05-03-2018, 03:54 AM | #1 |
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S55 issue even in M2 Competition
Good morning guys,
how do you think about this known issue ? As far as I heard, the M2C has the same issue. Nothing fixed seems to be fixed... BMW F80 M3 & F82 M4 S55 engine crank hub spinning problem BMW comment: BMW saw this issue first time on an engine test bed long time before the first vehicle was delivered. The same issue is known from a 4 cyl engine - same parts/system. The real problem is not the hub (2) or the wheels (5). It´s the bolt (3), which holds the wheel and crank hub. The bolt dissolves because of vibrations coming from the vibration damper (1) in front of it - or from any other imbalanced source. If it dissolves, your chain wheel spins and timings adjusts. So why not just tighten the bolt, or make the hub and wheels from one piece? Because this system works like a fuse. This "fuse" protects your crankshaft against imbalanced parts and vibrations. If you fix the bolt (weld etc), it can't come loose and you risk damages to your crankshaft and bearings etc. The "solutions" some tuners offer are very dangerous, BMW constructed everything for a reason. Example? You can't (or its very difficult) set timings with a fixed wheel. We spoke honestly with the engineer, about solutions, whats possible. The reality is: there's no solution. You can fix the bolt but you open a range of new risks. You can install a one piece hub/wheel - and of this the engineer urgently advised against - you risk even more damages. JoeFromPA is right - there are over 40k vehicles and just round about 40 (BMW said this) known cases, most of them with only wrong timings. You even can't check the bolt, only thing you can do is change the bolt every year or every xxxxx miles/km. The bolt is tightened with 200 Nm and 2x 260 degrees Last edited by Winterstorm; 05-03-2018 at 08:53 AM.. |
05-03-2018, 04:09 AM | #2 | |
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Nkc1600.50 |
05-03-2018, 06:59 AM | #3 |
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The link was broken or bad for me.
The description of the 4 cylinder motor that BMW had too much harmonic vibration on and went to this type of crankshaft nut on sounds to mi like the S14. The crank hub/bolt/harmonic balancer setup on the s14 did not have any issues even up to 8000 rpm ( stock limiter 7200) |
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05-03-2018, 09:46 AM | #4 |
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It is mainly a problem for cars dated pre 12/2015 and the majority were pushing big power. BMW implemented a new bedplate after 12/2015 and its seems to have fixed the issue. 99% of the failures fall on early built M3/M4. With that said, I been to many BMWCCA events and HPDE. Never met another M3/M4 owner that actually had the problem. Only known cases are what I have seen on the forums. Even then it is a fraction of a % of S55 powered cars. Heard of more N54 and N55 letting going due to tuning than S55.
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Day Laborer1746.00 Brandt51889.00 |
05-03-2018, 11:39 AM | #5 | |
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10-20-2018, 10:22 PM | #7 |
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Not to blow this out of proportion. But this happened to my 2018 f80 comp dct at 2k miles. There are a handful of other 18 m3/m4s with this issue as well. Agreed majority are tuned, but many are not. When mine got fixed under warranty the engineer assured me the bolt was tight and torqued to spec. He's seen a few sch and the common issue was the friction washer between the hub and timing gear either breaking or simply not gripping enough. My crank hub was completely intact just slipped a little. This resulted in the timing being off. However the repair would've been at least 5k out of pocket if you were tuned.
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FSociety3812.50 |
10-20-2018, 10:27 PM | #8 |
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There is a poll on M3/M4 thread, a whopping 4 members reported crank hub issue on stock tune. Have got to be getting close to 100,000 S55 units now produced. In reality it is a fraction of a percent. Not specific to S55 either, N54 and N55 have had it as well.
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10-20-2018, 11:54 PM | #9 |
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Seen these go on multiple power levels stock - upgraded turbos. Some cars are perfectly fine, some just cant handle. Will be installing the Gintani or Max Psi solutions on our new M2C soon.
