[DieGrüneHölle]

Originally Posted by spetsnazos

You have BMW reliability stats or is that a random poll on some enthusiast website that's driving the hypothesis?

Info a year ago on the forum, from someone who is a reliable source of info.

BMWblog has F80 M3 at 34,677 units when it ended production. M4's were produced at higher rate and the introduction of the M2comp and M2CS. S55 production number will be well over 100,000 for sure.

[chris719]

Originally Posted by DieGrüneHölle

Yes N55 has the same exact crank hub parts. Even the N54 shares a similar setup and uses some of the same parts.

Spun crank hubs have happened on N54, N55, and S55. It is a weak point of this generation of motors.


Seen several cases reported on various BMW forums and from vendors on the forums. There was another N54 that spun a few months ago, it was a higher hp build.

If you think the failure rate is low on S55, you should do the math on N54 and N55. They have made so many more N55 engines than S55 it isn't even comparable. It is hard to find reports of crank hub failures on N55. It's really best to compare stock cars.

The bottom line is that S55 has a crank hub problem that is worse than the other engines sharing that design, for whatever reason. Maybe it's power, maybe it's something else, but S55 spins it stock occasionally while the others almost never do. No, this is not nearly as bad as the S65/S85 issue, so I am not trying to blow it out of proportion. It is a risk you need to accept if buying one.

[ChrisK]

Originally Posted by spetsnazos

While I agree with the point you're trying to prove, you're comparing a poll for mere enthusiasts and then lumping it against all cars sold .

You divide 5 cars into the number of people polled and even then all you're getting is enthusiast results

enthusiasts would be here and reporting an issue, and more likely to own these cars in the firs place. I'm not trying to make a point - I guess.

[ChrisK]

Originally Posted by DieGrüneHölle

Actually as of July last year there had been about 75,000 S55 powered cars built. It will be approaching 100,000 eventually.

Failures are a fraction of a percent.

Thanks! I was hoping someone would check my numbers!

[ChrisK]

We have to see how this plays out.

[ChrisK]

Originally Posted by Poochie

I can't believe is a simple washer is root cause of this the S55 failure and apparently it still hasn't been addressed yet.

#Sad

If it was a simple fix, there is no way BMW wouldn't have done it. Even for BMW this is ludicrous.

[DieGrüneHölle]

Originally Posted by ChrisK

Thanks! I was hoping someone would check my numbers!

It is hard to find exact numbers, they seem to only be published when a model goes out of production.

F80 was 34,677 units. For comparison the E90 sold just under 10k and the E92 just over 40k. So a 4 to 1 ratio(sedan vs coupe). By the time the F82/F87 are out of production and same production rates hold true compared to E9x/F87N55. There could be upwards of 160,000+ S55 powered cars produced.

[akkando]

Originally Posted by chris719

Yep, the failure rate is not high, but I've seen more than 5 total stock failures just in the posts in the F80 section over the years. Not everyone takes the poll.

It would seem that power is not really the issue until you reach high levels. When the stock cars fail it might be some kind of manufacturing or vibrational issue.

There was a theory that it was a vibration issue and is related to spending time in the higher RPMs. The S55 has 600 more RPM than the N55 and folks who are tuned might be more likely to rev it all the way out to 7600.

Who knows.

Def think don't tune until you get one year of driving on the car to work out any early gremlins on the car through warranty.

[ChrisK]

This is interesting.

The hub, washer and sprocket parts at the center of the S55 failure are literally used on every BMW. Could the bolt torque be the failure point?

http://www.realoem.com/bmw/enUS/show...97#11237574827

[ChrisK]

Originally Posted by akkando

There was a theory that it was a vibration issue and is related to spending time in the higher RPMs. The S55 has 600 more RPM than the N55 and folks who are tuned might be more likely to rev it all the way out to 7600.

Who knows.

Def think don't tune until you get one year of driving on the car to work out any early gremlins on the car through warranty.

That makes sense. The bolt loosens and bingo.

[AlpsRider]

Originally Posted by chris719

Not entirely true. This almost never seems to happen on N54 and N55s for whatever reason, even modded ones. S55 may have different vibrational / resonance behavior which causes this more often. It clearly isn't only power related as we have already seen 2 cases of stock M2C doing this, which is significantly detuned.

It is entirely true that they have the same parts regarding this issue.
Edit: Don't forget that the S55 in the M2C is putting out the same torque as the S55 in the M3/M4.

[M-Pilot]

Originally Posted by DieGrüneHölle

Actually as of July last year there had been about 75,000 S55 powered cars built. It will be approaching 100,000 eventually.

Failures are a fraction of a percent.

^This.

