Differential replacement

N

NiallR

Member
Hoping someone can help with some work required on my 56 plate Z4 - it's a 2.5i manual 6spd model on 106k miles.

I've had it in at my local BMW specialist to have both rear wheel bearings replaced to solve a horrible whirring/squealing noise... I've had a call today to say that, unfortunately, these wheel bearings do still need replacing, but that the diff is also knackered. Apparently there's no drain on these diffs so they didn’t get a sample of the oil but the mechanic could physically feel/hear the bearing.
They've quoted - what is to me - a huge amount of £ for a new OEM BMW diff and said that they wouldn't be comfortable using non-OEM / second hand for the work... From some research it looks like I have two alternative options:

A) full rebuild bearing kits are available for sub £200 online. Finding a garage that’ll be happy to take the old diff apart and fit new bearings etc is the harder part... I don’t have the knowledge/skills/guts/tools to try and attempts this.

B) general notion seems to be that I should seek out a used replacement diff and find somewhere that will swap it for me. Questions are:
- what diff do I need? They all seem to be very specific and I can’t find exactly what model I need for my engine/gearbox setup...
- where do I get one of these diffs? Found a few eBay breakers but not much else
- how much is this likely to cost to swap over?

Praying that this isn’t something that makes the car financially impossible to keep hold of. I only bought it a month ago so very keen to get it fixed but without spending the same amount on it that I paid for it!

Thanks in advance
 
Just remove the diff and get it to JC Racing in Thirsk

John will sort it out for a reasonable price and then refit it in the car.
 
NiallR said:
Apparently there's no drain on these diffs so they didn’t get a sample of the oil
Click to expand...
While I don't know if ALL the E85/6 diffs had drain plugs (mine certainly does) they could pop a tube in the fill plug and suck some out, if they can't be bothered to do that I'd be going somewhere else.

You just need to match the specific diff code, they're pretty bulletproof so I wouldn't baulk at a second hand one. I have a spare that I picked up from someone breaking for £60 so I can return to stock if I ever sell.
 
NiallR said:
A) full rebuild bearing kits are available for sub £200 online. Finding a garage that’ll be happy to take the old diff apart and fit new bearings etc is the harder part... I don’t have the knowledge/skills/guts/tools to try and attempts this.
Click to expand...
Wise, a rebuild isn't really for the average DIYer.
 
Quick update in case anyone else finds themselves in a similar boat...

Bought a replacement diff, it’s the 3,38 ratio that you need for the 2.5i 2006+ model - worth triple checking for your car as they all seem to vary. It’s from a breakers who have checked it over and provide a 90day warranty so fingers crossed should be golden.

It’s booked in with RBM to have the old diff removed and replacement installed before being topped up with oil. Crisis averted!
 
If you need to find the BMW part number, what other BMWs use the same part, and the diff ratio, bung the last 7 digits of your vin into realoem.com - it's a bloody helpful tool for all sorts of bits, but most importantly will help you track down the right 2nd hand part if you're surfing breakers / ebay :)

For what it's worth I'm pretty certain they all have drain holes, just that some (billed as 'sealed for life' - yeah thanks BMW) are difficult to access without removing the diff. Sounds like your garage may be being a bit lazy....
 
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