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Help! Rear Differential rebuild problems...

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Old Oct 6, 2010 | 10:17 PM
  #1  
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Help! Rear Differential rebuild problems...

Hey, guys - thanks for the help so far...hopefully I haven't jumped out of the frying pan and into the fire.

I have an '86 F250 with the Ford 10.25 rear axle (4.10) ratio. I just rebuilt the differential after noticing that my pinion seal was leaking. I replaced the carrier bearings, front and rear pinion bearings, oil seal, and diff. case gasket.

Now... I put it all together according to Chiltons (mistake, maybe?) the carrier/axle/pinion assembly was very tough to turn by hand - but it turned. I figured that this was due perhaps to new bearings (the old ones were LOOSE!) - also my left rear brake drum was a b#@*h to put on.

I took it for a spin, and it worked - kind of. It feels like the brake is on. And - when you go to shift, there's some sort of horrible "clunk/grind/clang" sound - can't tell if it's coming from the differential, my driveshaft, or brake drum. In gear, it's fine - tried 1st, 2nd, and Reverse (going very slow!)

Can anyone shed some light on this problem?

Thanks!
 
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Old Oct 7, 2010 | 12:00 AM
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did you measure for backlash? you might have over tightened the crush sleeve on the pinion gear.
 
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Old Oct 7, 2010 | 06:14 AM
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No - I made sure that I replaced the shim on the pinion gear (between the teeth and the rear bearing; plus, the assembly was difficult to move BEFORE I tightened the pinion nut; I only torqued it to the minimum value (160 ft/lb).

The book doesn't mention how to measure for backlash - what is it and how do I measure?
 
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Old Oct 7, 2010 | 09:50 AM
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May have to use different side shims. The new bearings will have a different depth that has to be adjusted for. I just did the 92, and it was tight going to gether, but in the end was ok, and I didn't go with new bearings, but did go with the carrier from an86 truck. That was an experience I am not likely to repeat, older carriers don't play well with the new speed sensor housings and trigger wheel...
 
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Old Oct 7, 2010 | 10:18 AM
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Hi, Roger - thanks for the info - and the side shims were tough going in - had to use a deadblow hammer and punch to get them in place.

How do I remedy this? Have I damaged anything by taking it for the short spin? Can I simply replace the side shims, or am I looking at a whole new diff?

Thanks!
 
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Old Oct 7, 2010 | 10:23 AM
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Originally Posted by DigitalCowboy

The book doesn't mention how to measure for backlash - what is it and how do I measure?
you have to get a dial indicator on it.

and did you do this process to check to see where the pinion gear is riding on the ring gear? if you dont have it right then your gonna wear the gears early.
 
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Old Oct 7, 2010 | 10:36 AM
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The trick to the shims is that they are certain thicknesses, and also control the depth the ring and pinion meet at.

^^ beat me to it.
 
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Old Oct 7, 2010 | 11:11 AM
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sucks to say since i hate not doing stuff myself, but if you want your gears to last forever, its better to just take it in, bite the bullet and pay the few hundred bucks it costs to have it installed.
 
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Old Oct 7, 2010 | 05:11 PM
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I second Oreo ... I am as well one of those that does everything myself, I have done many, however when I have access to someone I trust that does a lot of them, I have them do them!

It's more of an Art then Science IMO.

-Enjoy
fh : )_~
 
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Old Oct 7, 2010 | 11:12 PM
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well, I have to laugh at myself - this was one project that I was definitely NOT prepared for... even though I spent more time and $$$ preparing than when I swapped the motor!

Oh well - talked to a few folks around here and I got the same answer - better off to let someone else do it! So I'm off to the shop.

Damn the Chilton's manual - there's no mention whatsoever about properly installing/adjusting a differential... but Randy's Ring & Pinion has a whole @#$%ing book about it!

Anyway, thanks for the advice, everybody - and for myself (and anyone else reading) - what IS the proper, step-by-step process for rebuilding/installing a diff?
 
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Old Oct 7, 2010 | 11:37 PM
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To do it correctly, from fresh, you have to do the dial indicator for the backlash, which is the spacing between the gears, set by the crush sleeve on the pinion. The side adjustments with the shims control the depth at which the gears meet. Too far out and you will rip the edges off the teeth, too deep and you put pressure on the ring gear, and can potentially break things that way as well.
 
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