Xc70 Awd

[Bazanga]

I am considering buying AWD parts from a breaker. How do I describe what I need. Would "the front diff unit from the front end of the prop shaft and the Haldex unit from the rear end of the prop shaft" describe it?

[luggsey]

Originally Posted by Bazanga

I am considering buying AWD parts from a breaker. How do I describe what I need. Would "the front diff unit from the front end of the prop shaft and the Haldex unit from the rear end of the prop shaft" describe it?

I think most breakers sel the rear di and haldex as one.

[Tannaton]

Good Morning....

The "front diff unit from the front end of the propshaft" isn't actually a differential. It is most commonly known as the "transfer box" and less commonly known as the "bevel gear".

The rear differential is actually two units bolted together and sometimes they are sold separately. They are the haldex unit and rear differential - the Volvo terminology for the haldex unit is the "AOC" (Active OnDemand Coupling) and specialist Volvo breakers may refer to it as this.

However I would add that if your car is pre 2003 model year, then it may not have a haldex coupling - it will be a simple, non-electronic viscous coupling.

[Bazanga]

Thanks luggsey and Tannaton
I can turn the Propshaft so assume I have defective Spline or Bevel or both. Therefore need the Transfer Box to recon?
Should I get both the AOC and the Diff? My car is 2004 91000 miles so I expect it to have a Haldex 3. Would the Haldex 4 be interchangeable?
However based on what I have read and viewed the AOC should be OK when serviced as on Utube - Volvo Sweden?

[Tannaton]

Originally Posted by Bazanga

Thanks luggsey and Tannaton
I can turn the Propshaft so assume I have defective Spline or Bevel or both. Therefore need the Transfer Box to recon?
Should I get both the AOC and the Diff? My car is 2004 91000 miles so I expect it to have a Haldex 3. Would the Haldex 4 be interchangeable?
However based on what I have read and viewed the AOC should be OK when serviced as on Utube - Volvo Sweden?

If you can turn the propshaft - then the connection between the gearbox and the transfer box has failed. 99% of the time it is the splined sleeve. You can buy a repair kit from Volvo for approximately £120 with a new sleeve, seals etc. Usually this is all that is needed but in about a quarter of cases the splines on the transfer box are damaged in which case you will need to replace that too. You will not be able to tell until you remove the transfer box - only then will you be able to inspect the splines.

A couple of other points:

- The splined sleeve nearly always fails where is mates to the transfer box, not the gearbox.

- Your 2004 model has the earliest generation of Haldex that Volvo used - never the less it is very reliable and you are most unlikely to need a rear diff or AOC unit. I'm not 100% sure but the later Haldex is most unlikely to be interchangeable. The AOC coupling also contains the electronics that run it (DEM - Differential Electronic Module).

[100K+]

Agree all the way with Tannaton. The sleeves are usually shot in these circumstances. They are a "sacrificial" part either by design or accident, being MUCH less expensive than the bevel gear unit.

Other common failures of the AWD are caused by defunct Haldex pump; easy to verify, DEM pressure sensor, easy to spot if you have a DICE, or water ingress damage to the DEM controller, can be resolved with specialist help.

Cheers

Bob