XC90 Propeller Shaft Question

[SuperHerman]

I have a 2004 XC90 T6 that I am sorting through. I have everything sorted and the car is running very well. My question concerns the propeller shaft.

Specifically is the propeller shaft suppose to be straight all the way back to the rear differential? Stating the question another way - if I took a string and pulled it tight from bevel gear to the rear differential it would form a straight line - should the propeller shaft follow the same path - remaining straight at each joint? Looking at the prop shaft it seems to bend a tad at the first joint and at the following two joints. Maybe it is an optical illusion and the heat shields are slightly bent (although they are in great condition and show no abnormal damage).

The first front joint off the bevel gear is not 100% straight though. The prop shaft is not bent and has about 50k miles on it as it was replaced by Volvo with a new one a number of years ago. Everything is intact and in proper shape including the center carrier bearing.

Possibly the propeller shaft is too long?? This would explain the bends as they would make the propeller shaft longer, but would not explain why the vehicle had no issues for almost 50k miles.

At 60mph or greater I get a slight vibration that we are thinking is propeller shaft related. We have checked the transmission, differentials, bevel gears, wheel bearings, suspension, tires ... We have also repacked the propeller shaft CV joints, but have not tested for changes as we are awaiting a haldex seal that is easy to replace when the shaft is removed. These joints showed crusty joint grease.

So I am wondering if the slight angles found in each joint may be the cause of the vibration or is this normal? Any observations or thoughts?

[traudesa]

For what it's worth, mine is also not perfectly straight in exactly the way you describe. I replaced mine a few months ago and both the old one (which was certainly original) and the new one looked like that, so I'd say it's designed that way.

As for the vibration, you can disconnect (or remove) the shaft from the angle gear and take a test drive to see if that changes things at all. Removing the shaft should only take a half hour or so and you won't need to drop the exhaust. I'm guessing I know the answer already, but are the joints at either end and in the middle in good condition? That is, are the boots torn at all?

If you end up having to get a new driveshaft or any of the joints, I highly recommend Colorado Driveshaft.

http://coloradodriveshaft.com/volvo.htm

[SuperHerman]

Traudesa: Thanks for the response. After posting yesterday I looked for some time at various general drive shaft discussions and by design they are meant to flex as the front engine/transmission and rear suspension articulates. If it were straight it would not be able to handle the movement.

I have a 2004 XC90 T6 - can it be operated without the driveshaft? I know the 2.5 it can be, but unsure on the 2.9. I will discuss it with the mechanic.

The rest of the propeller shaft is in good repair. Mechanic regreased the front and rear seal as the lube was hard and crusty.

I have used Colorado Driveshaft before on my XC70 and they were a standup operation. Hopefully the regrease will solve my problems.

[traudesa]

Oh you can most definitely run it without the driveshaft. It's FWD full-time, and engages the rear wheels when slip is detected. The shafts are always rotating and the Haldex system simply engages input from the engine as needed.