Clutch/transaxle rattle

[Sinovac]

I know there are many posts on the "rattle" issues with this car but I have not seen an explanation for the clutch/transaxle rattle when the car is hot and the transmission is in neutral. The owner's manual states that due to the "high performance" nature of the clutch/transaxle, it can rattle when in neutral and this is considred normal. Mine can sound like a Ducati clutch at times!

Why DOES the GT unit rattle?

Also, may I please be identified as an owner.

Thanks,

Paul

 

[mardyn]

Yea, that scared the crap outta' me too when I first heard it... I think they call it neutral gear roll over noise... wth is up with that? Sounds to me like there's too much clearance between components on the main and cluster assys in the case... but what do I know?

I'd like a reasonable explanation as well.

mardyn

mardyn

 

[Roger Vincent]

Clutch Rattle in neutral

Whenever we changed to an aluminum flywheel with the C4 Corvettes (ZF transmission), this rattle occured. It sounds like a failed throwout bearing, but it's just the nature of the beast. It only occurs when in neutral. Maybe this is similar?

I just pm'd Paul, but I would like to see where it is acknowledged in the driver's manual. Mine is an 05 and I couldn't locate that statement. Maybe only in the 06 manuals?

 

[dbtgt]

I was told by a development engineer for the GT that because the transaxle case is so long, when it heats up to the upper limit of its operating temp, the run out clearances are such that we experience the rattle. This also explains the 2nd gear crunch when it is cold as the clearances are tighter until it warms up. It is apparently difficult to design a compact aluminum 6 speed transaxle case that can accomodate the thermal expansion and contraction without these characteristics. Neither of the issues are considered to be a reliability concern.

 

[Sinovac]

'06 manual explanation

Page 98 of the '06 manual under the "driving section" states:

"Due to the high performance of the powertrain, a certain amount of noise from the transmission is normal. This noise will be most noticeable when the vehicle is idling in neutral with the clutch pedal out but can also occur when driving away from a stop."

I found no other references in manual.

Best regards,

Paul

 

[gwbartlett]

My GT does the same thing-gear noise in neutral when hot with the clutch out. It is very noticable from the outside rear of the car and much less noticable inside of the cockpit. In comparison most front engine, manual transmission cars have loads of insulation between the gearbox and the interior so gear noise inside of the car is difficult to hear. From the outside rear of the GT there is no insulation, only transmission so any gear noise is going to be obvious. From underneath of my 2003 911 Turbo (rear engine) gear noise was also obvious, but not quite as pronounced. I think that it is just the nature of manual transmisions .
-GWB

 

[1827]

The old Muncy M22 "rock crusher" trans in Chevy muscle-cars (mine was a '69 Z/28) had awful rollover noise. The reason was the straight-cut gears instead of the helical gears in the M21. It has to have clearance for all the reasons above (aluminum case, etc.), but the M22 was MUCH stronger, with less friction loss. Enjoy the noise; without it, you've got problems....