AWD: 850: Failure Modes of P80 AWD?

[Volvolene]

I'm finding the search function as uncooperative as that on the Saab forum! I would have thought searching "AWD" in this section would have come up with something. Al+Wheel+Drive didn't work either, as it discounts "All" as being too short a word.

Anyway, I would like to know how they fail. Electronically or mechanicallY? On a test drive/inspection how would I detect a problem? What mileage might be the life expectancy? I hear people remove the prop shaft - any consequences in terms of warning lights etc.? Any differences between the 850 and V70 systems?

Many Thanks

[Volvolene]

Has anyone ever had any problems with the AWD system, and what happened?

Thanks - Volvolene

[SteveSarre]

Hi

I only know about 1998/1999 V70s.

Listen for unwanted noises when driving. at high speed or low, and when sharp turning at low speed.

If you remove the propshaft (best done on a lift), then there will be no drive to the rear wheels, ie you will be in FWD only.
Doing that will not trigger any sensors or errors etc. No electronics are involved.

The usual reason people do that is usually because the centre bearing or one of the end CV joints on the propshaft goes bad. Then they don't get around to getting the propshaft rebuilt (or you can buy new) so they just live with FWD. Don't throw away the prop shaft or the bolts and washer/spacers. If you get under the car, you can visually inspect the centre bearing. CV joint gaiters may be split and then throw out the grease. Not expensive to replace those joints.

Other things that can go wrong are :
Leak from the rear diff (just replace the seal)

You should change the oil in the rear diff from time to time (100k miles?)

There is a connection sleeve at the inner end of the right hand front drive shaft which transmits torque to the angle gear and then to the propshaft. That can strip.

The rear drive shaft CVs seem to last a long time, but eventually I suppose they might go wrong. AFAIK you cannot buy them, but maybe you can get new ones.

If you have removed the propshaft you could remove the rear drive shafts if you want to save them for later or to sell. Similarly maybe you could remove the rear diff, but I am not sure.

There is a viscous coupling at the front of the rear diff, but I haven't heard of them failing (unless you run low on oil).

High mileage cars may wear out various bushings in the rear subframe.

AWD come with Nivomat rear shocks which are expensive.

Hope that helps,
Steve

[Luxobarge]

^^^WHS^^^

Additionally it's important on these to have even tread depth on all tyres, and keep the pressures spot on, especially front-to-rear. Otherwise the wheels have a slightly different rolling radius which puts extra strain on the AWD system, couplings and diff etc. This of course will potentially make it more expensive to run, and you'll probably find that a full AWD system will have slightly worse fuel consumption too.

[Volvolene]

Many Thanks for those replies.