descartesfool

After going through the break-in period by the book and putting on enough mileage to get it to the track point of 2400 km (1500 miles), I got to experience what a good car the Z51 is on the track. It took me the first warm-up lap and about a 1/2 lap more to see that this car has been tuned and designed to run on road racing courses. It just felt totally at home carving corners, braking deep and powering out onto the straights. My Z51 has the 7 speed manual and magnetic dampers. Tires were the OEM Pilot Super Sports

I first partially prepped the car as recommended on the track prep sheets:

1. Mobil 1 15W-50 oil, 1/2 litre above the top fill mark
2. Racing brake fluid: Castrol SRF Racing
3. Tire pressure to 26 psi all around
4. Set to Track mode, with Performance Traction management to Sport 2 (last one below Race mode) for the entire day
5. Bed the brakes on the way to the track with 6 medium stops to warm the rotors and then 7 hard stops to bed the pads followed by long drive cooldown.

Also changed the front pads to Hawk DTC-60's, but had no racing pads on hand for the rear, so left those stock. Scheduling issues meant I did not have time to get the track alignment done, so that was stock as well.

Took the car to my local track, Calabogie Motorsports Park, which I know extremely well as I have done hundreds of laps there since 2007 with about 10 track days per year there. Sky was mostly clear and temp was 28C (82F). Set up my Race Technology DL1 data logger and GoPro. Event has a ton of track time with seven 30 minute sessions, for a total of 3.5 hours flag to flag. I did not run every single minute, but probably got in 3 hours track time, and there were not many cars that day since it was the Canadian Grand Prix race in Montreal, with many people staying home to watch. But I would rather drive.

First session out at 9:00 AM feeling a little tentative and wondering how the car will behave at the limit. On the out lap the car is feeling strong and steady, good torque and brakes are working well. Start of first hot lap and I push the car pretty hard as I know the line and have run 3 different cars there over the years, and it just feels fantastic. I am smiling and thinking this is going to be a fun day. On every session I am learning the limit a little better. Car never really steps out, which is what had me worried most, with all the torque available. Rear end is panted and it doesn't do anything funny as you push hard off the apex. Only in a couple of spots does the rear end get light and that is over two crests. So I adjust my line a bit on the next sessions there so I can go full throttle over the crests without worrying about what the rear end is doing. Not sure if it is the PTM intervening or just the era end getting light or the LSD setting, but I gained more confidence with it as the day went on. I was able to push the car harder as the day went on, and while there were not too many cars on track, the only non race-car that was faster than me was a C6Z06 running on a set of fresh Hoosier R6's. I could kind of keep him in my sights for about 6 laps and we had a blast together, but he just had much more corner speed with those Hoosiers, and I could not quite keep up. I figure he was about 1 second a lap faster than me by how far he was gapping me in 2 sessions we ran close together. As I was pushing harder, I got the car to slide a bit and it felt really good and controllable. I am a very experienced track driver and usually in the top 5% in terms of lap time, and what I like to do is lap as fast as possible and set consistent lap times lap after lap. Another positive with my Z5 is that I could trail brake easily into corners without any wiggles or other nasty behaviour, which helps to get a good rhythm going. So al in all I was very impressed with the car on track, and it put a definite smile on my face.

And now the bad:

1) Got an engine check light. No idea yet what that is about.

2) Manual transmission overheats big time. Got it into the red zone for all sessions except the first one, with it at 150C (300F). Temp did not come down quickly, and in the cool down lap it just stayed in the red zone. Only with the cooldown over lunch did it get fully down to normal before going out. Sessions were 30 minutes on, 30 minutes off. Engine oil did not overheat and that was OK, and engine did not consume oil.

3) Coolant temp gauge was not in the red, but getting pretty close, with needle going up near the end of the gauge at the end of a session. Temp would come down very quickly though.

4) Front tires are almost toast. The centre of the left front is all scuppered with one side of the tread block down to the inner groove level, and the right front is not looking to good either. Pressure was a per GM's track setting, but alignment was stock. Still did not expect to wreck my front tires in one day at the track. I have 2 days with long road trip to VIR planned in 2 weeks. Can't see how that is going to work out with tires wrecked in one day on track. Have ordered some Nitto 315/30/18's, but can't drive on a long road trip with those.

5) Rear OEM pads are toast. They even started growling on my way home as the pad wear indicator must have been touching the rotor. Rotors look good, no issues, and front Hawk DTC pads look good. Hawk does not yet make track pads for the far, but based on my day, need race pads in the back as well. Forget the OEM pads for the track if you drive fast.

6) At the end of the day when I went to see the event organizer to say goodbye, with the car at idle, it started to make some really weird noise from the back end. Could not tell what it was. We got down to look and listen, and were wondering if it was the tranny, diff or mufflers making the noise. All we said to each other is that we were glad the car was under warranty. Noise eventually did go away.

7) AC stopped working. Well for a long while at least. I was getting really hot so between sessions I would let the car run for a while to cool it down with the AC on to cool the cockpit down. It worked until the end of the day and then just quit, blowing really hot air from the vents. I went for dinner after the track day with a buddy, and it was still not working on the way there. But it did start to work on the way back home. Not sure what is u with that.

