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Discussion Starter · #1 ·
Greetings... I swapped a new center section and gears in this weekend. It was my first 9" gear-set build. These are used gears and I had tried to just clean up the pumpkin, put the minispool in and put it back together. Well - it turns out that the yoke on the new center is about an inch shorter than the original so I had to swap them....

So - It is back together - I retorqued the pinion nut to ~175 ft/lbs. Backlash is .010" measured with a dial indicator - This feels too loose to me (but what do I know - it's my first time through this) but is right in the middle of the recommended range of .008 - .012. I put the thing back together and fill with 2 qts of 85-140 gear oil.

So the first drive out I hear a slight whine out of the gears... I have gone around the block twice - about 1 mile of total driving at low speeds/power/rpm and it seems to be quieting but I am not sure.

Is this normal? I don't want to tear everything down and recheck just to put it back together and have the same thing. I also don't want to figure out that it is wrong by buying a new set of gears...

Thanks In Advance...

Nathan
 

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Discussion Starter · #2 ·
Note - the fluid was about 1/8th of an inch below the bottom of the fill hole with the rear of the car up in the air. I did not recheck the fluid with the vehicle level but I need to get it on a lift - I expect that it is right at or maybe just slightly under the fill hole.

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<font size=-1>[ This Message was edited by: 65Custom on 2/28/06 12:52am ]</font>
 

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Perhaps when you changed the pinion it changed the backlash somehow? Maybe another check is in order if the whining continues.
 

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It is always hard to get the whine completely out when using used gears. The used gears already have a wear pattern on them, and don't mesh completely with other used gears.

The first 9in backends had what was called a hypoid whine in them. Some came from the factory with it, and dealers couldn't get it out.

If it is not too bad: I would add 8oz of STP to the gear oil and run it. When changing rear gears, I always add STP to the gear oil

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<font size=-1>[ This Message was edited by: rayell on 2/28/06 6:08am ]</font>
 
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