froggy47

Does anyone have a link to this sort of checklist? I know the c5z issues having run one for 4 years, and I am headed down the slippery slope to a c6z probably 09/10 model year.

Would like a little heads up on what I am in for.

Some c6z issues "may" have been addressed in later model years and some not so much.

For example do the c6z control arm bushings walk out of the ca's like c5's?

Does the seat rock/fall back/suck like the c5's?

That sort of stuff, I am sure someone has put this list together already, just need help finding.

davidfarmer

suspension is pretty much identical, wrap your lower ball joints and tie rod ends. Bushings move, but don't fail. My rear sway bar came lose, but that's just one of those things.

Seats don't rock like C5, but they don't really offer any more support though. Biggest issue I have is the stupid keyless ignition and electronic doors. Crawl into the trailer, crawl through the window, then car won't start because it doesn't recognize the key even though it's in your pocket. Often have to fish it out of my pants and start pushing buttons to wake the car up.

Anyway, drivetrain/suspension nearly identical, just keep doing what you already do.

Jason

Man I wouldn't want to open that can of worms for a track car.

froggy47

Found a lot of info in the C6 forum stickies, but it's not updated for 09/10/11 MY.

Will keep digging. I don't see any "announced" change since the dry sump oil capacity was upped 2009.

AU N EGL

TPMS on the C6s

None on the C5Zs

95jersey

It is quite the car, no one can deny that, but be prepared. Bushings are softer than C5Z, and walk out as fast or faster. Need to have sensors in every wheel (both street and track), you need to buy a special tool to reset so the computer can see the new tires or the car goes into disabled mode.

There are things that are better, both upper front and rear control arms are basically identical and you can add/camber by just removing washers. The rotors are better even though they are drilled.

Seats suck for anything but street, you will need a race seat and if the car is 2LZ or higher (which most used ones are) you will have no telescoping steering wheel and an air bag light.

Tires are $$$$, rotors are more expensive, and the brakes, don't get me started. The Devil designed those brakes to torture track rats. They work and work well, just an IMMENSE pain to work on compared to C5.

Figure the car will cost you 3 times the amount to run (in brakes, tires, rotors, and other disposables). Oil change takes 11 quarts on the 09,

The car is a beast, but the OEM suspension on Hoosiers will disapoint you if you are experienced, you will need coil overs. To make the car ride nice on the street, they softened the bushing while stiffening the suspension, which makes the car "float" at high speeds through corners...you have to experience it. Only coil overs resolved the situation for me.

So, your work is cut out for you....

Datawiz

I'm assuming you're going to primarily autocross this, as you did your previous car.

Some issues I've had with my 2008:

• Blew the crankshaft speed sensor on a Saturday during race weekend.
• Mine has Navigation and the unit has been replaced twice. I now take the DVD out when I race it. I think all of the bouncing around is what killed it.
• Follow RANGER's advice on flushing your clutch fluid often. I now do it every other event. Had to have the master/slave cylinders replaced at 1,500 miles. No issues since with 11,700 on the clock.
• I keep throwing check engine lights for the cat being out of range. They have already replaced the cat once under warranty.
• Had to have the tensioner pulley replaced after it got thrown.

Other than that, the car has been rock solid, considering it's been a multi-driver car for over 3 years and likely 80 events. Also, when I had the wrap replaced, the paint is absolutely showroom new. Way better than my C6 daily driver. I will always have a wrap on the cars I race.

VGLNTE1

Dont forget the crappy valves and rockers...if you buy an early year z

acrace

Currently autocrossing an '09 Z, ran an '03 Z for four years (and still have it).

I concur with the comments about the front control arm bushing. On my '09 Z, the upper bushing "walked" almost immediately. Highly disappointing.

From a cost viewpoint, I can't say that the C6 Z is much more expensive to run than a C5 Z . . . for autocrossing. Obviously there's a big price difference in the tires, and also used 19" are really difficult to find. I can certainly see that for track days that there is the difference previously mentioned.

I can't say that I've taken a scientific survey, but TPMS issues seem to be model year dependent. Seems that many of the folks with issues tend to be earlier year C6 Zs. With my '09, I can run without the sensors without any problems. It'll still let me turn off AH/TC (and the car behaves that way) without sensors in the wheels. I think that one of the issues is if you have the sensors programmed into the car but have alternate wheels actually on the car, and the programmed sensors are just close enough so that the car computer reads some of them.

