jpurban

Anyone know the physical difference between the 996 brake master cylinder parts 99635591040 and 99635591050?

I know the 1040 is for normally aspirated 996's with PSM (M476) and 1050 is for 996TT with PSM.

I ask because the 1040 can be had for $100 to $200. The 1050 is more like $500 to $600.

So, I'm wondering what it takes (if anything) to adapt the 1040 for use on a Turbo.

sfv_rider

Aahh, sweet 996 envy from the TT set.

ECS Tuning

The standard 996 master cylinder uses a 23mm piston, and the Turbo uses a 25.4mm piston due to the larger calipers. I believe everything else mounts up the same, so there's a good chance it will be a simple upgrade for Carrera owners. This would essentially would be a down grade for you and other turbo owners though, as you would be moving less volume.

jpurban

ECS, appreciate the feedback.

So, the Carrera bore is about 15/16 and the turbo is 1"... The units look the same and should be physically interchangeable, as you suggest. Both have one M10 and one M12 port, which is convenient.

Since the stroke is the same, I basically need to determine if a 10% loss in fluid displacement is acceptable as well as living with 10% more pedal travel. Seems like it should be...

ditto

It's your car and your choice but you will be modifying an excellent braking system and don't know what you will end up with. The master will pump 12% less fluid per inch of pedal travel. Will it bottom out before pumping enough fluid? Your calipers are not the same as the NAs, your car weighs more, goes faster. Most owners want better brakes not worse ...