9" Differential Case Size?


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By Ol Ford Guy - 15 Years Ago
I am getting ready to change the axle ratio in my 57.  I'm thinking Richmond Gear.  They advertise three installation kits with bearings.  They have different kits for different case sizes, 2.891, 3.062 and 3.250.  Is there a standard size that came in 57's? or is there a production variance?  Where do you measure the case to get the dimension?  I have two rear ends, and an extra 9" housing.  The gear in the car now howls terribly accellerating or decellerating and if I thought bearings would solve the problem, I would just change them...but the ring and pinion may be bad too, they look fine.  I also have the 3.10 rear end that came in the car, and I am going to convert it.  Since it is a fair amount of work to do this, I want to replace the bearings too.  Any thoughts and info appreciated.  I'm going to have a pro do the work.  I have experienced that even rear ends set up by a pro whine slowing down where as factory rear ends never seem to do that. 
By Hoosier Hurricane - 15 Years Ago
Paul:

Those three sizes indicate the OD of the carrier bearing cup, or the bore in the housing that the bearing fits in.  If you '57 case is original, it would be the smallest one.  There's no guarantee that it is original, since all the 9" housings will interchange.  Only way to be sure is to take it out and measure it.

Is the pinion nut tight?  Sometimes they work loose, that will cause a howl.

By lowrider - 15 Years Ago
The bearing size they're referring to is the size of the side bearing cups. You'll probably have to take it out and measure the side bearing cups to get the right ones. The whole assy. may have been changed over the years. You won't really know until you get it out and look at it. NAPA stores usually carries the bearing & cups, but don't buy the cheap ones (Chinese).
By Ol Ford Guy - 15 Years Ago
Well, I removed one of the caps and measured the bearing, still in the third member assembly, with my digital caliper.  It was 3.071,which is very close to the middle dimension I mentioned in my post.  Do I need to take  the bearing out and measure the ID of the cup?   I want to be sure I order the right kit.

Thanks,

By Ol Ford Guy - 15 Years Ago
Well, the bearing measures 3.062 after I removed it and wiped it off.  My extra 9" housing is the smaller diameter.  I'm pretty sure my cars third member is orignal to the car.  It could it be the larger size because it is an E Code car, I know ther Fordomatic is heavier duty.  As always, thanks for the help.
By Ol Ford Guy - 15 Years Ago
FOLLOW UP,  In addition the the larger carrier bearings, my car has a 4" pinion seal, which I am told is very uncommon.  It makes me think that E Code cars came with a heavier duty rear end.  The Case also has extra webbing.