XC70: Gearbox Gearbox bang 1-2 when hot

[LeighH16]

Hi folks

High miler D5 2006 auto here! Trying to fault find an issue but haven't quite been able to see another similar post. So once hot the gear change between 1 & 2 is horrifically harsh. I'm trying to convince myself it's not down to the gearbox but more down to a haldex/lack or servicing issue.

So from a standing start the car sets off as normal but then as it attempts to change gear there's a rev flair followed by a gear change I can only describe as being rear ended! But from then on it's fine. The 'kick' feels like its coming from the rear axle area rather than the front of the car, I.e the gearbox area/primary drive axle. It almost feels like its dropping into neutral then engaging 2nd without using the clutch but only sending the drive to the rear. I'm thinking perhaps it's the haldex pump causing a really strange awd engagement or it's really poor oil quality which is just sending the haldex brain a little bit wappy.

Anyone throw some light on it for me? I currently have the haldex off and the oil was crap I'm colour but the pump filter wasn't that bad

Cheers