Rear diff options

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Corasdad
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Fri Oct 17, 2025 7:04 pm

Whats the best rear diff for m52b28tu swap mine has a 1.8 auto diff in and it feel ok but is there a better option for normal spirted driving
Speedtouch
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Fri Oct 17, 2025 9:20 pm

There are a number of LSDs with differing gear ratios - try and work out what's best for your needs (based on whether or not you do a lot of motorway driving, etc.) from this list:

https://www.e30zone.net/e30wiki/index.p ... fferential

The lower the number, the higher the overall gearing will be. For most general purpose use, the Sport's 3.91:1 will be about right.
///M aurice
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viewtopic.php?f=6&t=279421
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flybynite
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Sat Oct 18, 2025 3:07 pm

Thing I would be most concerned about is what size is the existing diff. Small case diff wont last long behind an M52 Go for a medium case and as above something in the region of 3.25-3.95 depending on gear ratios.

There are some good web sites to calculate this, depending on what you need/want
Corasdad
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Sat Oct 18, 2025 5:57 pm

How doni know if my diff is small or medium, i cant afford an lsd at the moment but its on my list with rear disc conversion
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flybynite
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Sat Oct 18, 2025 6:28 pm

Corasdad wrote:
Sat Oct 18, 2025 5:57 pm
How doni know if my diff is small or medium, i cant afford an lsd at the moment but its on my list with rear disc conversion
Its all in the wiki
https://www.e30zone.net/e30wiki/index.p ... fferential

But if that is too much to read just count the bolts on the rear case 6bolts=small case, 8 bolts=medium case :thumb:
Corasdad
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Sun Oct 19, 2025 9:13 am

Thanks
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