What causes bevel gear failure?

[bcr72]

I just got the bad news from my dealer that the bevel gear needs to be replaced on my '04 XC at 74,000 miles. The cost is about $2300 US. I would like to know what causes this failure and if there is anything that can be done (by me, the owner/driver) to lessen the probability of it happening again. I asked these same questions to the Service Advisor, but she really did not have any answers.

[wgriswold]

I don't know what makes them fail, but I am a little worried about some noise that is developing when I drive up a moderate hill. As the car is stressed by the hill I can hear a low pitched growling like noise. What are your symptoms?

[bcr72]

I first noticed some RF wheel slippage, more noticable on wet roads. It started slowly, but then by a few days ago it the slippage was so pronounced that it was obviously a problem. By slippage, I mean that the tire was spinnning, no traction.

[gibbons]

What was the bevel gear lube, again? Maybe I will check mine at 70K miles. But that would be a lot of lube to weep out, I think I would have noticed that along with the drips since new from the turbo.

[BillAileo]

Gibbons,

Volvo Tech-Net Notes No 40-04, 10-13-2005, lists API GL5, BOT as the angle gear lube. Volvo part number 1161648. I know it is a synthetic lubricant and have been told that it is a 75W90 and the "BOT" designation probably refers to low foaming or exta low foaming. See this thread:
http://www.volvoxc.com/forums/showthread.php?t=8001
I buy the Volvo fluid when replacing the angle gear lubricant in my vehicles.

[bcr72]

I did specifically ask about the seals, and they told me they were not leaking, for what its worth. The car has been dealer maintained since new. It seems to me that it is simply just a poorly engineered system. 75 k is nothing for a drive train component. I expressed my opinion and told them that I have been a loyal Volvo customer for years (currenlty on my third one) but that it would probably be my last.

[howardc64]

I did specifically ask about the seals, and they told me they were not leaking, for what its worth. The car has been dealer maintained since new. It seems to me that it is simply just a poorly engineered system. 75 k is nothing for a drive train component. I expressed my opinion and told them that I have been a loyal Volvo customer for years (currenlty on my third one) but that it would probably be my last.

Before they go and replace the whole BG unit, you should ask them what is wrong with it.

I've read 2 failure modes in this unit on these forums

1. No lubrication. Gears are probably ruined if the BG oil leaks out. If you have no evidence of a leak... and fluid have always been in there, your gears should be okay at this mileage. You can ask them if the fluid level is okay (easy to check yourself although I'm not sure you are a DIY guy)

2. Transmission to BG sleeve gets stripped. If this happens, you actually don't need to replace the BG. Just the sleeve. Here is a whole thread on this with pictures + diagrams.

http://www.volvoxc.com/forums/showthread.php?t=12121

[bwik]

Our 2001 XC has 149k on original bevel gear, never touched. I am not over eager to have it replaced at this stage either.