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2017 GTi PP at VIR

victorofhavoc

Autocross Champion
Location
Kansas City
I'm not sure how the css bumper would affect the rotor temp, but I think they have extra airflow for the auxiliary heat exchangers mounted in front of the wheel well. What I do know is that we need more airflow through the main heat exchanger stack and all the airflow there is precious. I'm rethinking siphoning air from there for the brakes and going back to looking at my naca duct design we talked about. There's a lot of air that gets trapped in the wheel well, and there's really no room for fender louvres (I'm going louvre crazy over here, lol), so lowered ride height is pretty helpful there.

I'm really not sure why I'm getting fewer bubbles with booster being higher. They're not totally gone, but I can at least make it through most of the day without the pedal going to the floor.

I had the booster set at 5 stock and offset was 5 as well i think. My understanding is that the booster just provides extra pressure per pedal movement while offset delivers the final pressure. This would mean that a setting of 5 and 8 comes to a difference of 3 to have the booster increase pressure by that arbitrary value until pedal floor. Keep in mind pedal floor is far below end of realistic pedal travel to account for fluid loss, fade, etc. By moving to a value of 1 for booster and 4 for offset you'd have the pressure increase be the same, but just less pressure through the system as a whole. This would result in a longer pedal from a lower floor, but the same overall "feel". Going to 1 and 8 (what I was at before), resulted in a shorter pedal with less upfront pressure and a higher floor. With current setting being 4 and 8 I have more upfront pressure, a slightly lower floor, and a more even pressure throughout. It's definitely something to experiment with as it dramatically changes feel on track, but it's hard to summarize without "feel".

Maybe it's the extra pressure that raises the boiling point of the fluid just enough? Fluids under pressure have greater boiling points after all... Otherwise our radiators would kaboom all the time...

That's a good question on rear bias, and not one I can clearly answer as I'm still running the r8 rears that came with the non pp pad shape accidentally, so my rear rotors are getting less torque than usual. It has not drastically affected my trail braking though. I did go slightly more toe in in rear, and I hate it so I'll be backing out even more toe than before (I might just aim for 0 if it can be achieved, but I think the -2 camber might limit it).
 

Mini7

Autocross Champion
Location
Charlotte, NC
Car(s)
2017 GTi Sport PP
I do not know where the ducted air dumps into from the brake ducts. I’m assuming it going into the wheel fender somewhere. The opening of the CSS bumper is significantly larger than the regular GTi. I need to check how much a new AC coil costs because mine is all beat up and must be restricting airflow through all the heat exchangers.

“With current setting being 4 and 8 I have more upfront pressure, a slightly lower floor, and a more even pressure throughout. It's definitely something to experiment with as it dramatically changes feel on track.”

I will go back to stock settings and give it a try. As long as I can add pedal pressure and get a linear increase in retardation and not a spike that pushes me into the ABS zone. Just checked my VCDS spreadsheet. You are referring to the Hydraulic Brake Booster which is set at 8 as standard. Again I made multiple VCDS changes for an overall positive improvement. Switching off the “Straight Ahead Brake Stabilization” is most probably the biggest improvement overall. I will most probably reduce my rear toe in from -.24 to -.12 overall to help with rotation through the corners. I’m sure this will make the two big brake zones at VIR interesting with a “loose” rear. Plus I will have a more aggressive rear pad from PowerBrake. I may need to rework my trail-braking technique when I finally make it back to the track.

I have 034 adjustable rear toe links. How are you adjusting toe?
 

pseudorealityx

Go Kart Champion
Location
Decatur, GA
Car(s)
2017 GTI SE
Why run any toe-in in the rear with it being adjustable?

In my head, I've always liked zero toe. I like to use rear toe as a last resort for tuning a suspension, unless limited by a competitive classing requirement. I typically think there's a positive to dragging tires if you don't need to.
 

Mini7

Autocross Champion
Location
Charlotte, NC
Car(s)
2017 GTi Sport PP
Don’t have any rules to abide by.

