Pinion torque & backlash question. Please advise

TRUBBS

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Goin through and checking a new used rear end that was picked up from the yunk yard. It's a stock rear axel from an '01 f350, 10.5 ring gear, 3.73 locking axel code is s 409 h.

Just needing to know what the pinion nut is supposed to be torqued to

And what the backlash On the ring is supposed to be, thanks!
 

Aaron S

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There isnt an exact torque on the pinion nut. Its supposed to be tightened until you achieve a specific rotating torque on the bearings. I dont know what that is though.

I believe the backlash is somewhere in the .008 to .010 range.
 

91turbogsx

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Backlash was IIRC .008-.012.

And there is really no way to properly check pinion preload with the carrier in place.
 

91turbogsx

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Pull the axles and carrier out. There isn't a spec for the rotational torque with all that installed.
 

tbsimmons

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Another thing, if you move the pinion nut, I would take it all the way off and use blue loctite. I have had them come loose without using it.
 

dzldoctor

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Spec for backlash is .008-.015 ideal .012 The pinion nut rotational torque is about 25 in-lbs with no differential case.
 

TRUBBS

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Ok next dumb question how do I check back-lash? Axel is out & on jackstands. Reason I ask is the inside has "tiger stripes" from what looks like the ring was somehow rubbing the center (Carrier I assume?)
 

Pstroke96

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you have to put a dial indicator on the round side of the ring gear, hold the pinion from moving and push the ring gear as far as you can one way, set the indicator to zero push it the other way and read the indicator, thats your backlask
 

HOOV3R

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Use a dial indicator on a ring gear tooth. Turn it til it contacts the pinion on one side, zero your dial indicator, then rotate until it contacts in the other direction.
 

dave186

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Those specs are for new components. A used set of gears and bearings are going to have more backlash, and no preload.
 

Wayne

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For the Ford 10.25 and 10.5 axles pinion preload on new bearings should be 20-35 in-lbs. on used bearings it should be 6-8 in-lbs. Backlash spec should be set at .006-.010" regardless of wear. if you have too much backlash move the ring gear toward the pinion, if it's too tight then move it away. rule of thumb for setting backlash is move the carrier .010" for every .007" you need adjusted. when it's all done you still need to have a good pattern. If your pattern is bad after all of this then you need to adjust pinion depth.
 
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TRUBBS

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For the Ford 10.25 and 10.5 axles pinion preload on new bearings should be 20-35 in-lbs. on used bearings it should be 6-8 in-lbs. Backlash spec should be set at .006-.010" regardless of wear. if you have too much backlash move the ring gear toward the pinion, if it's too tight then move it away. rule of thumb for setting backlash is move the carrier .010" for every .007" you need adjusted. when it's all done you still need to have a good pattern. If your pattern is bad after all of this then you need to adjust pinion depth.

How do you move the ring gear towards the pinion? Sorry for the dumb question but we never have played with setting a rear diff up brfore
 

91turbogsx

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Add and remove shims from each side of the carrier. Factory shims are machined to an exact fit where most kits have a bunch of shims at varying thickness you can add or remove.
 

Wayne

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If you have the 2 solid factory shims, then you need to order an adjustable shim kit. If the different is difficult to get in and out you may want to keep the total thickness you have now, otherwise increase shim thickness to make it tight again. If you don't completely understand what I'm saying you better get a how-to manual, or pay somebody to do it. Mistakes of this nature are much more expensive than paying someone who knows what they're doing.
 

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