BMW 330D Rear Diff

[Jalo1548]

Hi all,

I was wondering if you could shed some light regarding an issue I have come across for replacing my rear diff on my 56 plate 330D.

The rear diff is caked in oil, the subtle whine has gradually turned into a grinding howl upon acceleration or deceleration although she's quiet at a steady speed (such as cruise control activation). Anyway, I plan to have the entire rear diff changed rather than repaired as this seems more than likely less labour intensive, but I am struggling to find the correct part. Most threads for this question seem to just point the user to wheel bearings or something other than the rear diff, but at 174k and with clearly seeing the diff is knackered I know this isn't the case.

What I am asking is, is the 2.79 ratio correct for my car? This seems to appear on one or two eBay listings, with the parts costing around the £170-225 area. Would you say this is fair pricing? I'm going to guess around 3-5 hours labour for the straight swap. Are the parts between the years or the engine displacements not interchangeable at all?

Many thanks in advance,

Joshua

[Krikkit]

You need to know the part number for the diff really, or work the FD out from tyre size, gear ratios and RPM/speed.

http://www.realoem.com/bmw/enUS/partgrp?id=VC92-EU...

[HustleRussell]

You are likely going to need to source a diff from a car of the same model and generation of yours with the same engine and gearbox.

ETA: My BMW was made in the 90s and back then each diff was fitted with a tag which identifies it's ratio, not sure if this is still the case but if so you'd be able to be certain about the spec of your current diff and the replacement by the numbers stamped on the tag.

Edited by HustleRussell on Wednesday 6th March 11:17

[rallycross]

Note For 330d the manual and auto use a different diff. Other engine sizes also using different diff.

325d 3.0 might be the same diff as yours as per above use real oem to check before buying used -

Drives shafts may be rusted badly and may need 2nd hand ones when you split your current rear axle.

Horrible job if rusty and big mileage like yours allow more time and chose a garage who are happy doing nasty jobs like this. When I did one had all sorts of aggro with using 2nd hand bits and then not fitting.

Something like this and get as much of it as you can drive shafts hubs etc less splitting is better, or get them to fit it!

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2...

Edited by rallycross on Wednesday 6th March 12:08

Edited by rallycross on Wednesday 6th March 12:10

[Jalo1548]

Hi all,

Thanks for the quick and very useful responses! It's a manual so I will have to look for that, added another spanner in the works. Any short term solutions for now until I can source the right part? I guess other than keep on adding oil I don't really have anything but it's like one step forward and two steps back!

Thanks again,

Josh

[rallycross]

You could put thicker oil in it something from Royal Purple with the thickest viscosity might help keep it going longer but the damage has already been done.

https://www.amazon.com/Royal-Purple-ROY01300-75W90...

Check if a 330i/325i diff is the same - either way manual 330d and manual 330i are both quite rare so you will need to ring round all the Bmw specialist breakers to find one.

.

[Slow]

Is there some sort of additive you can use which would help keep it alive a little longer/hide the noise? Just untill you get the part.

I know they made/make stuff meant to hide the noise from your bottom end bearings dying.

[normalbloke]

Nobody yet mentioned banana skins or ladies tights? Showing my age.....

[Equus]

normalbloke said:

Nobody yet mentioned banana skins or ladies tights? Showing my age.....

I was thinking sawdust!

[roverspeed]

normalbloke said:

Nobody yet mentioned banana skins or ladies tights? Showing my age.....

Why not men's tights?

[HustleRussell]

To be honest you'll spend £10+ on an additive and then spend a frustrating hour or two trying to get it into the diff so if the OP is definitely planning to replace the diff there's no point bodging it.

Assuming it's crownwheel and pinion wear, the diff probably isn't going to catastrophically fail and leave him stranded any time soon.

[Pupbelly]

Equus said:

I was thinking sawdust!

Beat me to it !

[Slow]

HustleRussell said:

To be honest you'll spend £10+ on an additive and then spend a frustrating hour or two trying to get it into the diff so if the OP is definitely planning to replace the diff there's no point bodging it.

Assuming it's crownwheel and pinion wear, the diff probably isn't going to catastrophically fail and leave him stranded any time soon.

Said he keeps adding oil anyway so I assume its fairly loose to get into the diff now. Like a 5 minute job if so.

[Mike-tf3n0]

HustleRussell said:

You are likely going to need to source a diff from a car of the same model and generation of yours with the same engine and gearbox.

ETA: My BMW was made in the 90s and back then each diff was fitted with a tag which identifies it's ratio, not sure if this is still the case but if so you'd be able to be certain about the spec of your current diff and the replacement by the numbers stamped on the tag.

Edited by HustleRussell on Wednesday 6th March 11:17

You should find an adhesive label on the top face of the diff but not visible whilst the diff is still installed. This will give you all the details you need for replacement including the ratio installed. I had to have a new diff in my 530d last year after the clowns at my local BMW specialist here in France wrecked the utterly silent original whilst attempting to replace the pinion oil seal. I suspect your diff is the same unit with a different ratio. The cost was around €3k.

[Jalo1548]

Hi all again,

So I've topped it up for the weekend and hoping to keep the grinding to the bare minimum. Basically I cannot justify the 500 quid or so for the part the 2.35 manual ratio is demanding when the auto diff 2.79 is pennies in comparison, especially as I don't really travel all that far to work and hardly break 40mph 😂

Does anybody know if any other diff ratio would fit, as in, are the casings the same for the auto just with altered ratios or are there rubber bungs or extra fixings that would prevent a straight swap? Otherwise I'll be down to my local joiners for some sawdust 😂😂😭

Thanks,

Josh

[HustleRussell]

Your engine speed is going to be 19% higher for a given road speed. Not a smart solution IMO.

[helix402]

As above. I converted a 330d from auto to manual and briefly had the auto diff before I found a manual one.

It was not pleasant with the wrong diff, very short gearing. An auto diff on a manual is popular with drift kings/heroes.

[Jalo1548]

I know but for the short term that might be a more feasible solution until I can source a cheaper part. It's literally 165 for an auto, and 550 for a manual. I rarely make it out of fourth gear on my daily drive and I plan to keep the car until graduation (2 years away)

My mechanic is a friend who has a ramp and did the diff switch on his 120d, we are hoping it's a similar straight on and off job but like someone said before there's a chance a few bits have seen better days after 174k on the clock!

So for now do you know if the straight swap is possible minus the ratio differences or are the casings/fittings different also?

Thanks

[helix402]

I know the E46 manual and auto diffs are interchangeable, afraid I’ve not tried an E90 swop.

There’s a 2.35 on eBay for £393.

[naturalaspiration]

According to BMW fans info the 330d manual and auto have the same diff 1:2.35.

http://bmwfans.info/parts-catalog/E90/Europe/330d-...