Any help would be very helpful, because it is kinda a weird situation that nobody knows about. So I have a 2008 g37s coupe, with about 80k miles that I just bought recently. It has a weird knocking/popping noise that you can only hear in the cabin that sounds like it’s coming from the transmission. Long story short, we took it to a transmission shop and they said it’s not the engine or transmission, and they said it sounded like the catalytic converter or the heat shield.

so, we ended up getting high flow cats which did not solve the problem. We realized that the sound actually somewhat goes away when you push down on the shift **** while driving, like as if you were to go in reverse. I have a video of the sound too, but what can this be!!!?!?

the shift **** also has a lot of slop, like you can move it side to side while in gear, not sure if that has anything to do with it

 

Do you have an AT or MT model?

 

It’s the manual transmission

 

Pull up your console and have a look at the shifter cup.

https://conceptzperformance.com/niss...800_p_8296.php

These can sometimes develop cracks and become damaged causing the shifter to become sloppy and possibly bang around, it’s not common but worth a quick look at. I’d imagine you would notice a very sloppy shifter motion as well.

If holding the shifter downwards cause the issue to go away, the problem is likely somewhere in the shifter mechanism or linkage assuming the shop throughly inspected the transmission as you mentioned.

Be warned removing the shift **** can and will destroy it if you don’t use a strap wrench.

 

Thank you so much for your help I really appreciate it! I wasn’t sure if it was worth taking everything apart to look at it, but I’ll definitely figure out if it’s something in there that might be making a noise

 

If you're going to go through all the effort to pull out your center console, and replace the shifter cup, and you've already demonstrated a willingness to use this event as rationale for getting HFCs, then keep going and get yourself a short-throw shifter. It's not that expensive, relative to those new cats. And certainly an easy install for your shop. IIRC, some models come with a new cup, and some reuse the OEM cup. But either way, driving with a STS is a very rewarding experience.


And oftentimes even if you do.