**DISCLAIMER: what i did in this post was dangerous and probably exceptionally stupid. If anyone decides to attempt to recreate this, they do so entirely outside of my influence or instruction. I'm not liable for any damages that may come from attempting the following activity on your own. if you drive through someone's house, it's your own damn fault.

Just got back in from running the car to 60mph on jackstands in my apartment parking lot. (if my landlord ever finds this i'm probably going yo get evicted on the spot ) here's my findings:

Procedure: jacked up the rear of the car and put it up on jackstands. ended up with about 2 inches of clearance between the tires and the ground. got in the car, turned it on, and slowly accelerated from 0 to 60, holding speed at 20, 30, 40, 50, and 60 for about 15-30 seconds to listen for the sound. shifted 1st-2nd around 2k rpm, 2nd-3rd around 2.5k, and 3rd-4th around 3k.

Safety precautions: Parked the G with a large metal dumpster in front of it to minimize damages if the car were to fall off jackstands. Chocked the front wheels to avoid hitting the dumpster if at all possible.

Conditions: 25* F. sunny. very little wind.

Results: The whistling was present between 40mph up through 60mph.. It acted as it does when driving normally, with pitch changing based on speed.

Conclusions: The noise is purely mechanical. wind from movement obviously plays no role in this issue. This eliminates every "bad seal" theory, as well as the "air intake damper" theory. The transmission and the rear diff are both still possible sources.

Notes:
*I stopped at 60mph for safety concerns, but the noise was still at that point, so i don't know where the upper range would have been. I don't think that really matters for this study though, as the point was to replicate without wind.

*VDSC must be turned off before you begin accelerating, otherwise the car will sense that it isn't moving and immediately kill any acceleration.

* Cruise control doesn't work with the rear wheels off the ground. attempting to activate cruse control with the rear up led to a quick acceleration spike followed by an immediate drop in RPMs.

*because of the cruise control not working, i was unable to get out of the car and investigate further where the sound was coming from. I did take a rubber hose with me though, and was able to wrap it around under the car and listen, and the noise was decidedly louder under the car. I was unable to get any further info from pointing the hose one way or the other, unfortunately.

*shifting without moving feels unusual. i had to go through a brief period of learning how to shift again, and burned the hell out of my clutch once.


So, there we have it. anyone have any thoughts?

 

wow, good stuff.

Another guess that i would contribute is that the lubricants takes awhile to get in all the nooks and crannies, this might explains why a new transmission will still have the noise. Having similar characteristics in lubricants, they should all take awhile to flow in cold weather. When warming up a car, it doesn't really make any internal movements(besides the one that's connected to the engine) in the gearbox to circulate the fluid. On long warm-ups...the heat radiated from the engine, slighty heats up on the tranmission on where it has contact with the engine. This may or may not be enough to warm the fluid. This is just my guess

I do, however, noticed that ever since I changed my trans and diff fluid to amsoil...the noise doesn't last quite as long as it use to.

 

I almost want to jack my car up just to see how the shifting would be.

 

Maxuz.....you are a brave man. This is very good R&D, I do not understand why only certain G35 have this problem

 

Great job Maxuz. Thanks for posting this up. I'm glad to hear there were no negative consequences from attempting this experiment.

Now it appears clearer it is a mechanical issue. If someone gets their car on a hoist it should be easier to isolate the origin of the noise. I will be doing that at the dealership once mine comes out of storage in another 5 weeks or so.

My car makes the noise from about 15mph and up. It's possible you might not be able to hear that pitch from inside the car and while stationary.

 

i was actually noticing today that i seem to pick the noise up aroung 20 mph when driving normally in my car. all i can figure is maybe load increases the friction between whatever is causing it, forcing it to manifest earlier. it definitely didn't start as early on the stands as it did driving this morning, and it's warmer today than it was then.

 

do you live in an area where it gets below freezing? A good amount of G drivers live where snow doesn't even exist. Not to mentioned that there are drivers that only drive their G in the spring/summer and keep it storage in winter.

 

Yeah, that could be the case. I find the noise will happen at temperatures below 50-55F although it's not entirely consistent with that. It might be that the car hasn't fully cooled down when it doesn't do it at 50F.

 

Well, I just got my car back. They replaced the transmission from the bell housing back and put some new fluid in it obviously.
As for first impressions, it definitely feels different. My old tranny as far as I can remember was a bit slower to throw and had a slightly slower (less springy) clutch as well. The throws in this one are still a bit notchy as per most Gs, but my clutch seems to be taking up a bit quicker/with more spring in it. It drives just fine and the shifts while driving seemed to have smoothed up a bit. It's hard to tell exactly without having a side by side comparo, but it feels good/slightly better.

As for the actual noise, there was none present when I went to pick it up, but it is also 50 degrees out today so that does a whole not of nothing to ID the true issue. It is supposed to snow tomorrow with a low of 15, so I will let it sit and freeze until tomorrow to see if anything has changed. If not, I'll promptly head back to the dealer...

 

^good stuff. Let us know.

 

I received this PM from a member:

 

Air damper doesn't make sense anymore. The noise has been reproduced without any wind.

Better let Harold know he's been lied to.

 

Well it's been a few days of slightly below 32F temps, but nothing really really cold.
The whine is gone altogether it seems, I tried very hard to just get in the car and go when it was cold, same 30-40mph in 3rd or 4th, and there is no audible whine at all.
As for the whistle/whoosh, I cannot really tell if it is gone 100%, I hear some noise, but I can't tell if I'm trying to hear any little thing or if its tire or other noise.

Maxuz, I talked to the department and they would be glad to take care of your car if you came in. They would of course have to ID the same problem, so if it is, they will take care of you. I'm still waiting to see if the problem is 100% fixed, it seems much better, but I haven't put my perfect sticker on it...

 

^ very interesting! 32 would have been well cold enough to make the noise happen before, so thats promising!

PM me the info on the dealer please. they're a good distance away, so i'd have to work something out with them i imagine. did you have one guy that you were working with that i could talk to that would know what i was talking about when i called?

thanks for keeping us all in the loop. let us know how it's going as it gets more broken in.

 

PM sent, and yes I'll try to post updates as things happen or if it's truly resolved.