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

burgerkong

Go Kart Champion
Location
Ontario, Canadeh
Your outer pad is already dragging? That should not happen, are you sure?

What you are describing (sitting and standing on the brake pedal and it slowly sinks) that happens to all, even with the stock caliper. It has to do with the two step MC and the ECU power assist causing a huge increase in pressure vs pedal effort. I can't say for sure with your calipers, but I can say for certain with the Macan/Q5 caliper those mods do prevent this from happening. I explain why in the post (with a diagram). There is nothing dubious about using RPV's, they have been used in countless street and track applications for decades.
There is no other larger MC options for this car, and other than going to a different caliper (like the ST40), there does not appear to be any other way to improve it. As the original guinea pig now with thousands of hard street and track miles, it works and is perfectly safe.
The only thing I am butt hurt about is the fact that no one mentioned the brake pedal issue before I spent the time and money to upgrade to these calipers. The issue was very apparent from my first test drive, then I find that everyone noticed it but did not want to talk about it (why I still don't understand), but great thanks.
The stock system has a lot of intentional slop in it because VW is using the ECU to actuate the brakes for you. If you don't like that because it makes it difficult to modulate the brakes under track conditions you can turn off some of the ECU assist, but then you are left with a lot of unnecessary and unwanted pedal slop.

The modifications I did go a long way towards fixing that slop, and it has to do with the two step MC I show and talk about in my post. I did this to fix this issue for myself, and I did. You post telling us you are having the same issue and I am just trying to help. I would not describe myself as "butt hurt" just perplexed when I am the only one here who admits to having the same issue and has found a working solution.

You can learn to live with it (apparently that is what most have decided to do), or try my recommendation, or get a different caliper. The only one that reportedly does not suffer from this same issue is the ST40, and I believe it is because they have a significantly smaller piston displacement (almost 25% smaller). I bet that also keeps the MC in stage one, that combined with the smaller MC/caliper ratio I am sure give a very high and firm brake pedal. If I was going to spend $3-4K on a brake upgrade, that is the one I would get.

This is supposed to be just for fun, and arguing with arm chair engineers is not my idea of fun, so good luck.

There are so many fallacies with your initial posts and questionable data collection methods, I don't even know where to begin. Instead of belittling everyone and calling them 'arm chair engineers', how about we get back to facts, and not conjecture?

1607838207485.png


You regularly use 'belief', 'bet', 'suspect' and a whole host of words that essentially translate to 'I think this is correct, therefore it must be how I put it'. Or simply, assumptions.

1) The VW M/C isn't a stepped bore design. If it was a stepped bore design, you would see two DIFFERENT piston diameters listed. Instead, what we have is ONE diameter listed - 23.81mm. (refer to: https://www.abs-bv.fr/pdp/61546 ). Not only that, the diagram you referenced shows a step bore FOR THE REAR CALIPERS. Step bores are used mainly to compensate for rear brakes that need large fluid movement (aka drum brakes). Shitty diagram of the MK7 system below (P/N 5 & 6 are the hardlines to the rear of the vehicle):

1607841032626.png


2) Your conclusions come from test methods that are flawed. Let's start with your piston retraction testing setup. The normal procedure is to hook up a dial indicator (positioning it such that at rest the indicator is reading greater than zero) and apply minimal pressure (only enough to move the piston until the seal deforms and no more) then let off the pressure. You elected to A) use a deformable aluminum C channel (with laughable wood spacers to 'center' the block), and B) used feeler gauges. You didn't bother listing how many trials were performed and if there was any averaging employed, but yet expect everyone to believe on blind faith?

3) You didn't bother repeating your lubrication efficacy test. Once you discovered RRG 'gave' you a retraction value better than OEM, you just left it at that. How old was the OEM grease? Because the RRG was definitely newly applied.

4) The 'objective' test images are ambiguous. Just how are you even gauging the activation point? The pictures show you applying the brakes, BY HAND. Unless there is gauges and numbers backing up the application force, plus how much the pistons come out, this is not objective at all. I can manipulate those images in seconds, it proves nothing.

