V70 AWD 1998

mantz.josiah · Post by **mantz.josiah** » 22 Mar 2016, 16:31

Hey Everyone,

Looking at a v70 wagon awd on craigslist. Owner says the rear differential is going. Can I just remove the driveshaft to the rear tires and continue driving it as a FWD car? Would this still work even if the differential is bad? Thanks!

Post by **scot850** » 22 Mar 2016, 17:31

If they are talking correctly and it is the rear differential, then no it is not as easy as removing the prop-shaft and driving as a FWD as the rear axles are still attached to the differential and will still turn the differential. You will need to pull the rear axles from the rear diff and pull the prop-shaft to isolate the differential. Leave the differential and torque tube/viscous coupling in place. They won't serve any purpose but the VC case supports the front of the diff.

I'm sure that someone out there will have had a rear differential fail, but I am not one. Unless they have not fixed rear diff seals and let it run dry, I would check that they actually know what is failing as they may be wrong.

Neil.

mantz.josiah · Post by **mantz.josiah** » 22 Mar 2016, 18:29

that's a huge help. the seller stated that the rear differential "clunks". Would I be able to test that it's a differential issue rather than a prop shaft issue by seeing if it still makes the noise while in neutral? I'm assuming if it truly was a bad differential it'd make the noise whether power is going to it or not. Thanks for your patience. Obviously I don't have much experience at all!

Post by **scot850** » 22 Mar 2016, 20:01

We are always gentle with newbie's so rest easy!

The AWD system has it's faults and they can become very expensive to fix (if you want to).

The major parts that can cause the 'clunk' or issues in the AWD system are typically:

1) The Angle Gear - This is attached to the transmission and effectively turns the power 90 degrees from the transmission to put drive to the rear wheels. This fails by either the splined collar stripping the splines from the angle gear shaft and so loosing drive to the rear. This itself is not always an issue and is where folks may pull the prop-shaft and drive in FWD. However, the angle gear itself can fail or the bearing at the rear to the prop-shaft at which point you have a dilemma. There are various 'bodgies' as I call them which involves removing the angle gear and jamming the drive collar in the transmission to prevent oil loss and driving in FWD. I have just seen this done on a 2000 V70XC. I'm not sure how effective it is, but others who have done it may chime in. If the Angle gear is good and not leaking you but not transmitting drive then you should be ok assuming the issue is there.

2) Prop-shaft. This is usually the biggest issue. The bearings fail at the front due to the proximity to the muffler/cat/turbo heat. If this is the issue remove the prop-shaft and run in FWD or fix the prop. The second failure is the center carrier bearing in the middle of the prop. Again, same solutions!

3) Viscous Coupling - This is a fluid clutch pack in simple terms these can leak or just fail. Often the clunk you get will actually be no worse than the mounting bush for the casing. Replace that and all is good. Even if you remove the prop-shaft if this is bad it is probably good practice to have this bush in good shape as it supports the rear diff and can clunk even if not being driven. The other VC issue is the front bearing can fail but that tends to give a whooshing/rubbing noise. Again if the VC fails you are not getting any drive to the rear, remove the prop-shaft as it is extra weight serving no purpose.

4) Rear differential. It can fail if it runs dry, but typically they are fairly robust. If this is actually the issue we have covered the solution for this. Replacing is not worthwhile as the expense is high as you have to drop the whole rear sub-frame and fuel system/tank to split the rear sub-frame which cradle the differential. Look up my replacement of the rear sub-frame on my 2000 V70R. Not pretty and very expensive!

5) Rear axles - Again not a common fault but they have CV joints that can fail due to the boots failing.

My honest suggestion is if you are not experienced with these cars or any cars, is have a repair shop look at it. Take this list with you if they aren't experienced with Volvos. You may get lucky and the issue is fixable by removing the prop-shaft. But make an informed decision or take someone with you who can diagnose the issue for you.

Good luck and let us know how you get on!

Neil