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      11-08-2019, 05:46 PM   #111
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Originally Posted by F87source View Post
It could if the crank bolt is loose, so a CBC js probably a good idea.
So in other words luck of the draw plays a big part here?

Shame on BMW.
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      11-08-2019, 06:33 PM   #112
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Quote:
Originally Posted by 1mm2 View Post
So in other words luck of the draw plays a big part here?

Shame on BMW.
I heard the crank bolt comes loose over time as a result of the dct kick down, essentially the shock wasn't enough to spin the hub but it was enough to loosen the bolt. In other words it wasn't BMWs fault from the factory but I guess luck does have to do with if it spins loosens or not. Atleast a CBC is really cheap, I believe sub $100, and the install is really easy as well.
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      11-09-2019, 03:31 AM   #113
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Quote:
Originally Posted by F87source View Post
It could if the crank bolt is loose, so a CBC js probably a good idea.
this ?

https://www.ecstuning.com/b-vargas-t...t-s55-cbc~vtt/

Did you do that your m2c ?
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      11-09-2019, 04:11 AM   #114
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Originally Posted by armiii View Post
I don't have an m2C. But yes those are the CBC made by VTT to prevent the bolt from backing out.

But like I said before if you're under warranty I would bother with this until the warranty is nearly over.
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      11-09-2019, 05:08 AM   #115
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Quote:
Originally Posted by F87source View Post
But like I said before if you're under warranty I would bother with this until the warranty is nearly over.
I actually disagree with this. If the primary purpose of the CBC is to stop the bolt backing out because overtime it moves a fraction here and there then it would make sense to do the install sooner than later. Otherwise you are just stopping the bolt backing out any further at a later date which the bolt may of already moved a bit and hence locking it in a compromised position.

If you are going to get rid of the car before warranty runs out and not modding I agree don't waste the time.
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      11-09-2019, 07:36 AM   #116
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Quote:
Originally Posted by F87source View Post
I heard the crank bolt comes loose over time as a result of the dct kick down, essentially the shock wasn't enough to spin the hub but it was enough to loosen the bolt. In other words it wasn't BMWs fault from the factory but I guess luck does have to do with if it spins loosens or not. Atleast a CBC is really cheap, I believe sub $100, and the install is really easy as well.
So why wouldn't BMW just recall the vehicles for this fix and give everyone piece of mind?
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      11-09-2019, 12:08 PM   #117
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CBC is not a 100% solution as friction discs can still fail and cause a hub spin. However, the fact that there is not a single failure reported with CBC installed might be indicative of bolt becoming lose being a common reason for SCH in my opinion. The chance of SCH happening is very low already when you look at all the reported cases vs number of S55 cars produced so far. I think CBC lowers this risk even more and costs a fraction of what a keyed hub would. Therefore, I thought CBC was a nice safety net (even though being not 100% fail proof as mentioned earlier) and decided to go with it. I have been running it since I hit 5K miles. I currently have nearly 11k miles and 9 track days. I have been on BM3 CS+ map since I got the CBC installed and so far so good. I'm not planning to do a keyed hub anytime soon either. If you look at all the SCH cases, almost all of them resulted with just a timing loss (only seen one case of piston hitting the valves and it might be a money shift). I'm aware of the fact that forums in general aren't a 100% representation of the real statistics but I still think SCH is such a rare occurrence. Btw some of those 6MT SCH cases reported online are due to money shift but obviously owners rarely come forward and admit it for various reasons.
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      11-09-2019, 03:57 PM   #118
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Quote:
Originally Posted by MR RIZK View Post
I actually disagree with this. If the primary purpose of the CBC is to stop the bolt backing out because overtime it moves a fraction here and there then it would make sense to do the install sooner than later. Otherwise you are just stopping the bolt backing out any further at a later date which the bolt may of already moved a bit and hence locking it in a compromised position.

If you are going to get rid of the car before warranty runs out and not modding I agree don't waste the time.
You have to retorque the crank bolt before you put on the CBC so it won't matter if it got a bit loose (a nm less etc. Otherwise if it did get too lose your hub would've slipped) as long as the friction disc didn't slip which means the hub didn't move. The bolt just sandwiches the whole assembly, whether or not it is in the correct position shouldn't really matter so long as the hub itself doesn't move.

I guess it's up to the end user what they do but for me if the bolt slipped and BMW saw that CBC they would probably have reasonable grounds to deny warranty.

Quote:
Originally Posted by 1mm2 View Post
So why wouldn't BMW just recall the vehicles for this fix and give everyone piece of mind?
1) it's actually quite a rare issue.
2) if it isn't happening frequently enough it is cheaper to fix motors as they go vs. perform a recall. Just like on the sti with ring land failure.
3) the CBC isn't a complete fix, the friction disc can still spin.


