Snap Ring Question

[Jim Garry]

I've got half shafts that have a groove with an OD of 0.988".

I checked McMaster-Carr and the closest I can find to matching this is this: https://www.mcmaster.com/91590A133/
The part has a "released in groove" dimension of 0.94". This means the ring won't release back to its non tensioned dimension.

I checked with McMaster and over a number of back & forth emails they wrote:
"This external retaining ring (91590A133) is designed to apply radial tension to the groove in typical applications. The standard design is expected to be able to open up to a 1.010” ring inside diameter and spring back to a diameter below .936”, ensuring constant contact with the standard groove of .936-.944”. Based on your application with an .988” groove, the ring will certainly be under tension. However, it will have reduced thrust capacity, as you can expect the ring to dish under load when used on an oversized groove. We do not sell any retaining rings for a 1" shaft OD with a 0.988" groove OD, however you can review the larger groove OD sizes we sell for a 1" shaft here. These would be under less tension that the 91590A133 retaining ring designed for a 0.94" groove OD. "

Those alternative rings don't look very good to me and still don't seem to accomplish McMaster's stated goal. Can anyone offer some advice?

Thanks,

[R. Pare]

Don't over analyze the issue. The rings will do their job perfectly well on your halfshafts as the only time they may see the sort of load that would possibly overload them is in a crash.

[Bobsy SR 6]

Jim

As a thought, what about a metric sized ring. A quick check of McMaster showed a 25 mm ring is within .09” of your diameter. You didn’t mention the ring width but I would guess McMaster has the right sized ring.

Good luck
Tom

[Jim Garry]

Bobby, good idea but I'll go with Richard's advice to not overthink this. Thanks Richard.

[alangbaker]

Bobby, good idea but I'll go with Richard's advice to not overthink this. Thanks Richard.

I'm with those who think that perhaps you have a metric snap ring groove. At 0.988" or 25.0952mm, your groove is only 0.2mm (7 thou) larger than the groove diameter for a 26mm OD shaft.

I'd check the width of your groove, too. If it's 1.3mm (51 thou), then I think you're metric!

[Jim Garry]

Thanks Alan. I'll check.

[RussMcB]

I had my axles in a CV shop recently and they said they were VW type axles. He reached into a bin of several and handed me one.

But, good advice above and it sounds like you're all set.

[924RACR]

Defintiely metric; those measurements match with my halfshafts, which are indeed VW CVs. So shop metric, you'll be fine.

I probably have some of those kicking around as spares, even... but go to any decent import shop etc...

[billtebbutt]

Not to veer too far off the subject, but only a couple of years ago I learned that snap rings have a "right way" and a "wrong way" to be installed on a shaft.

The shaft in question was a MK9 stub axle shaft. The snap ring had left the groove, and was just spinning on the shaft. I only noticed it because gear lube started leaking past the axle seal, and sure enough the axle had walked out of the side cover a bit.

Snap rings have a "sharp" radius on one inner edge, and a "curved" edge on the other. In my case the ring had been installed with the curved edge facing the centre of the car. That, probably with a little radius on the edge of the ring land itself, was enough to let it push itself out of the land eventually.

Or, so I was told by my gearbox builder! But, sure enough, when I look carefully at snap rings now (under a magnifying glass since I am so darn old!), I can see the different profiles on the inner ring edges......

cheers,
BT

[john f]

Not to veer too far off the subject, but only a couple of years ago I learned that snap rings have a "right way" and a "wrong way" to be installed on a shaft.

The shaft in question was a MK9 stub axle shaft. The snap ring had left the groove, and was just spinning on the shaft. I only noticed it because gear lube started leaking past the axle seal, and sure enough the axle had walked out of the side cover a bit.

Snap rings have a "sharp" radius on one inner edge, and a "curved" edge on the other. In my case the ring had been installed with the curved edge facing the centre of the car. That, probably with a little radius on the edge of the ring land itself, was enough to let it push itself out of the land eventually.

Or, so I was told by my gearbox builder! But, sure enough, when I look carefully at snap rings now (under a magnifying glass since I am so darn old!), I can see the different profiles on the inner ring edges......

cheers,
BT

Caused by the blanking die that formed the ring to start with. Anything cut with a punch and die will have this edge.

john f