While the effort was laudable, there are simply too many areas where gut feeling (subjective-ness) was substituted for objective results, not to mention the misleading title of the thread. Low pedal? Sure, you don't have to press as much to get the pads to contact the rotor. Soft? Nope. The core of your modifications revolve around a check valve which maintain a small amount of line pressure at the caliper thus reducing the distance between the pads and rotors to effectively nil (that isn't even taking into account of pad taper, which is perfectly normal in ANY system). This doesn't result in a 'harder' or 'softer' pedal - check valves are designed such that there is minimal frictional losses one way (via spring rate for the plunger/ball). In other words, the RPV would have minimal effect on pedal 'feel'. Pedal position yes, but feel? Use some logic here.
 

GTIfan99

Autocross Champion
Location
FL
So I’ve read. Can you elaborate?

ATE 200 is too thick. If you want to run an ATE fluid, ATE SL6 is the correct fluid.

And for some reason, the Macan seals didn't like SRF, so I went with RBF660 and I'm not having any issues.
 

GTIfan99

Autocross Champion
Location
FL
There are so many fallacies with your initial posts and questionable data
collection methods, I don't even know where to begin. Instead of belittling everyone and calling them 'arm chair engineers', how about we get back to facts, and not conjecture?

View attachment 196031

You regularly use 'belief', 'bet', 'suspect' and a whole host of words that essentially translate to 'I think this is correct, therefore it must be how I put it'. Or simply, assumptions.

1) The VW M/C isn't a stepped bore design. If it was a stepped bore design, you would see two DIFFERENT piston diameters listed. Instead, what we have is ONE diameter listed - 23.81mm. (refer to: https://www.abs-bv.fr/pdp/61546 ). Not only that, the diagram you referenced shows a step bore FOR THE REAR CALIPERS. Step bores are used mainly to compensate for rear brakes that need large fluid movement (aka drum brakes). Shitty diagram of the MK7 system below (P/N 5 & 6 are the hardlines to the rear of the vehicle):

View attachment 196032

2) Your conclusions come from test methods that are flawed. Let's start with your piston retraction testing setup. The normal procedure is to hook up a dial indicator (positioning it such that at rest the indicator is reading greater than zero) and apply minimal pressure (only enough to move the piston until the seal deforms and no more) then let off the pressure. You elected to A) use a deformable aluminum C channel (with laughable wood spacers to 'center' the block), and B) used feeler gauges. You didn't bother listing how many trials were performed and if there was any averaging employed, but yet expect everyone to believe on blind faith?

3) You didn't bother repeating your lubrication efficacy test. Once you discovered RRG 'gave' you a retraction value better than OEM, you just left it at that. How old was the OEM grease? Because the RRG was definitely newly applied.

4) The 'objective' test images are ambiguous. Just how are you even gauging the activation point? The pictures show you applying the brakes, BY HAND. Unless there is gauges and numbers backing up the application force, plus how much the pistons come out, this is not objective at all. I can manipulate those images in seconds, it proves nothing.

While the effort was laudable, there are simply too many areas where gut feeling (subjective-ness) was substituted for objective results, not to mention the misleading title of the thread. Low pedal? Sure, you don't have to press as much to get the pads to contact the rotor. Soft? Nope. The core of your modifications revolve around a check valve which maintain a small amount of line pressure at the caliper thus reducing the distance between the pads and rotors to effectively nil (that isn't even taking into account of pad taper, which is perfectly normal in ANY system). This doesn't result in a 'harder' or 'softer' pedal - check valves are designed such that there is minimal frictional losses one way (via spring rate for the plunger/ball). In other words, the RPV would have minimal effect on pedal 'feel'. Pedal position yes, but feel? Use some logic here.

I don't have measurements, but I did feel a massive improvement in initial pedal feel and height switching from OE VW grease and RRG in my new Macan calipers. Again, not scientific, but it was obvious.
 

emichel6888

Go Kart Champion
Location
TX
There are so many fallacies with your initial posts and questionable data collection methods, I don't even know where to begin. Instead of belittling everyone and calling them 'arm chair engineers', how about we get back to facts, and not conjecture?

