Hi guys. Hoping you can help me. New to this forum. Looks like a good site. I don't have a Volvo, but I am working on my brother-in-law's 1998 V70 AWD. Currently is making a groan and chatter at different times on acceleration and turns. I assume this is clutch chatter from the bevel gear from the AWD. Car currently has just over 110,000 miles on it. He just bought is used. It has a new drive shaft with center support bearing. It has a new aluminum housing and bearing off the rear differential. It has an entirely different rear differential assembly (old one was replaced). Am I correct in assuming this car uses clutch plates like a posi to balance the bias from front to back axles? The tires are all match size and wear. When it chatters it sounds like it's coming from the rear, but I believe it's clutch chatter. I took the fill plug out of the bevel gear assembly and it smelled pretty cooked. I pulled up a TSB and the only thing it showed was how to drill and drain the assembly and put the proper type Volvo fluid in it. I am a strong believer in BG products and they make a product called "posi quiet" that seemed to fix many of my noisy posi rear axles. Does anyone have any suggestions?

 

Has the entire drive assembly been replaced(Driveshaft and Viscoous coupler?)

 

Sorry for the delay getting back to you. Many guests arrived for the holidays. Everything looks new from the front bevel gear back. Where is the viscous coupling? Is that what separates the torque front to back? Does it use clutch plates, because it feels like a clutch chatter to me? What is the fluid recommendation for the front bevel gear? Thanks. Any information on this system would be helpful.

 

The Viscous coupler is mounted to the front of the rear diff.
It is kind of a clutch setup.

You might also want to look into getting the transmission flushed.
Sounds funny but there was a bulletin awhile ago about almost the same thing and a transmission flush would fix it.