veppe

I'm very newbie here with my Corvette (-98 Pace Car, 60 kmiles with it), this is my first posting in this forum I bought this car about week ago and heard already during test drive some weird noise when slightly accelerating (and also when rolling) with 1st or 2nd gear in. I heard also some resonant noise, so I thought it was just that sound I heard. Still I'm not sure if it's some resonance, so I just want to check it here because I heard someone has got his transmission replaced by warranty because of some rustling noise from transmission (however I don't know details of the problem with that other Corvette, but only that it was also 6-speed C5). Of course my PC doesn't have warranty anymore, so I'm scared about some $$$ costs to fix this problem

So, has anyone had similar noise with 6-speed transmission? What was the actual problem and how to fix it?

P.S. I have had about 20 cars with manual transmission - actually had no car with automatic at all - so at least I know this noise is not something usual with manuals

lucky131969

How many cars have you owned where the transmission is in the rear of the car? Reason I ask...are you sure the noise is originating from the transmission?

veppe

None.. You're right I'm not sure if the noise is from transmission More probably it's coming under hood instead of rear.. Well, I don't then know if this is good or bad I think I need to investigate it more.. It's only little bit hard to investigate as I need to drive the car to hear the sound

I hope it's only some resonance caused by some loose thing or something...

dwestsr

I think what you are hearing is the typical torque tube "rattle". It usually happens right after the clutch is released and goes away as the rpm increases under light acceleration and any time you are in a lower gear at low rpm such as making a normal turn at low speed. I have this on my 2004 mn6 coupe. I too, was concerned until I drove a 2008 c6 and heard the same noise in a brand new car. In my car the noise usually is only present after the car is driven for a while and you never hear it when it is cold. From what I have read on the forum this is a normal noise and nothing to be concerned about. Go enjoy your vette and quit worrying!!!

C5B

Yeah, that noise sux. When I bought my 2003, new, I didn't notice it until I was parking the car the night I brought it home. Then, I shut the engine off with the tranny in neutral and the clutch out. I wish I had a picture of the look on my face.

It sounds like a $1000 rattle bucket when you do that. Bolts in a coffee can is the most accurate description, and it is just retarded. Nothing short of embarrassing if you do that and someone is within 100 feet to hear it.

I turned around and drove it right back to the dealer. They called the next day and said: "That's normal, it is actually supposed to sound that way." I was horrified that someone actually designed something to rattle.

So, clutch in, engine off. Wear down the thrust bearing even faster.... sigh.

- Colby

veppe

Thanks for those alleviative replies Actually I now remember I couldn't hear the sound so well when it was cold, but easier to hear something when I have driven it warm.

I had the very similar rattle noise in my previous Mercedes (old W124 300 TD) when I turned it off with neutral and clutch released. I investigated that noise also many times (and asked some mechanic to investigate too), but finally believed it was a feature.. :o But this resonance noise with my Vette is so different from my previous manuals so I really wondered it... Well, I believe you now it's a feature but maybe I still try to find some source for some resonance as it sounds so odd And maybe I will just test drive some other manuals just to compare I will get back to this thread if I find something really wrong

Thanks once more! This is great forum for Vette owners

veppe

This sound seems to come however from transmission I drove with my friend and we tried to locate the sound, I drove slowly by him and definitely the sound comes from rear. It's coming at least in 1st, especially if you first accelerate a little (until ~2500-3000 rpm) and then release the gas => the sound is very loud. Like metal to metal or something... Has anyone had/heard about similar problem?

av8rdavid

YES!!!!!!! I have the SAME noise...

In 1st gear till about 3K , then second till about 2500 rpm, bolts in a coffee can...

And then there is the "clutch must be engagaed before sutdown" noise avoiding method...

I think the "clutch must be engaged" is a common thing since my friends 2005 BMW 330Ci does the EXACT noise, but the 1st and 2nd gear noises must be of concern.

I'm getting ready to replace the fluids in the rear end and tranny....Anyone else experience this problem and find a solution?

Has anyone found detailed procedures on how to change the tranny and dif fluids?

MattZ28

I think you're talking about the throwout bearing noise...I haven't seen one 6spd Vette that doesn't have it.

kevin40zx

I think I have the same sound in my six-speed. Except I usually get it after start up when its really cold out. Under slight throttle or no throttle there is sound coming from the cluth area that sounds like a wire brush rubbing on the cluth disc. After the motor is warmed up it stops. I've had the same noise before and after recent clutch replacement. ???

jgump

I get noise too when it is cold. I'll post a movie. Mine sounds like a tambourine.

jgump

Here is the video

My car did this on the day I put it away for the winter. It sat for about a week in the garage in 20 degree F weather in December. It never made this noise before.

See video:

http://s203.photobucket.com/albums/a...rangeSound.flv

The noise sound like a tamborine and was coming from the trans area

av8rdavid

WOW, thats a whole new sound to my ears....It sounds to me like a loose heat shield?

Does it do it while driving?

LMH4C5

Veppe....I had the same sounds on my 02 MN6. Had the local stealership listen to it, they said it was a common sound when the interior of the Cat convertors lets go. They wanted $1,200.00 to install new cats. Went for a second opinion to a noted transmission and clutch specialist. They completely removed the clutch, transmission, and differential. Disassembled each of these items and inspected for damage. Everything was perfect. Their only conclusion was that the clutch springs were rattling because they were stretched out a little. I replaced the clutch with a stage 1 LuK and the noise went away by about 90%. That was three months ago and now the same sound is starting to come back. As the mechanic is a friend of mine, I am taking the car in next week (this time free of charge) so he can start checking everything else that might rattle. The sound drives me nuts. I hear it mainly at very low RPM in 1st and 2nd. Like driving in a quite area very slow with the drivers side door open so I can hear where it is coming from. The noise stops as soon as I accelerate.

