master cylinder ?

[79 cobra]

I ordered a master cylinder for my 79 .
It came a aluminum unit .
I ordered a 2nd one , it came steel . Same as on car .
Other than weight , is there a advantage of one over the other ?
Did 79s come aluminum too ?
Thanks

[TWITCH]

You need to check the part numbers. The difference will be in the piston diameters ( 1", 1 1/4", etc.). The larger diameter pistons were used for the bigger brake packages (LTD, SVO). I would use the larger diameter piston, it will "firm up" your brake pedal feel. Others may chime in that know more than me.

[cjwanner2000]

my 79 has an iron master cylinder. it's still the original one. as far as the bore goes, the 79 was 0.938, 80-82 was 0.875 and after that it switched to 0.827. the svo master cylinders were 1.125. the svo's are only supposed to be used if you have svo/lincoln brakes front and rear. if you don't have any brake upgrades, use a stock replacement m/c for proper brake operation. like was said before, i'd check those part numbers and make sure you have the right one

[Zap's 85 GT]

The benifits of an alluminum master cyl are weight and corrosion resistance. Iron ones corrode when moisture enters the brake fluid and the the rust flakes deteriorate the seals much faster. The outside of the master cyl will stay looking better using an alluminum one too.

[cjwanner2000]

The benifits of an alluminum master cyl are weight and corrosion resistance. Iron ones corrode when moisture enters the brake fluid and the the rust flakes deteriorate the seals much faster. The outside of the master cyl will stay looking better using an alluminum one too.

is this an option you can getor would it be for a different application? personally, if it's the same thing i would much rather have aluminum. anyone know for sure?

[Mustang5L5]

What are the part numbers on both MC's? Specifically the aluminum one?

[79 cobra]

I got a 3rd m/c it was aluminum too .
Well I picked the better looking of the 3 .
Its aluminum .
They all were the same part number from the suppler .
Being remans , they don't quite look the same .
It's at work .
I'll grab it tomorrow and look for a stamped number or something .

[cjwanner2000]

gonna polish that aluminum one before ya put it on?

[79 cobra]

No .
I might sandblast , then clearcoat it .
I'm changing the booster too .
I'll paint that black .

The m/c I have now is all rusty and weeping fluid .
A new seal didn't help .
For $12 I'll change it .
Booster is another $50 .

[79 cobra]

There are no complete numbers on it .