What's the difference between the LSD?

[missapei]

Iam looking to get a LSD in for my 2010 135i
I saw those numbers 3.08? 3.46?
What are the differences?
If I want no spins at 0-100, what should I choose?

[135]

It's the diff ratio, which works in conjunction with the gearbox gear ratios and tyre heights to determine acceleration and maximum speed in each gear.

The 3.08 is for a manual, while the 3.46 is for the steptronic. Some manual car owners upgrade their diff ratio to a 3.46 to provide more acceleration. To achieve the equivalent in an auto, you'd have to go to a 3.9 diff ratio - I haven't heard of a BMW gearing in this ratio suitable for the 1-series.

Decreasing the tyre height (Overall Diameter, OD) also has the same effect as changing to a lower diff ratio, i.e. a higher number. Both will induce more wheel spin or, at least, the likelihood of it occurring.

There would have to be online calculators that can work this out for you. I wrote several programs to do various speed related computations many, many years ago, before "online" was a word

[missapei]

Originally Posted by 135

It's the diff ratio, which works in conjunction with the gearbox gear ratios and tyre heights to determine acceleration and maximum speed in each gear.

The 3.08 is for a manual, while the 3.46 is for the steptronic. Some manual car owners upgrade their diff ratio to a 3.46 to provide more acceleration. To achieve the equivalent in an auto, you'd have to go to a 3.9 diff ratio - I haven't heard of a BMW gearing in this ratio suitable for the 1-series.

Decreasing the tyre height (Overall Diameter, OD) also has the same effect as changing to a lower diff ratio, i.e. a higher number. Both will induce more wheel spin or, at least, the likelihood of it occurring.

There would have to be online calculators that can work this out for you. I wrote several programs to do various speed related computations many, many years ago, before "online" was a word

Thanks for the explain, mine is 135i is 2010 model with n55 engine dct, if I want to get a used one, what brand is out there ? Or should I just get a new one from workshop so I won't get the wrong part.

[135]

Originally Posted by missapei

Thanks for the explain, mine is 135i is 2010 model with n55 engine dct, if I want to get a used one, what brand is out there ? Or should I just get a new one from workshop so I won't get the wrong part.

If you have a DCT then the diff ratio is 2.56 - the diesel variant has a 2.81. Different ratios and diffs but same theory as above. I'm not certain if the diesel ratio is interchangeable.

You could try Quaife, Wavetrac or Dinan. I'm not sure what else is available for DCT. You may find it difficult to source a second-hand DCT LSD.

An M3 DCT rear end swap with 3.15 ratio may be possible

As your car is a DCT, it may be an expensive option, whichever option you choose.

Since you're in Victoria, you could call Southern BM to discuss.