Funny shapes on rear axle centers

[screamineagle88]

I’ve been a shade tree mechanic for 30+ years now, and I still don’t know for certain what those funny shapes in the cups that are in the center of many rear wheel drive cars rear axle flanges are there for.
They look like they are there for something to help spin them.
Some look like 2 small triangular shaped tabs pointing inward. While others look like a set of wedges with a rectangular indent in the center. Like you put a rectangular bit into them and spin them. But if it spins too fast and over runs the bit the wedges kick the bit out of the hole.

I know this is a funky question, but does anyone really know what they are there for?

Topic

[Rob]

[quote=”screamineagle88″ post=173928]I’ve been a shade tree mechanic for 30+ years now, and I still don’t know for certain what those funny shapes in the cups that are in the center of many rear wheel drive cars rear axle flanges are there for.
They look like they are there for something to help spin them.
Some look like 2 small triangular shaped tabs pointing inward. While others look like a set of wedges with a rectangular indent in the center. Like you put a rectangular bit into them and spin them. But if it spins too fast and over runs the bit the wedges kick the bit out of the hole.

I know this is a funky question, but does anyone really know what they are there for?[/quote]
can you upload a picture I have no idea what your talking about…. Im thinking your talking something about a diffrental but have no idea

[Mike]

My guess is that they’re “drive dogs” that mate with special factory tools or fixtures when the axles are assembled. Either for holding the axle shaft stationary, or for rotating the axle when checking backlash patterns. Or maybe both.

[screamineagle88]

The only clear picture I could find is of the hub with 2 triangular flanges I was talking about. They are also squared off on some cars. But I think you’ll get the gist of what I’m talking about from the one picture.

My best “educated” guess is that they may be for hooking all vehicles that are coming off the line up to test equipment such as line dynos. To test the performance specks of all the cars coming off the line.
But I just want someone who knows this answer to pipe in and let me know weather my guess is correct or not.

Many vehicles these days don’t have these, and most aftermarket hubs either smooth dish that area, cap it off, or square it off and not put anything there but their logo stickers.

Attachments:

• Rearbreakshubcroped.jpg

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