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

jmason

Go Kart Newbie
Location
Frederick, MD
I'm more optimistic;)
 

emichel6888

Go Kart Champion
Location
TX
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.

If you read my post How to fix/improve low soft Brake pedal with Residual Pressure Valves and seal lube In particular post #1 and #6 the reason why this happens and how to fix it is all laid out. The short answer is lube the piston seals and throw on some inline RPV's, problem solved. I had the same issue with the Macan Brembo calipers, sorry it is long, and I tend to ramble but...

You know how even with the stock brakes you get in, step on the pedal, start the car, and the brake pedal drops and get soft and mushy? Well with these to simple low cost modifications my brake pedal does not change at all. It stays high and firm all the time! I explain how and why this happens in those two posts, one of the best modifications I have done.

Good luck.
 

Gvazquez

Go Kart Champion
Location
North Carolina
The 40168 code didn't work. I couldn't get the VCDS ABS bleed procedure to work.

I have performed 6 pressure bleeds, 4 two-person bleeds, each followed by a road test that activates ABS, all in accordance with the erWin manual. (The erWin manual does not include an ABS bleed procedure.) I'm still intermittently seeing a few air bubbles during bleeding from all of the calipers. The pedal feels better, engagement is high, and the brakes work well on the street, but I can still (too easily IMHO) force the pedal to the floorboard.

I performed a master cylinder pressure bleed down test, adapting the procedure described in the erWin manual (looking at data acquired by VCDS instead of attaching a pressure gauge to a caliper). In three tests, the first test exhibited excessive pressure loss. The other two did not. I think the first test got into the smaller bore portion of the MC (reached with longer pedal travel) while the other two did not. I'm going to conduct the test a couple of more times to get better confidence in the results.

Still, I've reached the end of my patience and have scheduled an appointment with my favorite VW/Audi indie shop. In talking with them, they said that they have seen similar problems on client cars with high piston count BBKs.
I feel you pain on that. I think there's something wrong and it can be fixed cause there's plenty of people with bbks that don't complain about this. Mine is basically doing the same thing. The only thing that fixed it was going back to stock rear brakes. It was borderline undriveable for me though.
 

jmason

Go Kart Newbie
Location
Frederick, MD
Mine is basically doing the same thing. The only thing that fixed it was going back to stock rear brakes. It was borderline undriveable for me though.
Yeah, I read about your issue. Very strange indeed! Have you had a chance to sort it out?
 

Gvazquez

Go Kart Champion
Location
North Carolina
Yeah, I read about your issue. Very strange indeed! Have you had a chance to sort it out?
I haven't yet looked into it at all cause I haven't been driving the car lately. I'm gonna take the rear apart soon and order new ss rear brake lines to see if that changes anything.
 

scrllock

Go Kart Newbie
Location
MI
Sounds like the Neuspeed calipers have the same shortcoming as the Macan kit, mismatched piston diameters for your master cylinder sizing. Non-PP GTI has a smaller MC right? PP/R/S3 might be somewhat better. Do you know the piston diameters?
 

GTIfan99

Autocross Champion
Location
FL
Sounds like the Neuspeed calipers have the same shortcoming as the Macan kit, mismatched piston diameters for your master cylinder sizing. Non-PP GTI has a smaller MC right? PP/R/S3 might be somewhat better. Do you know the piston diameters?

No, they all use same MC.
 

emichel6888

Go Kart Champion
Location
TX
The Macan/Q5 calipers piston displacement is not a mismatch (for the Golf R/PP brakes), they are actually very close to the stock caliper displacement. The issue with pedal height is caused by the increased amount of piston retraction. If you have air trapped in your system the manual says to use a pressure bleeder at 30 PSI and bleed both front calipers at the same time. I have used this method and it seems to work well.
 

jmason

Go Kart Newbie
Location
Frederick, MD
If you have air trapped in your system the manual says to use a pressure bleeder at 30 PSI and bleed both front calipers at the same time. I have used this method and it seems to work well.
I performed the bleed at 30 psi. I didn’t bleed both front calipers at the same time. That would require four hoses and bottles!
 

jmason

Go Kart Newbie
Location
Frederick, MD
I'm hoping to install an RS3/TTRS master cylinder and booster over winter.
I haven’t found a part number for the RS3 MC. The online parts all list the GTI MC as a “possible “ fit.
 

emichel6888

Go Kart Champion
Location
TX
I performed the bleed at 30 psi. I didn’t bleed both front calipers at the same time. That would require four hoses and bottles!
Well two bottles and two hoses, you don't have to bleed both sides of the caliper at the same time. I believe the idea is to push fluid through all channels of the MC and ABS unit at once to force out the air. I usually start with the inside caliper pistons and finish with the outside, then the rears one at a time. I use a half gallon of cheap DOT 4, once you are sure you have all the air out then replace with the expensive high temp stuff.
Seems to work well and is a lot faster than repeatedly flushing, driving, and then flushing again. Good luck.
 

Gvazquez

Go Kart Champion
Location
North Carolina
I performed the bleed at 30 psi. I didn’t bleed both front calipers at the same time. That would require four hoses and bottles!
Does that mean you solved the issue you were having? With the pedal to the floor?
 

jmason

Go Kart Newbie
Location
Frederick, MD
Does that mean you solved the issue you were having? With the pedal to the floor?
I didn’t bleed both fronts at the same time, so no, issue remains unresolved.
I did perform some more MC bleed-down tests. I think I’ve concluded the MC is working properly. I guess that leaves air in the system as the culprit.
That said, I’ve thrown in the towel and am taking the car to a shop.
 

jmason

Go Kart Newbie
Location
Frederick, MD
My prediction. They find nothing and tell you it's normal.
Give that man a prize!
Shop performed more bleeds. I had them install SS lines on the rear brakes. Things might be slightly better, not a dramatic improvement I had hoped for. No one thinks the MC needs replacement.

The shop had installed a RS3 MC for a customer, but it didn't seem to match up with the system. It was ultimately removed. So that approach doesn’t seem viable.

So I think I’m at the end of the line. At this point, maybe the problem is between my ears.
 

emichel6888

Go Kart Champion
Location
TX
No it's real, and you can fix it. I already told you how, just turn off the brake booster functions per page one of the Macan thread, then lube the piston seals and add an inline RPV per my post. It cost very little and is not that hard to do. I am telling you it is a night and day difference.

Or as you say just live with a grabby soft lower pedal, not exactly fun or confidence inspiring IMO, but to each his own.
 
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