When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
So this weekend I had my first road course experience with the GTR at Heartland Park Topeka. It was a 'different' type of HPDE weekend in that only 'Advanced' drivers were allowed to take part as the other parts of the weekend was taken up with PCA Cup Racing activities. There were two DE run groups; I was in DE 1 the more 'experienced' group with passing everywhere although only on the left with a point by per the course stewards instructions.
I drove every session in 'Race' mode with ESC 'Off', and with the TC set to the first 'red' marker; so four lights showing iirc.
Here's my thoughts on the car:
Engine:
I have to agree with other reports that the car is putting out more than the 577hp at the engine; it is super fast. When I was ahead of two well driven C7 Z06's I could pull them on the straights, and when I was somewhat close behind them I could reel them in. Granted they were both M7's so with the DCT being so much more 'efficient' as a transmission, it helps in that torque isn't lost during a gear shift, but I was also pulling over 140 mph at the end of 'alpha zero', (an uphill section before the end of the main straight) which is quicker than I ever was in my '15 Z06/7. I would have still been accelerating over the hill, but my 'attachments' aren't that large anymore! lol;
Transmission:
I actually left the transmission in 'Auto' mode for three of my four runs on Saturday whilst I got used to the car. 'Race' mode essentially keeps the engine at 5K-7K rpm the whole time in this setting. It's a fantastic transmission that worked flawlessly, always being in the 'correct' gear even when being lazy and letting it shift for itself. So smooth. In fact it's smoother when left to its own devices than shifting manually at times;
Fluids:
Engine and transmission ran very cool during every session. Granted the ambient was high 60dFs/low 70dFs, but my engine oil never went above 220 dF and the transmission stayed lower than 200dF. This despite the engine being in the upper extremes of the rpm band at all times on track. Such a contrast to my Z06/7 A8 which was always an exercise in temperature management re: engine oil/water temps;
Tyres:
So this I think is the 'weak link' of the car; specifically the front tyres. I just don't think there's enough rubber there tbh. I was using the OEM MPSC2s btw. I started every session with the rears at 26 psi and they never went above 35 psi, and most times remained at 33 psi. I felt I had excellent grip at the rear even though I forgot to adjust the angle of the rear wing for more downforce because I'm a dumbass. But the front would get to 38-41(!) psi regardless of where I was setting the cold pressures. Hence after about 5 laps the front grip really started to 'go away', and I had to back off. I never experienced extreme understeer (push) luckily.
So the car really needs to have the MPSC2 ZP tyres (R03 option in the ROW) installed on it which not only put more rubber to the road, but it's more of a track compound. These will I'm sure lower the track times around 2-3 seconds/lap as well as not 'give up' as fast as the OEM SC2s. Even better of course would be a dedicated 18"/19"(?) track wheel/tyre setup with some Hoosier R8's installed if they are made in the correct sizes. (Christ I wish BBS would make some CCH wheels for this car ASAP to increase our choices).
Regardless I have a lightly used set of the MPSC2 ZP tyres left over from my Z06/7, and I'm going to have them installed on the OEM wheels the next time I head to the track so hopefully that will help.
Brakes:
Iron brakes: If you have these and have ever gone to the track before, or if you enjoy high performance driving in other areas, you know that you have to 'bed-in the brakes in order for them to actually work to their maximum. You can read about this on various brake sites if you haven't done it before such as Essex and Stoptech.
CCM brakes:
This is where I think MB have done us a grave mis-service in not telling those of us with the CCMs to do the following: Burnish the brakes before you do any really high performance driving.
This can be done two ways: find a deserted straight road and do a series of hard, 50 to 60 of them!, braking maneuvers from 60 mph down to around 5 mph without engaging ABS. This is nauseating tbh, but it is one of the only ways to condition the brakes for a heavy duty cycle. The pads will smoke like hell, but this is normal.The other way to perform the burnishing procedure which IMHO MUST be done is to do it at the road course, which is what I did. On your first run session you get progressively faster each lap until you start to notice that the brakes are 'fading'. At this time you must pit, or you can lose the ability to rapidly stop pdq!
