Help with transmission noise diagnosis!

[ebncrdr]

My transmission is a TCI Streetfighter TH350 with 1500-2200 stall with maybe 500 miles on both the converter and trans. My problem is when I shift to drive, there is a noticeable clunk as it goes into gear. As I then I release the brake and the car moving at idle speed, there is a loud banging or hammering type sound. As soon as I give some throttle the sound goes away. This noise only happens in DRIVE and in no other gears. It's almost as if the choppiness of the idle causes it to start, and only happens at when the car is creeping at idle rpm 900-1100rpm.



I have a new driveshaft/u-joints, no slop in the pinion, bolts on the converter are tight, SFI rated flywheel, it's a polyurethane trans mount, and motor mounts are in good shape. I've had the inspection cover off everything appears ok.

I can provide more info as needed, but I am hoping someone can at least get me headed in the right direction.

[andrewb70]

Is it a one time clunk or cyclical clunking at low speed?

Andrew

[ebncrdr]

It's just one solid clunk when it goes into gear. After that the hammering noise is inconsistent. Sometimes it's faint and others it is extremely loud. It's only as the car is creeping at idle rpm.

[ebncrdr]

Here is a video of the noise. Car is in drive, rolling with no throttle

http://vid18.photobucket.com/albums/...E11D7B8A50.mp4

[ebncrdr]

Could the clunking noise be caused by sloppy differential noise transferred up the driveshaft? The trans and converter are only 5 months old and I just installed a new built driveshaft. I put the rear on jack stands and there seems to be quite a bit of backlash in the gears. The pinion yoke feels right with no play. It is the original 8.5 10 bolt and the only thing in the drivetrain I haven't touched yet.

[andrewb70]

Michael,

Watching the video it seems that the noise is more in rhythm with the engine sound than with the rolling motion of the drivetrain. Have you checked all of our motor mounts and exhaust mounts? This sounds like metal to metal slapping. Towards the end of the video the car is barely moving but the noise is increasing in frequency as your slowing down.

Andrew

[ebncrdr]

Yes I definitely agree it's in rhythm with the engine. It sounds loud in the video but it's even louder in person. Motor mounts are good, looked at them this morning. I have a decent cam in the engine and at idle it gives the car a lurching back and forth motion at that speed in the video. I had the car in drive and a stop in front of the wheel. My thought was I could get out and listen, but there was no noise. Only when I started rolling did it start again. This is what led me to look at possibly the rear end being sloppy with excess backlash or other issue. Any bit of throttle and poof, the noise is gone. From what I have diagnosed I think it's not an engine issue for sure. Runs great, revs great. No noise in park, neutral, or reverse.

In the morning I am going to run the car with the rear wheels off the ground and see what happens.

[69_Sportsroof]

I can't listen to the video at work but one thing to check is the park lever if it's a violent motion at slow speed. Inside the tail housing there is a rod with a spring and a lever that locks the car in park, if the pivot spring is loose/incorrectly installed the parking pawl can randomly hit the shaft, which has rounded cutouts. At low speed it will bounce in and out noticeable and you will feel it, at high speed it will tend to just ride the top of that gear and just make a ton of noise. This should present in reverse though too.

Ive also seen bands break and make a lot of noise, once they let go the piston that applies them just jumps all the way to the bottom of the housing, making a loud slap, and the broken band ends just flop around in the trans.

[ebncrdr]

I would definitely like to hear your thoughts on the video sound. A broken band would also cause the trans to slip though wouldn't it? I assume that it would make noise all the time too.

The parking lever is something I will look at. It doesn't make any noise in reverse. I have also noticed if I give the engine the slightest amount of rpm the noise goes away. I am beginning to think this isn't a trans issue, and possibly my torque converter.