Slipping drive...not clutch
 

Driving on the weekend I exited a roundabout in second gear and the revs suddenly increased greater than the road speed but without the clutch in. Driving along in every gear, as I accelerated, the revs increased with load on the throttle and I had to back off and feather the accelerator or it would appear to slip and overrev.

Local garage have changed the clutch for a new Excedy one but it is still doing the same. When accelerating, too much throttle makes it overrev and not increase speed as though you engage the clutch.

The garage think it must now be something in the gear box and that it is not sending drive to all the wheels. They are proposing to take the gearbox out to send it to be inspected. What are the possible causes for this? Is there a transfer box in the gear box that can fail? Can it be reconditioned?

Thanks.

Rear drive shaft not all the way in the diff can cause it

As said above I had a similar problem and suspected clutch was at fault, the front driveshaft had come out of it's outer joint.

Thanks for the replies. Subaru dealer have come back to me and diagnosed the rear nearside driveshaft connector / joint. Apparently there are no parts in the uk so it is having to come over from Japan.

At least it's not gearbox or worse. Looks like you were spot on Ben.