GTR1999

Before disassembling the rear to replace the bearings and seals I wanted to check all measurements. One thing I didn't like was the gear pattern,seemed to be toward the toe of the gear. Checking the GM manual it sayd to apply 40-50 ft/lbs of torque to the pinion to get an accurate pattern. Iguess this loads the bearings/gears? The manual says to apply the parkingbrakes to create drag :crazy: Well that's not going to work since the rear is on an engine stand! Anyone have a better way to get an accurate pattern check? I'm thinking of using a strap wrench on one yoke to create drag what have you done?
Thanks,
Gary

Wrencher

40-50 isn't much. Basically they just want a load on it. Ideally, you want a pattern that is in the center of the gear, covering about 3/4 of the length on both the load and coast sides. Doesn't always work out that way, even from the factory. If the pattern isn't way out on the tooth, or one end or the other, and it didn't whine, it's probably fine. DON'T TRY TO "FIX" IT! Unless your replacing the gears, you MUST put it back as close as possible to where it was. This is why you have to check it first. Use white lead or light colored grease and take a picture. I've built tons of diff's, and it's not rocket science. Check the backlash while it's still together as well. You can sometimes tighten this up a little on a used gearset without adverse effect. Good luck.

Hans

SmokedTires

If you just plan on disassembling the differential to replace bearings and seals, you shouldn't have to change the shims in the ring or pinion when you reassemble it. One thing you can do is check the backlash with an indicator at 4 different spots to see what it is before you take it apart.

GTR1999

I agree completely with both of you guys, but here's my point. On this differential I'm just replacing the seals and bearings,but will change the gear set when I do the 69 next year sometime. I want to be sure I have the tools and procedure down so I can do this job whenever I want or help out friends in the area do theirs.
I have checked everything before disassembling it so I have a good reference point when I put it back. I held the pinion tight so it wouldn't move and checked the backlash= .005" checked the bearing preload to move the pinion in In/lbs = 4-5 in/lbs. The last thing I wanted was to check the pattern and that's where I'm at now. I used prussian blue and it looked like the pattern was closer to the toe then center. This is my question: the book says to load it 40-50 ft/lbs to get a correct pattern-chances are when I do this it will be better, but how do you guys load the pinion when you check it or do you have another procedure? Many time the procedure and tools listed in the GM manuals are not practical and other procedures/tools can do the job just as good.
Thanks for the help,
Gary