Hi
Hope I can get help here, 1999 Volvo V70 XC AWD after getting stock a few time I find out that I don't have anymore traction on the rear wheels, and there is no noise no leaks it just quit without warning, I was thinking of replacing the oil in the Bevel gear but I don't if that will help any suggestions

Thank you
Jocelyn

 

Jocelyn, you would get the same result on my 2000 V70 XC AWD. The reason is that I had the tail-shaft removed, because the bevel gear started whining like a jet engine and the tail-shaft joints were wearing out. Cost to replace bevel gear and tail-shaft was around $4k. Now that there is no load on the bevel gear it runs quiet, but of course I have no power to the rear wheels. No problems now for over 20k miles. Do you know for sure you have a tail-shaft?

 

Yes I have drivve shaft but I removed it for now till I fix it
I bought the parts and will do it pretty soon Thank you

 

I have a 1999 V70 XC being run without the drive shaft too. The good news is that it will run like this just fine, and indefinitely if you want, so I wouldn't worry about rushing the job.

The system as I know it is a GKN built (not Haldex, the first Haldex was in 2001- 2002?), viscus coupling, a simple system. By design, it is temp all wheel drive at best, reliable, but not a true continuous all wheel drive like Subaru's or Audi's, etc.

GKN: VC without center differential. The VC fluid activates (hardens creating drag) as it heats up. The heat is caused when there is a difference in rpm speed difference between the output shaft (front axle speed) and input speed (rear axles). It won't ever fully lock when running normal, but it adds extra torque until the axles rpm's are spinning at the same speeds reducing the friction difference. This would be why it is recommended that all tires be of the same type and diameter.

Will the bevel gear move with the transmission in N. (can you, or a friend turn it by hand, either by turning lifted front tires, or direct) If yes, or when the center drive shaft was on, did it spin with the front wheels? Yes?

The simple type of VC (activate by heat only) has two ways of commonly failing.

1) rear wheels always engaged do to the fluid aging prematurely. This is the worst type because of the damage to the drive train it will cause quickly (no give in a turn on dry pavement, things break).

2) What I think you might be dealing with, loss of viscus fluid over time, seeping through old seals. the older VW Synchros and Honda "Real-Time 4WD" had these issues too, and loosing fluid is more common.

you were spinning your wheels, yet without activation. The fluid is similar to the engine driven fan clutch of older trucks. It can be replaced and seals can be replaced. The trick will be your resources (you, a friend, or shelling out the money) for removal of the VC to work on it.

I've removed these before and it's not horrible, just takes some time, patience, and hopefully a dry place to work I hope this helps.

 

Thank you for the information
If I understand I should start by changing the oil in the bevel gear is that right, first I tried to turn the wheels when the car was up I could turn the front wheel and the rear wheel was turning also and vise versa everything is turning fine but the car was on park I will try again on N

 

Glad to help if I can.

The Bevel Gear (angle gear) is up front and does need fluid changes every 50,000 (my local Volvo dealer advises)......But this is not what I was referring to.

The angle gear is mechanicaly connected and if it was failing you would have many more problems, its not the angle gear, at least by your description.

The Viscous Coupling (VC) is located in the back. The VC has a special type of fluid (Silicone oil). The fluid is different from the gear oil.

The VC is a system in between the front axle and the rear axle with a separation between both points of torque (front is power-rear is passive torque from the wheels rolling), connected by a fluid that hardens when heated, that in effect connects the front to the rear at that time.

If their was no warning, no bad mechanical sounds, just a sort of passive not functioning and it does not interrupt the front axles, then VC is your culprit.

The VC is located in the torque tube. The torque tube is between the center drive shaft and the rear differential. "IF" its the VC, the torque tube would need to come down to have access.

What concerns me is in your description;

"I could turn the front wheel and the rear wheel was turning also and vise versa everything is turning fine but the car was on park"

I think you might have intended on saying something else?

A vehicle in park should not be able to have any wheels up front turning, they should be locked by the transmission.

Main thing here, is that, the car is still a front wheel drive car all day long. It's fine that way. When you want to repair the awd then their are more options than what you might be told at the dealer and they are not terrible (if you are relying on paid help, labor is always tough though).

I hope this helps,

 

I guess you are right I want be able to turn the wheels if the car was on park so I guess the car was on neutral, so if I understand I will not have to remove the bevel gear and check that coupling between the tranny and BG ? so now the drive shaft is not on the car I will have to replace the oil in the front part of the rear differentiel is that what you are telling me ? Do you know what type of oil goes in there ?
Thank you so much for your help
Jocelyn

 

I'll get some pictures for you.

Correct on the bevel gear (Volvo calls it an angle gear, part#8602678 or 8602679, attached to your transmission).

If this is the viscous coupling (because you said it was a silent failure without, what I call, mechanical drama didn't happen, I think it may be the only explanation for the loss of power to the drive wheels) then the bevel/angle gear having routine gear oil service will not restore power to the rear wheels, so my answer would be no, you don't need to change the oil in the bevel/angle gear.

The Torque Tube is located in the back. There are two parts to it.

1) The Tubular Body (part#9183945)
2) The Clutch (part#9183905)

The Clutch is the Viscous Coupling. This would be the part that has failed.

This item (Clutch/VC) is not designed from the factory to be serviced. I do know of this item being repaired by some people of exceptional skills, but other than that, replace it with a factory one, a used one, or if a part cross number is available than the modified part, are the only ways of bringing your awd back to life.

The Torque tube is simple to take off and install with some average mechanical skills

This is a good technical article on the VC and testing. The older VW's have a very similar system both designed in Germany. synchro.org/VCTest.html

I gave the part numbers from Volvo so you can have a diagram and cost info. After looking it up, after the sticker shock, remember that your car was designed as a front wheel drive with a part time awd in a pinch..You can drive your car without any damage to the awd as a front wheel drive car until you can afford to fix, or not. Don't panic.

 

Thank you so much for these precious information I really appreciate your help

Thank you
Jocelyn