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Initial Observations on the Performance of Neuspeed BBK in Track-Day Environment

jmason

Go Kart Newbie
Location
Frederick, MD
TLDR: Worked fine.

Introduction

This is an initial review of the Neuspeed 6-piston 340mm BBK (caliper and Neuspeed slotted two-piece rotors) used in a HPDE environment. It is necessarily subjective in that I have few measurable quantities to support evaluation. Many of the observations are relative to my experience with a Brembo 330mm 4-piston BBK fitted with one-piece slotted rotors.

Brake performance depends on many factors that are listed below:

  • Car: 2015 non-PP GTI. No engine mods, some suspension mods. ESC completely off. No change to ABS.
  • Brake pads: Hawk Performance DTC-60. This is the same pad compound I have used with the Brembo BBK.
  • Brake Fluid: ATE 200. This is the same fluid I have used for all my HPDE events.
  • Tires: Hankook Ventus R-S4 235/40/17, with five track days prior use and a one-year storage interval since previous use. Likely not as sticky as when new.
  • ABS Adaptations: A number of adaptations were made as listed below:
    • Straight Ahead Brake Stabilization – Not Activated
    • Hydraulic Brake Assist – Not Activated
    • Brake Booster – 1
    • Hydraulic Brake Booster - 1
  • Track: Summit Point Motorsports Park “Main” circuit. This circuit is 10 turn, two-mile course with a 2980 ft long main straight, at the end of which I was achieving about 115 mph (down from a usual 120). There are two heavy braking zones, one at the end of the main straight leading into a fairly tight 180-deg right-hand turn (“The Loop”), and the other is at the end of a downhill straight leading into a tight 90 deg left-hand turn (“Eva Gardner Turn”).
  • Ambient temperature: 90 deg F
The Event

My HPDE event was a two-day affair of 7 sessions totaling about 105 minutes. I cut most sessions short to preserve the tires and limit the time that the engine oil temp was over 270 deg. It was supposed to be a three-day event, but oil leakage (from the joint between the intercooler outlet and hose, so obviously oil in the intake and a high-pressure leak resulting in loss of boost pressure [see comment above about top speed]) and a catch can half full of oil discovered after the seventh run meant that I aborted before the end of the second day.

BBK Fitment

This BBK fits snuggly inside my Neuspeed RSE16 8.5x17 wheels, no spacers required. There is 1.5mm clearance at the narrowest point between the caliper and wheel barrel. There is no evidence of contact between the caliper and wheel. There is some evidence of tire rubber temporarily caught between the caliper and wheel. There was no damage to the caliper or wheel due to the stuck tire rubber.

The tight clearance is of some concern. To minimize risk of something getting stuck, I use 18” wheels for non-track duty.

Brake Pedal Travel/Feel

I don’t have a measurement of the difference in travel, but the travel felt slightly longer, although not excessive in my opinion. Heel and toe braking motion was not effected. Travel did not increase during the event. Either I got used to it or the travel may have slightly decreased over time.

Upon returning home, I replaced the track pads and two-piece rotor with pads supplied with the BBK (iSweep brand) and one-piece rotors. In this configuration, it was immediately apparent that the brake pedal travel is as what it was with the Brembo BBK.

I will need more experience with the new BBK to get a better handle on the perceived difference in pedal travel observed with the different configurations.

On track, I found that the initial bite and torque to be greater than what I was used to. It required a light touch at initial brake application and thereafter, as if there is too much brake assist. With practice, I was able to develop a better feel for the set-up. Still, it was fairly easy to overdo my initial braking and overwhelm the tires. (As an aside, one reason for the BBK upgrade was to support future use of stickier tires.) When the Hawk pads are worn out, I may try a pad compound that has less initial bite and a lower coefficient of friction (Pagid RSL19 or RSL29?). Alternatively, perhaps there is an ABS adaptation that may be useful in addressing this situation.

With the street setup, the initial bite and torque seems to be consistent with the Brembo fitted with Hawk street pads.

Other Observations

There were no overheating issues such as brake fade, fluid boiling, or excessive pad wear.

