Impreza WRX STI F4-2.5L DOHC Turbo (2007)
Synchronizer Ring: All Technical Service Bulletins
M/T - Rattling Noises During Cold Idle
Number: 03-64-09
Date: 03/05/09
APPLICABILITY:
2006~2008MY Impreza STI
2009MY Impreza STI (early production)
SUBJECT:
6SP Manual Transmission Noise when Cold, Engine Idling
Introduction
If you encounter a customer complaint that there is a rattle type noise coming from the transmission, when the transmission fluid is cold, with the engine
idling, it may be coming from the 4th, 5th, and 6th baulk ring. The baulk rings were changed from a brass to a carbon type to improve gear engagement
and durability. The noise is caused by a stick - slip type occurrence of the baulk rings, which is not harmful to the function or durability of the
transmission.
The noise goes away after the transmission fluid has warmed up.
The noise will be decreased under the following conditions with the transmission fluid cold.
^
When the clutch pedal is depressed (clutch disengaged) engine idling.
^
When operating the vehicle in 4th, 5th or 6th gear.
To eliminate the noise, the baulk rings can be replaced using the brass type. However, when changing from the carbon to the brass type your customer
may feel a heavier shifting sensation. Make sure your customer is aware of that and have their consent prior to replacing.
Countermeasure in Production
The brass baulk rings were used in production starting in June, 2008 with VIN 9*800023.
Part Information
Repair Information/Procedure
