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Discussion Starter #1
I set the backlash on my 4.30's to tight. .0035 to be exact. I had a source telling me proper backlask was .004-.008. As it turns out Ford Spec is .008-.015. What should I do? re do them? They are quiet and everything seems to run great, aside from a vibration occuring at high speed I am beginning to attribute to the driveline. Anyway what is the problem with them being this tight? I run fully synthetic oil in the back (mobil gear oil) so are they getting properly lubed with this tight of a set up?
 

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Discussion Starter #4
Can you elaborate on bearing preload? I mean we preloaded the diff bearings before checking anything, but I'm not quite sure I know what you mean. The pattern looked great. Will backlash widen as the gears break in and get some miles on them?

Oh yeah, it all took about 4 hours.
 

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He means pinion bearing preload - the amount of torque required to rotate the differential from the properly-preloaded pinion. Should be from 12-24 inch pounds.

0.003 backlash - that's pretty tight, although if they're quiet I wouldn't worry about it. The only way to change it, assuming you didn't use any shims on the pinion, is to shim the carrier away from the pinion.

But, like i said, if they're quiet and if you can take it easy on them for 500 miles or so and not allow them to build up excessive heat, they should loosen up a bit.
 
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