Looking at interchange or aftermarket information didn't really help, because it seemed like within reason, i.e. any car with a 4spd auto, everything physically interchanged. But, I found different part numbers for outer boots based on turbo/non turbo, but no easy way of identifying what I had, or what I needed.
While the aftermarket support is pretty good for these cars, as can be seen from the no-core prices for complete CV axles, I wanted to stick with OEM if possible for quality reasons. The boots in particular seem to be a problem in that often the aftermarket stuff doesn't last. This meant I needed to find out what was really out there, and compare parts to find out what I could use. It turned into a bigger project than I expected as I tried to determine what these cars were originally supplied with.
So with this in mind, I dug around a bit, and scored some used and new CV parts, and here is what I found, or (disclaimer warning!) at least is my best guess.
Note this only applies to the FWD 4 spd auto for the 850, and probably the S70/V70/C70 with production dates as late as 12/98. I have no idea what is going on with the manual transmissions and AWD stuff other than the fact that they are different!
1) All CV axles have 26 splines at the hub. This is why they seemingly all interchange.
Here is an image of the axle I removed from my 1994 Turbo (which had been replaced about 7 years ago) next to a 1998 C70 axle which I reworked. I am pretty sure the C70 axle is OEM because it still had small bits of the Volvo sticker on it plus the inner boot was clearly marked Lobro. The compressed length was essentially the same, and it fit in the car with no problem.
2) There are two different types of outer CV joints. I will refer to them as naturally aspirated (NA) and Turbo for simplicity. It appears that the OEM turbos were supplied with the larger ones, but because the axles are interchangeable as assemblies you might have either.
These are your two options. There is clearly a difference in size between the NA (left) and Turbo (right).
These cannot be interchanged on a given axle because the inner spline size is different. Even though they all have 26 splines at the hub, the NA CV joint has 25 splines inside while the turbo has 28 splines. This means the actual axle shafts are different from NA to turbo.
Other easy to measure differences:
- The OD of the turbo unit is about 98mm while the NA is 90mm.
- The CV balls in the turbo are 19 mm compared to 18 mm for the NA.
Note that these both have a 48 tooth wheel for the ABS.
3) GKN (aka Lobro) is a good source for parts.
If you remember from the beginning of the post, this all started with boots. I found GKN outer boots with little trouble for both the turbo and NA CV joints. They are different, and this is where I think things can get confused because of the axle assembly interchangeability. For reference, these are the part numbers which I found from GKN:
- OEM NA (small CV joint) outer boot kit GKN 300427
- OEM Turbo (large CV joint) outer boot kit GKN 300439
The inner boot was a different story. I couldn't find a good GKN part number anywhere, which I found strange because (as I said earlier) I had a 1998 vintage inner boot on a Volvo axle that said Lobro.
So I started looking into interchange data in the aftermarket to see if there was anything close. It turns out that there is a bunch of overlap between a number of Audi's and Volvo as far as boots from some of the aftermarket suppliers like Raybestos. So I poked around and found A GKN part that appeared to be essentially the same inner boot, or at least close enough so that it would probably work.
Here's my slightly stretched out 16 year old original next to the new GKN part.
This particular boot contained in this boot kit (GKN 300597) is OEM on a bunch of Audi's. I used a 1994 Audi 100 S Sedan as the point of reference. This kit comes with an extra clip plus 6 bolts that you don't need, but includes the correct size clamps and two 80g tubes (for 160g total) of grease.
Here's the axle with the Audi spec inner GKN boot and a Volvo spec outer GKN boot. It was a little tight at the inner joint , but the inside geometry looked the same as the original so I am pretty sure it will hold up fine. Both of the boots kits were made in Italy.
4) The grease capacity of the joints is as follows:
- OEM NA outer joint 80g
- OEM Turbo outer joint 120g
- Inner joint, NA or Turbo, 190g
I had some trouble finding info on the inner joint grease capacity, but I actually came up with that number (190g) in two places, so I am pretty sure it is accurate. And yes, regreasing the joints is a very nasty job so I am trying to make sure I don't need to redo it too often.