Also regarding the failures reported on N54/N55s... Yes, both N54 and N55 share the exact same crank hub. I have never seen or heard spun hub on a N55 but have seen/read multiple spun N54 cases (in fact Ghassan Automotive spun their N54 hub a few months ago on a drag strip). There are various theories floating around the internet; however, the general consensus sounds like this is more like a RPM issue than high HP issue. Vargas Turbo reported on a different forum that their N54 spun pushing only 300 something whp but the car was pushed near 8K RPM. Many people think sudden changes in engine RPM is the biggest contributor (e.g. kickdown on DCT cars). That being said, this is still such a rare issue compred to other chronic issues seen on S65 or S85 for instance. As mentioned above, there are well over 70K S55s produced so far and even though the forum isn't a perfect representation of the real pic, the failure rate is pretty low IMO.

[chris719]

Originally Posted by AlpsRider

It is entirely true that they have the same parts regarding this issue.

You need to read more clearly, the part of your statement that wasn't entirely true is your conclusion that the N55 is just as susceptible to this problem because it uses the same parts. That is not supported by the evidence. It is entirely likely that the parts are just fine and there are other external factors that increase the chance of the hub spinning or bolt backing out.

You do realize that there are almost 0 documented stock N55 crank hub spins on the forum and they produced at least several hundred thousand more units of this engine, possibly millions. The sample size is massive in comparison. Every single 135, 235, 335, X3 35i, X5/X6 35i, 535, 740, etc... from 2009 until very recently

[M-Pilot]

Originally Posted by ChrisK

That makes sense. The bolt loosens and bingo.

Exactly! That's why I decided to add little bit of extra protection by getting bolt capture plate installed ($100 part, $400 labor). It's still not 100% protection like a keyed hub (e.g. MaxPsi hub) but much better than not having anything IMO. In the F80 forum, there are several people running only the bolt capture for the past couple years with full E85 tunes and not a single reported failure so far. As I said, this doesn't mean it's fail proof but I belive most of the crank hub failures are due to the loose bolt and this solution reduces the already low chances even more.

[M-Pilot]

Another thing to mention is that almost all the spun hub cases end up with timing loss without any damage to the engine. Based on the crank hub failures threads in F80 forum, over 90% people ended up upgrading their hub to a keyed hub after the failure. I don't know about OP's case so don't wanna make assumptions but BMW might have taken the easier route in his case which is to just replace the engine instead of opening it and inspecting any valve damage etc. and re-timing it etc. Because I know from personal experience that even for simple transmission problems that can be fixed, BMW just gives you a brand new one instead of fixing the broken part.

[AlpsRider]

Originally Posted by chris719

You need to read more clearly, the part of your statement that wasn't entirely true is your conclusion that the N55 is just as susceptible to this problem because it uses the same parts. That is not supported by the evidence. It is entirely likely that the parts are just fine and there are other external factors that increase the chance of the hub spinning or bolt backing out.

You do realize that there are almost 0 documented stock N55 crank hub spins on the forum and they produced at least several hundred thousand more units of this engine, possibly millions. The sample size is massive in comparison. Every single 135, 235, 335, X3 35i, X5/X6 35i, 535, 740, etc... from 2009 until very recently

You need to read more clearly. This is what I said.

"The N55 has the same part. That means all of the M235i and OG M2s have the same potential issue. Many of the M3/M4s that had the problem we're modded. Many of them were DCTs with modded software ie. high power with a jerky tranny."

Which is not what you claimed I said.

[M-Pilot]

Originally Posted by Tag

$20 says the s58 will have the same issue.

Nope, B58/S58 has a different design so no risk of spinning the hub. However, I'm willing to bet more than $20 that S58 will have some other unique problem

[Tag]

Originally Posted by cntzl

Nope, B58/S58 has a different design so no risk of spinning the hub. However, I'm willing to bet more than $20 that S58 will have some other unique problem

Do you have a reference showing the design difference? I'd like to read up on it.

[M-Pilot]

Originally Posted by Tag

Do you have a reference showing the design difference? I'd like to read up on it.

Post #175 -> https://f80.bimmerpost.com/forums/sh...1#post19415011

It's a long 28-page thread but has some useful info in it.

[hellrotm]

Originally Posted by Tag

Do you have a reference showing the design difference? I'd like to read up on it.

The B58 has the sprocket/hub integrated into crank. Also everything including timing chain is on rear of engine. S58 will have similar setup.

https://f80.bimmerpost.com/forums/sh...&postcount=175

https://f80.bimmerpost.com/forums/sh...&postcount=177

[GerardzM]

Stupid question, does BMW even race the S55?

If so what is their solution? Just drop in a new motor?

[Thescout13]

Originally Posted by GerardzM

Stupid question, does BMW even race the S55?

If so what is their solution? Just drop in a new motor?

They don't. And even if they did, motors last a few races, 1 season tops before needing to be rebuilt or replaced.