[JimG30]

Hi guys, Im a newbie on here and looking for advice please from you knowledgeable lot.
I have a G30 520d which has diff issues in that the bearing is goosed (BMW changed the pinion seal last dec but not the bearing).
So i need to change the diff, I bought one from a breakers online and gave reg number etc and they sent me my replacement - hallelujah!! However the metal triangle connector (that connects to donut) was smaller than mine - so I contacted them and they sent a replacement only to be sent the same again!! They didnt have the prop shaft to go with it so I sourced a prop shaft from another breakers, gave them the reg and they sent the exact same size of mine which is on my car, which doesnt fit new diff.
I cannot find any info anywhere as to why there are 2 different sizes on these diffs and to clarify the part number is exactly the same and is the ratio (8624221-05/EA0406:2,93)

Anyone had same issue or can shed some light?

the guibbo/donut do come in 2 different hole sizes but just cannot get the right diff?

[Chappers 71]

If the replacement diff is the same can you not just swap over the doughnut connector?

[JimG30]

cheers for reply - the issue is that the prop is also bigger on the end so the donut will only fit big on big or the other donut size is small on small if that makes sense.

So to confirm my 1st message, the new diff sent to me has a smaller output metal connector so the holes do not fit from the old donut, buying a smaller donut wont work as the prop is the same size as the old diff

[Chappers 71]

I may be sounding a bit thick but I meant can you not swap over the metal triangle that connects to the doughnut?

[JimG30]

I've looked into that too as that was my thinking but looks like it's secured with a triangle shaped nut inside...can't seem to find online a tool for it to take apart, but yeah you're right, that would make it so much easier

[DrVenture]

If I am reading this correctly, BMW would have had to remove the flange (and triangle nut) to replace the pinion seal. Then reattach the flange after replacing the leaking seal - and torque it to spec.

Quite a coincidence that the bearing is now shot! Or is it? My guess is they used an impact to remove and jam the nut back on, resulting in bearing failure.

Careful that you do not do the same when swapping the flange to the correct size. My thought is that the flange varies depending on the model and you definitely need to swap the flange.

Pic of the flange retaining nut might help.

[JimG30]

Yeah I know, I contacted them and they said if the bearing was too tight then I wouldn't have got 100 miles. They did it in Dec last yr so saying not their problem.....
Hopefully my Turkish mechanic will sort it. 🙏

[DrVenture]

Originally Posted by JimG30

Yeah I know, I contacted them and they said if the bearing was too tight then I wouldn't have got 100 miles. They did it in Dec last yr so saying not their problem.....
Hopefully my Turkish mechanic will sort it. 🙏

What I figured they would say. Problem is they would not have even removed the nut for the pinion, in order to replace the seal. So bearing preload is not the issue. Rather the abuse the bearing may have taken in the removal and replacement of the flange retaining nut.

In theory, a tool would be used to hold the flange without putting undue stress on the bearing and ring set. In practice, they would have went at it with an impact and let the gears and bearing take all the abuse.

As you said, water under the bridge.