This is super important every time you come off track, but especially the first time: Do NOT drive to your paddock area and stop the car. Drive around within the paddock if the track allows you to, to cool off every component of the car, and especially the brakes after this initial burnishing procedure. A great way to do this is to exit the track and drive somewhere to get fuel on a highway, BUT do not use the brakes unless you have to as you need them to cool completely from the track temps. Then park the car and allow the brakes to get cold. When done correctly the pad at the pad/rotor interface will obtain a white, ash looking appearance. This is what a burnished CCM pad looks like when done correctly btw, and I'll post a couple of pix of my F and R brakes for illustration purposes.
Lastly and again this is SUPER important: NEVER allow the car to automatically engage the Parking brake when you stop after coming off of the track even with a cool down period. Just place the transmission in 'P', and then pull the parking brake handle towards you as you shut down the car. This will prevent the parking brake from engaging, and IF the parking brake in these cars work off of the rear discs, it will stop the rear pads in particular from being baked and potentially ruined from the extreme heat of being applied to a super hot CCM rotor.
My brakes after doing the burnishing procedure above worked great on track, even though I noticed some slight extra compliance of the brake pedal after a couple of 'hot' laps. This wasn't due to overheating the OEM brake fluid as I'd switched ti to Castrol SRF, but rather I think is due to the OEM CCM pads being more street/rotor friendly versus being track oriented. Hopefully we'll have more options soon.
BTW: I did four 'fast' 25 minute sessions on Saturday and I have toms of brake pad material left;
Electronics:
As I said I ran in 'Race' mode with ESC 'Off' and with TC set on the 4th-5th setting. The car was super stable running it without any 'nannies', but I did work my way up slowly speed wise over a couple of sessions, and the rear was easy to catch in this fashion.
One really interesting item: in the above settings the 'Active Brake Assist' (ABA) is NOT active. Now you have to have ESC 'Off', but when you do there is no need to go to 'Settings' and deactivate 'Active Brake Assist' since it is unavailable. You can not even turn it back on. Further I know it wasn't working in the background, as at no time did the car try to slow itself down even when I was on the bumper of a car in front and had been gaining at a decent rate of speed. This is the way the car should be set-up: if in 'R' mode with ESC 'Off' and TC active it's pretty obvious you shouldn't be on a public road, so ABA doesn't need to be on. (I'd be interested to see if those of you with early '18 built cars have the firmware set-up the same way from the factory, or whether there had been some kind of change).
Sorry for the length of the post, and if you don't ever intend to 'track' the car it could well be meaningless for you except I would 'bed-in' your brakes. BTW: my brakes were always a little 'grabby' when coming to a complete halt prior to burnishing them. Now they are super smooth and so easy to modulate on the street. That alone makes it worthwhile doing.
Bish
Rear pad after burnishing; not as easy to see as the fronts. Sorry.
Great post Bishman - those that actually track the car should find this interesting and helpful, thank yuo for your time to share with the community. I am still a die hard steel brake person for track use, but those that are outfitting their cars with ccm will, or at least should, love the input you provide.
Do you only have 4 sessions on the GTR at this point? I think I had about 12 (30 minute sessions before I started noticing issues). From instructions from the ADA, over 7 laps you have to do 1-2 cool down laps and then let her sit and make damn sure the BRAKE is off, which is a PITA to disengage correctly every time, IMO when you park the car in RACE it should just not activate the parking brake.
Do you only have 4 sessions on the GTR at this point? I think I had about 12 (30 minute sessions before I started noticing issues). From instructions from the ADA, over 7 laps you have to do 1-2 cool down laps and then let her sit and make damn sure the BRAKE is off, which is a PITA to disengage correctly every time, IMO when you park the car in RACE it should just not activate the parking brake.
5 sessions; four of which were at real speed.
Did you ‘burnish’ the pads prior to use?
