Concerned about CS

[bmwcscam]

Hello everyone,

I will try to make this short, but I just picked up a white 2020 M4 CS last week. it has now 5,900 miles on it, and I love everything about it. Drivetrain, DCT, suspension setup, OLED tail lights, etc etc. The only thing I was planning to do was change the tires from the PSS to the Cup 2's, as I read that BMW engineered the suspension with this tire compound, so I think it will enhance the performance somewhat.

However, my main concern after reading some forums is the S55 crank hub issue.

Should I be concerned?

This is a vehicle I plan to keep for some time, and it will have all parts/services completed long before they are due, etc. The car will remain completely stock.
I have read in places where this design was intended by BMW as it saves the motor from potentially more catastrophic damage if the failure point is not at the crank hub. Also, the motor is the same one used on the M4 GT4 and M2 CS Racing, so it cannot be the case (in my mind) that BMW knew this was a poor design. I do not know what to think, and ultimately it has made me consider selling the vehicle for something else....which may be a bit extreme.

Any thoughts are greatly appreciated with regard to my specific vehicle and intended usage.

[k_mann]

Its my understanding that the crank hub is only an issue when going stage 2 and up. Potentially stage 1 as well. But I don't recall anyone spinning a hub on a stock motor. Save of course someone money shifting in a manual....that could potentially cause it.

[G35POPPEDMYCHERRY]

tbh most of us don't even use >50% of this cars potential...put good tires on it PSS PS4 the toyos whatever just not shit tires

crankhub is blown out of proportion

[m3elmo]

1) this is blown out of proportion. It's not like the rod bearing issue of the S54 engine.
2) You are under warranty, and if you want you can get the extended warranty.

[THEROK]

Zero concern. It can be readily argued that the S55 is the most reliable out of production M engine made to date with the CS/GTS having the extra oil capacity and pump to handle even greater lateral and longitudinal Gs.

Enjoy!

[Ultimateone]

It's been made way more crazier than what it actually is because of Youtube and shops because for them it equals $$.
If you're keeping the car stock I would not worry about it.

[F80_Kbo]

Drive the car and enjoy it. You have a factory warranty. If something occurs then have the dealer address it

[Keca10]

This is one of the most bulletproof modern engines out there.

Enjoy your car.

[Wanted_M]

OP,
I would say its a divided issue by believers and non-believers until it bites you. I opted for the Vargas hub/CBC for a piece of mind as my first mod, done, no more stressing or guessing what if, what if... You need to make that determination and do what your gut tells you, that's what I did. In all honesty, you have warranty, if it fails, they will fix it with the same garbage design and move on. If you tune it and your hub slips game over, warranty is bye bye Felicia .

The first question you need to ask yourself is, what's my goal for the CS, will it become a tuned track rat, 1/4 mile beast, roll race queen or just a stock weekend cruiser and go from there. At a minimum at least install a CBC and happy trails!!

By the way I have Cup2's on the car F-265/35/19 and R-285/30/20 with APEX 12mm spacers. Car grips really nice and definitely a step up from those PSS garbage tires that offer no traction.

My .02 cents

[Gbcarmona]

I have a friend who is a proper mechanic at a BMW dealership and he said over all his time there he has only seen 2 engines (out of M2C, M3, M4) where that happened but they were both tuned (not sure how much but certainly tuned and not standard).
I have always wondered why people feel the need to get even more power…maybe if you live is a very nice, hot and dry place…in the U.K., most of the time is wet and damp and difficult to put half the power down, let alone all of it!
Awesome car btw!

[Skuru96]

If you plan to daily drive this car, I'd keep the PS4s, cup 2s wear out faster and aren't the best in wet weather.

Crank hub issue is blown out of proportion. Yes you can spin them under stock power but it's mainly for tuned cars. Since you said you're going to keep it stock, you should be fine. Don't use the kickdown feature and it'll be fine.

[clutchdj]

it happens on stock motors. w/DCT you'd have to constantly hit the kick down switch.. and go from like 5th to 2nd.

from what I've seen it doesn't happen much to the track cars because they are not constantly dropping gears; and if so its at a liner rate. 5th-4th-3rd; etc.

Take what I am saying as a grain of salt and don't be fooled because no one knows the real reason why the hubs spin because it's so random.

I track my m3cs but I'm not looking for trophies (b/c I'm slow :-) and I did the gintani CH for peace of mind. stock ecu.

[bigj505]

If staying stock then it's a no brainer to NOT do the crank hub. I'd only consider the possibility once you are near the end of the warranty. Makes no sense to spend thousands of dollars on a stock car with a warranty.

[3R1CS0]

Get it at your own discretion. I'm sure it has been mentioned a million times. It happens on a very very small amount of all S55 but with that being said it CAN happen. As you tune and push more power the chance of the crank hub spinning increases.

I agree with others that it is blown out of proportion. I personally would get it on a out of warranty car. Otherwise, what's the point?

[M5D]

Sky is falling creates so much money for Indy shops! They even know unless you push the shit out of the s55 motor there is no issue with spun hubs, but then again charging 3 to 5k means they have to say better safe than sorry!

[M3JetPilot]

I just got my first M in November. Was super worried and did tons of research. There were two things that helped me stop worrying.

1. The percentage chance of failure is no different than anything else that could fail.

2. Seeing the number of parts that are left over after the crank hub "fix".

Crank hub fix or not, either way there is risk. I baby my car so there's even less reason for me to take on the risk of someone going that deep into the engine and fixing something that isn't broken.

[F80_Kbo]

Also consider if you go ahead and "fix the crank hub" will your service department be inclined to not honor the warranty since the engine has been opened up. Just some food for thought

[bmwcscam]

I appreciate everyone's thoughts on this. I am going to keep it how it is and drive it hard!

[CanAutM3]

I've had my M4cs for 3 years and did over 70 track days with it. No issue with the crank hub. Keep the engine stock, and live worry free

[NYG]

Originally Posted by CanAutM3

I've had my M4cs for 3 years and did over 70 track days with it. No issue with the crank hub. Keep the engine stock, am live worry free

This. The crankhub issue is almost EXCLUSIVELY an issue with tuned cars. The rare case with an untuned car always has questions marks as to whether it was tuned prior or even the credibility of the person claiming it.

Also used to track my M4CS HAAAAARD and my engine was always reliable and ran ice cold even on the hottest days.

I never tuned it.

I ran Cup 2s, NT01s, Toyo RR, you name it.

[NYG]

Oh and I used kick down ALL THE F'IN TIME.

[jmg]

Originally Posted by NYG

This. The crankhub issue is almost EXCLUSIVELY an issue with tuned cars. The rare case with an untuned car always has questions marks as to whether it was tuned prior or even the credibility of the person claiming it.

Also used to track my M4CS HAAAAARD and my engine was always reliable and ran ice cold even on the hottest days.

I never tuned it.

I ran Cup 2s, NT01s, Toyo RR, you name it.

What are your impressions of the CUP2's as a track tire?