Clunk from Bellhousing
Thread Starter
Teching In
Joined: Feb 2008
Posts: 15
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From: Palo Alto, CA
Clunk from Bellhousing Okay guys this drive-train has been a real pain in my butt. Heres the deal, The previous owner abused my car so I bought it knowing it had a bad transmission. Its a 99 Camaro SS with t-56 and 4.10 gear ratio.
So the first thing I did was rebuild the transmission and change to an Ls7 clutch, flywheel, pilot bearing, slave cylinder, and then bleed it. A month later I lost the clutch pressure because of a defective slave cylinder. So this time the dealership pulled the tranny because I did not have the time. The only charged the labor because the part was under warranty. It was hard to get in gear for a bit but it sorta just started to shift perfectly. One day I noticed the car had a vibration at 70-90 miles per hour.
I figured it was wheel out of balance. So I balanced all my wheels in class. The vibration continued so I was going to do a NVH test on it (Noise Vibration frequency test). When I lifted the rear wheels to drive it 70 I heard a terrible clunk sound. So i left it in 5th and jumped out to see where the sound was coming from. Sounded like it was from the bell housing. The clunking was not as bad when I let it run in 2nd gear. It is a loud clunk and it goes away in neutral so its not engine related. Also when driving the car with wheels on the ground obviously, I do not hear any clunk at all. Can someone explain what is wrong with my car now, and why it makes that sound when lifted off the ground??? Thanks guys for any help or advice
So the first thing I did was rebuild the transmission and change to an Ls7 clutch, flywheel, pilot bearing, slave cylinder, and then bleed it. A month later I lost the clutch pressure because of a defective slave cylinder. So this time the dealership pulled the tranny because I did not have the time. The only charged the labor because the part was under warranty. It was hard to get in gear for a bit but it sorta just started to shift perfectly. One day I noticed the car had a vibration at 70-90 miles per hour.
I figured it was wheel out of balance. So I balanced all my wheels in class. The vibration continued so I was going to do a NVH test on it (Noise Vibration frequency test). When I lifted the rear wheels to drive it 70 I heard a terrible clunk sound. So i left it in 5th and jumped out to see where the sound was coming from. Sounded like it was from the bell housing. The clunking was not as bad when I let it run in 2nd gear. It is a loud clunk and it goes away in neutral so its not engine related. Also when driving the car with wheels on the ground obviously, I do not hear any clunk at all. Can someone explain what is wrong with my car now, and why it makes that sound when lifted off the ground??? Thanks guys for any help or advice
Last edited by reddevilSS; Jun 18, 2009 at 12:34 PM.
it sounds like it has something to do with the angles the drivetrain is operating at - check your driveshaft, it might be as easy as tightening a bolt in a bit more.
i'm more of a novice with cars, but if the sound is more noticeable when the wheels are spinning faster (5th gear compared to 2nd gear), the problem is likely atleast past the transmission, too.
i'm more of a novice with cars, but if the sound is more noticeable when the wheels are spinning faster (5th gear compared to 2nd gear), the problem is likely atleast past the transmission, too.
Thread Starter
Teching In
Joined: Feb 2008
Posts: 15
Likes: 0
From: Palo Alto, CA
I took it back to dealership. Apparently the transmission mount loosened up after the strip. The sound is gone, but the vibration is still there. Maybe the drive-shaft is out of balance? Everything is tight so I am not really sure. I was thinking of replacing the differential with a Moser Ford 9 inch. Does the stock drive shaft work with the ford 9". If so I will replace mine and u-joint and maybe vibration will go away.
Thread Starter
Teching In
Joined: Feb 2008
Posts: 15
Likes: 0
From: Palo Alto, CA
I decided to remove my drive shaft and take it to get balanced. He balanced it and told me that there is a weird sound coming from the center of the shaft. The vibration has gone away significantly. There is still a little vibration at a higher speed like around 85-90. But I would say 70% better. I am ordering a 12-bolt moser (changed my mind) so hopefully the vibration disappears. I needed a rear end anyways so its perfect timing.
