Z4M Crank Rod Bearing Shells

[Mr Tidy]

Just updated my vote!

I spent some time trying to decide whether to get mine done and as I plan to keep it until I can't drive it I figured I might as well book it in with Ross @ RBM Hampshire for some new shells for peace of mind, rather than just put off a job that will need doing anyway at some point.

Although my car has done just under 78K miles it has had 7 previous keepers, so I thought there was a fair likelihood of one of them not being gentle enough while the engine got properly warm.

And because we all like a photo here are the original shells.

[mr wilks]

Just updated my vote!

I spent some time trying to decide whether to get mine done and as I plan to keep it until I can't drive it I figured I might as well book it in with Ross @ RBM Hampshire for some new shells for peace of mind, rather than just put off a job that will need doing anyway at some point.

Although my car has done just under 78K miles it has had 7 previous keepers, so I thought there was a fair likelihood of one of them not being gentle enough while the engine got properly warm.

And because we all like a photo here are the original shells.

what was the history like up to you getting it ?

[Mr Tidy]

Well it seems to have begun life with BMW UK as they did the running-in service and then it had another 6 keepers before I got it.

Not sure why but it was almost 2 and a half years until it got it's first service at 24K miles, although it was an Inspection 1.

Then 2 years later it got an oil service on 36K and 2 years after that another Inspection 1 on 48K.

18 months later another Oil Service on 60K, an Oil Service a year later on 65K and nearly 3 years later another Oil Service on 68K.

Then just under 2 years after that I had an Inspection 2.

So although it isn't perfect it's far from terrible. That's why I suspect it's been put under load before it was properly up to temperature.

Still now I've seen what came out I'm just glad I got them done!

[RichieP]

Hi Mr Tidy.... did you get the oil analysed before you had the bearing shells replaced ?

[Mr Tidy]

Hi Richie, I did get a sample taken when it had it's Inspection 2 but that was during lockdown so Ross couldn't find anyone who was taking samples for analysis!

And I'm pretty sure I read that a one-off oil analysis wasn't too conclusive, it was better to have a few done and compare results over time. So as it's a keeper I thought I might just as well get them done - luckily.

[BMWZ4MC]

Looking at the photograph, you made a very wise and timely decision Mr Tidy. It would have been a great pity if your car in particular had spun a shell after you spent so long lusting after and agonising over whether to buy an ///M.

[Ed Doe]

Still makes me laugh when people get hung up on the run in service for these cars. Sure it might have a bit of wear if not done properly but after however many owners and 50+k miles it's far more a lottery in terms of how the car has been driven from cold.

I know it's easy to say but if I were ever ato be buying an S54 car again I'd be factoring in new bearings as part of the cost after buying. Having seen my (3rd set) bearings after just 14k, it just isn't worth taking a risk assuming they're OK whe you don't know how the previous owners have driven the car. And when a new crank is £2.2k from bmw, before you get into a set of new rods if they've been ovalled from spinning a bearing, and anything else (like oil pump) that's knackered from picking up the bearing swarf, plus a rebuild from a reputable engine builder it's simply not worth the risk.

[just-right]

Just took an oil sample which I will send of to be tested. It will be interesting to see if the metal content has evolved in any way since the last one.

[DSGRNMCM]

So rang the garage today, the car will not be ready until next Tuesday (Good job I called...)

Anyway, they had replaced the bearings with OEM ones, and have kept them for me to look at. They said that they had been replaced at some stage, as the ones they removed were AP Racing ones. No where in the history does it mention this, so I cant put a date on it. This does lead me to think that maybe the car has not been so well looked after if it has had a bearing change already, and at 90k the second set had wear (not yet seen). But my peace of mind is sorted.

[Ed Doe]

Sure they were ap racing not ACL? I wasn't aware ap racing did bearings!

I wouldn't be worried if it's had them before, in fact I'd say it's an indication its been looked after if someone's spend over a grand on a preventative maintenance item!

[R60BBA]

I wouldn't be worried if it's had them before, in fact I'd say it's an indication its been looked after if someone's spend over a grand on a preventative maintenance item!

Precisely this ^

[DSGRNMCM]

Yeah big bills are a good sign of intent / care. But does two sets of bearings that are worn mean that the car has not been warmed up correctly and / or thrashed?

[RedUn]

Yeah big bills are a good sign of intent / care. But does two sets of bearings that are worn mean that the car has not been warmed up correctly and / or thrashed?

I wouldn't worry too much, it's an s54, you can guarantee every single one on the roads has been thrashed at some point, that's the point of it

[JoshsZ4M]

Yeah big bills are a good sign of intent / care. But does two sets of bearings that are worn mean that the car has not been warmed up correctly and / or thrashed?

I wouldn't worry too much, it's an s54, you can guarantee every single one on the roads has been thrashed at some point, that's the point of it

Great to be getting them done, but I would absolutely agree with this. My car’s 2k miles in to the new set of shells, I warm the car up carefully, and only do 2k miles a year, but those miles are enjoyable fast road miles... so I’ll probably have them done again if it ever gets to 100k miles under my ownership... worth every penny after another 15-20 years of use (hoping I still own it by then, I have every intention to). I mean, either it will be shells or I’ll be having an electric motor installed instead and the engine will become a centrepiece to our living room

[RedUn]

Yeah big bills are a good sign of intent / care. But does two sets of bearings that are worn mean that the car has not been warmed up correctly and / or thrashed?

I wouldn't worry too much, it's an s54, you can guarantee every single one on the roads has been thrashed at some point, that's the point of it

Great to be getting them done, but I would absolutely agree with this. My car’s 2k miles in to the new set of shells, I warm the car up carefully, and only do 2k miles a year, but those miles are enjoyable fast road miles... so I’ll probably have them done again if it ever gets to 100k miles under my ownership... worth every penny after another 15-20 years of use (hoping I still own it by then, I have every intention to). I mean, either it will be shells or I’ll be having an electric motor installed instead and the engine will become a centrepiece to our living room

It's easy to get lost in the world of depreciation and maintenance costs etc.

S54 =