One constant recurring complaint on this forum about the C6 six speed, is that the clutch action leaves much to be desired. It is hard to explain the problem, but it is safe to say that the C6 clutch on my Z51 takes some time to get accustomed to, and requires a bit more concentration than the clutch on a Toyota. Some say the clutch action is non-linear or that the clutch spring seems to vary in strength through the full motion of the clutch engagement. The clutch is not heavy but it is tricky. I am not exactly sure just what the problem is, but I do know that you certainly have to concentrate on getting the proper clutch engagement when starting from a stop in 1st gear.

Part of the solution is to reduce the clutch throw. That has been discussed on this forum before. I did that some time ago by putting a small piece of 1/4" plywood under the small wing on the clutch arm. That helped, but more than occassionally, I would still get a jerky start in 1st gear.

This was beginning to annoy me, and I started to give it some serious thought. It appeared to me that problem was one of gaining greater control of the clutch as it is released, i.e. firm pedal control right up to the point of engagement.

When you depress the clutch, you use the full ball of your left foot. As the clutch is released upward, the front part of the ball of your foot normally rotates upward slightly and loses contact with the pedal. All control of the clutch pedal is now concentrated on the rear portion of the ball of your foot, and you are maintaining control of the pedal by putting pressure on the lower portion of the clutch pedal. In a lot of cars with tame and understanding clutches this is OK. But in the C6 you are not able to achieve enough control of this particular clutch because you are only using a small portion of the ball of your foot, on just the lower edge of the clutch pedal.

It seemed to me that the solution to the problem might be to maintain the full ball of your foot on the whole of the clutch pedal, throughout the full engagement process. I tried a very simple fix that has cured the clutch problem for me.

Some time ago, one of our posters "Hoonse", described how he used four bolts which he put through the holes in the clutch pedal, as a method of extending the clutch pedal so that he could move his seat further back. Using this basic idea, I put an 8mm bolt (about an inch long) through each of the top two holes in the clutch pedal. I also used flat washers on each side of the pedal, and tightened each bolt down with a nut containing a nylon locking insert. The upper portion of the clutch pedal is now extended out about 3/8" (the height of the bolt head).

With this setup, the whole ball of your foot maintains contact with the full clutch pedal throughout the engagement process. You have much greater control of the clutch and the starts from 1st gear are much smoother, and it really feels good. The only downside is that it looks kind of dorky. It is a stupid and simple fix but it seems to solve the problem.

 

Thanks for the info. I'm gonna concentrate on how I put my foot on the clutch pedal. I just bought a C6 6spd last Saturday. I have been having problems driving the car smoothly particularly from a standstill. Before this car I had not driven a stickshift in 2 years(when I had a 2000 Trans AM WS6). I have been thinking my problems can't just be because previously I had not driven a manual in so long.

 

The fix I suggested is on my wife's C6. She drove a C4 6 speed for 10 years with no problem. I bought her the C6 and she immediately complained about the clutch. I tied it and soon began to see that she had a good point, the clutch on the C6 is tricky.
If you make a strong mental effort to keep full and firm foot contact with the clutch pedal all the time when shifting, you can avoid the "bolts in the clutch pedal" fix that I proposed.
But, some of these quirky things can take a lot of the fun out of driving the C6. The fix I proposed is simple and you can shift normally without thinking about concentrating on how to engage the clutch.

 

Pic?

 

[QUOTEWith this setup, the whole ball of your foot maintains contact with the full clutch pedal throughout the engagement process. You have much greater control of the clutch and the starts from 1st gear are much smoother, and it really feels good. The only downside is that it looks kind of dorky. It is a stupid and simple fix but it seems to solve the problem.[/QUOTE]
I briefly experienced the same thing during a test drive. Is there any indication GM is addressing this or are any of our supporting suppliers developing a solution?

 

[QUOTEWith this setup, the whole ball of your foot maintains contact with the full clutch pedal throughout the engagement process. You have much greater control of the clutch and the starts from 1st gear are much smoother, and it really feels good. The only downside is that it looks kind of dorky. It is a stupid and simple fix but it seems to solve the problem.[/QUOTE]

I experienced the same thing during a brief test drive....thought it was just me.

Is there any indication GM is addressing this....or are any of our supporting vendors developing a solution?

 

The clutch is desgned to handle 400+ HP. Its not going to be as smooth to engage as a Corolla or Civic....

