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12 Bolt Aluminum Cover - Added strength or no?

300 Views 7 Replies 7 Participants Last post by  joe_padavano
Hey guys. This is for all you Chevy truck 12 bolt experts out there. Do you believe that a cover such as this adds any real overall strength to a 12 bolt? From the vendor:

Rim Automotive wheel system Bicycle part Silver Watch

"Made from 356-T6 cast aluminum, these girdles incorporate a reinforced crossbar. The crossbar houses the load bolts that apply pressure to the bearing caps. This feature, along with the thick casting, prevents bearing cap deflection under severe loads. Which in turn greatly reduces or eliminates (in most cases) bearing cap fatigue and failure. "

Thoughts?

Thanks,

Brent
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· Old(s) Fart
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The whole point of these girdle style covers is that you adjust the two preload bolts to minimize deflection in the bearing caps holding the carrier in place. The problem with this design is that aluminum only has about 1/3 the stiffness of the iron center section, so unless you crank on the bolts a lot, the aluminum cover deflects under load. It's not the best design, but it probably provides SOME additional support to the caps. The real problem is that people confuse "strength" with "stiffness".
 

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Thats a nice 356-T6 casting. Its well machined and the 2 examples I saw were very well done (We design and finish machine aluminum castings at Auto Gear). As far as the bearing cap pre-load bolts? No idea if thats good bad or indifferent. I suppose I'd say Buy it because its a lot more leak resistant than a stamped cover; and she pretty. Is it going to save your rear if you're locked in a race? 12 bolts are plenty strong; how much overhead does your ride need?
ETA: I agree with Joe's assessment above as well.
 

· Hates: Liver. Loves: Diesel
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The truck version of the 12 bolt uses a 10-bolt type pinion shaft/bearing. I have a feeling that the pinion is your weak point. I don't think adding a girdle is going to prevent explosions since the carrier bearings are plenty beefy. Unless you're launching with wrinkle walls and 500 lb-ft, I wouldn't worry about it.
 

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I run ‘em as standard practice on these GM axles they do stiffen up the carrier housing a little and often a little is all you need. I think as much as anything they change the frequency response to fatigue causing vibrations in the carrier more-so than adding some amazing reinforcing strength to the bearing caps. Rather like adding a halo brace to engine main caps it moves the fatigue frequency response away from the shake, rattle and roll that wants to crack the major cast structures.

Bogie
 
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