Outer CV boot confusion - 98 V70 T5 - turbo auto FWD

[S Carlson]

My 98 V70 T5 is eating through CV boots. I've had to replace them once every two years, which is crazy as the original ones lasted roughly 18 years. I finally found out that FCP had the wrong boots listed as fitting my car (N/A boots for smaller joints) and I'd been trusting their catalog and just stretching them on to the fatter axles and joints. And that sucks. I am now very good at changing CV boots, however. Takes only a minute when you're so experienced as I am at this point.

So I emailed and called a few times and they are refunding me at least for the ones I've bought for the latest repair. Very well.

This brought up more confusion on my end, however. They said the right part number for this car is 31256240, which checks out with the Volvo catalog listing for automatic turbo cars. These don't cross-reference with anything aftermarket (except on shady websites), and genuine Volvo is expensive. But the Volvo number 31256237, the outer boot spec'd in the Volvo catalog for manual turbo cars, does cross-reference, to GKN number 300439. This has a joint diameter of 90mm and axle diameter of 24mm AND in the GKN catalog it says it fits both the turbo auto and the turbo manual.

So my question is, are the outer joints on the auto and manual turbo cars different sizes? Are the axle shafts themselves a different diameter? Why does Volvo have two part numbers for outer boots, turbo and non?

Thanks for any information.

[erikv11]

Short version: buy GKN only, and you want 300439. Nice detective work.

Here is more of a summary post, with a link to a definitive post by NorthernLights: viewtopic.php?p=598820&hilit=300439#p598820. Beware, there is excessive redundancy in CV boot posts on this site!

Regarding the manual/auto differences I am not sure. I would look for posts by MVS member tryingbe or someone else who has actually worked on a manual axes. But since you have a generic 98 auto/turbo/FWD you can be very confident with GKN 300439.

[S Carlson]

So Volvo has the two different part numbers for the outers just to confuse us?! Well that is fine.

I ordered a 300439 to have on hand "for next time". In the mean time, that thread has me confused about the inners now! Volvo has two part numbers for the inners as well, and it looks like they are different diameters. I had just been using the Audi 300597 boot, which has a 21mm axle hole and 82mm joint hole - on my axle and inner joints which measure 24mm and 92mm respectively! I see I've been stretching the heck out of that one too. No wonder my inners also fail after a year or two. And I thought the rubber was just getting bad.

I went to try to find an inner boot that has the right specs (24/92mm). Looked through the Empi catalog (https://images.carid.com/empi/info/pdf/ ... atalog.pdf), which has nifty diagrams of the inside and outside profile of various boots with measurements. Came up with the outer TRW outer boots for 1985 Cadillac Deville. These are 26mm/91mm. They are $1 on Rockauto. I am going to buy one or two.

[erikv11]

I would not trust any CV boot manufacturer other than GKN. Inner boot I use GKN 300597 for both turbo and non-turbo P80, automatic trans. None have failed. Are you sure those are factory axles, could that be the difference for you?

[S Carlson]

I would not trust any CV boot manufacturer other than GKN. Inner boot I use GKN 300597 for both turbo and non-turbo P80, automatic trans. None have failed. Are you sure those are factory axles, could that be the difference for you?

The axles are original to the car. I am the second owner, and I have a full service history. The axles even have the Volvo bar code on them!

Furthermore, if you go to page 4 of the thread that Northernlights started, far from containing "zero new information", you will see MVS member cn90 describing an identical axle to mine (and identical car, automatic etc), having the same problem I had. cn90 went with a genuine Volvo boot. The Audi boot GKN 300597 is a full 10mm smaller than my and cn90's inner joint. And I believe that's why my inners have begun to show cracks after only a few years.

Here's the page with cn90's post.
viewtopic.php?t=64252&start=30

And to be clear, I wouldn't trust Empi or Rein boots either. Been there, done that. But the Empi catalog and the GKN catalog, taken together, can reveal how cross-references are created and what actually fits versus what is "a bit of a stretch". The empi catalog allows a stretch (recommending the same boot for two different sized joints), then you cross-reference it back to the GKN catalog and you get a stretched GKN boot. This is part of why Empi boots fail, I think. So, it's possible that using a correct-sized TRW inner boot might get me farther than a wrong-sized GKN one, if I can confirm the sizing.

I'm having a good email conversation with FCP. I am trying to get them to measure a couple of genuine Volvo boots to help us get to the bottom of all this.

Basically, what I'm getting so far is that Volvo has two part numbers for the same outer boot (31256237 for manual, 31256240 for auto)

But the inners are different: 31256230 for turbo auto (92mm joint/24mm axle) and 31256225 for non-turbo auto (82mm joint/21mm axle, cross-reference with Audi boot, GKN 300597).

And maybe there are exceptions. Between the SMI and TRW racks, the five or ten evap system variants, and the 10 or 11mm rear caliper bolts, these cars seem to have been put together with whatever Volvo had on hand at the time. I wouldn't be surprised if that extends to CV joints.