will a s4 master brake cly bolt straight up or not?? or could i use the bore off a s4 and bolt it onto the s3 diafram????

 

master not mater.

 

I wouldn't!
I know that there are at least 3 Master Brake Cyls from series 1-3, and *none* of those are interchangible (though their parts MIGHT be, I wouldn't try it)... Why take a chance on your brakes, they save your life countless times a day. Spend the cash to get either a new or rebuilt Master Cyl for *your* type of car.

Jon

 

no they are not. The master cylinder on our cars have tho bolts that mount it to the firewall at 12 and 6 oclock whereas the FC has them at 10 and 4