View attachment 196031

You regularly use 'belief', 'bet', 'suspect' and a whole host of words that essentially translate to 'I think this is correct, therefore it must be how I put it'. Or simply, assumptions.

1) The VW M/C isn't a stepped bore design. If it was a stepped bore design, you would see two DIFFERENT piston diameters listed. Instead, what we have is ONE diameter listed - 23.81mm. (refer to: https://www.abs-bv.fr/pdp/61546 ). Not only that, the diagram you referenced shows a step bore FOR THE REAR CALIPERS. Step bores are used mainly to compensate for rear brakes that need large fluid movement (aka drum brakes). Shitty diagram of the MK7 system below (P/N 5 & 6 are the hardlines to the rear of the vehicle):

View attachment 196032

2) Your conclusions come from test methods that are flawed. Let's start with your piston retraction testing setup. The normal procedure is to hook up a dial indicator (positioning it such that at rest the indicator is reading greater than zero) and apply minimal pressure (only enough to move the piston until the seal deforms and no more) then let off the pressure. You elected to A) use a deformable aluminum C channel (with laughable wood spacers to 'center' the block), and B) used feeler gauges. You didn't bother listing how many trials were performed and if there was any averaging employed, but yet expect everyone to believe on blind faith?

3) You didn't bother repeating your lubrication efficacy test. Once you discovered RRG 'gave' you a retraction value better than OEM, you just left it at that. How old was the OEM grease? Because the RRG was definitely newly applied.

4) The 'objective' test images are ambiguous. Just how are you even gauging the activation point? The pictures show you applying the brakes, BY HAND. Unless there is gauges and numbers backing up the application force, plus how much the pistons come out, this is not objective at all. I can manipulate those images in seconds, it proves nothing.

While the effort was laudable, there are simply too many areas where gut feeling (subjective-ness) was substituted for objective results, not to mention the misleading title of the thread. Low pedal? Sure, you don't have to press as much to get the pads to contact the rotor. Soft? Nope. The core of your modifications revolve around a check valve which maintain a small amount of line pressure at the caliper thus reducing the distance between the pads and rotors to effectively nil (that isn't even taking into account of pad taper, which is perfectly normal in ANY system). This doesn't result in a 'harder' or 'softer' pedal - check valves are designed such that there is minimal frictional losses one way (via spring rate for the plunger/ball). In other words, the RPV would have minimal effect on pedal 'feel'. Pedal position yes, but feel? Use some logic here.

Good grief this is a back yard garage hobby project, tinkering and testing with what I have laying around the garage, we are not redesigning rockets for NASA here. So yes, the test methods are not micron level production lab precision, sue me. However, they are more than adequate to see what is happening, and it allowed me to come up with some effective modifications with just a little trial and error.

You regularly use 'belief', 'bet', 'suspect' and a whole host of words that essentially translate to 'I think this is correct, therefore it must be how I put it'. Or simply, assumptions.

That is true because I am trying to be honest about what I know, and what I think I know. I think I know why these modifications work, but I am not 100% certain. What I do know from actual experience is that it does work. This is just like when I came up with the DP O2 CEL fix (among others) using similar backyard hobby methods, and I got a lot of the same push back on that one too. In that situation I ended up making several modified sensors for some well known forum members struggling with the same issue, they installed them and guess what? There are folks out there right now running aftermarket high flow down pipes with no tune and O2 readiness, and have not had a CELL or failed inspection for over two years running. That was a bit more involved so I did not mind doing that, but this one is super easy so… I got nothing out of it, just found a fix for my own problem and just like trying to help others in the community. This feels just like that, only I have say folks like you make me want to stop bothering. I don't mind skepticism and questions, but the personal attacks? You might notice I typically ignore you, but you did make a couple of good points (as well as some fallacies) so I will give it one more try.

To your points:

1. I tried to research if this MC is stepped or not but could not find definitive information one way or the other. Do you know for a fact that stepped MC's list both piston sizes? Because every MC I could find only lists one size even for those that are definitely stepped, I assume they only reference the smaller primary size. If you have information that shows otherwise I would be interested to see it.