Oh, on my '09, 25 psi seems to be the cutoff where I get the low pressure warning. But at 23 or 24 psi, I can still hit reset and turn off AH/TC.

Bill Dearborn

Probably not much difference in cost when autocrossing other than tires. On the track it will have most of the problems the C5Z had plus a few of its own related to the brakes. So far with the built in OEM oil cooler I haven't had to add any extra cooling but the brakes are a huge PIA and costly. Tires are costly due to limited selection and low volumes. My C5Z had PS, wheel bearing and tie rod issues over 6 years of tracking and autocrossing while the C6Z has had PS, huge oil leaks from the front cover seal and rear axle/wheel bearing wear issues that required the replacement of both rear axles and wheel bearings. The C6Z isn't as good of an autocrossing car but it is one hell of an animal on the track. Leaves the C5Z and most other cars in the dust. About the only thing that will out run it is the ZR1.

Bill

froggy47

Thanks guys.

I figure to run 18's in the back (local class allowance) will replace the padlets with a standard pad, put tpms in a pressure vessel to address a few problems.

Probably poly bushings when the oem walk.

Am concerned about the oil leaks as I just had this crop up on my c5z.

I don't get that they can't make a decent gasket to hold oil on a hand built motor.

:thumbs

How much negative can you get with stock adjusterment? F/R?

froggy47

travisnd

They have awesome motors that break valve springs and drop valves, have valves that break and fubar the motor and these cool off-set rocker arms that puke the needle bearings and cause accelerated valve guide wear... which leads to the aforementioned breaking valves.

Engines are so awesome the guys in the C6Z forum think it's normal to need a rebuild every 30 hours of track use and defend GM's crappy dry sump by saying it wasn't engineered to be a track car

acrace

So, do you have one now?

froggy47

I found a low miles 09 mid 50's in TX. I like to buy in late Dec, sellers seem a little xtra motivated, that's when I got the 04.

I thought the valves & rocker arms were better in the later motors, anyone got info?

AU N EGL

and 04 is just about bullet proof. Change the oil often and get the oil analyzed.

travisnd

AFAIK they never changed anything other than the dry sump tank and oil capacity... it seems to be a design flaw of the off-set rocker arm. Katech has been testing them and has a valve guid upgrade they do on all the engines they build.

There's a thread in the C6Z forum right now where a 6700 mile 2009 broke a spring and dropped a valve while the guy was driving to work. The car was stock. GM is putting a new motor in it under warranty.

froggy47

Yes, I think I saw that thread.

Bill Dearborn

I believe what you are referring to are issues they had with with some of the 07s. The exhaust valve issue is different.

I have had an 08 since Aug. 09. Bought it with 13K miles (street and highway driving/daily driver) when it was 18 months old. Since then I put another 12K on the car including 43 track days, a bunch of autocrosses and street driving a a couple thousand mile trip. At my last track event on 8/30 of this year I dropped an exhaust valve on number 1 cylinder. GM replaced the engine under warranty. Including myself I personally know 5 Z06 owners that had the same problem on 6 cars. One guy had it happen on two consecutive cars, an 08 and an 09. There have been at least 20 near identical failures reported in the C6Z forum.

The valve spring did not break. The head of the exhaust valve broke off and after doing some major damage exited through the intake valve and was found in the intake manifold.






No idea what caused it but I do know LS7s made from 06 through 09 model years have had this failure.

Bill

96CollectorSport

Did you check the valve guides on any of the other valves on either of the heads? It seems like either the guides will feel loose or they will gaul up. One of my friends just had his LS7 (06Z) let go at Rd Am a month ago and we saw gauling on several of the other valves on that head.
It seems like if you are planning on tracking an LS7 - have the heads gone through, replace the guides and switch to Iconel exhaust valves.
Checking guides isn't that tough, it's pretty much just like swapping springs.
After that friend had his motor let go I had another guy drop the car off at our shop to check the guides and guess what? Loose valve guides (06Z), the heads are coming off and they will be gone through before next season.