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six speed

M

marckschwartz

Guest
I just bought a new 2002 six speed coupe. When the clutch is out there is a rattle that is louder when the car is warmed up. It disappears when I engage the clutch. It has been in three times and the answer is absurd. I am being told that some fifty other owners across the country have complained and it is an engineering problem with no fix. Not every six speed has this problem!!!

Next week our zone technical rep is supposed to evaluate. Any suggestions??
 

c4c5specialist

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Nope, but someday.
Hi there,
I would be interested in hearing what your zone rep has to say on this.
Please keep us posted, as there is always some driveline resonation through the vehicle, as the driveline, with no load, will make a little noise.
Besttoyou, c4c5:hb
 

B/STOCK

Well-known member
Joined
Oct 24, 2001
Messages
188
Location
RI USA
Corvette
2000 Magnetic Red Vert & 2015 DSOM Coupe Z51-3LT
I thought Chevrolet had that fixed in 01. My 2000 sounds like a bucket of bolts is rolling around when it's in neutral with the clutch out. I know many owners, I among them, have asked their dealer if this was a problem. I was told it was a issue with the 2000 but it was normal. Every dealer seems to be giving the same answer. Will let it go at that for now but will be all over GM when the warantee gets thin. Just get it documented. Hope you enjoy yours as much as I do mine and good luck. Please keep us up to date. Michael
 
B

Boater Chuck

Guest
I also have a 2002 M6 and have a very slight noise occasionally in neatral with the clutch up. I have not brought the car back to the dealer since it only has < 2,000 on it, but I will certainly document the noise when I do bring it in.

Sounds like a throw out bearing to me - If the car even has one!?

Good luck.
 
V

vettedreamer

Guest
i have a 2002 coupe 6 speed also & when the clutch is out it sounds like the flyweel's coming off. i will take back and see if they
have solution for it.
 
C

cute301guy

Guest
I have a 2000 6 speed vette, when in nuetral it too makes funny sounds, espically when I shut off the car, without holding the clutch down. I took it into the dealer ship, and they said its normal. The couter shafts in the trans are winding down they say... It's seems like its the same thing you guys are talking about. The trans feels solid though, but that noise sounds like a future problem for all of us. Keep us updated on how it turns out.


-Jonny
 
V

vettepilot

Guest
Just a silly question for all, are these cars the first you have owned with standard transmissions, as opposed to automatics?
I have had always had 3/4/5/&6 speed standard trans in all my sports/GT cars over the span of about 35 years of driving. The drive train in each car is going to be heard when there is no torque load on the drivetrain. Especially so in the C5 vettes, that's a lot of rotating mass between the engine and differential when in neutral. You have the flywheel, clutch assy. driveshaft, and the transmission shaft and gears all rotating, add the engine power pulses at an idle and it's no wonder you can hear it.
Somebody mentioned that theirs made a bad rattle sound when the engine was shut down with the clutch out. When the engine is shut down with the clutch in, the rotating mass is reduced to the flywheel and pressure plate, so there is less inertia trying to rotate the engine. When shut down with the clutch out, the entire rotating mass is trying to continue driving the engine from the rear, of course the engine compression is working against the inertia created by this rotating mass, so there will be some roughness created by the kickback from the compression as the whole thing comes to a rest.
During cold start-up, the lubricant in the transmission is heavy, thus providing more cushion and sound insulating property. When warm or hot, the lubricant runs more freely, greatly reducing those properties. Normal wear on the transmission syncronizers, gears, bearings etc. will cause the entire transmission to rotate more freely over time, this reduces internal parasitic torque loads, making the geartrain sound "loose".
No doubt that due to manufacturing tolerances some will cars sound worse than others, but you might want to take the above factors into consideration before you think there is something drastically wrong with yours.
BTW, no I don't work for GM or any other interested party.
I'm just an old car buff from the old school.
Stan
 