Regardless I think that given these OEM pads, twelve 30 minute sessions is all you could expect out of them as that’s a lot of track time. After my next track weekend in about a month I’ll have about 12 sessions in total on the car and at the very least I’ll be pulling the pads to check on their condition due to your experience and the amount of use on them at the time.
Since these pads aren’t durable (soft) I’d double down on the statement re: extensively cool down the car prior to parking it after coming off track, and even if you don’t engage the parking brake, just the front and rear pads sitting so close to a massively hot heat sink (rotor) is going to cause them thermal stress unless you take the effort to cool everything.
I copied the following over from the Z06 section of the Corvette forum. It gives a fantastic explanation of why the burnishing procedure is so important to do on a CCM equipped car. Thanks to JVP over there for a fantastic write-up!
Why do I have to burnish the brake pads in my new ZR1 or Z07-equipped Z06?
Pad Burnishing
The pad material that's attached to the pad backing is made by pouring a slurry of muck into a mold and letting it set. That slurry of muck includes a bonding agent, or glue of sorts. That agent needs to be there, but it will cause a problem if the pads get overly hot.
When a non-burnished pad gets hot (I don't know the exact temp), the bonding agent will begin to out-gas and boil off. What happens with that gas is that it forms a barrier between the pad and the rotor. An air cushion of sorts. And an air pocket pressing against a spinning rotor is not as effective at stopping the car as a pad pressing against it.
The driver experiencing this will note that the pedal will get somewhat soft and resist slightly when they try to slow the car down. Simply pressing the pedal harder will force the air pocket to evacuate, and the pad will then come into contact with the rotor.
This unsettling feeling is called green fade. It feels like the pad is fading, but it isn't. The car will stop, but it takes a harder pedal press to make that happen.
Thus the burnishing procedure. The stops in question need to be done sans ABS, ie threshold braking the car, so that a constant pressure is kept on the pad during the stop. This is to help build up the heat in the pad. The goal here is to bake off the top layer of bonding agent from the pad so that an air pocket forming becomes impossible or highly unlikely.
GM has determined that, on average, it takes 50 60-0 stops in 10 minutes' time to get the pads hot enough for that. Basically what you're looking for is the pad to start fading bad during the procedure. That generally happens around stop 40 or so, when braking distances feel like they're increasing dramatically. Once this point has hit, the gasses are beginning to boil off. A few more stops after that point and the brakes will feel like they're grabbing before you even touch the pedal. At that point: you're done. Drive the car for a while at legal speeds to cool the pads.
Why not bake ALL of the bonding agent out? Well, if you do that, the entire pad will fall apart. That's not a good idea, right? Instead, the pad will continue to slowly boil off the rest of the bonding agent over time as you wear the pad down. You'll never notice it happening though.
How do I know I've done it right?
As described in the owners manual, once you've correctly burnished the pads, you'll see a white outline around the edge of the pad, right where it meets the rotor. It'll look something like this:
What's the track burnishing procedure for?
The street burnishing procedure is to prevent green fade, as described above. Your owners manual also describes a track burnishing procedure, which has you perform a series of 7 or 8 laps at your local road course, and then park the car after a cool-down lap. The first few laps should be done at increasing speed, and the last few should be done at slower and slower speeds.
Why do this? To further season the pads for high-temp use. The street burnishing preps the pads, and is enough for cars that are only driven on the street. But those that see continued high temps (ie, high speeds) at the track will need to perform this procedure after they perform the street one.
But I never drive my car really fast. Do I need to do the burnishing?
There's a lot of miss-information out there that the street burnishing procedure only needs to be performed if you're going to race or track your car. That statement needs to clarified carefully, to: if ALL you do is drive your car on the street and highways at legal speeds and NEVER intend to carve canyons, drive quickly up or down a mountain road, or perform high-speed runs (legal or otherwise), then you don't need to perform the burnishing. However, if there's even a remote possibility that you will do any of those things, it'd behoove you to at least perform the street burnishing.
