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TT-RS/Golf R master cylinder

the bruce

Go Kart Champion
Last edited:

the bruce

Go Kart Champion
When fitting RS3/TT-S or most aftermarket brakes to a Mk.VI GTI (23,81 mm MC) you'll
get increased pedal travel. A bigger MC reduces wheel travel. Both is simple physics.

- 22,22 mm (Mk.V GTI)
- 23,81 mm (Mk.V R32, Mk.VI GTI, Golf R)
- 25,40 mm (RS3 + TT-RS)

That's the way it is at least in continental Europe. RHD cars at least do come with different
brake booster.
From what I read unfortunately the 25,40 mm MC does not fit smaller brake boosters.

Interesting to see VW changed from the small 22,22 mm MC on the Mk.V GTI to the same
23,81 mm MC the old R32 already had. That does mean a Mk.VI GTI is better prepared for
fitting R-brakes than the Mk.V GTI.

If you want to buy 'uprated' brakes I strongly recommend to determine the effective surface
of the caliper pots before you make any decision. This is extremely important. Sadly most
people don't know what they're doing when buying 'big brakes'.
 

Talguy

Go Kart Champion
Bruce,

how intensive of a install would it be to fit that BMC into our cars. Do you know if we would have to bend new brake lines also.
 

the bruce

Go Kart Champion
piston size/area



1. stock front caliper:


Golf/GTI - Ate FN3 54 mm caliper: 2290 mm²

S3/R32/R - FNRG 57 mm: 2552 mm²



2. aftermarket - proper match:


Boxster: 40 mm + 36 mm > 1257 mm² + 1018 mm² = 2275 mm²

Brembo GT caliper A: 40 mm + 36 mm > 1257 mm² + 1018 mm² = 2275 mm²

Stoptech ST-40: 38 mm + 34 mm > 908 mm² + 1134 mm² = 2043 mm²




3. aftermarket - poor match:


Forge: 707 mm² + 1046 mm² + 1164 mm² = 2917 mm²

Q7/Touareg/Cayenne (three variants):

34/36/38 mm : 907.920 + 1017.876 + 1134.115 = ~ 3060 mm²
32/36/38 mm : 804.248 + 1017.876 + 1134.115 = ~ 2956 mm²
30/34/38 mm : 706.858 + 907.920 + 1134.115 = ~ 2749 mm²



4. master cylinder diameter:

- 22,22 mm > 388 mm² (Mk.V GTI)
- 23,81 mm > 445 mm² (Mk.V R32, Mk.VI GTI, Golf R)
- 25,40 mm > 507 mm² (RS3 + TT-RS)



ps
If you know the piston diameter: Pi * radius² = area
 
Last edited:

Talguy

Go Kart Champion

the bruce

Go Kart Champion
AP Racing kit added:


piston size/area



1. stock front caliper:


Golf/GTI - Ate FN3 54 mm caliper: 2290 mm²

S3/R32/R - FNRG 57 mm: 2552 mm²



2. aftermarket - proper match:


AP Racing 6-pot CP7068-00 (355x32 ) > 2350 mm²

Boxster: 40 mm + 36 mm > 1257 mm² + 1018 mm² = 2275 mm²

Brembo GT caliper A: 40 mm + 36 mm > 1257 mm² + 1018 mm² = 2275 mm²

Stoptech ST-40: 38 mm + 34 mm > 908 mm² + 1134 mm² = 2043 mm²




3. aftermarket - poor match:


Forge: 707 mm² + 1046 mm² + 1164 mm² = 2917 mm²

Q7/Touareg/Cayenne (three variants):

34/36/38 mm : 907.920 + 1017.876 + 1134.115 = ~ 3060 mm²
32/36/38 mm : 804.248 + 1017.876 + 1134.115 = ~ 2956 mm²
30/34/38 mm : 706.858 + 907.920 + 1134.115 = ~ 2749 mm²



4. master cylinder diameter:

- 22,22 mm > 388 mm² (Mk.V GTI)
- 23,81 mm > 445 mm² (Mk.V R32, Mk.VI GTI, Golf R)
- 25,40 mm > 507 mm² (RS3 + TT-RS)



ps
If you know the piston diameter: Pi * radius² = area
 

TXBDan

Go Kart Champion
Well that explains why my Stoptechs have such a nice firm pedal with less travel
 

the bruce

Go Kart Champion
Indeed, Dan !! :thumbsup:


Found some more - Boxster S and 993/996 Turbo:



piston size/area



1. stock front caliper:


Golf/GTI - Ate FN3 54 mm caliper: 2290 mm²

S3/R32/R - FNRG 57 mm: 2552 mm²



2. aftermarket - proper match:


AP Racing 6-pot CP7068-00 (355x32 ) > 2350 mm²

Boxster: 40 mm + 36 mm > 1257 mm² + 1018 mm² = 2275 mm²

Boxster S: 40 mm + 36 mm > 1257 mm² + 1018 mm² = 2275 mm²

993 Turbo: 36 + 44 mm > 1018 mm² + + 1520 mm² = 2538 mm² (on the edge)

Brembo GT 'A-caliper': 40 mm + 36 mm > 1257 mm² + 1018 mm² = 2275 mm²

Stoptech ST-40: 38 mm + 34 mm > 908 mm² + 1134 mm² = 2043 mm²



3. aftermarket - poor match:


Forge: 707 mm² + 1046 mm² + 1164 mm² = 2917 mm²

996 Turbo: 40 + 44 mm > 1257 mm² + 1520 mm² = 2777 mm²

Q7/Touareg/Cayenne (three variants):

34/36/38 mm : 907.920 + 1017.876 + 1134.115 = ~ 3060 mm²
32/36/38 mm : 804.248 + 1017.876 + 1134.115 = ~ 2956 mm²
30/34/38 mm : 706.858 + 907.920 + 1134.115 = ~ 2749 mm²