Quote:
Originally Posted by cntzl View Post
CBC is not a 100% solution as friction discs can still fail and cause a hub spin. However, the fact that there is not a single failure reported with CBC installed might be indicative of bolt becoming lose being a common reason for SCH in my opinion. The chance of SCH happening is very low already when you look at all the reported cases vs number of S55 cars produced so far. I think CBC lowers this risk even more and costs a fraction of what a keyed hub would. Therefore, I thought CBC was a nice safety net (even though being not 100% fail proof as mentioned earlier) and decided to go with it. I have been running it since I hit 5K miles. I currently have nearly 11k miles and 9 track days. I have been on BM3 CS+ map since I got the CBC installed and so far so good. I'm not planning to do a keyed hub anytime soon either. If you look at all the SCH cases, almost all of them resulted with just a timing loss (only seen one case of piston hitting the valves and it might be a money shift). I'm aware of the fact that forums in general aren't a 100% representation of the real statistics but I still think SCH is such a rare occurrence. Btw some of those 6MT SCH cases reported online are due to money shift but obviously owners rarely come forward and admit it for various reasons.
+1
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      11-09-2019, 04:31 PM   #119
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Quote:
Originally Posted by cntzl View Post
If you look at all the SCH cases, almost all of them resulted with just a timing loss (only seen one case of piston hitting the valves and it might be a money shift). I'm aware of the fact that forums in general aren't a 100% representation of the real statistics but I still think SCH is such a rare occurrence. Btw some of those 6MT SCH cases reported online are due to money shift but obviously owners rarely come forward and admit it for various reasons.
Please educate me here, timing loss= limp mode/easy fix?

Someone here experienced engine/tranny replacement on M2C DCT while cruising due to SCH.
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      11-09-2019, 05:42 PM   #120
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Quote:
Originally Posted by 1mm2 View Post
Quote:
Originally Posted by cntzl View Post
If you look at all the SCH cases, almost all of them resulted with just a timing loss (only seen one case of piston hitting the valves and it might be a money shift). I'm aware of the fact that forums in general aren't a 100% representation of the real statistics but I still think SCH is such a rare occurrence. Btw some of those 6MT SCH cases reported online are due to money shift but obviously owners rarely come forward and admit it for various reasons.
Please educate me here, timing loss= limp mode/easy fix?

Someone here experienced engine/tranny replacement on M2C DCT while cruising due to SCH.
There are a ton of threads about this on the F80 forum. I had a 2016 M4 Comp (had it for 21K miles and 10+ track days) before my M2C so I have been following almost every single source on this issue for the past 2-3 years. After all this research, my previous post sums up what I concluded so far. As I said, in almost every SCH case, you can re-time the engine be done with it. If you look at the F80 forum or BM3 Facebook group etc, almost all of the people who experienced a SCH were able to save their engines. In fact, that's when many people upgrade to a keyed hub. You can contact any major vendors on this forum as well, such as AutoTalent, SSR Performance, EAS etc. and ask them how many SCH cases they have seen and were able to just upgrade the hub after the failure. I'm not saying catastrophic engine failure is impossible with SCH. I just think it's very very unlikely. Spending $3K-$4K on something that is very unlikely to happen doesn't make much sense to me. Again, CBC only cost me ~$550 out the door and I'm not planning to spend anything more unless I have to. Long story short, I'm not an expert and do your research before making an important decision based on a single post like mine or someone else's.
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      11-09-2019, 05:50 PM   #121
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Quote:
Originally Posted by 1mm2 View Post
Please educate me here, timing loss= limp mode/easy fix?

Someone here experienced engine/tranny replacement on M2C DCT while cruising due to SCH.
If the slip is minor and the crank position sensor catches it in time and triggers a limp mode yes to an extent. Adjusting timing is easy if you have the super expensive BMW tools and the know how, otherwise it'll probably be pretty expensive for a shop to do it.

If it slips too aggressively and the pistons hits the head worst case scenario you'll need a new motor, best case scenario just a new valve.


Quote:
Originally Posted by cntzl View Post
There are a ton of threads about this on the F80 forum. I had a 2016 M4 Comp (had it for 21K miles and 10+ track days) before my M2C so I have been following almost every single source on this issue for the past 2-3 years. After all this research, my previous post sums up what I concluded so far. As I said, in almost every SCH case, you can re-time the engine be done with it. If you look at the F80 forum or BM3 Facebook group etc, almost all of the people who experienced a SCH were able to save their engines. In fact, that's when many people upgrade to a keyed hub. You can contact any major vendors on this forum as well, such as AutoTalent, SSR Performance, EAS etc. and ask them how many SCH cases they have seen and were able to just upgrade the hub after the failure. I'm not saying catastrophic engine failure is impossible with SCH. I just think it's very very unlikely. Spending $3K-$4K on something that is very unlikely to happen doesn't make much sense to me. Again, CBC only cost me ~$550 out the door and I'm not planning to spend anything more unless I have to. Long story short, I'm not an expert and do your research before making an important decision based on a single post like mine or someone else's.
+1