Failing to do that with pads that get heated up will likely result in green fade, and a very uncomfortable driver.
So this weekend I had my first road course experience with the GTR at Heartland Park Topeka. It was a 'different' type of HPDE weekend in that only 'Advanced' drivers were allowed to take part as the other parts of the weekend was taken up with PCA Cup Racing activities. There were two DE run groups; I was in DE 1 the more 'experienced' group with passing everywhere although only on the left with a point by per the course stewards instructions.
I drove every session in 'Race' mode with ESC 'Off', and with the TC set to the first 'red' marker; so four lights showing iirc.
Here's my thoughts on the car:
Engine:
I have to agree with other reports that the car is putting out more than the 577hp at the engine; it is super fast. When I was ahead of two well driven C7 Z06's I could pull them on the straights, and when I was somewhat close behind them I could reel them in. Granted they were both M7's so with the DCT being so much more 'efficient' as a transmission, it helps in that torque isn't lost during a gear shift, but I was also pulling over 140 mph at the end of 'alpha zero', (an uphill section before the end of the main straight) which is quicker than I ever was in my '15 Z06/7. I would have still been accelerating over the hill, but my 'attachments' aren't that large anymore! lol;
Transmission:
I actually left the transmission in 'Auto' mode for three of my four runs on Saturday whilst I got used to the car. 'Race' mode essentially keeps the engine at 5K-7K rpm the whole time in this setting. It's a fantastic transmission that worked flawlessly, always being in the 'correct' gear even when being lazy and letting it shift for itself. So smooth. In fact it's smoother when left to its own devices than shifting manually at times;
Fluids:
Engine and transmission ran very cool during every session. Granted the ambient was high 60dFs/low 70dFs, but my engine oil never went above 220 dF and the transmission stayed lower than 200dF. This despite the engine being in the upper extremes of the rpm band at all times on track. Such a contrast to my Z06/7 A8 which was always an exercise in temperature management re: engine oil/water temps;
Tyres:
So this I think is the 'weak link' of the car; specifically the front tyres. I just don't think there's enough rubber there tbh. I was using the OEM MPSC2s btw. I started every session with the rears at 26 psi and they never went above 35 psi, and most times remained at 33 psi. I felt I had excellent grip at the rear even though I forgot to adjust the angle of the rear wing for more downforce because I'm a dumbass. But the front would get to 38-41(!) psi regardless of where I was setting the cold pressures. Hence after about 5 laps the front grip really started to 'go away', and I had to back off. I never experienced extreme understeer (push) luckily.
So the car really needs to have the MPSC2 ZP tyres (R03 option in the ROW) installed on it which not only put more rubber to the road, but it's more of a track compound. These will I'm sure lower the track times around 2-3 seconds/lap as well as not 'give up' as fast as the OEM SC2s. Even better of course would be a dedicated 18"/19"(?) track wheel/tyre setup with some Hoosier R8's installed if they are made in the correct sizes. (Christ I wish BBS would make some CCH wheels for this car ASAP to increase our choices).
Regardless I have a lightly used set of the MPSC2 ZP tyres left over from my Z06/7, and I'm going to have them installed on the OEM wheels the next time I head to the track so hopefully that will help.
Brakes:
Iron brakes: If you have these and have ever gone to the track before, or if you enjoy high performance driving in other areas, you know that you have to 'bed-in the brakes in order for them to actually work to their maximum. You can read about this on various brake sites if you haven't done it before such as Essex and Stoptech.
CCM brakes:
This is where I think MB have done us a grave mis-service in not telling those of us with the CCMs to do the following: Burnish the brakes before you do any really high performance driving.
This can be done two ways: find a deserted straight road and do a series of hard, 50 to 60 of them!, braking maneuvers from 60 mph down to around 5 mph without engaging ABS. This is nauseating tbh, but it is one of the only ways to condition the brakes for a heavy duty cycle. The pads will smoke like hell, but this is normal.The other way to perform the burnishing procedure which IMHO MUST be done is to do it at the road course, which is what I did. On your first run session you get progressively faster each lap until you start to notice that the brakes are 'fading'. At this time you must pit, or you can lose the ability to rapidly stop pdq!
