I have a 97 awd850 and just replaced the bevel gear assembly and the spline collar between the transmission and bevel gear after driving the car for six months as a fwd with no drive shaft to the rear. I replaced all the seals on the bevel gear housing, new oil in b.gear, transmission and rear differential. My wife drives the car to work and back every day and told me that it makes a noise backing up with the wheels turned, I couldn't produce the noise in our snowy yard. During a trip to town on the week-end I produced the noise on dry pavement and all I can describe it as is a mechanical clunk that I could both hear and feel in the car. It does it backing up with the wheels turned just as described by my mechanically aspiring wife! I thought perhaps the rear diff clutches locking up and then letting slip with a clunk? Not to sure how to diagnose the problem..... Help?

 

Just talked to my wife again and she hasn't heard the noise in reverse if the wheels are straight only if the wheels are cranked one way or the other.

 

most of them do it, i think its normal, because the AWD system disengages in reverse.

You have a pretty rare car, do you have any pictures of it?

check out my writeup
https://volvoforums.com/forum/volvo-...edition-40602/

 

Yes I do know it is a fairly rare car, I don't actually have any photos of the car other than when I had it apart in the garage. It is a green wagon and had been very badly neglected and mis-treated by the previous owners, that's how I got the car for free.
Are you sure this is normal, your car does this? If it is the awd dis-engaging why only the noise when the wheels are turned?

 

I'm just guessing, but it might make noise when the wheels are cranked because that changes the the amount each wheel is turning in relation to each other. I don't know about Volvo but in other AWD or 4WD units the clutches start to fight each other to divide the power to the wheels. Some with tight differentials will actually "hop" a bit when against the stops and moving slowly.

Your best bet is to ask other AWD owners like you have.

I ran across another post with someone who was running without the rear wheels hooked up. Does the transfer case work ok with the rear shaft removed?

 

I would think normal AWD bind! All 4x4 and AWD systems will bind on full turns. My truck is ok in 2 wheel but binds in full or even partial turns on dry pavment but can't feel it much in gravel or dirt!

 

I have not experienced this sort of sound or feel in any other 4wd or awd car or truck I've had, I have had both awd and 4wd Subarus and 4wd Toyotas. Driving my 4wd Subaru loyale in 4wheel on dry road I can feel the tires not wanting to turn as the diffs are locking but the volvo just makes more of a clunk that I can actually feel. The 850 works fine with the rear driveshaft removed, I did so because the bevel gear spline was worn.

 

well subaru has there own AWD system, volvo didnt have the best AWD system in those years.

How do you properly diagnose AWD issues? - Volvo V70R

 

I have had a bit of time to play around with the car and I have been able to make it click in reverse with the wheels straight. I seems that the noise occurs when the orevrride clutch lockout on the viscous coupling engages and dis-engages. On my snowy road I can spin just the front tires (in reverse) then hear the click and the awd is engaged. I suspect that it is more pronounced on dry road surfaces when traction is good and there is more torque on the system.
My main concern with the noise is wear and tear on the system while backing up on dry road conditions. Anyone have the same experience?