Reardrive Contact impression check.

[activpop]

I would think this isn’t done too often. Should I consider this at 16k and are there even  any shims available?

[gstallons]

Uhhh. Please explain . I've lost my psychic abilities again.

[activpop]

You havent been studying your service manual...lol. Section O, page 6. Diagram bottom left shows different shapes of wear on pinion gear so miniscule idk if I could tell the difference in real life...certainly not a measurable difference.

[docc]

1 hour ago, activpop said:

You havent been studying your service manual...lol. Section O, page 6. Diagram bottom left shows different shapes of wear on pinion gear so miniscule idk if I could tell the difference in real life...certainly not a measurable difference.

Ah, okay, the reardrive. I amended the topic title.

[gstallons]

Thank you .

[Pressureangle]

ok, now that I understand what is at hand,

No, don't touch it. Hypoid gears are carefully set when new and wear in together. If you change anything at all, they will have to wear in again- at best- and you run the risk of point loading them and overheating or seriously wearing them. When re-assembling a hypoid gear set that's worn in, you don't even check the pattern on the drive face; you check the pattern on the coasting face because it's more accurate as it's smaller and doesn't have 'flex' built into it from heavy loading.

[activpop]

Thats what I figured.  It seemed like an odd maintainenance requirement and adjustment with no measurements, but thought I would ask while the wheel is off. All I wanted to do is lube up all areas accessible, including universals and do a clean up.

[Pressureangle]

I can't think of any reason this check is part of 'routine' maintenance except as a *non-disassembled* check for loosening bearings. On something larger and quieter, one would only ever check wear pattern if the gears became noisy. 

[MartyNZ]

When I needed a replacement rear drive, I got one from Italy. It was in good order, except for freeplay that I thought was too high, been that way from new. The workshop manual did not help me, it is sparse and seems to apply to earlier models. I made pinion and crown wheel shims, then made tools (a bit crude) to allow measurements. After 14 tries, I eventually got both preload and freeplay low enough to be happy with. A slow and tedious process. Contact impression interpretation is a black art, with vague contact marks that need a strong light and a good imagination. You will never get it perfect on a worn C&W set.

The bevel box is now quiet and runs cool.

However, if your box is ok, then the only maintenance needed is oil change and spline grease.