Transmission Noise

[Jeb]

It's an automatic in an 87 Vert with about 96K miles.

When the car is shifted from Park to Reverse or Drive, the transmission makes a sound as though it's "snapping" into gear. It's an audible "clunk" that sounds almost like a u-joint is taking up slack, if you know what I mean.

The U-joints are new (all 6 of them) and I've looked at them and felt them and I don't think any of them are bad. There doesn't seem to be any play in either the drive shaft or either half-shaft however the noise became noticeable after the u-joints were changed.

Anyone have any ideas what this might be? I have a feeling it's something inside the transmission but I'm not sure since sound travels so much it's hard to determine where exactly it's coming from.

Help!

 

[Vettefan87]

When you shift it from Park to Drive how much does the motor move? You may have a bad motor mount, or tranny mount. My brother (vetteboy86) has had a lot of problems with clunks, when shifting from Park to Drive, and under acceleration. His vette goes in and out of gear very hard, while mine does not. I would check to see how much the motor is moving, and possibly get underneath the car and see how much the tranny is moving as well.

 

[WhalePirot]

As you've already done U-joints, I was thinking a view from underneath the car, while someone shifts it as you describe, will help a great deal. Listen for where the noise originates and look for movement.

 

[G Winter]

GM Flexplates have a nasty habit of cracking in the center near the bolts. Check to see it you can hear any click when you rev the engine in park.
Glenn

 

[Rufus1050]

Jeb, when you changed out the half shaft joints, did you check the axles for looseness? Jack up the rear with the tires on and do the drill with the 12 & 6 and 9 & 3 hand positions...see if there's much play. If you've already tried this then it's back to other diagnostic measures. Someone else reading about your problem will come to the rescue. Good luck with your challenge...

 

[Rufus1050]

Hey Jeb...just noticed that you're from the bayou state! What part? I'm from Lake Charles. Just wondering, okay...

 

[Jeb]

I checked the hubs when doing the U-joints and they're tighter than ticks.

I think I may have stumbled on something though. I readjusted the cable to the throttle control and the noise has subsided somewhat. It's still there but is now barely noticeable.

I'm from the other end of the Bayou State, Rufus. Covington. We're just on the north side of Lake Ponchartrain about 3 miles north of I-12.

How's Bayou?