 

To me it feels like GM put some sort of a clutch delay valve in the line. I've owned Beemers with the CDV and this is exactly how they feel. If GM is using a CDV, a simple non-restrictive coupling could easily restore smoothness to the clutch action.

Does anyone know if GM is, in fact, using a CDV in the C6?

 

On the contrary, for a car with big HP, the clutch is surprisingly light and since I fixed it, it is smooth as a snake!. Speaking of snakes, I drove a Viper (400+ HP) recently, and the clutch is far smoother than the C6. It is incorrect to assume that a big HP car has to have tricky clutch.

 

Interesting mod. Why not just shift your foot down a bit so that the pedal hits in the center of the ball of your foot just as it starts to grab? That's what I do and it works fine for me. You have to "tip toe" it a bit when you press it to the floor to keep your heel from hitting first, but when you release it, the bottom edge of the pedal will be right in the middle of the ball of your foot where you want it. Seems like that is an easier solution... just move your foot down a bit so that it is hitting the right spot when you need the most control: when it is just starting to grab.

Any manual car I've ever driven takes some getting used to, especially when it comes to finding the best position for your foot on the pedal. You may simply be used to riding your foot a little higher on the pedal than it needs to be on the C6.

Mike

 

That is probably a good solution, it is really a question of how to achieve maximum clutch control as the clutch engages, and your method would probably work. There are likely other ways to achieve the same result.
But as I mentioned, the C6 is my wife's car, and I don't want to start teaching her how to use the clutch. I just fixed it my way and she is now happy. That was much easier than giving her clutch instructions. She doesn't have a clue as to what I did, nor does she care. It now works OK and she no longer complains.
Also, I drive another car with a standard tranmission, a 2003 Boxster S, and I would like to have the clutches on both cars act in a similar fashion, rather than attempting to adjust to whatever car I am driving. With my modification to the C6 clutch pedal, the clutch action on both cars are now more nearly the same.

 

Letting loose in 1st, I find keeping my heel on the floor as the "pivot/lever point" helps me get a smoother release. Then again, if you don't touch the gas, and release the clutch slowly, it won't stall like most other cars would.

While nothing like the non-hydraulic high performance/competition clutches of my old ***-pickup-truck-racing-days, this is a stiffer pedal than your average yuppie-hauler.

I've done the embarressing, pop the clutch/stall it out in front of a parking lot full of friends. We all get a good laugh, then I tell them to jump back into thier Nissans and laugh there...

Rick

 

Nor is as smooth as the clutch on my CTS-V (which also has 400 HP). It's definitely something that GM should address, but won't.

BTW, I had it into my dealer and they agreed with my assessment. But they didn't have any solution.

 

cool fix, what type of bolt did you use....Ie Button head, Allen, machine, carriage, etc. I'm thinking allen....knurled.

 

I used an 8mm diameter bolt that was 20mm long. I had some flanged frame bolts, this is the type with a wide flange at the bottom of the hex that eliminates the need for a washer. But I did use a washer, because the 8 mm was a bit too small for the upper holes in the clutch pedal.
I think a 10 mm bolt about 25mm in length would work better. The type of bolt I used also had a recessed head (rather than a flat head), which I choose because it seemed to offer a better traction surface for my shoe. I think just about any bolt of 10 mm or 3/8", about 1" long would work fine. You don't want your foot to slip off the bolt so it might be wise to find one that has a head that offers some traction for the bottom of your shoe.
I know this sounds like a weird fix but it really does work. If it is not for you, it is easy to remove.

 

I test drove a C6 and found the clutch much easier to engage then the Z06 clutch I had in my C5.

That said, on my C5, I had a hockey puck bolted to my clutch pedal, also for sake of allowing me to put the seat a bit farther. It too looked very dorky, but it served the purpose. And, I don't have pics, as it wasn't something I was particularly excited about showing off.

 

I unfortunately don't have my digital camera handy and can't post a photo. But I notice that on the C6 Corvette General Discussion page there is a posting started today called "Advice on MN6 Gear Box". As part of that thread one of our members "Hoonse" posted a photo of how he extended his clutch pedal using four bolts.
I really stole the basic idea from him, except I just used two bolts to extend only the upper part of the clutch pedal. I should post a link to that page except I can't figure out just how to accomplish that.
Maybe if Hoonse reads this he can take credit for the idea and can also attach the link to his photos.