B/STOCK

Well-known member
Joined
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Messages
188
Location
RI USA
Corvette
2000 Magnetic Red Vert & 2015 DSOM Coupe Z51-3LT
Stan I put 39 years of driving 3 thru 6 speeds and beleive me when I say my 00 6 speed noise is far from normal. If you shut down this car with the clutch out it makes enough noise to draw a crowd. Seriously, people looking under the car to see what fell out. I personaly never let the car idle with the clutch out because the noise is embarrassing. If all the trannys made noise it would be understandable, but some make little if no noise and some just rock and roll. My I add that mileage seems to make no difference. At 10k mine sounds the same as day one. This is one of those things that you have to hear it to beleive it. Will sumit a audio link after the car comes out of winter storage. Michael
 
V

vettepilot

Guest
Wow,
From what you're describing during the neutral idle and making that much noise, I'm sure I would be concerned also. I certainly didn't mean to insinuate that there was nothing wrong with any of them. What I have seen over the years are situations where people have had automatics in every vehicle they owned, then they suddenly make the switch to a manual tranny and can hear the drivetrain, something they never experienced before.
I guess it can be quite disconcerting to have a new Vette sitting there clunking and grinding away, while onlookers are supposed to be admiring this new purchase. And, as we all know, once the Corvette Warranty is gone, most repair bills start at $1000.00 and climb faster than the power curve.
Stan
 

c4c5specialist

Technical Advisor
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Messages
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Nope, but someday.
Hi there,
Please understand that you are not dealing with a conventional transmission here. You also have a torque tube back bone that also has lash built into it, as it will slip into either end, the clutch plate, or the input shaft to the transmission.
As the power pulses, from the compression strokes, are not smooth, this results in back and forth type movement in the driveline. You are stopping that movement, when you disengage the clutch, therefore, no rattle.
This is a normal condition, and the designs of the driveline are there to cause this.
In order for this driveline to handle the power that it has, this is a byproduct of this, and should be thought of as such.
Besttoall, c4c5:hb
 

B/STOCK

Well-known member
Joined
Oct 24, 2001
Messages
188
Location
RI USA
Corvette
2000 Magnetic Red Vert & 2015 DSOM Coupe Z51-3LT
c4c5specialist Thanks for the explanation. Could you tell us why some of the trannys make a ton of noise and the rest are relatively quiet? Thanks Michael
 

c4c5specialist

Technical Advisor
Joined
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Messages
3,682
Location
New Haven, Ct. USA
Corvette
Nope, but someday.
Hi Fast red,
Well, honestly, I have seen some with higher mileages, and some with lower mileages.
I would suggest manufacturing tolerances. The vehicles are still mass produced motor vehicles, and in that, there are tolerances.
Some, are probably at the correct tolerance, and the noisier may be at the outside edges of tolerances.
This is simply theory, as I have c5s in my service stable, that are noisy, and have 10 miles, and then I have 50k cars that are exactly the same way, with NO problem in durability.
So, your guess is just as good as mine on this. Just know, that there is NOT one thing that can be done about this issue. It is simply a design trait.
Besttoall, c4c5:hb
 

B/STOCK

Well-known member
Joined
Oct 24, 2001
Messages
188
Location
RI USA
Corvette
2000 Magnetic Red Vert & 2015 DSOM Coupe Z51-3LT
Thanks c4c5. I don't have a problem with the noise as long as it proforms properly. You know how short the cruise season can be in New England. Thanks again Michael
 
V

vettepilot

Guest
Fast Red Vette,
I just noticed your Town/State on your post info. I was originally from Foster, R.I., wife from West Greenwich. I think my highschool, (Ponaganset) used to play Barrington in Hockey, and Basketball, can't remember about football, we always lost in those days( the 60s). Have you always lived there?
Stan
 
C

C5 Nik

Guest
No noise but difficult to get into reverse

Hi guys,

I have a 2000 --6 spd w/ 29k on it and I have had it to two local dealers about the difficult to get into reverse when cold problem. It will grind and make terrible noises. This is not the first corvette or 6 spd I have owned and I think it is terrible.

Dealer #1 told me to put the shifter into different gears before cranking and putting into reverse (3-4, 4-3, 3-4, etc...)that is ridiculous. I checked the manual to verify that I do not have to put it into other gears to "warm it up"--the manual is on my side.

Dealer #2 told me that I have to get it over that second little notch before I put it into reverse. C4C5 you might be able to answer this...How is the transmission designed that I would need to get it past the notches??? They said that it was fine and it was not adjustable.

