Gearbox

[Ivelosttheplot]

Is it correct that my 1976 911s 5 speed would have a magnesium gearbox casing.

it’s removed from the car during its restoration .the box works well with no issues but  it’s fairly corroded but I’ve seen worse, mainly in the fins , I’m having to use a wire brush to removed the rough areas . Not sure if that’s correct for magnesium if that’s what it is.

a buddy stripped his magnesium box and had it 2 pack painted about 6 years ago and has never had any leaks so I think that’s the route I’ll go

thoughts ?

regards Keith 

[Type911]

File a few shavings off and set fire to it

[mean in green]

Reminds me of the scandalous disappearance of a reel of magnesium ribbon from third year Chemistry. Somehow strips of it appeared on the playground black market at lunchtime…

[Jonny Hart]

So shave some bits off for sale in the school playground and set fire to the gearbox.    Great advice guys!  👍 🤣

[Ivelosttheplot]

I Was hoping for a few more positive answers on the issue other than set fire to it 🤪 but  if all else fails I’ll save it for the fireworks night bonfire

[Type911]

I was serious! File some part of the case where its nice and thick on the flange then use a blow torch on the filings, you only need a few bits

[Gezzer]

Magnesium casting require reprotection if cleaned aggressively otherwise they will start to corrode again.

If they are blasted it should be with soda or nut shells afterwards they should be cleaned thoroughly and reprotected immediately  with chromate as they were from the factory.

I had my fan and housing (also magnesium) done at Greatwood Classics, maybe a good place to start and they are very friendly. Talk with Angus.

[waddy]

On 13/03/2022 at 00:12, Ivelosttheplot said:

Is it correct that my 1976 911s 5 speed would have a magnesium gearbox casing.

it’s removed from the car during its restoration .the box works well with no issues but  it’s fairly corroded but I’ve seen worse, mainly in the fins , I’m having to use a wire brush to removed the rough areas . Not sure if that’s correct for magnesium if that’s what it is.

a buddy stripped his magnesium box and had it 2 pack painted about 6 years ago and has never had any leaks so I think that’s the route I’ll go

thoughts ?

regards Keith 

I have a 1975 magnesium box which has sat in my garage for the last 15 or more years, but was about 35 years old then. It has been painted black since I bought the car and this has protected it fine, there has been corrosion which is not very extensive. There are a number of people who can repair or chromate magnesium parts including EB Motorsport who can also repair albeit at a fairly high price. There is a considerable weight saving with these magnesium boxes.

 

Ian

[johndglynn]

It should have a mag box at this age - mine is magnesium also.

For future reference, this thread on Pelican talks about some options to protect magnesium. Even if chromated, Mg benefits from a bt of tectyl or something on top. Our resident metallurgist Mr @TopCarrera may have something to add.