This is super important every time you come off track, but especially the first time: Do NOT drive to your paddock area and stop the car. Drive around within the paddock if the track allows you to, to cool off every component of the car, and especially the brakes after this initial burnishing procedure. A great way to do this is to exit the track and drive somewhere to get fuel on a highway, BUT do not use the brakes unless you have to as you need them to cool completely from the track temps. Then park the car and allow the brakes to get cold. When done correctly the pad at the pad/rotor interface will obtain a white, ash looking appearance. This is what a burnished CCM pad looks like when done correctly btw, and I'll post a couple of pix of my F and R brakes for illustration purposes.
Lastly and again this is SUPER important: NEVER allow the car to automatically engage the Parking brake when you stop after coming off of the track even with a cool down period. Just place the transmission in 'P', and then pull the parking brake handle towards you as you shut down the car. This will prevent the parking brake from engaging, and IF the parking brake in these cars work off of the rear discs, it will stop the rear pads in particular from being baked and potentially ruined from the extreme heat of being applied to a super hot CCM rotor.
My brakes after doing the burnishing procedure above worked great on track, even though I noticed some slight extra compliance of the brake pedal after a couple of 'hot' laps. This wasn't due to overheating the OEM brake fluid as I'd switched ti to Castrol SRF, but rather I think is due to the OEM CCM pads being more street/rotor friendly versus being track oriented. Hopefully we'll have more options soon.
BTW: I did four 'fast' 25 minute sessions on Saturday and I have toms of brake pad material left;
Electronics:
As I said I ran in 'Race' mode with ESC 'Off' and with TC set on the 4th-5th setting. The car was super stable running it without any 'nannies', but I did work my way up slowly speed wise over a couple of sessions, and the rear was easy to catch in this fashion.
One really interesting item: in the above settings the 'Active Brake Assist' (ABA) is NOT active. Now you have to have ESC 'Off', but when you do there is no need to go to 'Settings' and deactivate 'Active Brake Assist' since it is unavailable. You can not even turn it back on. Further I know it wasn't working in the background, as at no time did the car try to slow itself down even when I was on the bumper of a car in front and had been gaining at a decent rate of speed. This is the way the car should be set-up: if in 'R' mode with ESC 'Off' and TC active it's pretty obvious you shouldn't be on a public road, so ABA doesn't need to be on. (I'd be interested to see if those of you with early '18 built cars have the firmware set-up the same way from the factory, or whether there had been some kind of change).
Sorry for the length of the post, and if you don't ever intend to 'track' the car it could well be meaningless for you except I would 'bed-in' your brakes. BTW: my brakes were always a little 'grabby' when coming to a complete halt prior to burnishing them. Now they are super smooth and so easy to modulate on the street. That alone makes it worthwhile doing.
Bish
Rear pad after burnishing; not as easy to see as the fronts. Sorry.
Front brake pad showing 'burnishing'
Front brake pad post burnishing
Rear pad post burnishing
Awesome write up Bishman! Crazy to hear you were pulling on C7 Z06's in the straights. Goes to show what a beast this car truly is.
Originally Posted by sroumeliotis@eurogermantown.com
Awesome write up Bishman! Crazy to hear you were pulling on C7 Z06's in the straights. Goes to show what a beast this car truly is.
It’s a fantastic drivetrain for sure. In the corners the Z06’s were faster, so faster than me over the course of a lap, but it was my first time with the car.
It’s a fantastic drivetrain for sure. In the corners the Z06’s were faster, so faster than me over the course of a lap, but it was my first time with the car.
Bish
I bet as you get used to the car and switch to the corvette tires, you will be faster in the corners.. glad everything held up so well on your track day
"50 60-0 stops in 10 minutes' time" seems like an awful lot. Tough to find an abandoned road that will allow a driver to do 50 stops on the street.