8) Driving home in Eco mode on the highway, half way there is a loud banging type sound from behind me every second every time the car goes into V4 mode, which goes away a few seconds after car goes back into V7 mode. I switch modes a few times to see if it is just the V4 mode that causes it, and it seems to be that. I then go back to ECO mode, and it starts gain, so I go into touring mode, and banging does not stop this time. Now I am home.

So it was a bit of bliss and a bit of misery. Really, really liked the car's performance on track, but very disappointed with the issues all in one day. Trashed tires, trashed rear pads, overheating tranny, funny noises, engine check light, etc. Car is not truly track worthy like a GT3 for example. Not sure what to do next except take it to dealer for some fixes, but that will not get me new tires, new brake pads or better transmission cooling. Gm needs to make this car better if they want to pretend it is track worthy

leadville1

Well this is a very good honest assessment of the car. I am puzzled by several things.

1. This is a Manual transmission with a cooler on it and it is overheating? That just seems almost unbelievable....How much of that is the exhaust and catalysts sitting right beside them?

2. Street tires trashed in two days on the track? Holy cow I guess the alignment does make a difference. I was thinking about doing my first events on street tires but I think I will just go ahead and switch out to the track tires right away. I wonder if the 245 is just working way too hard on this car, it seems like a really narrow tire for this car.

3. The coolant was also ready to overheat, this amazes me as well. With all the ducting they have you would think at speed it would be efficient at cooling...(catalysts again raising underhood temps?)

4. The stock brakes don't surprise me, I am going to be using Xp-20's front and rear.

I wonder if the noises you were hearing were related to the overtemp fluids in the car. Not sure if the differential is using high quality synthetic, but one thing I would do is flush all those fluids before you next event and see what you find in the dif and tranny. If they are getting to 300 degrees it is most likely done anyway.

mjw930

Part of the problem may be induced by using PTM mode 2. It's been reported that PTM mode 2 will eat rear brakes, heat up the ediff and on an automatic, send the trans temps through the roof. Based on the way you were pushing the car, PTM mode 3 might be a better choice.

*C7*

We need to clarify PTM mode 2 VS PTM mode Sport 2 ???

descartesfool

Front left tire trashed in one day on track, not two. Don't know anything bout automatic overheating. My car is a manual Z51 and it was in the red zone every session. Not sure what the PTM mode numbers are, but if Race mode is PTM mode 5, I was in PTM mode 4 all day, not 2 or 3. Mode was the one just before Race mode, and it indicated "Active Handling Off"

*C7*

There have been reports of active handling intervening in sport 2 (mode 4 ) and race (mode 5 ) even though the display and the manuals state that active handling is off.

Once again I would love to see the software listings for these modes. At least then we would know what the hell was actually going on.

Hot Rod Todd

With a stock alignment it's not unusual to burn off the edges of the tires on the track. Most people run the air pressure above optimal levels to minimize the roll over on the tires. I ran about 32psi cold, which heated up to 40 psi on the autocross course. Not the best handling pressure I'm sure, but you don't kill your tires so fast.

descartesfool

Dropped in to dealer this morning to report issues and book an appointment. After describing everything, service rep asked me if it felt great on tack, and I said an enthusiastic yes. Car made its loud weird noise from the rear end on startup at idle this morning, and that cleared up like it did at the end of the track day. Did not make it the second time I started it at the dealer. Issue with loud banging noise when in ECO V4 mode is still there. Can't use ECO mode for now.


First pic is showing things warming up, oil and transmission.


Next picture shows oil warm, and manual transmission temperature at maximum 150 C (302 F)


Next picture shows oil temperature reading at about 127.5 C (261 F)


Next picture shows transmission temperature at 143 C (289 F) after some cool down time in the paddock.


Last fuzzy picture taken during cool down lap and coasting shows water coolant above middle, and it actually went up to at least 3/4 of the gauge if not more, but it came down quickly from there on cool down lap, and I was not about to yank out my iPhone at full tilt on track to take a picture. Transmission temperature at max again.


I need a proper transmission cooling solution for this car!

AFVETTE

I have read the Z51 A6 has overheated but this is disconcerting that the M7 has over hating issues too.

Did GM skimp on the new Z51? I tracked my 06 Z51 at Road America and never had any heat, tire or brake issues even after 50 laps over a two HDDE.

leadville1

A lot of it is how you drive it as well. Road America has such long straights you get a lot of time to cool the car. I can watch my temp gauge drop 5 to 7 degrees on the straights there.

Also you can't compare driving styles, there are a lot of people who go to the track on HP Plus vs. DTC 70's and one can make the brakes last forever and the other will go through a set of pads in a weekend.

I drive my car hard on the track and rarely get more than three track days out of set of pads even with cooling on my M3 using PFC 01's.

If you drive hard and brake late your going to use up the tires and brakes. I will have a report in a couple of weeks, I will have headers on my car that are ceramic coated with cats back after the X pipe. My guess is this will make a difference in underhood temps and scavenging. Those cats sitting up right next to the motor can't help fluid temps.

