[BatMobile]

Hey everybody. Curious if this is normal stuff for a manual tranny. It seems that when rev match over revs (it guesses 4k rpm but I'm in middle of breaking or it just guessed wrong and I end up letting of clutch and into a gear that brings the rpm to say 2k instead of the 4 it guessed) During those times when I let off clutch there is like a clunk noise. I'm assuming it is something making up the difference between the revd engine at 4k and bringing It to 2k. Btw no clunk and smooth downshift when it revs matches correctly. I can also replicate the clunk if I rev match myself incorrectly.

Are the clunks normal when rev match doesn't match it up right? Should I only downshift when rev match is on and I'm looking to accelerate, or when I know it will be in the upper rpm range heading into a corner?

Anyone who understands why it would make a clunk in the situation I described about would be much appreciated! Thx

 

[Jerry U]

Hey everybody. Curious if this is normal stuff for a manual tranny. It seems that when rev match over revs (it guesses 4k rpm but I'm in middle of breaking or it just guessed wrong and I end up letting of clutch and into a gear that brings the rpm to say 2k instead of the 4 it guessed) During those times when I let off clutch there is like a clunk noise. I'm assuming it is something making up the difference between the revd engine at 4k and bringing It to 2k. Btw no clunk and smooth downshift when it revs matches correctly. I can also replicate the clunk if I rev match myself incorrectly.

Are the clunks normal when rev match doesn't match it up right? Should I only downshift when rev match is on and I'm looking to accelerate, or when I know it will be in the upper rpm range heading into a corner?

Anyone who understands why it would make a clunk in the situation I described about would be much appreciated! Thx

Use rev matching all the time and have noticed overreving. Perhaps it depends on how quickly you release the clutch. Don't recall a "clunk." Many of my downshifts are not from a high rpm start. I often am going from 6th to 4th or even 3rd so I do need a high rpm match. That occurs when cursing at ~60 mph on a country road then making a turn onto another road and putting the car in the proper gear to accelerate after the turn.

 

[BatMobile]

Thanks. Can you try going like 45 in 5th, over rev on your own. Say 4k and down shift into 4th and let off clutch? Keep windows closed and listen for a clunk noise. I don't think it has to do with letting off clutch fast. If if does its bc the rpms have a chance to go back down to proper range bc I'm letting off slow

 

[Jerry U]

Thanks. Can you try going like 45 in 5th, over rev on your own. Say 4k and down shift into 4th and let off clutch? Keep windows closed and listen for a clunk noise. I don't think it has to do with letting off clutch fast. If if does its bc the rpms have a chance to go back down to proper range bc I'm letting off slow

Just came back in after 30 mile drive into town. Listened for a Clunk but just read your post so didn't try your suggestion. Another thought, the C7 has a dual mass flywheel. Saw a post about possible noise from it but not related to rev matching. With a sudden change in rpm there could be a noise, but I have not heard it.

 

[BatMobile]

Just came back in after 30 mile drive into town. Listened for a Clunk but just read your post so didn't try your suggestion. Another thought, the C7 has a dual mass flywheel. Saw a post about possible noise from it but not related to rev matching. With a sudden change in rpm there could be a noise, but I have not heard it.

Thanks Jerry! Interesting on the dual mass flywheel. How do they describe that noise when sudden change to rpm? I have noticed, and you have to get it right, when say accelerating hard in 4th at like 50mph, and if you let off and gas and coast, there is a clunk a few seconds after. Every so slight clunk. most probably wouldn't notice. Wonder if that is the dual mass flywheel.

 

[BatMobile]

Stingray owners, can a few folks try the above and let me know if you get the same result? Curious to know findings. In addition, I have noticed a light clunk if I accelerate and then let off the gas quickly. Has to be in the right range to get it but curious if this has been noticed by others.