[nomiS330d]

Sad times, my diff is humming! I have changed the prop centre bearing hoping it was that but it's not although listening to it whilst spinning it by hand it was definitely slightly noisy so i'm glad i've done it now anyway. Whilst the car was up in the air i got my lad to get the car up to 30 mph which is when it's noisiest and i crawled under to listen, it's definitely coming from the front bearing of the diff. I've watched a good video on youtube how to replace the bearings and think i'm up to it although not sure because of things like measuring the backlash etc. Has anybody else done one and can inspire some confidence in me or should i just get a pro to do it? If so, does anybody have a rough price for this service? I'll remove it and drop it off to keep labour costs down.
Before i do all this though i'm going to ring Birds BMW who fitted the quaife 3 years ago just in case the bearings are part of the quaife lifetime warranty but i can guess what their answer will be!

[Phil325i]

I feel your pain. I'm on my fourth diff (yes you read that right). The reason BMW diffs are no better than chocolate teapots these days is that they stopped using roller bearings and substituted ball bearings.

Birds can replace the ball bearings with tapered roller bearings for a price. If I ever go for a Quaife, I intend to get Birds to fit it and change the bearings at the same time. They don't do this as standard as part of fitting the Quaife, you have to specifically ask for it.

[nomiS330d]

I wish I’d know that 3 years ago! I rang them this morning. They want about a grand to do just the pinion bearings! I’ve found a kit online which is £330 for the pinion or £400 for the 2 drive shafts as well. I didn’t think they would be that expensive. Decision time for the future of my ownership of the car........

[Andystobbs]

I did the full set on our 116i. Wasn't particularly difficult but the crush sleeve for pinion preload was a major suck it and see arrangement. Seemed to go OK but blink and you miss it as far as the sweetspot goes when tightening the pinion nut.

Also it was full of metal in the oil from the diff gears themselves which were badly chipped and worn generally. I cleaned it and threw it back together but it never sat well with me. Still going silently now 15 months (and not as many annual miles due to covid) later.

[nomiS330d]

Had a quote from a company to do all the bearings (he said they won’t just do the pinion bearings without the other 2). £500 if I drop the diff off or £575 if I drop the car off. Given the cost of the bearings that doesn’t seem too bad so I think I’m going to go with that. Could have done without this expense at this time of year but I don’t want to leave it too long so they fail and take the quaife out.

[mjn77]

Finding someone to repair a diff is a nightmare. The input seal on my 335d went bad and started to weep.

Could i find somewhere to do it? Nope. Most places didn’t get back to me with a price, some said no point, you need to refurbish everything, others said, we can do it, but wouldn’t take my booking.

[mjn77]

And don’t forget you’ll need two special tools to do the job. A super slimline 50cm spanner to remove the prop from the diff and then a fancy spanner to remove the flange on the diff.

[nomiS330d]

Originally Posted by mjn77

And don’t forget you’ll need two special tools to do the job. A super slimline 50cm spanner to remove the prop from the diff and then a fancy spanner to remove the flange on the diff.

Not on mine. It’s 6 bolt guibos both ends. I had the prop out last week, it’s easy on the guibo equipped cars.

[mjn77]

Git.

[nomiS330d]

I’ve found a place local to me that’s going to do my bearings next week. The guy had a drive and said it’s definitely the diff pinion bearings that have gone bad. Luckily it turns out he’s a big bmw fan, had several E21’s, and knows the diff well.....nice bloke too!
I’m going to take it out tomorrow and drop it off at his house to keep the cost down but it’s still going to be £400! An expense I could do without just after Christmas but there you go.

[nomiS330d]

I took my diff out last weekend and dropped it off so I’ve been without a car all week, a right pita. I’ve got tomorrow off giving me a long weekend and the diff is ready for collection, they’ve even painted it for me! While it’s up in the air I’m going to do the CDV delete as I want to bleed out the old clutch fluid anyway. I’ve also ordered some gearbox oil along with the diff oil.
So, a day of car tinkering for me at some point but the weathers against me, had quite a bit of snow today. It’s not going to stop me because I’m desperate to get my car back.

[mjn77]

Who did you use? I'm pretty certain the diff in the M3 is going to need some attention soon.

[nomiS330d]

Gearbox UK a few miles away from me in Armthorpe.
I’ve changed the gearbox oil today which was worryingly filthy! I’ve put it in a water bottle and it’s black! Whilst under there I’ve done the cdv delete and refreshed the clutch fluid.
The diff is back in with all the mounting bolts and drive shafts loosely bolted up. My helper was at work today so I did it alone, bit sketchy trying to Jack it up and steady it at the same time but went well.
At this point I got very cold so gave up for the day. Should be back together in an hour or 2 tomorrow.

[nomiS330d]

I’m now a happy boy again! Got it all back together and it’s lovely, smooth and silent again! Nice feeling to have new fluids in the gearbox and diff and the CDV delete feels good. Not a night and day difference but definitely feels like the clutch engages more crisply and the peddle feel is smoother.