Gear grind sound 7AT?? Transmission problem? help!
 

After a 5 hour drive I noticed that when I start up the car and I shift from P --> R it makes a gear grinding noise. Is it my transmission that got damaged? I don't see how I could have damaged it. I was driving very casually with no redlining. The only bolt on mods are HFC, CBE and K&N Intakes. If it is my transmission, my warranty should not be voided due to the bolt ons if I call the dealership right? Its a fairly new 2010 7AT with ~5000km.

Nah...my 350Z used to do a low-sounding groan when it'd go into reverse all the time. It's normal. If it's not that, also make sure your foot is firmly planted on the brake pedal - it could've just been your pads on the rotor.

My 350Z was an AT too, btw. The 5AT and 7AT are virtually identical in design, with the only difference being an extra 2 gears. I'm not surprised if the 7ATs make this noise too.

it makes the same noise as i put it in Park from reverse. It sounds as if the gears aren't matching up, like its scraping each other.

Take it to the dealer for a warranty call

I would take it to the dealer. I had problems with my auto tranny making a loud clunking sound when going from park to reverse/drive. Dealer replaced my tranny I think the mileage was around 10k.

Did you ever find out the issue? Mine just started doing this today!

Thanks

yeah! turned out that one of the bolts holding my exhaust onto the car came loose and the frequency of the exhaust from P--> R caused it to rattle. Tightened the screw and it was all fixed.

great you figured it out because automatics should never grind its all done through friction bands and clutch packs so if you have a true grind in an auto take it in asap (as in the gears are always meshed together in the planetaries, unsure on pawl setup in the z auto but i'm assuming its constant too)

I have the AAM Short tails. I dont think they would be that loud of a rattle.

I took the car out this morning when it was 34 degrees. Let it warm up, then i took it slow.

It didn't grind. I got to a stoplight and took off slow but gave her a little more power for a 45-60 MPH pull & it started again at high RPMS..

Would me exhaust do that?

I would try and set up an audio recorder and record the sound the next time it happens and take it to the dealer. It was rough trying to replicate the problem when I took it in. You should definitely take it in to get it serviced. It could be a simple problem like exhaust rattle or it could be a transmission problem. Better safe than sorry in my opinion.