There are several reasons that make me think our cars do have a stepped/quick take up MC. For starters the stock calipers are low drag, then see the image below, on the left is an actual MK7 Golf R/GTI MC, on the right is a standard MC. From the outer casting step and the example image of a QTMC, it kind of looks like it is the same no?


MC compare.jpg


Second, your assumption that the primary and secondary chambers affect the rear and front calipers respectively is also false. See image below, virtually all front bias cars (like ours) use a "Dual Diagonal brake circuit". Which is why lines 1 and 2 off the ABS unit feed the left rear and right front, and 3 & 4...

Brake system overview1.jpg


This is so if you were to have a brake line failure, you still have one front and opposite rear brake to slow the car with some degree of stability.
dual diagnal brake.jpg

The stepped/QTMC QT piston chamber does not only affect the primary chamber. The larger fluid displacement/pressure actuates both chambers. Perhaps this will give a better explanation of how it actually works:
QTMC overview.jpg

2. Like I said, I used what I had, and while it was not ideal, the measurements were reasonably accurate for what I was trying to determine. That C channel was not from home depot, I made sure the back was in line with the pistons and it was very solid. I took at least three measurements in each configuration, mainly to make sure I wasn’t pushing the piston with the feeler gauge, and the measurements were all very consistent. A more accurate rig would require custom machine pieces, and for what I was doing... Also, the results were consistent with expectations so...


3. That is true, the only test I did was on OEM lubricated seals on calipers with around 40K on them. At the time of testing I did not have the VAG lube on hand so... I have since purchased some and have intentions of trying it out at some point. It is possible that fresh VAG lube would work just as well, but I don't know that and could only recommend what I know works. It is a PIA removing and lubing those seals, and I did not want to recommend something I was not sure about only to not have it work. Because you are right, I am flying blind. If fresh VAG lube does give more retraction, is it still okay? I have no idea, for now I know the RRG does work for sure so...


4. Also true, but why would I be here encouraging people to try this if it doesn't work as well as I said it does? There is no other way I can prove it short of someone coming over and trying it out in my car. I am in the DFW area and would welcome anyone to do so. I am not selling anything here, and it is not like I haven't proven on other modifications that I have done and recommended, so what is my angle?


When I started this project I was just hoping to raise the pedal height, the fact that it also significantly improved the pedal firmness and feel surprised me as well. Like I said, short of removing and disassembling the MC I cannot say with absolute certainty that it is a stepped/QTMC however, based on what I have observed it is the only rational explanation I can think of that fits all of the facts.


Here is how and why I think it works:

The QTMC is designed to use the larger QT piston to get the pads to the rotor as quickly as possible, once there it should transition from QT mode to compensate mode (per diagram above) using the smaller primary/secondary pistons. When you get in the car and step on the brake it is firm and relatively high however, once you start the car the vacuum booster kicks in and pushes the MC just past the QT mode. Once that happens you go from stage one to stage two (see diagram below). Obviously this is not to any sort of scale (just a rough metaphor/concept example), but essentially this is what is happening the moment you start the engine. Now you tell me, which will provide a firmer higher pedal stage 1 or stage 2?

Then it gets better, let’s say you are applying 50 lbs. of force on the brake pedal; the vacuum booster turns on and just pushes the piston past QT stage 1 and now that same 50 lbs. has been amplified causing more distortion of the brake components and now it takes larger brake pedal movements causing smaller displacement on the brake system albeit with greater force. So the pedal starts to move even more, only now you also have the vacuum brake booster helping you out and the way that works as the pedal moves down it applies more and more assist! So as you site there standing on the brake pedal the brake system pressure is ramping up more and more, and that is what causes the pedal to sink even lower and feel mushy/soft.


Brake pedal theory.jpg

So you have a two fold effect, the longer amplified pedal movement from the piston ratio MC transition change, combined with the added force of the vacuum brake booster that also only increases as the pedal goes further down. It is no wonder the pedal drops and goes soft when you start the car. Now by reducing the piston retraction by a certain degree the QTMC never gets close to that transition point from just stepping on the brake. So even with the added force of the vacuum booster the larger QT piston stays in play and there is virtually no movement of the brake pedal.