Run HPDE at VIR. I look for predicable handling and whatever can gain me time on the stopwatch. Zero rear toe will make the car as loose as a goose. Not bad for the slow-medium corners but there are some fast momentum corners like the uphill esses, T-10, where you do not want the car to be loose.

I will work up to that in increments so I can get used to the change.
 

Mini7

Autocross Champion
Location
Charlotte, NC
Car(s)
2017 GTi Sport PP
Gordan, Just got confirmation that the 350x34 6-piston PowerBrake BBK will clear the 17x9 ET42 Apex wheels.

Woohoo!

So a larger heavier rotor is in my braking future. 😉
 

pseudorealityx

Go Kart Champion
Location
Decatur, GA
Car(s)
2017 GTI SE
Don’t have any rules to abide by.

Run HPDE at VIR. I look for predicable handling and whatever can gain me time on the stopwatch. Zero rear toe will make the car as loose as a goose. Not bad for the slow-medium corners but there are some fast momentum corners like the uphill esses, T-10, where you do not want the car to be loose.

I will work up to that in increments so I can get used to the change.

Understood. For most transitional movements, damping would be my initial go-to to keep the car settled. But I've never driven VIR, only watched various in-car.
 

Mini7

Autocross Champion
Location
Charlotte, NC
Car(s)
2017 GTi Sport PP
VIR is a super fun track to run. Highly recommended. 3 long straights, if you count the uphill esses as a straight. Some technical section. Relatively safe with good run-off areas in most places.


How far is Decatur from Road Atlanta? Most probably will head down to Road Atlanta next year.
 

Autobahn

Autocross Champion
Location
Huntington Beach, CA
Car(s)
'18 Golf R
Gordan, Just got confirmation that the 350x34 6-piston PowerBrake BBK will clear the 17x9 ET42 Apex wheels.

Woohoo!

So a larger heavier rotor is in my braking future. 😉

Any info on the new Powerbrake kits? Been slightly interested in them along with Trophy kit, still pondering. I do know I want to stay in the 350mm range
 

pseudorealityx

Go Kart Champion
Location
Decatur, GA
Car(s)
2017 GTI SE
VIR is a super fun track to run. Highly recommended. 3 long straights, if you count the uphill esses as a straight. Some technical section. Relatively safe with good run-off areas in most places.


How far is Decatur from Road Atlanta? Most probably will head down to Road Atlanta next year.

VIR is on my to-do list.for sure.

I'm just over an hour from Road Atlanta and about 90 min from Atlanta Motorsports Park. While slower, I really like the flow and constant action of AMP. Don't dismiss it.
 

Mini7

Autocross Champion
Location
Charlotte, NC
Car(s)
2017 GTi Sport PP
Any info on the new Powerbrake kits? Been slightly interested in them along with Trophy kit, still pondering. I do know I want to stay in the 350mm range

Not a whole lot at this point. I’m told they are going to an internal crossover tube and shaving dimensions to make for a more compact profile. I’m assuming to make it easier to package into a 17” wheel. You’re getting a Motorsport spec BBK at a reasonable price point. Comparable features to the AP Essex BBK but at a lower price point. Similar pricing to the Trophy spec Stoptech but with a 6-piston caliper and larger pad profile. I do not believe they Stoptechs have the castellated pistons of the AP and PowerBrake calipers.

Covid shutdowns has impacted the go to market timing. The quality of the PowerBrake components is great. My choice of 17” Track wheels restricted me to the smaller 4-piston option. With Apex designing a purpose built track wheel for the MQB platform, it has opened up the option for me to go to the larger BBK.

The Trophy spec BBK is a great option as well.
If you track on a regular basis and are more experienced, then a BBK is a pre-requisite IMHO. PP brakes are not up to the task.
 

victorofhavoc

Autocross Champion
Location
Kansas City
If you track on a regular basis and are more experienced, then a BBK is a pre-requisite IMHO. PP brakes are not up to the task.

