[Tantibus]

Hi guys!

I have a question in relation to the differential ratios on the f32 models.

I’ve blown my rear differential and was wanting to source another one, but the ratios are different.

There’s a 3.15 and a 2.81 ratio. I was wondering if there’s a way to find which one can be used without looking at the diff under the car and what each of them are for?

It’s a 2015 420i, auto gearbox and n20 engine.

If someone can help, it would be a huge help!

[rjd_F30]

How did you blow your differential?

I would go to realoem.com and look up the part number for your differential and then go from there.

[Tantibus]

Thanks for the reply!

I’m honestly not too sure, it’s likely because I’m putting down too much power, but I was sure that the bottom end would be able to handle the power gains.

I did check out realoem.com, wasn’t lucky enough to find the part I needed.

Thanks so much for your help though!

[Okhan19]

Hi that model came with a 3.15 differential if it is an automatic you can check. https://www.automobile-catalog.com/auta_details1.php

[rjd_F30]

Originally Posted by Tantibus

Thanks for the reply!

I’m honestly not too sure, it’s likely because I’m putting down too much power, but I was sure that the bottom end would be able to handle the power gains.

I did check out realoem.com, wasn’t lucky enough to find the part I needed.

Thanks so much for your help though!

Hmmm, I think this should be the page for your car. https://www.realoem.com/bmw/enUS/sho...diagId=33_2122

This is the differential for an October 2014 build, right hand drive, rear wheel drive 420i with an automatic transmission. If that info is correct (less the build date, I just guessed yours) then it looks like you should have a 3.15 final drive ratio. Hope that helps! If any of that info is wrong, post the exact details of your car and I can take another look.

[johnung]

Originally Posted by Tantibus

Hi guys!

I have a question in relation to the differential ratios on the f32 models.

I’ve blown my rear differential and was wanting to source another one, but the ratios are different.

There’s a 3.15 and a 2.81 ratio. I was wondering if there’s a way to find which one can be used without looking at the diff under the car and what each of them are for?

It’s a 2015 420i, auto gearbox and n20 engine.

If someone can help, it would be a huge help!

Getbmwparts is a good source for correct part numbers too