The pads that fit the Neuspeed caliper are the Brembo “M” pad design (190mm long, 73mm high). This is a 17mm thick pad (5mm backing plate, 12mm pad material). New at the beginning of the event, all four pad’s thickness was 16mm at the conclusion of the event, a 1mm reduction. This is significantly less than what I have observed with the (smaller) pads installed in the Brembo BBK.

I’m not sure I can definitively comment on brake bias. I did note that the rear pads did wear during the event, so something was happening back there. I didn’t feel any instability under braking.

There was no discernible decrease in braking distance, and none was expected. Track conditions and tires are the limiting factor here.

Conclusion

There’s no getting around the fact that a 6-piston BBK is an expensive proposition. The upgrade addresses several shortcomings of my Brembo kit and it appears to provide significant performance headroom. Given my experience to date, in my opinion it is a solid and worthwhile (if pricey) upgrade.
 
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3rdOne

Go Kart Newbie
Location
NC
Thanks for the review. I’ve been thinking of the Neuspeed or StopTech BBK.
How much performance increase do you think is attributable to the larger rotor diameter?
 

jmason

Go Kart Newbie
Location
Frederick, MD
Thanks for the review. I’ve been thinking of the Neuspeed or StopTech BBK.
How much performance increase do you think is attributable to the larger rotor diameter?
I don’t know. I imagine most of the difference is due to the larger pads.
 

3rdOne

Go Kart Newbie
Location
NC
Ah yes. Bigger pads certainly make a difference. Larger rotors may not make as much a difference in power but maybe heat soak
 

1970something

Passed Driver's Ed
Location
WA, USA
Thanks for the thorough review. What was the PN of the Brembo 330mm kit you had?

Curious if the 1.3mm clearance between caliper and wheel barrel concerns you. I have 17” wheels on my PP gti with min 2.5mm clearance and I have already gotten a scratch on one of the wheels from a rock stuck between the caliper and wheel.
 

jmason

Go Kart Newbie
Location
Frederick, MD
Yes, the tight clearance is of concern. I only use the 17” wheels on the track, 18” on the road, hopefully limiting the chance of getting something stuck.
Black Forest Industries sells the Brembo BBK I used. 1A56016A.
 

Mini7

Autocross Newbie
Location
Charlotte, NC
Car(s)
2017 GTi Sport PP
1.5mm is tight but doable. As long as you didn’t have any rubbing once things got hot. Getting a small rock caught between the wheel and caliper will happen eventually.

The larger pad from the 6-piston caliper will last longer than the same pad in a 4-piston caliper. More swept area will result in slower wear.

The larger rotor will only improve brake torque marginally, but the increased rotor mass will reduce brake temps, further improving rotor and pad life. Pad friction coefficient and caliper piston size will have the greatest impact on brake torque.
 

jmason

Go Kart Newbie
Location
Frederick, MD
Here's an update to my experience with the Neuspeed 6-piston BBK.

Brake Pedal Travel

One of my first impressions was that the pedal travel was less with the street pads (iSweep) than on the track. I can confirm this impression, which I believe is due to the level of braking required on the street vs the track and the difference of the pad compounds. At least the way I drive on the street (gently), not much braking effort is required. Only a small amount of pedal force is required to effect a stop. On the track, the level of braking effort is much greater. This results in longer pedal travel. The brake pedal is even with or just below the gas pedal when braking hard. This relative positioning makes heel and toe a little difficult to consistently perform.

A long time ago, I replaced the stock pedal covers with Awe Tuning covers. My plan is to install a spacer under the brake pedal to build it out about 1/4" so that the brake pedal is above the gas pedal under hard braking. This should make it easier to consistently heel and toe. Other options might have been to move the gas pedal lower (increase the distance from the seat back to the gas pedal without changing the brake pedal distance), but I didn't see a way to do that. Better yet would be to change the length of the lever arm between the pivot of the brake pedal and the attachment point of the master cylinder. Increasing this length would result in greater movement of the master cylinder shaft relative to pedal travel. I haven't looked under the dash to see if this is possible, but given likely packaging constraints, I'm not optimistic. Another option would be to install a master cylinder with a larger diameter bore. From what I've read, the MQB master cylinders for the performance oriented cars whether VW, Audi, or SEAT, are all the same diameter bore, so no obvious solution there. I'm not keen on installing the pressure valves mentioned in another thread in this section.

