XC90 AWD Repair

[Petered]

I think that the corrosion may be what is known as fretting, see extract from Wikipedia below:
"Fretting refers to wear and sometimes corrosion damage at the asperities of contact surfaces. This damage is induced under load and in the presence of repeated relative surface motion, as induced for example by vibration. The ASM Handbook on Fatigue and Fracture defines fretting as: "A special wear process that occurs at the contact area between two materials under load and subject to minute relative motion by vibration or some other force." The amplitude of the relative sliding motion is often in the order from micrometers to millimeters, but can be as low as 3 to 4 nanometers[1]. The contact movement causes mechanical wear and material transfer at the surface, often followed by oxidation of the debris and the freshly-exposed surface. The oxidized debris often act as an abrasive since it is usually much harder than the underlying metal surfaces. However, fretting can also occur in inert gases or in vacuum (e.g., in space)."

[Mixam]

Look on Swedespeed for pics of the faulty spline

[RoyMacDonald]

Haven't found the pic but did find this little nugget of info......

At the shop I work at, we believe it has a lot to do with water getting in between the angle gear and the trans. When we pull these things out they are covered in as much rust as the Titanic. Its not just a problem with the, R its all of our AWD cars.

Guess it's time to get underneath with the Dinitrol again!

Roy

[Mixam]

See my new thread "Why Bevel Gears Fail" which shows pics, microscope pics, and the reasons why this is a crap design and why they are failling all over the world!!.

Pretty damning.
Not everyone uses forums and not everyone who has this problem is aware of it. However, if you search on swedespeed or the US Volvo forums you will see pages and pages and hundreds of threads for this problem going back to the 850's V70's etc etc.

[RoyMacDonald]

Found a lot on the "R" cars. Including

......."Check on diagnostic computer - no codes are stored - found that rear drive shaft is not spinning
Replace connecting socket between trans and angle gear and final drive assembly"

So it seems like at least one US mechanic can diagnose whether the AWD is working. Some pics.....



Old part design



New part design









The part on the right is for a 1 st generation Haldax unit. The one on the left for a second generation.



This is for a fourth generation. Apartently it's a different material to the others.



Roy

[RoyMacDonald]

Found this......"The D5 part mates to a 1500nm rated angle gear"

The D5 part being the sleeve in the last photo above.

Just to add these guys are considering fitting the D5 XC part to their 'R' Volvos........"OK boys and girls, the news is IN. We don't have cross sectional photos yet, but the hardness tests have been done. The ogiginal part came in at an HRA of 60 (surface and core) the D5 part comes in at 59 for the core and a 65.3 for the surface, this part has been case hardened. This is not a linear scale, so this represents an increase in tensile strength of about 33% which is a decent increase. Overall it is still considerably softer than the part used on the TF-80SC equipped vehicles which has an HRA of 70 and an approx tensile strength about 2x higher than the D5 part and almost 3X higher than the original part used on the R.
The conclusion has to be that the D5 part seems to be an improvement in terms of wear characteristics, according to the materials guys at BAE the part should wear considerably slower than the original part. Since wear is the mode of failure, this is a benefit.

In terms of finding the absolute best part, the D5 falls short in terms of dimensions, the fitment of the teeth is the same as the stock gear therefore the mating characteristics would be the same.

If you want an improved part that will last longer than stock, get the D5 part

If you want the best part available, better fitment, etc, then we're still looking at a custom part.

We should get a victim/volunteer to pop a D5 gear on their R at some point."

Also this......."If you have a R that has a stripped bevel gear input shaft and are out of warranty, then the thing to do is buy the bevel gear from the 06-07 GT R and then buy the collar gear the 2009 XC70 D5 AWD uses P/N: 30783419 which should mate the one to the other. Also, if you are looking at installing a stronger angle gear, this part would allow you to install the 1500nm rated unit from the XC90 V8/S80 V8. This part is on its way to be now and we'll have results on that soon and be able to say for sure whether it will work for this purpose."

This is reassuring......"If you have a 06-07 R with the TF-80SC automatic transmission, you already have the stronger part which is why they have an almost zero failure rate"







Roy

[4wheeldriver]

HAve to admit the 4th gen stuff looks a bit hardier than the 1st and 2nd. When did the 4th start being fitted Roy??

[Beeman]

Roy, do you NOW admit that there is a serious problem with Volvo's AWD???

[RoyMacDonald]

Originally Posted by Beeman

Roy, do you NOW admit that there is a serious problem with Volvo's AWD???

Please be spesific about which generation and part you are asking a question about.

If you are talking about the 4th generation splined sleeve Serious? No If you're asking about the earlier sleeves still no because they can be changed for the new part according to Swedespeed.

Roy

[Rockhopper]

A little pedantic perhaps? Not wishing to offend, but tbh Roy, it does come across as though you actively try to dismiss an issue that is clearly in evidence by the numerous posters, not just on here but worldwide. Whether or not a part can be changed for another is irrelevant. The sleeve fitted on my D5 and many others was (and perhaps still is?) not really fit for purpose.

If it wasn't a perceived problem, this issue would have been posted about once or twice and then put to rest. By posting thread after thread almost every day on the subject says a lot....