Corvette Z06 Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
528 Posts
Discussion Starter · #1 ·
Does anyone notice shifting from 3rd to 4th is hard when the tranny is extremely hot?

I was out playing with a friend who also own a Z and and another friend in a Supra TT. After playing for awhile, my friend in the Z complained that he couldn't shift into 4th because it would grinds so much. I didn't noticed it in mine. I guess because I always have mine in 6th whenever possible, until we are ready to race. I guess he had his in the lower gear the whole time we were playing around that was why his tranny got a lot hotter than mine.

Anyway, afterward, on my way home, an Eclipse GSX well modded with DSM racing and tons of other stickers all over his car wanted to play with me. I ran my Z in 3rd and 4th a lot for about 7 mins or so because this guy had tried every combination of runs to see if he can pull on me. But, he was no match for the Z at all. During the course, I had notice couple of times I was having a hard time shifting from 3rd to 4th which I never had before. Then I put it in 6th for a few minutes. The Eclipse tried his last trick by getting a head start from behind, I dropped the Z into 3th and caught up with him in no time. I then shift into 4th, and this time no problem (I guess the tranny had cooled down). I slowed down, the Eclipse caught up with me and give me few respect bows. I gave him a thumb-up, then he exit.

After this experience, it leads me to think that the tranny in the Z is hard to shift from 3rd to 4th when it is very hot. I had notice some other people in other thread had complained about a grinding noise shifting from 3rd to 4th too.

Could this be the symptom?
 

·
Registered
Joined
·
837 Posts
I not convinced that tranny heat has anything to do with the problem you're experiencing.

I'd suggest two possibilities:

(1) running on the street is different than the dragstrip. On the street there are many distractions (other traffic, scans for cops, what's your opponent getting ready to do); this will disrupt your shifting routine and cause you to miscoordinate movement of the clutch and shifter or to pull the shifter down and to the right hitting the notch between 4th and 6th. That is the most likely explanation.

(2) check your clutch fluid. Is it discolored and full of black oily goo? If so it's symptomatic of cooked clutch fluid that affects adversely the responsiveness of the clutch when you are banging repetitive shifts through the gears at high rpm. If this is the case, have the clutch hydraulics bled and replace the fluid with some high temp racing fluid.

If it isn't #2, then it's likely to be #1.

Ranger
 
G

·
I agree , heat is not the issue. It's a combination of #1 and #2 answers Ranger had listed above ... I have experienced the phanomenon myself, at the track - no less - and felt kinda stupid about it, because most people grind or miss 3rd, instead of 4th - but it has happened to me to .... so fluid problem or actual shifter replacement to a tougher shifter (ripper, kirban or the new hurst) should be the fix.

Question is, do you SLAM ? Are you a hard and "buck wild" shifter, like myself ? :D:D:D
 

·
Premium Member
Joined
·
652 Posts
I have simular problems with my '01 Z06.
When I shift at high rpms the clutch is on the floor by the time I go into 4th.
1st fix in March was a flywheel and clutch assembly.
While in Atlanta for the race earlier this month it started again.
I took it in to service on the 16th and the master cylinder was replaced. Brought it up to 6000 rpms in 3rd and the clutch is still on the floor.
It is so bad now that if I rev the engine at a stop while my foot is on the clutch, the pedal is on the floor.
I use my Corsas instead of my horn.
Back to the dealer 2morrow.:-?
 

·
Registered
Joined
·
837 Posts
FRC Tom said:
....When I shift at high rpms the clutch is on the floor by the time I go into 4th. 1st fix in March was a flywheel and clutch assembly.
While in Atlanta for the race earlier this month it started again.
I took it in to service on the 16th and the master cylinder was replaced. Brought it up to 6000 rpms in 3rd and the clutch is still on the floor.
It is so bad now that if I rev the engine at a stop while my foot is on the clutch, the pedal is on the floor....
Tom,

I had the same sticking clutch problem. At my own expense I had my clutch hydraulics bled and the fluid replaced with ATE Super Blue Racing which has a much higher dry and wet boiling point. Pedal now behave normally.

My belief is that the clutch fluid gets "cooked" running at high rpm/temp over time. Once it's cooked the clutch pedal acts up. When queried, the Chevy Tech Center has the dealer start changing out parts, when the real solution is routine bleeding of the clutch hydraulics and use of higher temp-tolerant fluid.

Let me know what you think.

Ranger
 

·
Registered
Joined
·
528 Posts
Discussion Starter · #6 ·
Ranger said:


Tom,

I had the same sticking clutch problem. At my own expense I had my clutch hydraulics bled and the fluid replaced with ATE Super Blue Racing which has a much higher dry and wet boiling point. Pedal now behave normally.

My belief is that the clutch fluid gets "cooked" running at high rpm/temp over time. Once it's cooked the clutch pedal acts up. When queried, the Chevy Tech Center has the dealer start changing out parts, when the real solution is routine bleeding of the clutch hydraulics and use of higher temp-tolerant fluid.

Let me know what you think.

Ranger
I think Ranger had some good points here. If it's the clutch, shouldn't it acts up all the time? It could be the fluid, because I had a problem with the brake fluid overheated one time in another car, and I lost my brakes momentarily. I haven't check the manual, but I think GM put the same fluid in both the brake system and the clutch. A higher boiling point fluid is making a lot of sense. I'll try that along with changing the tranny fluid to Redline and see what happen.

Thanks all..
 

·
Premium Member
Joined
·
652 Posts
Ranger said:


Tom,

I had the same sticking clutch problem. At my own expense I had my clutch hydraulics bled and the fluid replaced with ATE Super Blue Racing which has a much higher dry and wet boiling point. Pedal now behave normally.

My belief is that the clutch fluid gets "cooked" running at high rpm/temp over time. Once it's cooked the clutch pedal acts up. When queried, the Chevy Tech Center has the dealer start changing out parts, when the real solution is routine bleeding of the clutch hydraulics and use of higher temp-tolerant fluid.

Let me know what you think.

Ranger
Ranger,
We are on the same page with my problem, the only thing I do not understand is that it also does it when cold and the cylinder and fluid has just been replaced last week.
I have also heard that drilling the hole out larger between the master and slave cylinders was a fix.
I'm off tonight for some ATE, hope it works.

ddle,
I have redline in the engine, tranny, and rear.:)

Tom
 

·
Premium Member
Joined
·
652 Posts
I just found out from my dealer that they are replacing the entire clutch hydraulic system in my '01 Z06.
I hope this is the final answer.
 

·
Premium Member
Joined
·
652 Posts
hcvone said:
I would start by changing the fluid and replacing the shifter, see what that does for you. :)
All these things have been done Carl to no avail.
This is not the dealers idea but GM tech.
I just want my clutch pedal back.:(

Tom
 

·
Registered
Joined
·
3,646 Posts
Haven't had any type of shifting problem with mine....But I also doalot of hghway driving so things don't heat up:) :)
 
1 - 11 of 11 Posts
Top