V-ring seal effectiveness vs. wheel bearing seal design

Discussion in 'Discussion Forum' started by dllubin, Jun 10, 2018.

  1. In the process of preparing the engine/drivetrain for installation, I discovered that my left rear wheel bearing was bad. I decided to replace the inner V-ring seal and retrofit an outer V-ring seal (74s did not come with one) when replacing the bearing. The V-ring seal appears to rest against the seal on the side of the wheel bearing when installed. It appears that it was designed to protect the interface between the inner race and the wheel bearing seal. My new wheel bearing arrived and the seals on it are attached to the outer race and the seal interface is at the inner race. I could see how the V-ring seal adds protection to that interface.

    I decided to replace the RR inner V-ring seal at the same time since it is pretty easy to get to unlike the outer seal which requires pressing out the hub (That means replacing the bearing and this one was low mileage, being replaced shortly before the old engine blew). After I removed the axle, I took a look at the bearing and found that the seals on it are attached to the inner race and the seal interface is at the outer race. The V-ring seal does not reach that interface so I cannot see how it would add much protection to this type of bearing. On the plus side, since both seals are rotating together, there should not be any wear.

    I'm not sure what the prevailing trend is in X1/9 wheel bearing seal design, but in the future I will look for ones that have the seal attached to the outer race so that the V-ring seal has a chance of doing it's job.

    For reference, the new bearing with the seal attached to the outer race is an OMCAR 007A11700. The existing bearing with the seal attached to the inner race is a GREEN 4339308.

    Fiat X19 New LR Wheel Bearing.jpg

    Fiat X19 RR Wheel Bearing.jpg
  2. Dr.Jeff

    Dr.Jeff True Classic

    Sin City
    I can't speak from experience with these particular bearings. But in general I've found variances like you describe (which race the seal interfaces with) will exist from part to part. It could be due to different manufacturing facilities they have around the world, or design changes over time, or different sub-manufacturers or suppliers, or a number of reasons. And that is with just one part maker; the variances will be much greater with other part manufacturers, which the car manufacturer will change from time to time. Things were not always this way in the past. But as everything has become more of a world market the rules are changing.

    On a side note, I read an interesting trade publication awhile back discussing a huge problem with counterfeit parts flooding the market. And bearings was one of the items they mentioned in particular. They said even the original part makers could not readily tell the difference in some cases, and such parts have become intermixed with the real stuff even at the top levels of the supply chain. Not that I think this has anything to do in your situation, I was just reminded of it while discussing parts manufacturers.

    As for the "V" seal. I seem to recall other members also saying they see no benefit to it. Naturally we have some here that will say the wonderful Fiat engineers must of had a good reason for it. Who knows, maybe someone can give a plausible rational behind it.
  3. I have a feeling that the V-ring seals (at least the outer ones) were used as a Band-Aid for the wheel bearing problem Fiat was having with the early cars. One would think that a wheel bearing with a robust seal would not need it. They obviously made improvements to the bearing seal with time. I managed to get about 20K on the factory set of bearings - not bad as many were DOA after the cars were shipped to the US. My next set seems to be crapping out at around 60K so a 3x improvement there without the use of outer V-ring seals. According to my records, this should be the last of the second set so hopefully I'm good for a while. Fortunately, these bearings are pretty easy to replace. I've never had to use anything other than a vice and hand tools.
  4. Paul Valente

    Paul Valente Automotive Engineer

    Motor City USA
    The rational behind the v-ring is that the bearing grease seal needs help. Between an inner an outer race of a bearing is a great place to live when you are a seal. No run-out. No shaft-to-bore misalignment. You get to run on a ground surface that is hard as a rock (Rc 58+). What could be better? The only problem is is that it is single lip. Most automotive seals you see are multi-lip seals now. There is still one sealing lip but there are other lips to help protect it.

    They aren't all this elaborate but you get the idea:
    The V-ring is just an auxiliary device to try to protect the bearing's integral seal form debris, pressure-washers, etc.