Brake Feel

I replaced the Hawk DTC-60 pads with Pagid RSL 29 pads for a three day event on Summit Point Main. The Pagid's had a little less bite, which is what I was looking for with this pad. Modulating the degree of braking was easy. No complaints with this set-up.

Pad Wear

Over 10 sessions (2 were in the rain), the Pagid pads wore down by 1 mm. I'm pretty happy with this, but I think when I have grippier tires, the wear rate will increase. Still, it's significantly less than with my Brembo BBK. And yes, for those keeping score, the large Pagid pads better last longer as they are double the cost of the Brembo BBK pad. At this point, I think the cost/benefit is in favor of the larger pads. I won't know for sure until the Pagids are worn out.
 

jmason

Go Kart Newbie
Location
Frederick, MD
My sense is there is a normal degree of braking action throughout the pedal stroke. The stroke is too long under hard braking conditions for my liking. I should add that I think the level of pedal pressure required is appropriate. I would not want more brake boost. Unfortunately, what I have just written is qualitative. I apologize that I don't have quantifiable data.

So the real question is why does the pedal stroke increase when pressing the pedal harder? What is the source of the compliance? Is the caliper flexing? It does have a bridge, but who knows? The Neuspeed kit includes SS brake lines, so I guess not there. Flexure of the master cylinder or its mounting to the firewall? The pedal mechanism mounting flexing? The pads compressing? Questions abound!

My understanding is a pressure valve mentioned in another thread can alleviate a dead spot by holding the pad closer to the rotor. That would reduce pedal travel that occurs before there is any braking effect.
 

Mini7

Autocross Newbie
Location
Charlotte, NC
Car(s)
2017 GTi Sport PP
Pagid RS29’s are kind on rotors and easy to modulate.

The larger pad will give you a longer lasting pad. More area to wear through. So the caliper piston size may be contributing to the the longer pedal. Larger pistons will require more displacement from the master cylinder.
The residual pressure valve mod may help a little.
 

Autobahn

Go Kart Champion
Location
Huntington Beach
You can try a fluid that compresses less than ATE and make sure you get a good brake bleed with high pedal engagement. That’s usually good to reduce travel a bit. I have a friend with the same front pad/caliper brake setup on his Golf R, no complaints on travel.
 

GTIfan99

Autocross Champion
Location
FL
You can also reduce piston retraction using Red Rubber Grease on the pistons. There's a thread about this same issue with the Macan calipers and it looks to be the easiest and simplest way to improve the feel, along with good fluid and a good bleed. Also, pad compound has an effect on pedal feel.
 

jmason

Go Kart Newbie
Location
Frederick, MD
I think I'm beginning to convince myself that the issue isn't initial travel, but more like a "soft pedal". I haven't ever performed the VW-prescribed post-bleeding procedure that is suggested to address a soft pedal. I'll give that a go to see if it helps. My typical procedure is to use a power bleeder pressurized to 12 psi max and run nearly a quart of brake fluid through the system using ATE 200. I don't think there has ever been any air in the brake lines and there aren't any leaks that I'm aware of.

I did a Google search on the subject of brake fluid compressibility. I didn't know that was a thing! Next time I do a complete flush, I'll try Motul to see if that helps.
 
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GTIfan99

Autocross Champion
Location
FL
I think I'm beginning to convince myself that the issue isn't initial travel, but more like a "soft pedal". I haven't ever performed the VW-prescribed post-bleeding procedure that is suggested to address a soft pedal. I'll give that a go to see if it helps. My typical procedure is to use a power bleeder pressurized to 12 psi max and run nearly a quart of brake fluid through the system using ATE 200. I don't think there has ever been any air in the brake lines and there aren't any leaks that I'm aware of.

I did a Google search on the subject of brake fluid compressibility. I didn't know that was a thing! Next time I do a complete flush, I'll try Motul to see if that helps.

What is the VW procedure?
 
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