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Differential ID

Guest Anonymous

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Guest Anonymous


I have a BMW differential that I think is from a 2002, but would like to know more about it. It has cast on the top:

HH2 80 1207 719 000-40

(the 000 could be GGG or QQQ)

On the end cover: 3311-1204-898 2.2 225

I see no separate ring and pinion numbers (where should they be), but it does have (etched by hand) on the end of the pinion: -72.

I need (for a trike project) something between a 3.20 and a 3.64 ratio. What do I have, what's it from, can a different ring and pinion set be put in it (assuming it has a 3.90 or 4.11 now)?


M D Nugent

Renton, WA

URL for a picture of it is:


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Guest Anonymous

1. When i turn the input (driveshaft) flange counterclockwise, both output (axle) flanges turn together in the forward direction, and when I turn the input flange clockwise, both output flanges turn together in the reverse direction. [isn't that backwards from US and British differentials? I think to get their output flanges to turn forward, you turn the input flange clockwise.]

2. When I turn one output flange, though, the other output flange turns in the opposite direction, and I can feel a noticeable notchiness as the output flanges are turned without also turning the input flange (a problem, or normal?).

Is that LSD or not? I seem to remember that when I turned a rear wheel on my Quaife-equipped 914, the other rear wheel turned the same direction (unlike a stock 914 where they'd turn in opposite directions).


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Guest Anonymous

the picture you show has the diff upside down, and that's the only way you'd get the results you describe.

That's assuming your description of (counter) closckwise was from viewing it from the front

the casting marks "GGG" are an indication of the grade of cast iron, GGG = nodular / ductile

The gear ratios are stamped in the side of the case, may be hard to read if rusty.

Here's what the ratio marks look like for 3.90:1 (10 pinion & 39 ring gear teeth)


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Guest Anonymous

Thanks for the response - the picture helped, too.

I finally found the stamped numbers on the one I have - they're 11 and 43 (3.90909...) and I've also been told that the diff is from a 320i rather than a 2002.

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