If anyone else has any ideas, I'd be happy to check them out next week.

jgump

It went away after the car warmed up. I'll know better next month when I take it out of storage.

O4-/-C5

See if this is what you are talking about.
Go to a dealership and get the following service information:
DOCUMENT ID# 1858665
Its five pages long and shows a normal noise problem identified as "Gear Rattle" in 6 speed transmitions.It specifically mentions Corvettes.
Hope this helps.

kevin40zx

I accually think that could a possible source of the problem. I'm not in the habit of agreeing with stealerships but I've had lots of "weird noise" problems on cars that were attributed to different exhaust components. Heck I had a terrible belt squeeling sound on Vette about a year ago that turned out to be coming from the exhaust seals after the header pipe.

BlackZ06

Document ID# 2031927

Subject: Manual Transmission Operating Characteristics #03-07-29-004D - (10/17/2007)

Models: 2008 and Prior Passenger Cars and Light Duty Trucks with Manual Transmission

This bulletin is being revised to add the 2008 model year. Please discard Corporate Bulletin Number 03-07-29-004C (Section 07 -- Transmission/Transaxle).

Important: Even though this bulletin attempts to cover operating characteristics of manual transmissions, it cannot be all inclusive. Be sure to compare any questionable concerns to a similar vehicle and if possible, with similar mileage. Even though many of the conditions are described as characteristics and may not be durability issues, GM may attempt to improve specific issues for customer satisfaction.

The purpose of this bulletin is to assist in identifying characteristics of manual transmissions that repair attempts will not change.
The following are explanations and examples of conditions that will generally occur in all manual transmissions. All noises will vary between transmissions due to build variation, type of transmission (usually the more heavy duty, the more noise), type of flywheel and clutch, level of insulation, etc.

Basic Information
Many transmission noises are created by the firing pulses of the engine.
Each firing pulse creates a sudden change in angular acceleration at the crankshaft. These changes in speed can be reduced with clutch damper springs and dual mass flywheels. However, some speed variation will make it through to the transmission.
This can create noise as the various gears will accel and decel against each other because of required clearances.

Gear Rattle
Rattling or grinding (not to be confused with a missed shift type of grinding, also described as a combustion knock type of noise) type noises usually occur while operating the engine at low RPMs (lugging the engine).
This can occur while accelerating from a stop (for example, a Corvette) or while operating at low RPMs while under a load (for example, Kodiak in a lower gear and at low engine speed).

Vehicles equipped with a dual-mass flywheel (for example, a 3500 HD Sierra with the 6-speed manual and Duramax®) will have reduced noise levels as compared to vehicles without (for example, a 4500 Kodiak with the 6-speed manual and Duramax®). However, dual-mass flywheels do not eliminate all noise.

Neutral Rattle
There are often concerns of rattle while idling in neutral with the clutch engaged.
This is related to the changes in angular acceleration described earlier. This is a light rattle, and once again, vehicles with dual mass flywheels will have reduced noise.
If the engine is shut off while idling in neutral with the clutch engaged, the sudden stop of the engine will create a rapid change in angular acceleration that even dual mass flywheels can not compensate.
Because of the mass of all the components, this will create a noise. This type of noise should not be heard if the clutch is released (pedal pushed to the floor).

Backlash
Backlash noise is created when changing engine or driveline loading.
This can occur when accelerating from a stop, coming to a stop, or applying and releasing the throttle (loading and unloading the driveline).
This will vary based on vehicle type, build variations, driver input, vehicle loading, etc. and is created from the necessary clearance between all of the mating gears in the transmission, axle(s) and transfer case (if equipped).

Shift Effort
Shift effort will vary among different style transmissions and synchronizer designs.
Usually the more heavy duty the transmission, the higher the shift effort because of the increased mass of the components. Shift effort can also be higher in cold weather because the fluid will be thicker.
Medium duty transmissions will not shift as quickly as a Corvette transmission. To reduce shift effort, do not attempt to rush the shift - allow the synchronizers to work as designed. Shifting harder will only increase the chance of rushing past the synchronizer leading to grinding while shifting.

Non-Synchronized Gears EDITED OUT - NOT APPLICABLE TO C5

Skip Shift
Currently, the Cadillac CTS-V, GTO, and Corvette (other models may follow) equipped with the 6-speed manual transmission have a feature referred to as a "skip-shift".
This feature only allows a shift from 1st to 4th gear when the indicator lamp is illuminated on the dash. Dealers cannot disable this feature as it was established to help meet fuel economy standards.
The conditions for this feature are: engine coolant at normal operating temperature, vehicle speed of 24-31 km/h (15-19 mph), 21% or less throttle being used (refer to Service Information or the Owner Manual for more details.)

kevin40zx

Thanks for posting that service bullitin. I've definatley experienced gear rattle, neutral rattle, and backlash. The noise I experience sounds nothing like these. Its more of a rustling like the OP described.

veppe

Yeah, the noise of mine is also something not in that service bulletin. As I said in first posting, all my cars (~15) have been manual, so I'm very familiar with the common rattles and noises coming from manual transmissions.

Actually that cat related guess is good, I have heard similar issues with weird noises (in Mercs). But I think it should have then at least some noise also when idling/throttling at neutral ?!

My next step will be anyway to change the clutch because it's often shaking when releasing the pedal from stop. So I hope it will also solve this weird noise problem Any recommendations for clutch? Just OEM?