You can also get a kick down blocker to stop kick downs as well to help alleviate the possibility of spinning the hub.
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      11-09-2019, 07:42 PM   #122
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Quote:
Originally Posted by cntzl View Post
There are a ton of threads about this on the F80 forum. I had a 2016 M4 Comp (had it for 21K miles and 10+ track days) before my M2C so I have been following almost every single source on this issue for the past 2-3 years. After all this research, my previous post sums up what I concluded so far. As I said, in almost every SCH case, you can re-time the engine be done with it.
It's good to know your research didn't dissuade you from getting the M2C.
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      11-09-2019, 08:21 PM   #123
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Quote:
Originally Posted by 1mm2 View Post
Quote:
Originally Posted by cntzl View Post
There are a ton of threads about this on the F80 forum. I had a 2016 M4 Comp (had it for 21K miles and 10+ track days) before my M2C so I have been following almost every single source on this issue for the past 2-3 years. After all this research, my previous post sums up what I concluded so far. As I said, in almost every SCH case, you can re-time the engine be done with it.
It's good to know your research didn't dissuade you from getting the M2C.
Absolutely not! If I was really worried about SCH, I would have either kept my M4C (because it wasn't tuned) or moved to a different platform.
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      11-09-2019, 08:29 PM   #124
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Originally Posted by cntzl View Post
Absolutely not! If I was really worried about SCH, I would have either kept my M4C (because it wasn't tuned) or moved to a different platform.
I get overly paranoid about these things. My Z4M and 1M were flawless, as were my 911s.

I'd love to have hard figures on the overall % of S55s affected.
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      11-10-2019, 02:15 AM   #125
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Originally Posted by 1mm2 View Post
I get overly paranoid about these things. My Z4M and 1M were flawless, as were my 911s.

I'd love to have hard figures on the overall % of S55s affected.
No one knows the real numbers, but anecdotally it seems much smaller than the S65/S85 engine rod bearing issues.

The reason BMW doesn't recall it is the same reason that BMW didn't recall the S65 or S85 - the majority of the failures happen out of warranty. Sad to say, they don't really care, they go with whatever their actuaries think is the lowest risk to the business.
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      11-10-2019, 05:33 AM   #126
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Originally Posted by chris719 View Post

The reason BMW doesn't recall it is the same reason that BMW didn't recall the S65 or S85 - the majority of the failures happen out of warranty. Sad to say, they don't really care, they go with whatever their actuaries think is the lowest risk to the business.
Agreed, and thus my paranoia as I would want the M2C as a long term keeper.

Have there been many SCH cases out of warranty that you know of or does it happen early if at all?
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      11-11-2019, 04:38 AM   #127
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Agreed, and thus my paranoia as I would want the M2C as a long term keeper.

Have there been many SCH cases out of warranty that you know of or does it happen early if at all?
Iím not an expert and I havenít collected data, but it seems to be random from what Iíve seen. It might be a bathtub curve; there are certainly stock engines that have had the issue early in life.
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      11-11-2019, 06:08 AM   #128
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Iím not an expert and I havenít collected data, but it seems to be random from what Iíve seen. It might be a bathtub curve; there are certainly stock engines that have had the issue early in life.
Sounds like a two part story, some are defective and spin on stock cars under normal conditions and the non defective ones simply can't handle the extra force from tuned engines.
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      11-11-2019, 11:32 AM   #129
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It's totally random on both tuned and stock engines.

Considering BMW pushes 405hp - 454hp from the S55 Stock.
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      11-11-2019, 12:54 PM   #130
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It's totally random on both tuned and stock engines.
That's just it, if it were tuned cars only or those using kick down then I would feel a little bit easier but it seems to also happen out of the blue for stock cars.

Not the track record desired if you're planning on holding on long term...
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      Yesterday, 04:01 AM   #131
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It's totally random on both tuned and stock engines.

Considering BMW pushes 405hp - 454hp from the S55 Stock.
Did you do this upgrade in your car? I mean, crank hub upgrade?
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      Yesterday, 09:19 AM   #132
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Quote:
Originally Posted by 1mm2 View Post
That's just it, if it were tuned cars only or those using kick down then I would feel a little bit easier but it seems to also happen out of the blue for stock cars.

Not the track record desired if you're planning on holding on long term...
There are many 500WHP + S55s out there without any crank capture chugging along. I asked some BMW dealer shop techs the other day and they had no clue about it.

IMHO this is an issue that is blown out of proportion by forums where we hear all the bad but rarely the good of any car.

Also what performance engine does not have some sort of robustness issue or other weakness?
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