesn't rust, it does corrode. And trying to weld it is much the same as welding rusty steel, you have to cut it back to good material & build it up with weld from there.
Triple clamps would be made from structural Alloy, 6061 T6 & while I know they can be welded okay, I also believe their are some things that shouldn't be messed with too much, & triple clamps fall into that category.
You may not intend to ride it now, but you probably will at some point, not to mention the next owner.

[jimg1au]

according to zedder all these are the same part
Part # = 401-23435-00-98
Part Description = CROWN,HANDLE
Model Count = 6
MX125A 1974 125 MX125 Off-Road
MX125B 1975 125 MX125 Off-Road
MX175A 1974 175 MX175 Off-Road
MX175B 1975 175 MX175 Off-Road
YZ125A 1974 125 YZ125 Competition Motocross
YZ125B 1975 125 YZ125 Competition Motocross