C4 6-Speed wird loud noises from Transmission
Thread Starter
6th Gear
Joined: Apr 2023
Posts: 6
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C4 6-Speed with loud noises from Transmission
Hello guys! (Please excuse grammatical errors, I translate with app!) I'm new to the US forum! I come from Germany and have owned a C4 built in 1991 with L98 and 6-speed ZF black Tag and 40000 miles for 4 years! So actually almost a new car! I bought a C4 with manual transmission because I thought there were hardly any transmission problems....unfortunately I was wrong! Last summer, the Dualmass Flywheel started making noises! A loud, unrythmic clack of clack at idle! Whether the clutch is kicked or not, the noise is there! Since there was no DMF as a spare part, I had to convert to a single flywheel! However, the transmission now makes loud noises when starting up, i.e. under 2000 revolutions! Does anyone have experience with the transmission or similar experience? I did not find a solution in the German Corvette Forum!
Last edited by CaptainIglo; Apr 8, 2023 at 09:46 AM.
Zen Vet Master Level VII
Joined: Mar 2016
Posts: 5,218
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From: Southlake, TX
When you switch from a dual mass fly wheel to a single mass, there will be some normal noise at idle. To check, does the noise go away at idle when you push in the clutch? If the noise disappears, the system is functioning normal. A single fly wheel will be nosier than a dual mass.
Thread Starter
6th Gear
Joined: Apr 2023
Posts: 6
Likes: 1
Hi!
When I kick the clutch, the clack clack clack is gone! I knew that this problem would come at idle. Nevertheless, when starting in the first gear up to 2000 revolutions, I have a transmission noise, in the second gear and third gear under 2000 also...I drove a C4 with 100000 miles, this also had the noise, but much quieter!?
When I kick the clutch, the clack clack clack is gone! I knew that this problem would come at idle. Nevertheless, when starting in the first gear up to 2000 revolutions, I have a transmission noise, in the second gear and third gear under 2000 also...I drove a C4 with 100000 miles, this also had the noise, but much quieter!?
Thread Starter
6th Gear
Joined: Apr 2023
Posts: 6
Likes: 1
Thread Starter
6th Gear
Joined: Apr 2023
Posts: 6
Likes: 1
Engine mis-fire will cause noise from the dual-mass flywheel. And now that the flywheel is single-mass, the noise is from the transmission.
Engine mis-fire can cause noise from the flywheel and transmission. I've had it in my cars, and I would describe it as "clack-clack" like you have.
Engine mis-fire can cause noise from the flywheel and transmission. I've had it in my cars, and I would describe it as "clack-clack" like you have.
Safety Car
Joined: Nov 2008
Posts: 3,720
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From: Seattle Washington
If you go to the ZF Doc web site there is a lot of useful information. He has a shim kit that you could of installed when you switched to a single mass flywheel that will reduce the noise by 1/2. Keep in mind that this noise is not hurting anything in the Trans.
Racer
Joined: Nov 2015
Posts: 379
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I did a ZF swap a while ago and bought Spec's single mass flywheel, Stage 3+ clutch plate and pressure setting.
Did you balance the clutch and flywheel?
I used the whole package to be balanced at the machine shop. It was a little different from the original.
I have a black tag as well and the gearbox doesn't make any noise, and the clutch doesn't make any extra noise either.
Did you balance the clutch and flywheel?
I used the whole package to be balanced at the machine shop. It was a little different from the original.
I have a black tag as well and the gearbox doesn't make any noise, and the clutch doesn't make any extra noise either.
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Racer
Joined: Sep 2021
Posts: 360
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I’ve been through the same problem with my DMF, when hot it would make clacking sound because of slightly uneven idling. I converted to a single mass aluminum and now instead of the flywheel clacking there is the countershaft lash sound. Normally the DMFs make sounds before failing that’s why I replaced it but I think it’s possible it wasn’t that bad and the cause was the engine misfiring. When at low rpm and medium to high throttle it makes a sort of grinding noise. I’ve examined the transmission oil and it didn’t contain steel particles the. I’ve replaced the 5w30 with 10w60 and there is less idling noise but only until it warms up. The idle is set to 1000rpm and helps a bit. You could check the shimming kit for the counter shaft, I’m considering that. I’ve also bought a new pilot bearing.
Another problem I have is the clutch doesn’t engage smoothly but it shaking unless you rev the car to 2000rpm, even during shifts there is a short vibration, could be contaminated with oil or because of the countershaft or something misaligned.
Another problem I have is the clutch doesn’t engage smoothly but it shaking unless you rev the car to 2000rpm, even during shifts there is a short vibration, could be contaminated with oil or because of the countershaft or something misaligned.
Thread Starter
6th Gear
Joined: Apr 2023
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@Gale Banks 80' How many Time you need for install the Shim-Kit?
@MrBigDee I don´t know which Flywheel was used, But i have it as a Complete package of a German ZR1 Guy gekauft....it´s made of steel and weights 12kg
@Nilak i also had Castrol 10W60 in it and then tested 75w90! Quiet when cold until it was warm...how can i checked the shiming-kit for the counter shaft?
@MrBigDee I don´t know which Flywheel was used, But i have it as a Complete package of a German ZR1 Guy gekauft....it´s made of steel and weights 12kg
@Nilak i also had Castrol 10W60 in it and then tested 75w90! Quiet when cold until it was warm...how can i checked the shiming-kit for the counter shaft?
Racer
Joined: Sep 2021
Posts: 360
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I don’t know where you could buy the shimming set but probably at zfdoc.com and I think you can find info on how to install it. As far as I remember the transmission needs to be unbolted from the engine to gain access to the countershaft plastic cover that you remove, then remove the retainer clip and place thickest shim it can accept between the retainer and bearing…something like that.
Safety Car
Joined: Nov 2008
Posts: 3,720
Likes: 557
From: Seattle Washington
The Shim Kit is pretty easy to install once the Transmission is removed. Yes this needs to be done before installing it. Carolina Clutch I believe also sells a Shim Kit in addition to ZF Doc.