I actually wrapped my midpipe on my M3 because it went so close to the tranny it made a huge difference in my tranny oil temps.

descartesfool

I am with you on the items you mention, but you will see a Z51 is a ton faster on track than an M3. There were 2 M3's (V8's) at my one track day, and there was no comparison in terms of laptimes. No idea about the drivers of those M3's or pads or tires, but C7 has much more torque and will produce much more heat in everything than the M3, and it is faster in terms of top speed requiring more braking at the end of the straights due to mv^2 energy relationship, so harder on brakes and tires. You will be pleasantly surprised on how good it is on track. I am looking forward to hearing your report and others as well. I have only driven at Road America once, and as I recall it was pretty hard on brakes with those long straights. And 3 track days on race pads is about my average as well. As for the tires, I never drive on street tires on track, except in rare occasions. I was however not expecting to trash my LF in one day, and highly wear the right front. My 18" wheels are in my garage and R comps on their way. Won't do a single thing for transmission temperature though, or for the stuff that broke or got noisy or the check engine light.

leadville1

Your report today got me moving I ordered Cray's and Pirelli slicks for my car. I am going to do one event as a baseline and probably then order a better radiator, although I am really questioning why wait the car seems to need a larger radiator already.

I also have a track alignment getting done Thursday.

I wonder if your fill was complete on your transmission? I am betting though that my car will run cooler with the headers and ceramic coating. That is a lot of heat sitting so close to the fluids.

I find the transmission temp issue just baffling...especially with a cooler. How many manual transmission cars come with a factory tranny cooler with aux fans on it. Can you program the fans to work harder or faster.

I would perhaps talk to MTI and see what they have noticed. They told me to change out to all Redline fluids which I am doing right away.

VatorMan

The GM list also said to replace the fluid in the diff and trans as well.

Plus-Add water wetter. It will reduce your coolant temps.

B Stead

The PTM traction system probably does explain the rear brakes wearing out in one track day.

Run-flat tires at the recommended 26psi probably explains the tires wearing out in one track day. I doubt that more camber would fix that situation.

Coolant temperature raises the idea of having a track mode setting for the water pump or the water flow. Race cars either slow the water pump down with pulley size or they put a restrictor plate in place of the thermostat. If the car has a tune that could explain high engine temperatures.

I wonder how the electronic limited slip is holding up. Of course, race car limited slips are available if the OEM electronic unit could be disconnected from the car's computer.

High temperature of the manual transmission is probably just a reminder that synthetic transmission fluid is available
.

turbo8765

A zero pressure tire doesn't need a lot of tire pressure… and 26 cold was prob 35-36 hot assuming he has air and not nitrogen. The wear is due to lack of camber and a fairly soft for a street tire compound.

The guy clearly drives fairly hard. On two occasions I've destroyed a left front in a powerful street car with stock alignment. In one case it was the stock Conti's that came on the car, in the other it was an NT01.

Trans temps are concerning and hard to explain. Is it possible the vent/ducting/or heat exchanger are partially blocked? Pieces of rubber? I'm grasping...

turbo8765

IIRC it said per 24hrs of track time.

leadville1

I would guess something isn't functioning right in the cooling aspect of this car, either a blocked duct or cooler, maybe an underfill.

I have tracked my Manual M3 for years with NO tranny cooler and never had issues like this with heat.

Street tires that are starting with that much tread also tend to chunk and not handle high heat well. I am not sure how the E LSD would convert to the brakes wearing out. It has an LSD so it is really using the rear brakes to also act in conjunction with the LSD?

I would rather turn off the nanny's and drive the car. I guess I'll find out soon.

*C7*

I think you are going to find there is no way to turn the nannies completely off.

Please report back what you find............

descartesfool

Car is completely stock, OEM Z51 with mag dampers. No tune, no headers, no intake, nothing. Only mod is front Hawk DTC pads. Changed oil and brake fluid. Transmission did not overheat in the first session, but temp was hot when I went out for the second session, and it hit the red zone for every session after that. Really curious to know if others who have driven the car fast on track for 3 hours or so in one day have had issues. Can't be just me.

One thing I forgot to mention is how great the rev-match feature is. It works very, very well, and allows you to go full hard on the brake pedal, shift easily down from 4th to 3rd while hard on brakes, then into second, lightly release brake to trail-brake into corner. It allows you to put your full attention to the racing line, your exact brake point, and brake release point, without trying to get a perfect heel-and-toe every time. I cannot see ever driving without it. I have been doing heel-and-toe downshifts for 18 years and first learned it with a Hewland box in a Formula 1600 car. I would much rather concentrate my efforts on track on other stuff than heel and toe, as car does it perfectly every time. I know heel-and-toe makes some of my track buddies feel manly, but for me, a rev-match manual or a DCT is the perfect answer.

*C7*

I have seen oil temps. higher than yours at the track. However my coolant temps were rarely over 220 F.

I only monitored my tranny temps a couple of times but don't recall much above half scale.

I'm not familiar with your track. Do you use 2nd gear much ??

Do you spend much time at or near redline ??