There was a similar recommendation to solve the squeaky noise from my Ferraris' CCBs but those recommendations involved braking hard enough to activate ABS and were only a few hard 60-0 mph stops rather than the 50 recommended for proper burnishing of brakes.
"50 60-0 stops in 10 minutes' time" seems like an awful lot. Tough to find an abandoned road that will allow a driver to do 50 stops on the street.
There was a similar recommendation to solve the squeaky noise from my Ferraris' CCBs but those recommendations involved braking hard enough to activate ABS and were only a few hard 60-0 mph stops rather than the 50 recommended for proper burnishing of brakes.
Yea you just have to find a long road.. Get up to 60 and back down.. Up to 60 and back down.. Over and over.. You will definitely get queasy from the movement and sudden stops.. Not to mention the smell from the brakes..
I've done it a lot.. It never gets better lol
BTW you really don't want to do it so hard that abs gets activated.. But enough that it's generating good heat..
Hi Dave
Great write-up and glad to hear how well the car performed on track. Question re the rear brake pads: from the photos it appears that the pads leave a significant band of rotor area (relative to the fronts) on the inner edge untouched. Are these stock pads? If so, it would be interesting to learn why Mercedes designed that way - F-R brake balance or some other reason.
Yea you just have to find a long road.. Get up to 60 and back down.. Up to 60 and back down.. Over and over.. You will definitely get queasy from the movement and sudden stops.. Not to mention the smell from the brakes..
I've done it a lot.. It never gets better lol
BTW you really don't want to do it so hard that abs gets activated.. But enough that it's generating good heat..
Hi Dave
Great write-up and glad to hear how well the car performed on track. Question re the rear brake pads: from the photos it appears that the pads leave a significant band of rotor area (relative to the fronts) on the inner edge untouched. Are these stock pads? If so, it would be interesting to learn why Mercedes designed that way - F-R brake balance or some other reason.
Yes I noticed the same thing, but I’m assuming the brake engineers calculated that that amount of swept rotor area was all the car needed for the system to be balanced, since the fronts do so much more of the braking activity versus the rears. I do wonder if the rear rotor was still designed to be as large as it is even with all of the unused area so as not to make the rear disc look ‘puny’ versus the front, upsetting the ‘look’ of the car?
Honestly this just seems like nonsense, I've had multiple Porsches with ceramic brakes and no one in that community has ever mentioned pad burnishing. I never did anything like that in my cars and I could go out in the GT3 and brake as hard as I possibly could, lap after lap after lap with no issues and no excessive pad wear.
The procedure you describe is just "getting the brakes hot", this happens anyway! My pads also have white marks on them...
There are track burnishing procedures that can be done vs the street procedure..
Even when you buy aftermarket pads like carbotechs, they come with a burnish (or bedding) procedure. It's always been common practice to do before high performance events
Honestly this just seems like nonsense, I've had multiple Porsches with ceramic brakes and no one in that community has ever mentioned pad burnishing. I never did anything like that in my cars and I could go out in the GT3 and brake as hard as I possibly could, lap after lap after lap with no issues and no excessive pad wear.
The procedure you describe is just "getting the brakes hot", this happens anyway! My pads also have white marks on them...
”Nonsense” is a strong and strange term to use for a procedure, both ‘Street’ burnishing and ‘Track’ burnishing, that is mentioned in the manual of the C6 and C7 Corvette Z06 for those versions of the car that are ordered with CCM brakes.
An owner can probably drive the car to C & C and do the occasional high speed stop without ever bothering with one of the above procedures, and be none the wiser. But if you want to enhance the braking performance of your car without experiencing pad fade either during multiple high speed stops; driving aggressively down mountain switchbacks; driving on a road course, etc., then following the above is worth the time and energy.
Since you track your GTR you’ve managed to do the track burnishing procedure; luckily without enduring severe fade prior to the end of your first session; good for you.
04-29-2018, 06:58 PM
