Proper procedure from GM with used collar
Doing it correctly does not require a new crush collar. I'm interested in hearing why you feel otherwise. If no internal parts are being changed, using a new crush collar accomplishes nothing. A new collar is only needed when internal dimensions between the two bearing packs have changed.
GM gives full instructions on how to do it in the tech manual. If no internal parts are being changed, the collar can be reused as-is.
The crush-collar is simply a cost-cutting short-cut. It eliminates the need for an internal shim-pack to protect the bearings from too much preload. If there was no collar or shim-pack, there would be no pressure against the pinion nut to keep it from coming loose when bearing adjustment was correct. Same situation on front wheel bearings but they have lock mechanisms to keep the nut from backing off.
Direct from the GM factory tech manual for the 10 bolt 8.5" axle. Under the heading of "pinion flange/pinion oil seal replacement." Measure rotating torque of the pinion before disassembly. After reinstalling the pinion flange, "tighten the pinion nut in additional small increments until the torque necessary to rotate the pinion exceeds the original recorded valve by 3 inch pounds."
That is GM's recommended method to get preload back to where it was, plus adding a small amount and reusing the old crush-collar. Note that GM calls it a "collapsible spacer."
All that crush collar does besides help prevent excess bearing preload - is allow some pressure against the pinion nut so it will stay tight. If this was a more heavy-duty drive axle, there would be shim pack inside instead of a crush collar. This way, no matter how tight you cranked on the pinion nut, you would not ruin the bearings.
With the cheap crush-collar setup, new or used - it is easy to ruin the pinion bearings because there is nothing to stop adding too much bearing-crush.
I've seen many get ruined over the 50 years I've worked as mechanic, and that happens with any collar - new or used. A pinion with used bearings should be tightened so the rolling torque is 8 to 12 inch pounds with used bearings. 24 to 32 inch pounds with new bearings.
If just pulling the pinion flange to replace a seal, and not renewing the flange, it even gets easier. You mark the nut against the flange before loosening. Then when reinstalling you make sure you tighten up exactly as it was before with the marks lined up. Then tighten just a bit further and check pinion rolling torque.
Ill advised by who?
Doing it correctly does not require a new crush collar. I'm interested in hearing why you feel otherwise. If no internal parts are being changed, using a new crush collar accomplishes nothing. A new collar is only needed when internal dimensions between the two bearing packs have changed.
GM gives full instructions on how to do it in the tech manual. If no internal parts are being changed, the collar can be reused as-is.
The crush-collar is simply a cost-cutting short-cut. It eliminates the need for an internal shim-pack to protect the bearings from too much preload. If there was no collar or shim-pack, there would be no pressure against the pinion nut to keep it from coming loose when bearing adjustment was correct. Same situation on front wheel bearings but they have lock mechanisms to keep the nut from backing off.
Direct from the GM factory tech manual for the 10 bolt 8.5" axle. Under the heading of "pinion flange/pinion oil seal replacement." Measure rotating torque of the pinion before disassembly. After reinstalling the pinion flange, "tighten the pinion nut in additional small increments until the torque necessary to rotate the pinion exceeds the original recorded valve by 3 inch pounds."
That is GM's recommended method to get preload back to where it was, plus adding a small amount and reusing the old crush-collar. Note that GM calls it a "collapsible spacer."
All that crush collar does besides help prevent excess bearing preload - is allow some pressure against the pinion nut so it will stay tight. If this was a more heavy-duty drive axle, there would be shim pack inside instead of a crush collar. This way, no matter how tight you cranked on the pinion nut, you would not ruin the bearings.
With the cheap crush-collar setup, new or used - it is easy to ruin the pinion bearings because there is nothing to stop adding too much bearing-crush.
I've seen many get ruined over the 50 years I've worked as mechanic, and that happens with any collar - new or used. A pinion with used bearings should be tightened so the rolling torque is 8 to 12 inch pounds with used bearings. 24 to 32 inch pounds with new bearings.
If just pulling the pinion flange to replace a seal, and not renewing the flange, it even gets easier. You mark the nut against the flange before loosening. Then when reinstalling you make sure you tighten up exactly as it was before with the marks lined up. Then tighten just a bit further and check pinion rolling torque.
