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My mate has a dowl stuck in his crancases. one that sits between the cases themselves, not the cover.

Being a bike tech he wants my help. now I've done this many times. usually heat up the cases with a heat gun, give it a wiggle and jobs a good'un. rarely need more severe measures.

Told him that's what we should do but he seems to think that due to his cases being properly soft magnesium that a heat gun may risk warping the cases (we're talking Aprilia sxv). Now to me, that's bollox, but then I learnt my trade on BMWs and they're crankcases are practically made of iron lol

I'm fairly sure of what I'm going to do but just want to see what you lot think?

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thanks for the responses.

It's not about getting hot, but getting hot in a localised area. This will cause distortion with the right temperature differential and it just depends on the metal at which point this may be. the question is weather using a heat gun in a localised area could create that differential in this material.

I'm pretty sure the answer is no, but that's an educated guess rather than definitive knowledge speaking.

the alternative is to put the whole case in the oven, as it will all heat at once theoretically causing no differential bar that between the Mag case and the steel dowl. But we need an oven owned by an open minded women for that and is something we do not have lol.

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  • 3 weeks later...

Is it a solid/tubular or split dowel?

If solid, is it accessible with a small drill? - then try a self-tapper and pliers/extractor.

If tubular, skip the drill.

If split, it's possible to deform it using a chisel (screwdriver), so it becomes loose enough to pull/fall out - takes some care, though.

If heating, the oven is the best - I'm always wary of heating aluminium/magnesium/etc. alloys with a torch as they don't change colour as they get hot, just melt!

- Even better is a dishwasher - it gets warm and clean at the same time, but be careful with the chemicals.

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SXV cases aren't mag, and are very thin, so won't take alot of heat to losen the dowel. SXV cases are usually warped from the factory anyhow so a bit of heat might straighten them!

If you don't want to use heat, pack the centre of the dowel with grease, the get a drift that is a snug fit down the centre. Place the drift in the centre of the dowel and give it a sharp blow with a hammer. It might take a couple of attempts but the grease should hydraulic the dowel out of the hole.

When heating alloys, to tell when you have it hot enough, use the bounce test. The bounce test is were you drop a little water on to the piece and it bounces straight of in little droplets. At this point it should be hot enough to remove bearings etc, but not so hot that you are going to change the temper of the material.

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