You know I'm still going to add ducting since I think the big issue is airflow. We'll see if the PP setup holds up any better then. With the 2000 degree pad, I still got it hot enough to glaze. I'm curious to see how much the ducting will help, since all of my local mechanics are recommending that route before a BBK. Somebody has to Guinea pig things!! :D
 

Autobahn

Autocross Champion
Location
Huntington Beach, CA
Car(s)
'18 Golf R
Not a whole lot at this point. I’m told they are going to an internal crossover tube and shaving dimensions to make for a more compact profile. I’m assuming to make it easier to package into a 17” wheel. You’re getting a Motorsport spec BBK at a reasonable price point. Comparable features to the AP Essex BBK but at a lower price point. Similar pricing to the Trophy spec Stoptech but with a 6-piston caliper and larger pad profile. I do not believe they Stoptechs have the castellated pistons of the AP and PowerBrake calipers.

Covid shutdowns has impacted the go to market timing. The quality of the PowerBrake components is great. My choice of 17” Track wheels restricted me to the smaller 4-piston option. With Apex designing a purpose built track wheel for the MQB platform, it has opened up the option for me to go to the larger BBK.

The Trophy spec BBK is a great option as well.
If you track on a regular basis and are more experienced, then a BBK is a pre-requisite IMHO. PP brakes are not up to the task.

Thanks for the info, sounds like a good product based on feedback I’m seeing online.

I’m used to braking deep into the apex coming from my previous platform, MKV R. I was using Carbotech XP20 with RacingBrake 4 piston 345 mm BBK with vented stainless pistons and Pirelli takeoff slicks. You need a lot brake for heavy grip. Looking for a similar brake setup on my Golf R after I get my Clubsports installed with a slightly less aggressive pad to go with R comps
 

Mini7

Autocross Champion
Location
Charlotte, NC
Car(s)
2017 GTi Sport PP
You know I'm still going to add ducting since I think the big issue is airflow. We'll see if the PP setup holds up any better then. With the 2000 degree pad, I still got it hot enough to glaze. I'm curious to see how much the ducting will help, since all of my local mechanics are recommending that route before a BBK. Somebody has to Guinea pig things!! :D
No question that cooling air will help with brake reliability and extend pad and rotor life. You are just pushing out the inevitable.
You will be more consistent and faster with a BBK over a PP setup. PP will not handle slicks.
 

Mini7

Autocross Champion
Location
Charlotte, NC
Car(s)
2017 GTi Sport PP
Thanks for the info, sounds like a good product based on feedback I’m seeing online.

I’m used to braking deep into the apex coming from my previous platform, MKV R. I was using Carbotech XP20 with RacingBrake 4 piston 345 mm BBK with vented stainless pistons and Pirelli takeoff slicks. You need a lot brake for heavy grip. Looking for a similar brake setup on my Golf R after I get my Clubsports installed with a slightly less aggressive pad to go with R comps

I dropped 2-seconds at VIR on brakes alone. Was super consistent with laptimes. There is something to be said for being confident in your equipment. Didn’t have to do courtesy bleeds during the day between sessions to keep a firm pedal. Like I had to with PP brakes. Backing off halfway through a session because the brake pedal gets longer and longer. Not fun. PowerBrake made a strong recommendation to go with their 350x34 BBK. I chose to go smaller because I was committed to 17” track wheels/tires. Brake ducts will extend rotor and pad life, even for a BBK.

The winning 2019 Dakar rally car had PowerBrake water cooled BBKs. They know there stuff when it comes to brakes.
 

victorofhavoc

Autocross Champion
Location
Kansas City
No question that cooling air will help with brake reliability and extend pad and rotor life. You are just pushing out the inevitable.
You will be more consistent and faster with a BBK over a PP setup. PP will not handle slicks.
I'm not so sure. 50 min+ sessions, no doubt the BBK will keep more consistent, but spec e46 cars often run similar weight and smaller brakes. They're significantly better balanced though. For 50 min sessions I would move to an endurance pad that trades some friction and start temp for wider and flatter temp range.

With R16 pads and PP brakes i can lock my yoko a052 at almost any point, and I bet they'll lock slicks too. It's not like a BBK increases clamping pressure, it just distributes it better across the pad/rotor.
 
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