3)Fixing Subaru Transmission Noise

Courtesy of ALLDATA

In cold temperatures, thermal contraction causes a shrinking of the transmission case. In high temperatures, thermal expansion causes the case to expand. These temperature changes affect the amount of pre-load on the transfer driven shaft bearings. In some cases, when bearing pre-load is near the limit of specification, this thermally induced pre-load change may cause damage to the bearings and result in a high-pitched noise from the transmission.

The following Subaru models equipped with the 5MT manual transmission may exhibit this condition: 2000-‘09 Legacy and Outback; 1999-2014 Forester; and 1999-2014 Impreza (Including WRX).

Subaru offers an updated extension case featuring the addition of a “dish plate.” The machining depth of the extension case has been increased to accommodate the new dish plate. (Fig. 1)

When used along with a selective thrust washer, the spring tension of the dish plate helps to maintain a consistent amount of pre-load on these bearings throughout varying temperature conditions. Find the measurement procedures and the rest of this technical article here.