All I can tell you is that when I step on the brake and start the car the pedal does not move or feel different at all. The pedal feels firm and stays high, it is very easy to modulate, the ABS still kicks in but you have to really step hard for that to happen making threshold braking much easier. It works great on track and the automatic braking for dynamic cruise and automatic emergency stopping feature does not seem to be affected at all.

It works far better than I had hoped it would, which is why I am trying to share this discovery with you all. So when I see folks talking about it, I am like hey try this what have you got to lose? Lubing the seals is not going to cause a problem and is generally recommended, and the RPV’s are cheap and super easy to install or remove. Try it, then tell me I am full of it. I wouldn’t be here taking the time to write all of this if it was BS.

The only concern I had is wondering if the QT check valve would hold up under hard braking since it is intended for relatively low pressure initial take up. But If it doesn’t, the brakes will still work only with the a much lower soft pedal. However, so far it has worked great, and I am reasonably certain the Stop Tech ST40 caliper does the same thing only perhaps more so due to the much smaller piston displacement they use. I am told those calipers provide a very high and rock hard brake pedal, and after seeing the piston displacement they use I believe it. Folks have been using those for years under extreme conditions so…

I even spoke with the folks at Stop Tech support a while back asking about their seal channel cut, and they had no idea what I was talking about. They referred me to one of their senior design engineers who called me back a few days later. When I explained to him about low drag calipers and QTMC’s he said he had never heard about it. Which given that design was developed for production cars to try and improve fuel economy, and they focus solely on high performance brake systems, it is not surprising. However, he did say they use a straight cut, meaning minimal piston retraction (better for performance), that combined with the much smaller piston displacement, and that is how and why they give a high rock hard brake pedal. I hope this all makes sense.
 

Cuzoe

Autocross Newbie
Location
Los Angeles
Hmmm, I've got two GTI/R master cylinders at my house, were part of my plan to upgrade when I put 17z's on my Golf. I could get some pictures of them I guess, haha.

One of them is an earlier part number, maybe up to 2017...
5Q1614019 NREP

The other is the current part number, just got delivered this week, ordered 6+ weeks ago but apparently shipped to the dealer from Germany...
5QM614019 F
 

burgerkong

Go Kart Champion
Location
Ontario, Canadeh
Hmmm, I've got two GTI/R master cylinders at my house, were part of my plan to upgrade when I put 17z's on my Golf. I could get some pictures of them I guess, haha.

One of them is an earlier part number, maybe up to 2017...
5Q1614019 NREP

The other is the current part number, just got delivered this week, ordered 6+ weeks ago but apparently shipped to the dealer from Germany...
5QM614019 F

I think the OE changed from TRW to ATE (or vice versa) depending on revision, who knows. Unless you're willing to gut it too lol.
 

emichel6888

Go Kart Champion
Location
TX
All I can say is that one of us is going to be eating humble pie:

View attachment 196315

Will update.
For you perhaps, because right or wrong you seem to think everything is a pissing contest. Whereas I am just interested in what works and what doesn't work, and then trying to understand why. I actually look forward to what you find either way, if it turns out not to be the reason, all that will mean is there is some other explanation. I can't think of one right now, but it will be interesting to see either way.
As I have said repeatedly I don't know for certain if it is a QTMC, but I have several good reasons to think it is, and it is the only explanation I can think of for how the brake pedal responded to these modifications. So whether it is a QTMC or not, it does not change the fact that it works, because it does. You might not believe me, but honestly I don't really care so much because it is hard to argue with actual experience.
Several folks have already bought the RPV's so I am confident eventually someone else will try it and verify my results. To be sure I will be very surprised if it turns out not to be a QTMC, but I won't be upset about it at all. So thanks, again I look forward to your report.
 

Cuzoe

Autocross Newbie
Location
Los Angeles
I think the OE changed from TRW to ATE (or vice versa) depending on revision, who knows. Unless you're willing to gut it too lol.
Tentative plan is to have my MC replaced early-mid January. After that I'd be happy to gut the one they don't use. But assuming the one you just picked up arrives first, please tear that one apart and post what you find before I rip into a perfectly good new one, haha.
 

jmason

Go Kart Newbie
Location
Frederick, MD
ATE 200 is too thick. If you want to run an ATE fluid, ATE SL6 is the correct fluid.

