Clutch - Clutch Appears To Be Slipping
Notes

SOURCE: Subaru Tech Tips

TITLE: Clutch Appears to Be Slipping

APPLIES TO: Impreza WRX

SERVICE TIP:

If you encounter an Impreza WRX with a customer concern that the vehicle's clutch slips under hard acceleration but drives normally under light acceleration, it might not be the clutch that's the problem. Before you yank the transmission to get to the clutch, put the car on the lift. Start the engine and put it in gear. Release the clutch and see if all four wheels are turning. If they are not, inspect the one that is not turning. The Technical Support Line has received a couple of calls with the above concern and in both cases the retaining clip on the inner end of the rear axle shaft has come off. This allows the axle shaft to move outward slightly to disengage from the side gear of the rear differential but, the wheel bearing retainer assembly will not allow the axle to come out completely. Since these vehicles have a limited slip rear differential, there is enough drag on the axle to move the car under light acceleration but not under heavy acceleration.

The repair is simple. Just push the axle inward and it should reengage the retaining clip. If this procedure does not work, then you will need to remove the rear differential cover to re-install the clip and/or examine the axle. If the vehicle is an Impreza WRX STi, you might find that the vehicle won't move unless the DCCD is in the 'Manual' mode. In this case the cause may be a failed rear axle shaft or joint assembly.