4. master cylinder diameter:

- 22,22 mm > 388 mm² (some Mk.V GTI, Mk.V + Mk.VI Golf)
- 23,81 mm > 445 mm² (Mk.V R32, Mk.V GTI, Mk.VI GTI, Golf R)
- 25,40 mm > 507 mm² (RS3 + TT-RS)



If you know the piston diameter: Pi * radius² = area
 

the bruce

Go Kart Champion
:23:
 

the bruce

Go Kart Champion
piston size/area



1. stock front caliper:


Golf/GTI - Ate FN3 54 mm caliper: 2290 mm²

S3/R32/R - FNRG 57 mm: 2552 mm²



2. aftermarket - proper match:


AP Racing 6-pot CP7068 (355x32 ) > 2350 mm² (small bore version of CP7040 caliper for Mk.V/VI)

AP Racing 6-pot CP5570: 27.0 + 31.8 + 38.1 > 573 mm² + 794 mm² + 1140 mm² = 2507 mm²

Boxster: 40 mm + 36 mm > 1257 mm² + 1018 mm² = 2275 mm²

Boxster S: 40 mm + 36 mm > 1257 mm² + 1018 mm² = 2275 mm²

993 Turbo: 36 + 44 mm > 1018 mm² + + 1520 mm² = 2538 mm² (on the edge)

Brembo GT 'A-caliper': 40 mm + 36 mm > 1257 mm² + 1018 mm² = 2275 mm²

Stoptech ST-40: 38 mm + 34 mm > 908 mm² + 1134 mm² = 2043 mm²



3. aftermarket - poor match:


Forge: 707 mm² + 1046 mm² + 1164 mm² = 2917 mm²

996 Turbo: 40 + 44 mm > 1257 mm² + 1520 mm² = 2777 mm²

Q7/Touareg/Cayenne (three variants):

34/36/38 mm : 907.920 + 1017.876 + 1134.115 = ~ 3060 mm²
32/36/38 mm : 804.248 + 1017.876 + 1134.115 = ~ 2956 mm²
30/34/38 mm : 706.858 + 907.920 + 1134.115 = ~ 2749 mm²



4. master cylinder diameter:

- 22,22 mm > 388 mm² (some Mk.V Golf)
- 23,81 mm > 445 mm² (Mk.V R32, Mk.V GTI, Mk.VI GTI, Golf R)
- 25,40 mm > 507 mm² (RS3 + TT-RS)



If you know the piston diameter: Pi * radius² = area
 

the bruce

Go Kart Champion
some more:


piston area



1. stock front:


O2 RS/Golf/GTI - Ate FN3 54 mm: 2290 mm²

S3/R32/R - FNRG 57 mm: 2552 mm²



2. aftermarket - fits properly:


AP Racing 6-pot CP7068 (355x32 ) > 2350 mm² (special version of CP7040-caliper for Golf V/VI, Scirocco etc.)

AP Racing 6-pot CP5570: 27.0 + 31.8 + 38.1 > 573 mm² + 794 mm² + 1140 mm² = 2507 mm²

Boxster: 40 mm + 36 mm > 1257 mm² + 1018 mm² = 2275 mm²

Boxster S: 40 mm + 36 mm > 1257 mm² + 1018 mm² = 2275 mm²

993 Turbo: 36 + 44 mm > 1018 mm² + + 1520 mm² = 2538 mm²

Brembo GT 'A-caliper': 40 mm + 36 mm > 1257 mm² + 1018 mm² = 2275 mm²

Stoptech ST-40: 38 mm + 34 mm > 908 mm² + 1134 mm² = 2043 mm²

Mov'it:

4s2 - 36 / 44 = 2538 mm²
4s3 - 36 / 44 = 2538 mm² (u.a. als VAG-Kit mit 322x32er Scheibe, geht unter 17")
4m6 - 36 / 44 = 2538 mm²
6m1 - 28 / 32 / 38 = 2554 mm²



3. aftermarket - mismatch:


Forge: 707 mm² + 1046 mm² + 1164 mm² = 2917 mm²

Mov'it:

4s4: 40 / 44 = 2777 mm²
4s5: 38 / 46 = 2796 mm²
6m3: 30 / 34 / 38 = 2749 mm²


Brembo 8-pot RS4/R8/Gallardo: 28 + 28 + 32 + 32 mm > 2840 mm²

Brembo 8-pot RS6 : 4192 mm²

996 Turbo: 40 + 44 mm > 1257 mm² + 1520 mm² = 2777 mm²

Q7/Touareg/Cayenne (there are 3):

34/36/38 mm : 907.920 + 1017.876 + 1134.115 = ~ 3060 mm²
32/36/38 mm : 804.248 + 1017.876 + 1134.115 = ~ 2956 mm²
30/34/38 mm : 706.858 + 907.920 + 1134.115 = ~ 2749 mm²



4. master cylinder:


- 22,22 mm > 388 mm² (some Golf V, evtl. some Scirocco etc.)

- 23,81 mm > 445 mm² (Golf V R32, Golf V GTI, Golf VI GTI, Golf R, Scirocco 2.0T + R)

- 25,40 mm > 507 mm² (RS3 + TT-RS)



5. rear:


GTI/RS: C38 > 1134 mm²

S3/R32/R: C41 > 1320 mm²

Movit 4m1: 28 / 30 = 1323 mm²

Movit 4m2: 28 / 30 = 1323 mm²



Pi * Radius² = area
 

2013R

Drag Race Newbie
I guess no one has tried the Golf R master cyl on the GTi yet. Bleeding that thing would be a bitch..
 
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