SG4247

I just replaced the blown out GM motor mounts with new GM mounts.

Now, I have a transmission grind/whine like noise coming up through the center console shifter area under light throttle acceleration. Really odd sound. Fine at idle and low rpm.

Car has 42k miles with 2” Kooks, MAMO msd, and a MGW shifter and has been really good for NVH so far.

And ideas where to start? I have looked at the exhaust and don’t see any problem areas. The engine is now like 1/4” higher in the chassis then it was before. Is something rubbing somewhere?

Spaceme1117

I bet that your intake manifold is now rubbing on the underside of the hood or possibly the cowl. Check what your clearances are in those areas.

SG4247

Intake looks ok, both to the cowl and firewall.

it is like 3/16” from the cowl on the pass side.

This sounds like drive shaft or bearing noise coming from the torque tube up the shifter maybe?

Never had anything like this noise before on this car from the shifter console area.

grinder11

Don't forget the engine does "twist" under acceleration......

SG4247

I did notice last night, I can hear this noise when moving at like 40 mph, clutch in, and engine revved above like 2,500 rpm.

Gets worse when I let the clutch back out.

So, the driveshaft would be rotating in both instances right? Clutch in or out, with the car moving?

Spaceme1117

Another possibility is that the noise/vibration is normal. New engine mounts are much much stiffer than old worn ones and ZO6/ZR1/GS mounts are supposed to be firmer than base C6 mounts. So what you are feeling may just be normal.

When I replaced my 10-year old stock mounts in my GS with exact same part number, new stock mounts, I noticed the car felt and sounded a bit different.

SG4247

I am totally blown away by this - as my exhaust sounds different as well.

But why? How or why would the new mounts have anything to do with the drive shaft, or torque tube?

It is very concerning to me. Sounds like bad bearings.

Spaceme1117

The new mounts will allow more vibrations through the car to you. Perceived and real feel and sound of the car can change.

And the old mounts may have been hiding existing problems that may have been in the drive line.

SG4247

So, I was actually considering pulling the torque tube next.

But,

Do, you guys think I should pull the console apart, and look at the MGW shifter assembly next?

And why would a 2008 Z06 42K mile driveshaft/driveline NEED anything at this point?

If I had installed solid mounts, id say oh well, thats what you get. But with OEM liquid filled mounts it should be damn quiet in my opinion.

2000FRCZ19

Both my 06 and 07 z06s had a similar sound like this at slow speed especially when coming off throttle. My 02 z06 had the same sound as well. it was even louder with a short shifter installed. Sometimes it would almost sound like fluid flowing.

SG4247

Whats odd about this is there is no problem when the drivetrain is cold. As it starts to warm up, noise appears and then gets worse and worse.

SG4247

So, I removed the center console and all the shifter boot material, and went for a drive with all of that stuff off.

OMG! that torque tube is a noise amplifier - echo chamber. I can hear every rocker arm working, lifter noise and the twin disk clutch rattle at idle with the pedal out.
But, I also hear and feel noise and vibration in the torque tube when pulling away from a stop sign in 1st when the clutch is out and then again in 2nd when the clutch is out just for a brief time.

Then occasionally at cruise, the whole tube will start growling and vibrating.

Then get this, with either window down, a massive amout of super hot air comes up the tunnel through the shifter opening and burns my hand resting on the shifter. I mean more hot air than that the heater could ever generate on full blast. Putting my hand on the torque tube while driving, with the window down and it is freaking hot.

Roll up the window, all hot air flow stops in the tunnel, and the tube cools down.

I m now convinced the bearings in my torque tube are toast. Maybe the couplers too.

This air flow thing is bizarre.

harry604

i just replaced my motor mounts with oems ones
and i have this weird sound now when im accelerating
i thought it was missing or something since i just put oem plugs and wires too

SG4247

I would say be sure to jack the thing back up and inspect the exhaust carefully from front to back.

I found a likely exhaust contact spot on mine.

I also pulled the torque tube out today, and I see some significant wear on the input shaft bearing surface. Enough for the input shaft to wiggle and vibrate.

So, I am installing a new pilot bearing and new torque tube assy from GM.

harry604

yup i went back under, and the flange from the cats and mid pipe are touching the tunnel plate…

double06

On your MSD, it actually hits in the back where the bolts for the manifold clam shell are (it will scrape your firewall). Some people have used a button head bolt for that one area along with a little grinding of the manifold.

Hib Halverson

"double06" is spot on. Where it scrapes is difficult to see with the manifold installed. Maybe you could see it with a borescope, but you can easily see if you pull the manifold.

On my car, there were obvious marks on the firewall. I had to both switch to a button head bolt and grind on the edge of the manifold.

That eliminated the rub and the noise.

torquetube

There must be higher pressure under the car than alongside the windows, which would make sense. You open the windows, the cabin pressure drops and all that engine compartment air comes rushing in.

harry604

i created a gap before tightening everything up
went for drive and still have rattling

harry604

i jammed some exhaust warp between the flanges and tunnel plate and now the rattling is gone