I crawled under the car today and checked out the two flex discs that are connected to each end of the driveshaft. The rear disc seemed good. Bolts seemed very secure with no play. However, I did notice a number of tiny horizontal (when looking at the bottom of the disc) cracks in the disc itself. These cracks are very thin, not much thicker than a hair, and none of them make it to where the bolts go through the disc, they begin and end in between the bolts.

Are these cracks cause for concern? I definitely have a problem somewhere along the drivetrain, as the car clunks terribly, sometimes. Other times it shifts perfectly. It usually clunks worse from 3rd to 4th (with second gear start). The clunking is unpredictable otherwise.

Because it feels like it is coming from the rear of the car, and because it shifts perfect sometimes, I don't think it is the tranny itself.

The front flex disc seemed good as well, with secure bolts. I could only see the side of this disc that is metal(?), and I did not see any cracks. I need a dentist's mirror to see the other side, and I will look tomorrow.

There was one thing I thought was funny about the whole thing. I had the car backed onto ramps to observe the rear disc. I could turn the driveshaft about five degrees back and forth, with a metal clunking stopping me each way. This is how I could really tell that the bolts were secure. The odd part is that when I put the front of the car on ramps and observed the front flex disc, the shaft would not move at all. what's going on here? Is it just that the driveshaft is easier to manipulate further back from the transmission, maybe a leverage thing? Or is something not right here?

Thanks for your time.

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