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A real good brake setup

bostonaudi

Go Kart Champion
Location
Charleston, SC
Car(s)
1995 BMW M3
So usually at beginning of year I make a few tweaks to the car to try something new, and it was time do something about the brakes. After running front R32 brakes for a while with RB rotors and having the rotors fail early, I sold the brakes. The big R brakes aren't bad and can generate good stopping power, but they are heavy and barely fit 17" wheels, and only some at that. I left the rear R32 brakes installed as they seem to work well on the GTI. I was also using average metal master rear pads at rear to keep rears from being too biased.

I was recent beneficiary of another member upgrading to Stoptechs and bought his Boxster front setup. I installed a set of HPS pads for street at all corners. I was out bedding in the pads, and holy crappers this thing stops fast! This is an excellent setup, the front Boxster with rear R32 combo is well balanced, and using same HPS pads at all four corners works great. The car doesn't get squirrelly under very hard braking which it was previously susceptible to. The front Boxster conversion works great, the smaller 4 pot Brembo calipers seem to be a spot on match for the stock master cylinder, and the nice thing is changing pads is a matter of pressing a pin out rather than unbolting the calipers. Porsche also has a great pad selection available, while front R32 brakes do not. I think the Boxster conversion is the best bang for buck, as you get much better feel and clamping force, it uses stock rotors, which keeps costs down, and these calipers are much lighter than the stock calipers, which can be felt over bumps. It stops so well I might even leave the HPS pads in for a track outing. The only negative on the Boxster conversion is my OEM 18" Huffs need a 4 mm spacer. My 17" Enkei PF01's clear with lots of space.

Other change is suspension, halfway through installing a new set of Koni Yellows with DG springs. Going with a GC coilover conversion on the Koni's later this spring. Been driving around with Koni's just on the rear and it already feels good, rear is less choppy than stock shocks. I installed rears at a turn from full soft but feels like it could use another half turn. This is a good street setting though.
 

tmw2442

Go Kart Newbie
Location
SC
Car(s)
Mk7 R
Glad you like them; the hps pads will wear very quickly on the track. Don't be suprised if they are over half way gone after 5-6 sessions.
 

bostonaudi

Go Kart Champion
Location
Charleston, SC
Car(s)
1995 BMW M3
Glad you like them; the hps pads will wear very quickly on the track. Don't be suprised if they are over half way gone after 5-6 sessions.
I burn up em up typically that fast. DTC-60 usually about done after 4-5 events.

They seem to be a very good match for the rear R32 brakes. Stable, straight line hard stops.
 

tmw2442

Go Kart Newbie
Location
SC
Car(s)
Mk7 R
I burn up em up typically that fast. DTC-60 usually about done after 4-5 events.

They seem to be a very good match for the rear R32 brakes. Stable, straight line hard stops.
5-6 20 min sessions not events for me. 2 events and they would be gone. I would start to glazed them on the track driving 8 to 9/10 tenths with stock software. It would take the whole drive home for them to wear the glazing and feel right again. You have so much more clamping force in front that HPS pads will fade the pads completely out at CMP and at Roebling they would last a few laps with the K04 draging they car down for turn 1. The pads in the calipers when you got them only had 8 sessions on them (1.5-1.75 events). The porterfields should hold up better being more along the lines of an HP+ pad.
 
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bostonaudi

Go Kart Champion
Location
Charleston, SC
Car(s)
1995 BMW M3
5-6 20 min sessions not events for me. 2 events and they would be gone. I would start to glazed them on the track driving 8 to 9/10 tenths with stock software. It would take the whole drive home for them to wear the glazing and feel right again. You have so much more clamping force in front that HPS pads will fade the pads completely out at CMP and at Roebling they would last a few laps with the K04 draging they car down for turn 1. The pads in the calipers when you got them only had 8 sessions on them (1.5-1.75 events). The porterfields should hold up better being more along the lines of an HP+ pad.
Good point, I'll swap em out.
 

cruizin01

Go Kart Champion
Location
C-bus Ohio
Car(s)
07 Rabbit
All the guys I know that have done this swap love the setup. As you state "great bang for the buck". Fits a large amount of wheels with only a small spacer.

My 2 peice rotors from coleman havent held up well with my 17Z setup and that was with almost all street driving. This year Im hoping to downsize just a little for better balance.

I have some boxster S calipers and some new brackets to try out on my car very soon. They use a slightly larger 320mm rotor. The pad should cover a larger swept area as the pad is quite a bit taller than the non S pad. The S pads have a build in damper also which should negate some of the pad squeal that a fair amount of people complain about.

I have a set of HPS pads for them but if I decide to keep them on my personal car Ill swap them out for Porterfield R4S pads.

If anyone is interested Ill have at least one spare set of calipers and brackets.
 
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JRutter

old man
Location
Bellingham, WA
Can you measure the piston diameters on the Boxster calipers? Curious to see how they compare to the Stoptech 4-piston.
 

tmw2442

Go Kart Newbie
Location
SC
Car(s)
Mk7 R
Boxster calipers are 40mm/36mm. Stoptech 38mm/34mm.
 

JRutter

old man
Location
Bellingham, WA
Thanks. Sounds perfect for R32 rear brakes then.
 

the bruce

Go Kart Champion
Location
land
Car(s)
Golf GTI Mk.V 2008
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
 
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JRutter

old man
Location
Bellingham, WA
Any idea on difference (if any) in piston size between the rear calipers on:

Golf/GTI/A3

R32/S3/Golf R

Rotor size goes from 289mm to 310mm.
 

Carfreak226

Detailer Extraordinaire
Location
92808, CA
Car(s)
2007 GTI MKV
I heard these squeal loudly under braking. Something to do with the harmonics of the caliper in relation to the chassis?
 
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