For your entertainment...

[ubercrap]

Check out the corrosion on this spare 004 transaxle of mine!

[vwbill]

Hey why would it do that near the edge? You think its from some kinda current issue from a battery source or just from sitting near a salt lake?
Is that case alloy? Have to do some heliarcin! I guess you could just make a access hole and match some rubber plugs to a cutout. Bill

[ubercrap]

I don't know if those are magnesium or not, but it is toast no matter what it is. Hell, I can't even begin to imagine how to fix something like that. It basically is flaking off into powder. It turns freely, so it can come in handy for parts if necessary.

[vwbill]

I cant remember if the bell housing comes off? It must! It looks like the corrosion is a big area but maybe that's just more of a surface thing!
Is mag. a composite pressed type material? The gear box area is gold to you though!! I dont even have a backup one! bill

[MGVWfan]

Don't know about the manual trans, but the auto diff housing is definitely magnesium alloy, the gear section is aluminium alloy. Looks like magnesium to me, from the nature of the corrosion. Too bad.

[ubercrap]

Right, the bellhousing and differential section are one piece, and the gear section is one piece. As per Ray's instructions, those pieces can be interchanged between transaxles for repair purposes.

[DeathBus]

WOW! That is Magnesium! I have seen hundreds of Type 1 engine cases do that same thing, moisture builds up in the magnesium and causes some sort of reaction like oxidation/rust. I bet that side of the bell housing was on the ground. Its weird that they kapt the magnesium cases for Type 4's when Type 3 trannies went Aluminum.

[raygreenwood]

Look for a trail. It is most probably from brake fluid leaking down from teh slave and puddleing. Then...get some oil there...then attract dirt which along with the oil, keeps that moisture in constant contact.
Or....it could have been metal from the clutch disc and galvanic action.....or it could have been high sulpher or sulphated gear oil....or something in the motor oil. Oddly....it could even have been a poor connection between the case and block. The ground cable goes to the tranny. There could have been electrolytic action from case to case due to poor ground.

Save every piece of that thing. The thing to remember is this:.....the pinion shaft bearing pre-load...is determined from the dimensions of the differential/ bell housing end case. Its not hard to re-determine when switching the diff innards to another housing...but it helps to have a place to start, and to know the thickness of the shim under the cast iron snout inside of the bell housing.
Once you have the pinion shaft into the new diff case correctly.....then you can measure to see if there are going to be any difference to the spacers on teh main stack of gears. Where the main stack ends up....dictaes....along with the measurement of the transfer case....which shim thickness each end of the counter shaft gear got, to match up with the mainshaft location. Ray

[DeathBus]

WOW! That is Magnesium! I have seen hundreds of Type 1 engine cases do that same thing, moisture builds up in the magnesium and causes some sort of reaction like oxidation/rust. I bet that side of the bell housing was on the ground. Its weird that they kapt the magnesium cases for Type 4's when Type 3 trannies went Aluminum.

I ment that Type 2 trannies went aluminum in 72. NOT type 3, I think they and the Type 1 4 speeds were mag, were the automatics aluminum or mag?

[ubercrap]

It is a shame that it is in that state, but it should be good for parts. Don't worry Ray, precious parts from this would have to be pried from my cold, dead hands, and possibly if you guys needed anything.

[MGVWfan]

Oh yeah Ray, good point...you can get some really NASTY galvanic corrosion if there's a substantial flow of current between the bellhousing and the crankcase in the presence of moisture (like normal road splash).