Transmission clunks when shifted to reverse

[Tetz]

Hello everyone.
I have problem with transmission making a clunking noise.

Car:
2009 Yaris 5-door liftback with automatic transmission.
ABS is standard.
It has only 450 miles on it.

Problem:
When the gear is shifted to reverse, it makes a clunk noise once.

When it happens:
Happens only after I drive 8 miles or more and shift the gear into reverse.
Happens even if I put the gear to neutral and wait a few secs before putting it to reverse.
Happens even if I put the gear to park and wait a few secs before putting it to reverse.

When it does NOT happen:
When the car is just started.
When I drive only 5 miles or less.
Once it makes a clunk noise, it won't make the noise again until I drive another 8+ miles.
If I drive over 30 miles without shiting to reverse, then it doesn't make noise.

So far, when I drive 8-15 miles, it made clunk noise 100% of the time.
When I drive 5 or less miles, it didn't make clunk noise even once.
I drove over 30 miles twice and it didn't make noise those two times.

The loudness of the noise is not consistent.
Sometimes, it's only a loud click. But sometimes it's loud enough of clunk that anyone would notice.

I wanted to see if anyone knows what this noise is.
I'm not wanting to taking the car to the dealer because it only can be recreated after driving 8 miles or more.
I'm thinking they would test it without driving that far and finds everything is ok.

Any help will be appreciated.
Thanks in advance.

[Toybilt]

I would check motor/transmission mount bolts. also you could open the hood have someone start engine put one foot on brake one on gas and run engine around 15 to 1800 rpm and shift trans from reverse to forward and forward to reverse listen for clunk and look for engine jumping around. it will move some but should not jump or rock so to speak

[Tetz]

Thanks for the reply.
I checked other 2 2009 Yaris 5-door liftbacks with automatic transmissions, and they both made the same noise.
It's pretty loud in the closed parking lot that even my wife noticed the noise when I didn't let her know about the noise.
I know 2007 model didn't make this noise... Maybe this started from 2009

[freeyellow2000]

Take it back to the dealership... it under warranty

[Tetz]

Originally Posted by freeyellow2000

Take it back to the dealership... it under warranty

I didn't take it back to the dealership because the other cars at the dealership were making the same noise.
And it stopped making noise after 2 weeks.
Weird.