And for some reason, the Macan seals didn't like SRF, so I went with RBF660 and I'm not having any issues.
ATE 200 (2.2 to 2.8 mm²/s @ 100 deg C), ATE SL6 (1.7 to 2.3 mm²/s @ 100 deg C), and Motul RBF 660 (2.59 mm²/s @ 100 deg C) are FMVSS No. 116 – DOT 4 compliant. ATE SL6 is the least viscous of these products.

From what I can find online, FMVSS No. 116 – DOT 4 and VW standard VW501 14 are compatible.

This is part of the product description for ATE SL6:
"This brake fluid for hydraulic motor vehicle brake and clutch systems is, due to its low viscosity at extremely low temperatures, particularly well suited to brake systems with electronically controlled hydraulic components which require rapid modulation of the brake pressure at the braked wheel, particularly in systems, called “Elektronische Stabilitätsprogramm” (ESP*) which used to prevent vehicle oversteer and understeer."

ATE 200 does not include this information, nor could I find a similar description for Motul RBF660. ATE SL6 boiling points are lower than ATE 200 and RBF660. I don't know if the difference is significant in track day usage.

I think I would amend your comment to say that ATE SL6 is better suited to street driving and when ESP is fully engaged. In a track day environment where maximum temperature tolerance is desired and ESP may or may not be fully engaged, ATE 200 or Motul RBF 660 may be a better choice due to higher temperature tolerance.
 
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GTIfan99

Autocross Champion
Location
FL
ATE 200 (2.2 to 2.8 mm²/s @ 100 deg C), ATE SL6 (1.7 to 2.3 mm²/s @ 100 deg C), and Motul RBF 660 (2.59 mm²/s @ 100 deg C) are FMVSS No. 116 – DOT 4 compliant. ATE SL6 is the least viscous of these products.

From what I can find online, FMVSS No. 116 – DOT 4 and VW standard VW501 14 are compatible.

This is part of the product description for ATE SL6:
"This brake fluid for hydraulic motor vehicle brake and clutch systems is, due to its low viscosity at extremely low temperatures, particularly well suited to brake systems with electronically controlled hydraulic components which require rapid modulation of the brake pressure at the braked wheel, particularly in systems, called “Elektronische Stabilitätsprogramm” (ESP*) which used to prevent vehicle oversteer and understeer."

ATE 200 does not include this information, nor could I find a similar description for Motul RBF660. ATE SL6 boiling points are lower than ATE 200 and RBF660. I don't know if the difference is significant in track day usage.

I think I would amend your comment to say that ATE SL6 is better suited to street driving and when ESP is fully engaged. In a track day environment where maximum temperature tolerance is desired and ESP may or may not be fully engaged, ATE 200 or Motul SRF 660 may be a better choice due to higher temperature tolerance.

I've yet to hear a complaint about RBF causing issues on this platform, ATE200 has its own thread for issues. Take it for what it's worth.
 

GTIfan99

Autocross Champion
Location
FL
FWIW, I noticed a few people with this typo. Castrol makes SRF. Motul makes RBF660 and RBF600. Not SRF 660/600. Very different compared to the Castrol product.

FWIW, we've had one person have issues with SRF and the stock Macan seals, so I've been using RBF660.
 

jmason

Go Kart Newbie
Location
Frederick, MD
FWIW, I noticed a few people with this typo. Castrol makes SRF. Motul makes RBF660 and RBF600. Not SRF 660/600. Very different compared to the Castrol product.
Corrected in my post.
 

burgerkong

Go Kart Champion
Location
Ontario, Canadeh
Tentative plan is to have my MC replaced early-mid January. After that I'd be happy to gut the one they don't use. But assuming the one you just picked up arrives first, please tear that one apart and post what you find before I rip into a perfectly good new one, haha.

As an update, if anyone cares, the MC is crossing the border into my grubby hands soon lol.

1608677254475.png
 
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