bugwhacker
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Our hubs have the same race 3920 in the inner and the outer position. We use a 3992 or 3994 bearing in the inner position and a 392 bearing in the outer. This is fine and dandy on the day they are manufactured and makes keeping spares on the shelf easy as you only need one hub loaded with the same race on both ends for all positions on the truck. When flipping our used hubs though this creates a bit of a problem.
The reason is this -
The bearings we use are 2 differant widths on the taper face.
The inner 3992 or 3994 are both 0.9375" on the cup face and the outer 392 is 0.7411" that is a differance of 0.1964" - a little short of a quarter inch.
So when we flip our hubs we will have a 3/4" bearing running on a 1" race in the outer position - this will most likley be okay.
Then we will have a 1" bearing running on a 1" race in the inner position that has had a 3/4" bearing ran on it wearing a 3/4" path in it for who knows how long - this is less than ideal.
For low speed crawling out in the woods this is most likely not going to fail for a long time. Running down the hiway though this could be a problem.
I myself because I plan to run alot of highway miles will at the very least replace my inner race for $8 when I flip my hubs. Of course replacing all the bearings and races with new matched units would be the perfect solution.
The following spec sheet clearly shows this with "Cup width "c"".
The reason is this -
The bearings we use are 2 differant widths on the taper face.
The inner 3992 or 3994 are both 0.9375" on the cup face and the outer 392 is 0.7411" that is a differance of 0.1964" - a little short of a quarter inch.
So when we flip our hubs we will have a 3/4" bearing running on a 1" race in the outer position - this will most likley be okay.
Then we will have a 1" bearing running on a 1" race in the inner position that has had a 3/4" bearing ran on it wearing a 3/4" path in it for who knows how long - this is less than ideal.
For low speed crawling out in the woods this is most likely not going to fail for a long time. Running down the hiway though this could be a problem.
I myself because I plan to run alot of highway miles will at the very least replace my inner race for $8 when I flip my hubs. Of course replacing all the bearings and races with new matched units would be the perfect solution.
The following spec sheet clearly shows this with "Cup width "c"".
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