Changing bushes the easy way - metallurgy question

[Robby]

I'm going to be changing the front suspension bushes on the Jag fairly soon. There are a lot of them, and I don't have a press. Removal is the hard bit, fitting the new ones is easy.

Last time I did this, on my old MR2, I took the wishbones off and put them all on a small fire, which burned out the old wishbones and left me with a nice clean surface.

The question is, will this knackered the properties of the Jag wishbones. Should I do it at all, and if so should I let the metal cool slowly, or should I plunge it into a bucket of water?

[oldbiker]

I`m guessing that it`s a pressed steel wishbone, in which case it will not be hardened, to harden a carbon steel you need to heat it to about 1300C and quench, To start to Temper (soften) hardened steels you would need to be heating to about 400C and above

(case hardening is more involved so forget about case hardening )

My guess is that it would be a medium carbon steel, unhardened. so as long as you don`t get it glowing it will be ok, Plastics melt at about 240C, I`m guessing that rubber would melt well before you reach that temperature.

but that is just my guess.

if the wishbone is made from forged steel I think heating to about 750C would start to affect the grain structure of the steel.

That`s about the best I can say.
however, if you checked google\wickipedia for heat treatment of carbon steel with reference to the eutectic point you may find more info
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[kingsmith]

just get a blow torch and just burn them out..they just set alight and shove a screw driver or something in the middle and waggle them around and they soon come out...

done that plenty of times..no damage done..


good luck
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[Robby]

I assume they're either cast or forged. Too substantial looking to be pressed. Last time I did it on the MR2 with pressed steel wishbones (I think) the fire had it gently glowing, dark cherry red.

The blowtorch idea could work, but there are at least 8 bushes and I'm a lazy bastard. The other big advantage of a proper fire is that it cleans off all the crap, so I can give them a quick going over with a wire brush afterwards and then give them a coat of hammerite.

I had a look on wiki, but it didn't tell me what I want. I have a book on materials somewhere that should say.