915 gearbox lower cover plate material?

Gary71 · Post by **Gary71** » Mon Jan 31, 2005 3:26 pm

Can anyone tell me if the cover plate on the bottom of a '72 915 gearbox that supports the selectors is magnesium or ali? It's cracked, one I can weld up, the other... maybe not!

davidppp · Post by **davidppp** » Wed Feb 16, 2005 8:53 pm

Hello Gary.

It is mag alloy..

I have had good luck welding this material with oxy acetylene by using a box full of argon...and the right rods..

TIG should work..but I'd preheat it all..

Kind regards
david

Gary71 · Post by **Gary71** » Thu Feb 17, 2005 8:06 am

Thanks for the advice David,

I've now spoken to my tame welder, who could weld tinfoil to cast iron, he came over all nervous and told me to buy a new one!

He basically said without detail understanding of the metallurgy he could not select the correct rod and promise it would survive. He was also concerned about distortion upsetting the flatness after putting the amount of heat in required to get the weld to take. So it might leak around the edges rather than through the crack

Bottom line is I found Mittelmotor can sell me a new one for £35....not nearly as scary as I first thought!! So for once I'm not going to bodge somthing!

Thanks again.

davidppp · Post by **davidppp** » Sat Feb 19, 2005 8:47 pm

I agree with your expert..

I should have mentioned that it will NOT be at all flat after welding!

Electron works fine as a rod..

Kind regards
David