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10-21-2018, 03:13 PM | #12 |
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10-21-2018, 04:11 PM | #13 | |
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The DCT common issue seems to be with kickdown and traction on! Update: I know about at least 3 occasions in 6MT spinning the hub due to money shift
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60-130mph 5.0s G80 M3 #OrlandoAutowerks Sauce IG: @bmwF9XG80 Last edited by FSociety; 10-22-2018 at 06:42 AM.. |
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10-22-2018, 12:04 AM | #14 | |
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But you'd have to upshift really really hard on a 6mt to get anywhere near the stress of the dct, and even then it wouldn't be close in terms of stress on a 6mt because you can't physically shift fast enough to match the dct. Also a correct to be made, iirc is that money shifting refers to a downshift into a lower than desired gear causing over revving and valve-piston contact causing a catastrophic damage, and a new engine to be required. Hence the term money shift. |
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10-22-2018, 04:02 AM | #15 | |
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Money shift will destroy your engine regardless of the S55 crank hub issue |
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FSociety3812.50 AndrewC198910931.00 |
10-22-2018, 10:11 AM | #16 |
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My s14 has no such issue.. BMW actually went with the 4 because of the short crank, they were having issues destroying them in the 6's they tried previously.
As for "the bolt is a fuse" comment. If this is indeed the case - why have they not given it a service life range? They even suggest "change the bolt every year or every xxxxx miles/km." So is this official? Change it every year? That's the service life? Surely there are several high mileage S55 out there by now - all of which on the original bolt... This didn't sound very scientific. |
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10-22-2018, 10:20 AM | #17 | |
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But the dct still does shift significantly faster, and because the faster the shift the larger the torque placed on the hub because the engine slows down faster which makes it easier to spin, hence the issue is less common on manuals. |
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10-22-2018, 10:41 PM | #18 | ||
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The leading thought to why there are more dct sch than manuals is simply because there are significantly more DCTs than MT produced. As for the "fuse" explanation. General consensus is that's also BS. Plenty of m motors with a keyed or fixed timing sprocket (not a crank hub attached with a friction washer) that have not exploded and are just as complex to "time/adjust". Kickdown has been reported to be an issue as well. However many sch have occurred without aggressive shifts or Kickdowns. Mine occcured when I was coming to a stop and the dct s3 setting automatically down shifted from 2 to 1 (didn't redline, just standard downshift Rev matching). Maybe my spirited driving prior to coming to a stop spun it and then the stop pushed it over the edge? I think I read somewhere that the sensor for the hub is extremely sensitive which is why we're not seeing too many instances of catastrophic engine damage? Again tuned cars seem to be more problematic. Possibly related to proportionately high low end torque? Many say this is blown out of proportion and I suppose if you crunch the numbers, it's pretty miniscule. Not like rod bearings which is more of an eventuality. The sch in s55 truly seems to be bad luck. However if you're tuned and you go in with an sch, you're more than likely screwed in regards to warranty. An sch at minimum requires significant disassembly and if the dealership is doing it--you better believe it's gonna be expensive. If the sch does MORE damage than just the timing being off, you're looking at a new engine (although this seems to be rare). The worst part of it all, I had to drive a loaner for 3.5 weeks! Last thing I want to do is drive a non M car everyday! Lastly, the M2C is magnificent! I still don't like the rear fascia/trunk lid and lack of 4 doors (i have 2 kids). An S55 in that small of frame seems insane! |
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10-23-2018, 01:39 AM | #19 | |
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10-23-2018, 01:44 AM | #20 | |
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10-23-2018, 09:26 AM | #21 |
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Hang on, is the bolt "dissolving" or backing out? Which is it?
If it "dissolves" couldn't someone source a stronger bolt? If it backs out - can't you add 272, increase torque and safety wire? I simply want to understand what is happening and if the bolt is the culprit. |
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10-23-2018, 10:30 AM | #22 |
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