Z4MC differential rebuild

N

Nooms1

Member
 Bedfordshire
Hi All

Unfortunately, I've a noise from the rear of my Z4MC which has gradually got loader. I've had it diagnosed as the differential. The car has only covered 23.5k miles which is a bummer! My guess is the garage that did the last inspection 2 service at 16K miles and diff oil seal replacement (for the previous owner) over tighted the nut.

Any thoughts/experiences would be appreciated on rebuild (a tad specialist to say the least) and third party rebuild (not so keen on exchange as I would like to keep mine)?

I'm looking to remove the diff myself at the moment. Any good guides/videos available. I don't believe it's an over complicated processjust a bit fiddly and heavy snd ill be doing it in a single garage ehich is far from ideal.

Thanks in advance

Steve (Nooms1)
 
It’s not too bad to remove but is is heavy especially when lying on your back. Some one like Everything M3s or a diff specialist will be required for the surgery.
 
Just give them the car and ask them to sort it out. You might save a few ££ by DIY removal but if you leave it all to the garage then if there are any issues in the future its 100% down to them, they cant blame faulty fitting!
 
3littlepigs said:
It’s not too bad to remove but is is heavy especially when lying on your back. Some one like Everything M3s or a diff specialist will be required for the surgery.
Click to expand...

Thanks for your reply. After loads of research, I booked in at everything m3s but cold feet when it was being done on an exchange basis and I want my original diff refurbished because of the low miles (23.5k). Eventually they agreed to do this but they needed the car for circa 3 days. I understand why now as they don't necessarily do everything, such as bead blasting, in house. The problem I had with this option is they fit a new modified E46 rear diff cover as the z4m cover is not available anymore from bmw. The mounting bushes were never available separately from bmw either. I still want to retain my original cover and pointed out other bushes are available including poly bushes (poss not ideal for a road car and not recommended by E3Ms). They've their way of doing the job and I respect that but I want to maintain originality. I'd still love them to do the job, based on my initial dealings with them and what others have said.
 
Rockhopper said:
Just give them the car and ask them to sort it out. You might save a few ££ by DIY removal but if you leave it all to the garage then if there are any issues in the future its 100% down to them, they cant blame faulty fitting!
Click to expand...

Thanks Rockhopper, I totally understand and agree that its the a better solution than DIY.
 
thecremeegg said:
Sure it hasn't just had the wrong diff oil put in?
Click to expand...

Thanks for your reply. I thought that myself and/or they never put enough oil in. I've been tempted to drain out what's there and refill with the correct oil/amount. However, its gone from a hum to more of a howl now so I fear the damage is done. Early garage indications were tyre noise (cupped/feathered tyres) to possible wheel bearing(s) which have since been dispelled.
 
Nooms1 said:
3littlepigs said:
It’s not too bad to remove but is is heavy especially when lying on your back. Some one like Everything M3s or a diff specialist will be required for the surgery.
Click to expand...

Thanks for your reply. After loads of research, I booked in at everything m3s but cold feet when it was being done on an exchange basis and I want my original diff refurbished because of the low miles (23.5k). Eventually they agreed to do this but they needed the car for circa 3 days. I understand why now as they don't necessarily do everything, such as bead blasting, in house. The problem I had with this option is they fit a new modified E46 rear diff cover as the z4m cover is not available anymore from bmw. The mounting bushes were never available separately from bmw either. I still want to retain my original cover and pointed out other bushes are available including poly bushes (poss not ideal for a road car and not recommended by E3Ms). They've their way of doing the job and I respect that but I want to maintain originality. I'd still love them to do the job, based on my initial dealings with them and what others have said.
Click to expand...

I kind of get what you're saying regards originality, but it all seems a bit confused? I guess if your planning to sell then I can somewhat see the point rather than it being a keeper.
If your going to fit poly bushes (I wouldn't either from what I've read and I track my car) then isn't the originality getting eroded anyway?

If you are absolutely sure it's the diff, then Dave Heasman (search Heasman Diffs) will sort your diff out to whatever you wish. You'll have to get it off the car and deliver to him though. He'll recommend the same as EM3's I imagine, but he'll fix yours to your spec if you wish. I'd get a 4.1 in there while it's open! :wink:
 
Hi Andy,

Thanks for your input.

The car is a keeper but Id dyill lkke to keep it as original as poss. The poly bushes and possibly other potential replacements, as the std BMW are not available, was discussed with E3Ms in a bid to retain my original diff. They will not entertain refurbing mine and its the e46 M3 modified cover or nothing.

I have already spoken with Dave Heasman and he can refurb it all incl the cover. I think he fits new E34 or similar bushes. Apparently it's 2 hours work just to bead blast the cover, so I get EM3s stance.

I've read about and seen videos on the 4.1 which appears to transform the car. Its an extra £1k on the rebuild but if I was regularly tracking my car then it would be a no brainer.

