Differential Girdles?

[Captain Ledd]

So I searched the internets, searched TRS and didn't find what I was looking for.

What exactly do these things do? I looked for a pic showing the underside of them and could not find one. Is all they really do just push down on the tops of the caps a bit? Not that I'm an expert on axles my any means, but that doesn't sound like it would help all that much. Or are there other parts to them? Do they actually work?

I was considering one when I went to the 8.8. Not nessecarily for strength, but the extra fluid capacity that most of them boast and cooler temps for when I tow. Was particularly looking at the Mag Hytech cover, though while it showed up on the girdle related searches, I'm pretty darn certain it isn't one.

*Edit:

Well I did find this:

And that seems like it would add some strength to the differential. Seems to be a Toyota thing though.

 

[Captain Ledd]

Ughhh... As is so common with when I finally decide to post a question, 4 links later...

This is "Trick Flow Specialties" girdle for an 8.8".

Well I guess that answers one of my questions. I still don't think it'll do much.

 

[flyingbrick]

My understanding is that they press on the bearing caps, to prevent ring gear deflection from the pinion gear, causing excessive wear/potential breakage in high HP set ups. In low HP, stock, or non off-road trucks, they don't do much. For towing I'd get the Mag Hytech cover though.
Please correct me if i am wrong.

 

[4x4junkie]

Yes, that's their primary purpose, it's to reduce gear deflection under load, which is a main cause of gear failure (stripped teeth) under high power or torque.
Running deep gears like 5.13 with big tires (not necessarily with big horsepower) is another good excuse to have one.

I have one on my BII even though I still have the 2.9L.

 

[martin]

I would think it might help if you were pulling in reverse. The coast side of the gears have more angle and therefore more force pushing the gears apart.

 

[Captain Ledd]

So the bearing caps actually deflect that much? I never would have thought of that...

I figured it would have been because they "walked" like on an engine (which is why I wondered how just pressing on them would help), not stretched enough to strip gear teeth. Makes alot more sense now.

 

[4x4junkie]

Not just the caps, the whole housing can flex enough to affect the gear mesh. The girdle helps make the whole thing more rigid.