Am I insane or is this completely "NORMAL???" like the excessive rattle you guys have?????

Thanks for lettting me vent. :mad

Nikki
 

c4c5specialist

Technical Advisor
Joined
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Messages
3,682
Location
New Haven, Ct. USA
Corvette
Nope, but someday.
HI Nikki,
NO, NOT NORMAL.
Honestly, I would first do a shifter adjustment, to confirm that the shifter has not moved.
Second, you say it only happens cold?????
If so, you probably have syncronizer issues, especially with the grinding. Now, are you allowing the shifter to line up, meaning that you are in neutral, push in the clutch, and then push the shifter to the right, and up, in one fluid motion??
If you are doing this, you should NOT have a problem, no grinding or anything. It may be notchy, when cold, but it should always go in.
Does it ever pop out of reverse???
Let us know, and confirm the shifter adjustment before proceeding.
besttoyou, c4c5:hb
 
C

C5 Nik

Guest
I have made sure that the clutch is all the way to the floor and put it into gear in a "fluid movement". Still it grinds.

How is the clutch adjustable?? Both dealers have told me it is not. :confused

It is giong back to the dealer tomorrow (the headlight motor went haywire) and I am going to have them re-evaluate the clutch issue..... I will keep everyone posted.

(I forgot to mention..it occasionally needs convincing to get into 1st)

Thanks for your help.
Nikki
 

c4c5specialist

Technical Advisor
Joined
May 29, 2001
Messages
3,682
Location
New Haven, Ct. USA
Corvette
Nope, but someday.
Hi there, Nikki,
Well, the clutch is adjustable, however, it will adjust on its own.
I am talking about the shifter, as sometimes, it may come out of adjustment.
If you want to blow their minds, ask them about fulcrum adjustment on the pressure plate. Basically, it will change the point at where the fingers pivot, based on clutch plate wear. To compensate, so your pedal stays at the same place longer for engagement.
Now, I would really have them perform a spin down test, to check to see if the syncronizers are working correctly.
Please keep us posted on this, take care, c4c5:hb
 
D

David-F

Guest
I would say it's a sycnro problem I have changes a lot of them especialy seeing how you do not have a problem going into first.

David Fulcher
 
R

rjsmith

Guest
marckschwartz said:
I just bought a new 2002 six speed coupe. When the clutch is out there is a rattle that is louder when the car is warmed up. It disappears when I engage the clutch. It has been in three times and the answer is absurd. I am being told that some fifty other owners across the country have complained and it is an engineering problem with no fix. Not every six speed has this problem!!!

You don't explicitly state this, but I am assuming you are hearing this noise when the transmission is in neutral and the clutch is engaged (i.e., the pedal is out). If the noise disappears once you put the transmission into first gear and engage (i.e., release) the clutch then the noise you are hearing is the transmission input shaft. Disengaging the clutch (depressing the clutch pedal) in neutral stops the input shaft from spinning so the noise disappears.

Stan (vettepilot) correctly stated that this noise will get louder as the transmission lubricant warms up and thins out.

My '92 with the ZF 6-speed was so noisy I swore something was wrong. I took it back to the dealer and their tranmission mechanic told me I was lucky, I had a quiet one. He wasn't kidding. I went autocrossing and sat inside other idling C4s with the ZF 6-speed. They were much louder than mine. I put 65,000 miles on that car, a lot of those in stop and go traffic on the 405 freeway in Southern California. I also drove the car in many autocross (Solo II) events. It never caused me any problems other than the coffee-grinder noises when the car was in neutral with the clutch out (i.e., disengaged).

For what it's worth, my Z06 with the M12 transmission makes a faint noise in neutral with the clutch out. However it's nothing like the noise in the ZF 6-speed. The noise disappears when I disengage the clutch and the transmission makes no noise when the car is in motion.

The ZF (Zendhausenfabrik, made in Germany) 6-speed was developed to handle the torque of the LT5 engine so the gears were relatively rough-cut. This is what accounted for the noise in those transmissions.

My advice is to sit in another car (actually as many as possible, go to an autocross) with the M6 transmission and get a sense for just how loud yours is in comparison.

Sometimes the dealer's mechanics know what they're talking about. Sometimes.
 

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