Brake master cylinder help

[Jaff.]

hi guys im putting brembos off a fiat coupe onto my 1.6 megane coupe and i want to make sure i have the correct master cylinder on the car before i go putting the engine in and not being able to change it.

having made a few measurments this is what ive come up with...

1.6 caliper -
54mm dia = 27 rad
therefore - pi x r2 = 3.14 x (27 x 27) = 2289.06 mm2
2289.06 x 2 = 4578.12 mm2

brembos -
2 x 32mm dia + 2 x 38mm dia = 2 x 16mm rad + 2 x 19mm rad
therefore working out one side of the piston (one big one small) -
pi x r2 = 3.14 x (16 x 16) = 803.84 mm2
pi x r2 = 3.14 x (19 x 19) = 1133.54 mm2

1133.54 + 803.84 = 1937.38 mm2
to calculate the full surface area of the caliper times 1937.38mm by 2 = 3874.76 mm2



so by those calculations the surface area of the brembos are quite a lot smaller than the 1.6 calipers. more than 10%...

10% of 4578.12 = 457
diffrence between the calipers = 4578.12 - 3874.76 = 703.36

therefore im 703.36 - 457 = 246.36 mm2 over the 10% diffrence...

going by this im going to need a smaller master cylinder otherwise im going to loose all feeling in the pedal resulting in me having a set of stoppers that is either on or off...

am i right?

 

[Fred@BTM]

woah woah woah woah WOAH!!!!


how about whack them on and try them?

 

[Alex H]

www.physicssport.net

 

[Jaff.]

Because Fred its a lot of work to change the master cylinder if they don't work.

 

[Fred@BTM]

just fit them to the car and give them a go!

why won't they work? most 4 pots etc are the "smaller" when calculated against OE, master cylinder output remains the same, therefore you should have better pedal feel if anything

 

[Jaff.]

They will work, but if those numbers are correct then I'm gonna have no "feel" in the pedal and the brakes are either gonna be on or off.

It's a big hassle if I fit them then put the engine in and run it to find I need a smaller master cylinder.

 

[105e]

What size m.c does the original fiat use? should give you a clue

 

[Jaff.]

Don't know, will have to search.

Was just given the calipers and disks by a mate