4th Gear Rattle Knock Noise On Acceleration

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4.0L WITH MANUAL TRANSMISSION – 4TH GEAR RATTLE/KNOCK NOISE ON ACCELERATION – 1800-2200 RPM APPROXIMATELY 45 MPH (72 KM/H)

2005-2007 Mustang eBay vehicles, equipped with a 4.0L engine and manual transmission, may exhibit a rattle or knocking noise on light acceleration between 1800-2200 RPM around 45 MPH (72 Km/h).

It is most evident in 4th gear after the engine/transmission has reached operating temperatures.

It has been described as a helicopter noise, similar to when you put a playing card in bicycle spokes.

This noise has no affect on vehicle performance or durability.

NOTE: THIS NOISE IS DUE TO A SYSTEM RESONANCE, COMMON TO SOME 4.0L/MANUAL TRANSMISSION EQUIPPED VEHICLES, AND HAS NO AFFECT ON CLUTCH/TRANSMISSION LIFE/DURABILITY. PERFORMING THIS PROCEDURE WILL GREATLY REDUCE THE NOISE LEVEL.

SERVICE PROCEDURE

Follow “Rattle/Buzz/Vibration from Center Stack (Radio/Heater), Steering Wheel, Seat, Floorpan, Gearshift Area” to eliminate any noise/vibration related to exhaust system alignment. If rattle noise still persists, then proceed to Step 2.

NOTE: THIS PROCEDURE WILL NOT FIX THE CONCERN IF THE CUSTOMER COMPLAINT IS:

ABOVE 55 MPH
ON COAST DOWN
IN 1ST OR 5TH GEAR
AFFECTED BY PRESSURE ON THE SHIFTER
A GRINDING NOISE

The noise specific to this procedure is most evident after the engine/transmission has reached operating temperatures. It is due to a resonance. The transfer path for the noise is through the gear shift lever area and transmission mount. If the noise can be replicated in 4th gear on light acceleration between 1800-2200 RPM, around 45 MPH (72 Km/h), then replace the flywheel with the revised flywheel listed in the Parts List. To be compatible, the clutch may need to be replaced depending on build date. See Steps 3 and 4.

NOTE: THIS PROCEDURE HAS NO AFFECT ON CLUTCH/TRANSMISSION LIFE/DURABILITY.

If the vehicle was built on or after 12/4/2006, then replace the flywheel. If not, then go to Step 4.
If the vehicle was built before 12/4/2006, then replace the flywheel, clutch disc, and clutch pressure plate.