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I just pulled the 3rd member out of my 79 F150 4x4 with a 31 spline 9” rear end and there seems to be zero slop or backlash between the ring and pinion. Does anyone know what the factory specs are? It’s a stock, open differential with 140k miles that has never been cracked open from what I can tell aside from replacing the wheel bearings and pinion seal within the last two months.
The reason for pulling the 3rd member is to put in a Detroit truetrac using the factory ring and pinion (3.50 ratio) and new bearings. I had plans of buying or borrowing a dial indicator to set it back up to the correct black lash but now I’m not sure what to do.
Set mine at .008 with new gears. Hold the pinion yoke or clamp it in the vice so it can't move and rock the carrier and rear gear back and forth. You'll see it then there has to be some or it would eat itself.
I must have jumped the gun posting that. Now that the cold oil has drained a little more I can hear and feel the backlash. A $28 harbor freight magnetic dial indicator confirms .012 backlash
Any tips for how would I go about setting the bearing preload?
i have a vice grip with flexible wand that locks down to hold an indicator.
I saw that at Harbor Freight but it looked like it would be kind of flimsy. I bought the indicator and magnetic base separate and it ended up being a couple dollars cheaper than the vice grip setup
