Does the 2002 Z06 have a trans problem. It seem that 3rd gear is a ?itch and grinds 50% of the time. Especially if I have to get it on. Normal granny driving OK, but any performance driving and 3rd gear just freaks.

Are there any time a adjustments I can ask the dealer to do.



[Modified by Rachel, 9:01 PM 8/20/2002]

 

Rachel, my Z06 is at the dealer now because the trans grinds occassionally going into 3rd and almost everytime going into 4th. This only happens at high rpm's. It also pops out of 4th gear.

Syncro's for 3rd and 4th had to be ordered and GM said they had none. They were ordered last week and today the 4th gear syncro's came in but still no 3rd gear syncro's.

This tells me that Syncro's are a problem in the MN12 trans. The mechanic showed me the new parts and said they are different than the MN6 trans.

There were a couple of posts about GM putting the MN6 trans in the Z06 starting about now. Was this ever substantiated?

 

Steve,
no change in the tranny.....just in the RPO ordering code......
They have deleted the M12 designation, and gone to a SINGLE #.......MN6...........this is for all 6 spds........
The ratios, and geasring is supposed to stay the same for the Z's......... :yesnod:

 

I have a similiar problem with my '02 Z06(2 weeks old - 1100 miles). I was running up through the gears and when I went into third something did not feel quite right but at the same time I was not too concerned because it did not sound like anything broke. But on the way back down - from 4th to 3rd - it grinded, had to go to 2nd instead and limp home, then to the dealer the next morning.(never was able to get back into 3rd without a grind).

It has been at the dealer since 8/12 waiting on parts(including 3rd gear synchro) for a rebuild.

 

Well...

We all have something in common, it's at high RPM is when this happens

What shall I say to the dealer - THEY ARE DUMB. They act as if I can't shift.

I told them that I had 5 or 6 speeds all my life and non acted like this.

Does this mean they have to rip the trans apart....

Rachel

 

Rachel, they have not done any tear-down yet so I guess they were able to determine what the problem was by driving it, etc. To do the rebuild though, they said that they need to take a 'few' things out of the rear-end of the car to get the transmission out. It pains me to think about it.

BTW, the grinding on mine was just in third and occurred at every part of the rpm range that I tried(probably ~1200-~3000).

Have you tried searching the other z06 forum. There were some posts out there about similiar problems that may help you. Hope you don't have what I have!

 

my 01 with 20k miles has the same problem going from 4-5 at higher RPMs. The big problem is that R is very hard at times to get into or it pops out when backing up. Car is going in on monday, guess its going to sit a while waiting for parts. As long as I get a loaner and get to keep the miles off. :cry

 

Just spoke to 2 dealers. They said because I have the CAGS installed the trans is not acting properly


ANYONE AGREES IT COULD BE THE CAGS INSTALLED ON MY CAR THAT IS DOING THIS AT HIGHTER RPMS'S

 

This is absolute BS, although if the dealer's taken that attitude you could have a problem. There's no way the CAGS defeat can affect transmission operation. The whole function of CAGS is to make the tranny behave differently than usual under certain conditions of gear, temp and rpm .. in this unique set of conditions, CAGS engages and a solenoid in the tranny makes it impossible for you shift to anything but 4th. If you are not in first, not warmed up, or not within a very narrow rpm range, CAGS will not engage and you can shift normally.

Disabling CAGS does nothing except prevent it from engaging. There is no affect on other transmission operations. This is simply a slimy way for your dealer to sidestep a warranty issue. Since you can remove the CAGS defeat in about 30 seconds, I'd suggest doing so before seeing any other dealers, since they are apparently either sleazy or stupid.

Good luck.

 

BTW, Rachel .. I have the CAGS defeat installed, and have had no problems with the tranny .. shifts smoothly, no grinding, etc. FWIW.

 

Rachel, same problem here. Grinding occurs when shifting into 3rd at high rpms, but is fine under normal driving conditions. I'll see what the dealer says in a couple of weeks.

 

There is a definite problem here that GM is covering UP.

Any more.

Rachel

 

My '99 MN6 grinded once in 3rd gear at ~6K. I replaced the fluid with Redline D4 ATF and it never happened again (It did grind once more at high RPM in 5th, but just once).

There are well known problems with Tremec synchros and shift forks. The transmissions are built in Mexico; there may be a quality control issue. Also, some stock shifters are defective (Local dealer just fixed a shifting problem by replacing the shifter). If anyone gets their trans rebuilt, you'll want to get the stainless steel shift fork(s) (about $50 each: not too bad).

I believe using better ATF may help prevent some of these problems (such as Redline, Royal Purple, even GM's Synchromesh (partial synthetic)). Need to make sure the fluid is rated to handle the high temp requirements of the MN12+Z06 HP.

My 2002 Z06 MN12 popped out of first gear once, but the transmission was new and tight, and probably was not fully engaged. Other than that, it appears to work fine so far. My only complaint with the car is a harmonic vibration at ~1600 and 3200 RPMs (most likely clutch/flywheel/pressure-plate/harmonic balancer related). The dealer won't fix it ("Normal"). When I get some time, I'll take it to a local engine builder and/or clutch/trans shop and get it fixed, then "battle" with GM for reimbursement (they've already stated they won't pay, even if I present them with the defective parts).

No car is perfect, but it would be nice if warranties were honored with more honor. :flag

SportsCars

 

The MN6 in my 98 Z28 popped out of 3rd twice when shifting and would grind sometimes. I had to be more careful in shifting and it stopped doing it. It was stock.
The MN12 is touchy but maybe the short throw shifter and doing positive shifts helps.

 

Total BS! No way could CAGS have anything to do with it.

My car has been sitting at the dealer now for over a week. The mechanic doesn't want to pull it apart until he has all the parts on hand. Everything has come in except the 3rd gear syncro's. While I won't go so far as to say Gm is covering up a problem, it does seem that there have been more problems lately than they were prepared for. I also had to wait for the steel (it's not stainless, BTW) shift fork to come in from D & D Performance. They were back-ordered for about a month. I spoke with the mechanic today, and he told me that GM was out of 3rd gear syncro's. So, they send out a message to all their dealers to see if anyone has the parts. If no response, they have it shipped directly from the manufacturer as it comes off the line. Latest word is that it will ship tomorrow.

If this issue gets bad enough, GM will put out a bulletin.

I am going to Corvettes at Carlisle on Saturday. GM has a display with engineers to answer questions. If I can get to one, I will see what I can find out.

 

Thanks - that would be super!!!!!!!

Rachel