Transmission rattle in 3rd gear?
 

Yesterday I drove about 150 miles to visit a friend and do some spirited driving in my 2014 NISMO.

While in the back roads, I kept the car above 3000rpm but below 6500rpm most of the time and shifting a bunch around some tights turn. After about 10 mins or so of driving like that I went into 3rd gear accelerating and as soon as I passed the 5000 rpm mark something in the area where passengers left foot would be located started making this loud chatter noise and the stick shift started vibrating as well. I assume it was coming from the transmission.

As soon as that happened I backed of the throttle and as soon as it went below 5k rpm it stopped, and I tried replicating it and it would do it again exactly above 5k rpm. It would never do it in 1st, 2nd or 4th, only in 3rd above 5k rpm. At the time the oil temp was about 240F and it was 90F outside. I got scared so I finished the fun for the day. I know it never did that before because on highway ramps I go in 3rd above 5k rpm many times.

Later I drove home 150 miles again, having fun while driving, accelerating and decelerating a lot throughout the whole time and the car was acting normal (don't think I went in 3rd gear above 5k rpm, but did try almost every other gear above 5k, except the 6th one :p).

Has anyone had this happen before? Any tips? I would I appreciate any input from your knowledge and experiences!

Maybe it was your friend's teeth chattering because you were scaring the crap out of him?



No seriously my old '08 350Z had this awful rattle when you would get it up around 5500 RPM that i figured out was the little plastic plug in the cigarette lighter/ac adapter thing near the passenger's left knee.

You sure it wasn't just a dash rattle or something?

Hahaha no it wasn't my friend, they were enjoying it. They got scared when they suddenly heard this really loud noise.

I am sure it wasn't something plastic in the cabin as this noise was really loud and I felt major vibration through the gear shifter. It was sudden and before in the same drive the noise didn't happen. It felt like something suddenly broke. I also know from driving my car that the clutch pedal and shifter do vibrate a bunch at higher rpms, but it wasn't even close to this. This almost felt like something was about to break or some teeth of the gear broke. I have been relieved to hear it stop when I dropped the rpms. This noise teeth chatter is not in any other gear no matter how hard I push it.

hi, i know this is from few years ago but i have recently faced a similar symptom with mine. did you ever get to find out anything about it?

Experienced this same thing yesterday. Any ideas?

I can do my best to help with this but I've only been working at a transmission shop for a few months.

Believe it or not the issue most likely isn't even with the transmission itself. Everything inside a transmission is inherently round so it almost never vibrates. The only times you will see a transmission vibrate is if you're missing teeth or if you have a bent mainshaft. Both of which you will have more obvious symptoms. The most common causes of vibration issues with our transmissions are a bad pilot bushing or a clutch housing that's out of line. Seeing how this issue is only in one gear the problem could be the shifter as well. Definitely replace your transmission fluid. And DONT overfill it.

Sorry, that's all I got. If you're still having issues after you replace the fluid send me a DM I know some manual transmission gurus at work I can ask.

How is transitions to and from 3rd gear around those rpms? Smooth? You could have something loose underneath. Put it up on a lift and just a visual check. Check bushings in the front suspension.

My cat mounting bracket was once loose and made some vibrations in higher rpms. Not gear specific though as far as I remember.

Just a thought here. You might also check to see if your exhaust is hitting the cross member in the rear portion of the car. Not all aftermarket exhausts have a great fitment there. I have had vibrations and contact there in the past. Noises do travel around in a car especially metal to metal contact.