Setting Pinion depth

Old 06-06-2007, 06:21 PM
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68bbnova
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Default Setting Pinion depth

On a 12 bolt chevy, where is the pinion depth measurement taken from, the machined surface for the caps? I want to replace my gears, but do not want to buy a depth measuring kit. I was wondering if I had a machined flat bar that would bridge the caps mounting points, could I use veneer calipers to measure the depth from there, minus the thickness of the bar? Thanks, Sean
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Old 06-07-2007, 06:36 AM
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dcarr511
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I just bolt a cap in with one bolt and swing it over the pinion to get my measurement. Never had a problem with it ....

Now that doesnt mean the cap is split in the dead center of the bore. Just something that has worked for me and others I know.
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Old 06-07-2007, 06:50 AM
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Originally Posted by dcarr511
I just bolt a cap in with one bolt and swing it over the pinion to get my measurement. Never had a problem with it ....

Now that doesnt mean the cap is split in the dead center of the bore. Just something that has worked for me and others I know.
Great idea Duane,I never thought of that,that will work :idea:
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Old 06-08-2007, 06:30 PM
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68bbnova
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Never thought to use the cap, but back to my question, if I measure thru the cap to the pinion, I subtract the cap thickness? The depth measurement is from the axle centerline? Thanks, Sean
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Old 07-21-2007, 07:57 AM
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Here is some interesting info I got from the MW webpage. The same info should be available for a 12 bolt housing. I'm sure if you have a good depth mic, and take some accurate measurments from the pinion gear the following info would apply just the same.

"Some gears do not have the engraved pinion setting depth (OEM gears); however, the setting depth can be calculated. The master housing dimension for 9" Ford is 4.375". This is the distance from the centerline of the thirdmember case main bearing bores, to the shoulder that the stock rear pinion bearing would stop against. By measuring the pinion head thickness, then substracting this measurement from 4.375" (master housing dimension), the setting depth is obtained. Some of these pinions are marked with a + or - and a number. This is the variance from the master housing dimension that the pinion needs to be set. Example: If the pinion is marked +2, the master housing dimension would be 4.375" plus .002 or 4.377"."
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Old 07-21-2007, 07:58 AM
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Old 07-21-2007, 09:44 AM
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Originally Posted by dcarr511
I just bolt a cap in with one bolt and swing it over the pinion to get my measurement. Never had a problem with it ....

Now that doesnt mean the cap is split in the dead center of the bore. Just something that has worked for me and others I know.
If you want to know where the center of the bore is just measure from the cap seat (bore split) to a metal ball placed in the bottom of the bore with a depth mike and add the ball size amount, divide in half.

Add to the numbers you got from dcarr511's method and there's your total.

Curtis
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