I'm getting ready to do my rear end gears. I'm going from 2.73 to 3.55 in my '91. Go the gears and bought a crush sleve yesterday. Can anyone give me some advice before I tackle this for the fisrt time.
Setting up the backlash and tooth contact pattern is critical to the life of a new gear set, not to mention a quiet running gear set. If it's not something you have done before I'd recommend spending the bucks to have a professional shop do it.
Mesh of gears is important and the central part of the ring and pinion teeth must mate and show a good contact pattern. Patterns off center indicate incorrect installation (incorrect shims, etc.) Gears should be somewhat tight and smooth turning running when finished (no binding). Assembling them a bit tight makes for a good break in and long life. This will also keep the mesh in the central part of the teeth. They'll loosen up as they break in.
When your setting the pattern, think about gear noise, it comes from point contact. So, when your looking at the pattern and adjusting things to center the contact patch pay particular attention to sharp edges in the pattern.
In the rears I have set up, I learned that the location of the pattern is not nearly as critical as the way the pattern looks. If you have a sharp edge (or dark spot) this is indicative of point or "line" contact occuring as the gear teeth move through their mesh pattern. Try to adjust this out, it will make the gearset much more quiet and improve it's longevity too.
Be patient, don't expect to get it right the first time. Be prepared to open it up and do it again. The second time you do it and the gearset responds to the adjustments you make will make it worth all the trouble. After that, gearsets won't intimidate you anymore and you'll be offering to do them for your buddies.
Each gearset is manufactured with a dimension called pinion depth. This dimension is etched on the gearset. On a 9", the pinion depth is controlled by a shim (or shims) that go between the pinion housing and the pumpkin. On an 8.8, pinion depth is controlled by a shim underneath the pressed on pinion bearing. If you can locate a pinion depth gauge, you'll be hours ahead and more accurate.
Then it will be a matter of setting the pinion preload, backlash (shims, 8.8) and carrier bearing preload.