    I certainly don't think the Fiat engineers were infallible by any means, Dr Jeff. What I think is a little foolhardy is when people defeat/remove/redesign systems that have not taken the time to understand. Case in point: the v-ring is certainly cheap enough, readily available, simple to fit (if you are doing the wheel bearings anyhow) and helps prolong the life of the grease seal. In short there is no downside. Yet, people will not only leave it off, they will advocate other to do the same because they've "never had a problem". Not saying that is you, Dr Jeff (you are one of my favorite posters :) ). Just explaining why the Fiat engineers are often defended.

    FYI Roger has some pictures of where it goes in this thread:
    Last edited: Jun 10, 2018
    myronx19 and Dr.Jeff like this.
  5. Dr.Jeff

    Dr.Jeff True Classic

    Sin City
    Thanks Paul, I hoped someone would help explain the purpose of those V-seals. I asked the question a long time ago and did not get a direct answer. Excellent description, as always.

    Just for the record, I've never had to change a rear wheel bearing, nor disassemble the rear hub assembly for any reason. Maybe I've been lucky there hasn't been any problems in that area to require attention. So I don't even know what the V-seals look like on either of my X's. But I have read posts saying there has been no significant effect with or without them. And there may be some truth to that in practice...no idea. To be honest, your description of them kind of makes them sound like a bit of a band-aid after-thought, rather than specifying a different type bearing/seal assembly?

    So would I replace them? I'd likely just clean and reuse the existing ones unless they were completely destroyed.

    As for automotive engineers, they are all complete idiots (just kidding) :p. I probably should have continued studying engineering back in my Bachelor's days. Might have enjoyed it more than the 4 other areas I pursued.

    Thanks for the info, appreciated as always.
  6. I can't speak for the later cars, but the 74s with the early hub style were probably never designed for the outer V-ring seals. They had a stamped sheet metal cover that while not close to water tight did protect the bearing seal from a direct hit. I question as to whether or not they were originally designed for the inner seal as well. There is a sheet metal "rain hood" with drain slit that press fits into the inner side of the pillar to protect the inner bearing seal. It was certainly not designed for ease of installation of a V-ring which is too big to fit through it. There is also no step on the hub or the stub axle to axially locate the V-ring - you've got to just hope it stays where you put it. Also, on both sides, the V-ring mates to the wheel bearing seal and not a metal surface. I would think they would have defined a different mating surface rather than rely on the bearing seals (The later cars use a metal plate for the inner mating surface.). Finally, the genuine Fiat shop manual I got in 1974 a few weeks after I bought the car has no mention of any V-ring seals in the photos, diagrams, or text. I can't remember if my car came from the factory with the inner V-rings or if I added them later, but to this day, it has no outer V-rings. Since I've got to change the LR bearing, it's a good time to see if I can make an outer V-ring work with these old style hubs.
  7. Paul Valente

    Paul Valente Automotive Engineer

    Motor City USA
    Usually, the only reason to have the inner race carry the seal (i.e. have an outer sealing lip) is if you are doing a really high speed application. If the seal spins fast-enough, an inner lip can lift off but, an outer lip will just form a tighter seal due to centrifugal force. A 1000 rpm Fiat wheel isn't high speed for a bearing and besides, the outer race doesn't spin. So the only thing I can think of is that the "Green" bearing has a cartridge seal like the one in the picture below. In a cartridge seal, there is both an inner and outer seal can and the seal lip rides on the inner can. So what you could be seeing is just the inner can and the actual seal lip is behind that. The idea is that then you don't have to make the inner race a nice seal surface.
    dllubin likes this.
  8. You might be on to something Paul. One thing I did notice about the Green bearing was that there was some free play between the inner race and the seal. When you reversed direction you could see a fraction of an inch of slop before the seal reversed direction. The other bearings I compared it with all had their seals rigidly attached to the outer race. I went to check out Green for info but it appears that they went out of business ~2012. They were in Cleveland.

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