M6 will not Shift into any gear while on

**knight721** · 12-13-2010, 02:00 PM

I hope you guys can help me before I take it to the dealer;
On February of this year I change the Slave and master cylinder and put in an stage one Zoom clutch. when I got it from the shop the clutch was pretty hard but the car shifted flowlessly, baby the new clutch for over 1000 miles. Then I parked for 2 weeks and when I was on my way home from work it got harder and harder to put it into any gear. If I start the car in gear it will go. the pedal feels like it has pressure on it, just not as hard. I bleed the system got all the air out and still could not get it into any gear. I took it back to the mechanic who did all the work and he is baffled as to why It will not go into gear. He says the clutch is to hard for on the Slave and keeps blowing it up? (not taking it to him again). I Just came back from a deployment (Navy) and spoke to a GM mechanic and he said that I have to use a GM Slave cylinder if I am to use a Stronger clutch? They want to charge $780 for the job, and do not have the money to start changing parts guessing. Hope You guys can give me some advice.

**Wesman** · 12-13-2010, 06:49 PM

Definitely sounds like a clutch hydraulic problem.

Are you 100% positive you got all of the air out?? They can be very tricky to bleed sometimes. The smallest bit of air trapped in the system will cause the clutch not to release fully, which will make it damn near impossible to engage any gears.

I usually use a mity vac bleeder to bleed the clutch, moves a large volume of fluid in a small amount of time. Sometime it still needs to be manually bled after that though by depressing the pedal and opening the bleeder.

It is impossible that the slave is "not strong enough" to release the clutch. Hydraulics are simple in theory, if you push the pedal down and there are no air pockets or fluid leaks, then the slave cylinder HAS to release the clutch.

So you basically have 3 possibilities. The first and simplest is air in the line. Bleed it again thoroughly and see if it helps. The second is a bad master cylinder. If the master it bad, it will allow fluid to seep past the cup and not build pressure. The third is the slave, which is of course the worst. If the slave is blown or leaking, you should see fluid dripping on the ground from the weep hole in the bottom of the transmission bellhousing. Thats a tell-tale sign that the slave has failed.

And as said, GM slave cylinders are the only way to go. The ones from the parts stores do not seem to last.

**tatertot91** · 12-13-2010, 08:44 PM

or you could step it up to a tick master cylinder, real nice piece

**knight721** · 12-14-2010, 02:30 AM

Thank you guys;
I bleed the system using a mighty vac pump. and it had a lot of air. I filled the reservour and pumped it a couple of times and it is still full, I see no fluid on the ground and the pedal has a nice feel to it. Which i think is why the master may be still good. I will try to bleed it one more time. If the master cylinder went bad, would I still have presure on the Pedal?

**jetaws6** · 12-14-2010, 06:02 AM

I had litterally the same symptoms you had. Brand new clutch 800 mi on it, babied it, and one day I was driving and it became harder and harder to shift until I couldnt get it into any gear. When the car was off I could shift fine, but when it was on I was locked out of my gears. When I started it in gear it would stall eventually.

took the trans out and found this

**knight721** · 12-14-2010, 06:44 AM

Ouch! did you end up replacing the fly wheel as well? That makes me wonder if the mechanic actually took it apart when I took it back. I hope mine is not that bad. what brand was your Clutch?

**Spaz** · 12-14-2010, 06:51 AM

Originally Posted by knight721

Ouch! did you end up replacing the fly wheel as well? That makes me wonder if the mechanic actually took it apart when I took it back. I hope mine is not that bad. what brand was your Clutch?

i'm pretty sure he had to at that point... that fly wheel would have been all chewed up... i had a similar thing happen but it was a piece of debris from the clutch instal... welded the clutch to the fly wheel... are you able to rev match to change gears???

**knight721** · 12-14-2010, 07:41 AM

I'm a little weary of doing that and damage it even more.

**knight721** · 12-14-2010, 10:18 AM

Well I just got a call from a friend of mine who has a Camaro and he was telling me that I might just be a bent fork, since I still have good pedal preasure. Hopefully that is as best case other than air in the line.

**Wesman** · 12-14-2010, 01:35 PM

Originally Posted by knight721

Well I just got a call from a friend of mine who has a Camaro and he was telling me that I might just be a bent fork, since I still have good pedal preasure. Hopefully that is as best case other than air in the line.

He must not know anything about your car.

98+ 6 speeds do not have a clutch fork at all. Its a concentric slave cylinder design, which is inside of the bellhousing.

**Cutlass** · 12-14-2010, 05:09 PM

Essentially you aren't getting enough travel out of the slave cylinder/throwout bearing to fully release the clutch. Either something is worn out or the hydraulics have an issue.
You could also try pumping the pedal a few times between shifts to see if you can pump up some pressure and get the clutch to release.
But sometimes you just need to tear into something and start inspecting parts until you find a problem.