I think I need to get a second opinion on the diff tbh.
 
Nooms1 said:
Hi All

Unfortunately, I've a noise from the rear of my Z4MC which has gradually got loader. I've had it diagnosed as the differential. The car has only covered 23.5k miles which is a bummer! My guess is the garage that did the last inspection 2 service at 16K miles and diff oil seal replacement (for the previous owner) over tighted the nut.

Any thoughts/experiences would be appreciated on rebuild (a tad specialist to say the least) and third party rebuild (not so keen on exchange as I would like to keep mine)?

Steve (Nooms1)
Click to expand...

Hey Steve.. which nut do you recon they over tightened?

I’d be very surprised that any indi/bmw joint could get that diff apart as it’s not the same as the M3 diff.. even more surprised if they could get it back together properly.

Might wanna read up on the special unit that is the z4 m diff..

I’d take this opportunity to install a proper lsd. :thumbsup:

Edit: also not sure why you need a new diff cover? Unless you smashed it with a hammer? Your indi doesn’t wanna fit new bushes to the ears? Find a new indi..that’s ridiculous.
 
thecremeegg said:
Sure it hasn't just had the wrong diff oil put in?
Click to expand...

Thanks thecremeegg, I also wondered that and thought it might be worth the £90 for the oil just to see if there is any difference. Although, the service invoice when the diff front oil seal was replaced lists the correct BMW oil with additive.
 
Vanne said:
Nooms1 said:
Hi All

Unfortunately, I've a noise from the rear of my Z4MC which has gradually got loader. I've had it diagnosed as the differential. The car has only covered 23.5k miles which is a bummer! My guess is the garage that did the last inspection 2 service at 16K miles and diff oil seal replacement (for the previous owner) over tighted the nut.

Any thoughts/experiences would be appreciated on rebuild (a tad specialist to say the least) and third party rebuild (not so keen on exchange as I would like to keep mine)?

Steve (Nooms1)
Click to expand...

Hey Steve.. which nut do you recon they over tightened?

I’d be very surprised that any indi/bmw joint could get that diff apart as it’s not the same as the M3 diff.. even more surprised if they could get it back together properly.

Might wanna read up on the special unit that is the z4 m diff..

I’d take this opportunity to install a proper lsd. :thumbsup:

Edit: also not sure why you need a new diff cover? Unless you smashed it with a hammer? Your indi doesn’t wanna fit new bushes to the ears? Find a new indi..that’s ridiculous.
Click to expand...

Thanks Vanne,

Its the front oil seal (prop shaft entry point).

Ive looked at the diff make-up and differences between the two models but I believe the last of the E46 M3 diff and or E90 series M3 was upgraded to cope with greater load/power, so Im not sure if that is what's being offered on an exchange front.

I hear you on what is deemed a proper LSD which I believe the likes of racing Diffs offer but I get its getting even more pricey.

No damage to casings/covers but some reluctance from indy on cover refurb and replacing the mounting bushes to the ears (so to speak!)
 
Nooms1 said:
Hi Andy,

Thanks for your input.

The car is a keeper but Id dyill lkke to keep it as original as poss. The poly bushes and possibly other potential replacements, as the std BMW are not available, was discussed with E3Ms in a bid to retain my original diff. They will not entertain refurbing mine and its the e46 M3 modified cover or nothing.

I have already spoken with Dave Heasman and he can refurb it all incl the cover. I think he fits new E34 or similar bushes. Apparently it's 2 hours work just to bead blast the cover, so I get EM3s stance.

I've read about and seen videos on the 4.1 which appears to transform the car. Its an extra £1k on the rebuild but if I was regularly tracking my car then it would be a no brainer.

I think I need to get a second opinion on the diff tbh.
Click to expand...

Since you are in Bedfordshire, you could come see my car and see if the 4.1 is worth the extra cost for you. To me, it made the car much more enjoyable (engaging) for fast road driving. I did most of the refurbishment myself and Dave Heasman did the backlash for me. The cover was fairly straight forward to refurbish.
 
lucasxdiniz said:
Nooms1 said:
Hi Andy,

Thanks for your input.

The car is a keeper but Id dyill lkke to keep it as original as poss. The poly bushes and possibly other potential replacements, as the std BMW are not available, was discussed with E3Ms in a bid to retain my original diff. They will not entertain refurbing mine and its the e46 M3 modified cover or nothing.

I have already spoken with Dave Heasman and he can refurb it all incl the cover. I think he fits new E34 or similar bushes. Apparently it's 2 hours work just to bead blast the cover, so I get EM3s stance.

I've read about and seen videos on the 4.1 which appears to transform the car. Its an extra £1k on the rebuild but if I was regularly tracking my car then it would be a no brainer.

I think I need to get a second opinion on the diff tbh.
Click to expand...

Hi Andy,

That's very good of you and thanks, I would love to take you up on your offer.

