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Discussion Starter #1
I know what the differeneces are between the small and big bearing 9" rear ends. My question is, are there any performance advantages to using a big bearing rearend vs. a small bearing one? I have a 9" truck housing that I'm narrowing and building up to use in my Mustang. My disc brake setup is for a small bearing rearend. I would rather stay with the small bearing ends for cost, but will upgrade to big bearing ends if there is a performance advantage.
 

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Performance advantage, I don't think so. I went with the big bearing so the FORD Racing rear disc brake kit would fit.
 

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Discussion Starter #4 (Edited)
Kinda what I thought Shaun. I just wanted to make sure I wasn't missing out on something staying with a small bearing setup. Until recently I never realized how much beefier the truck 9" housings were versus the Mustang 9" housings. Just ordered small bearing ends and a back brace. This should be a killer rearend when I'm done.


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I always go with big bearing housings and axles if the car has a decent amount of HP. The small bearing axles, regardless of spline count, are no bigger than a regular 8" axle. Most axles always break at the bearing, not the splines. Also, the small bearing housings are light duty, and the housing will distort where the spring perches weld to the housing. I avoid small bearing housings and axles like the plague, as they don't belong on a high HP car.
 

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Discussion Starter #6 (Edited)
Well, I'm using a truck housing. So it's much more stout than the car housing. The difference is very noticeable when you place the two housings together. And I have 31 spline Moser axles. They are the same as diameter as the big bearing axles. The bearing seat area is just about .15 of an inch smaller. So I'm not worried about strength of the axle shafts or the housing, I just wanted to know if anyone was aware of a performance advantage to big bearing over small. Because my rear disk brake setup is for small bearing, I want to stay with the small bearing unless using small bearings are going to hurt me.
 

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Well, I'm using a truck housing. So it's much more stout than the car housing. The difference is very noticeable when you place the two housings together. And I have 31 spline Moser axles. They are the same as diameter as the big bearing axles. The bearing seat area is just about .15 of an inch smaller. So I'm not worried about strength of the axle shafts or the housing, I just wanted to know if anyone was aware of a performance advantage to big bearing over small. Because my rear disk brake setup is for small bearing, I want to stay with the small bearing unless using small bearings are going to hurt me.
Make absolutely sure that Moser did not sell you their small housing axle bearing conversion. What they do is sell an axle that has the same diameter as the big bearing axle, but with a conversion bearing that will allow it to fit a small bearing housing. Their conversion bearing WILL FAIL in as little as 500 miles because the balls inside the bearing are way too small. Moser will not tell you this, but I fix two or three rear ends a year with those crappy bearings from Moser. I only use Dutchman axles now.
 

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Discussion Starter #8
Thanks for the info. They have the standard small bearing size seat area.
 
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