Since you are in Bedfordshire, you could come see my car and see if the 4.1 is worth the extra cost for you. To me, it made the car much more enjoyable (engaging) for fast road driving. I did most of the refurbishment myself and Dave Heasman did the backlash for me. The cover was fairly straight forward to refurbish.
Click to expand...
 
Hi All,

Some of the responses I received advised not to ignore tyre noise as others believed they had wheel bearing or diff issues but it turned to be uneven tyre wear/cupping.

I have now been to local tyre fitters/garage. Although my tyres are not that old, all 4 tyres have severe cupping and the nearside rear wheel is a little buckled. The fitter although ran the car in 2nd gear whilst listening for differential noise. He used a long probe on various parts of the diff but could hear no adverse noises to suggest that the diff was faulty. I really don't know what to believe now.

If I had a spare set of wheels and tyres, at least the rears, to put on then I guess that would confirm matters. If anyone close to Bedford has a spare set and wouldn't mind me putting them on my car for a short run up the road it would be much appreciated.

Looks like I'm going to have to replace the tyres anyway but its complicated by the fact I have to get the buckled wheel sorted as well. I also have a diff rebuild booked in the next two weeks. I dont want to lose the slot if it is actually the diff.

Any help would be appreciated!

Cheers

Steve (Nooms1)
 
Steve I have a full set of wheels and tyres for you to try. All tyres good as far as I am aware. Certainly no noise. My intention was to put the backs on my 240i but you can have the fronts. Trouble is I am in Spain at the moment and not back until 20 June. But if you can wait you can come to mine and you can swap. It’s a way though.
 
Nooms1 said:
I have now been to local tyre fitters/garage. Although my tyres are not that old, all 4 tyres have severe cupping and the nearside rear wheel is a little buckled. The fitter although ran the car in 2nd gear whilst listening for differential noise. He used a long probe on various parts of the diff but could hear no adverse noises to suggest that the diff was faulty. I really don't know what to believe now.
Click to expand...

I feel like I'm missing something....if your tyres are ruined then surely change the tyres as you'll need to anyway? How buckled is buckled? If it's slightly out of round it's not the end of the world, can balance them to account for it but really depends, your tyre fitter can advise.
What I would be asking is, how did the tyres get 'cupped' or damaged in the first place? :?

For context although not quite the same, I did a track day at Silverstone some time ago where at points I was picking up a ton of marbles on the tyres going off line on cool down laps. Next time out the car genuinely sounded broken, like the worst noise and vibration much like a totally ruined wheel bearing or worse until I'd deposited said pick up from the tyres. My point being don't underestimate the noise tyres which aren't running completely normal can make, I would agree with others that this sounds like a tyre / wheel issue as opposed to a 26k diff dying already.
 
CliveN said:
Steve I have a full set of wheels and tyres for you to try. All tyres good as far as I am aware. Certainly no noise. My intention was to put the backs on my 240i but you can have the fronts. Trouble is I am in Spain at the moment and not back until 20 June. But if you can wait you can come to mine and you can swap. It’s a way though.
Click to expand...

Thanks Clive, very good of you. I need to get sorted asap. Will catch up with you on your return in June. :D
 
AndyBeech said:
Nooms1 said:
I have now been to local tyre fitters/garage. Although my tyres are not that old, all 4 tyres have severe cupping and the nearside rear wheel is a little buckled. The fitter although ran the car in 2nd gear whilst listening for differential noise. He used a long probe on various parts of the diff but could hear no adverse noises to suggest that the diff was faulty. I really don't know what to believe now.
Click to expand...

I feel like I'm missing something....if your tyres are ruined then surely change the tyres as you'll need to anyway? How buckled is buckled? If it's slightly out of round it's not the end of the world, can balance them to account for it but really depends, your tyre fitter can advise.
What I would be asking is, how did the tyres get 'cupped' or damaged in the first place? :?

For context although not quite the same, I did a track day at Silverstone some time ago where at points I was picking up a ton of marbles on the tyres going off line on cool down laps. Next time out the car genuinely sounded broken, like the worst noise and vibration much like a totally ruined wheel bearing or worse until I'd deposited said pick up from the tyres. My point being don't underestimate the noise tyres which aren't running completely normal can make, I would agree with others that this sounds like a tyre / wheel issue as opposed to a 26k diff dying already.
Click to expand...

Hi Andy, I hear you on the tyre change but its just priorities on a finance front at the moment. Lucas Diniz, another forum member has very kindly offered to put his rears on mine to see if reduces/solves the noise. He also will let me experience his 4,1 set up which I am looking forward to.

The buckle is on the NSR inner edge which looks to be about a 5mm max runout. BMW mentioned the runout when they fitted the tyres but apparently managed to balance it out.

As you say, I need to establish the cause of the cupping. Car freshly MOT'd by BMW main dealer and nothing was highlighted.
 
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