Stage 1 Tune without Crank Hub Fix Yes or No?

[spuntyb]

Originally Posted by maddmatth

Did you find out exactly why it slipped? Was it the bolt or friction plate? I'm guessing the bolt since you just had stage 1, so a bolt capture may have been a good idea.

Not sure exactly, but this is it after it was removed

[j2dad5389]

Reviving an old thread because I’m curious..

An M4 competition or even CS is pushing stage 1 bm3 numbers, but are considered “stock”. Yet the inrernals are completely the same as the base. So shouldn’t it theoretically be safe to go stage 1 on stock crank hub since the competition and CS can handle the higher horsepower safely? If going stage 2 by all means I support the crank hub fix.

[FrznM]

Originally Posted by j2dad5389

Reviving an old thread because I’m curious..

An M4 competition or even CS is pushing stage 1 bm3 numbers, but are considered “stock”. Yet the inrernals are completely the same as the base. So shouldn’t it theoretically be safe to go stage 1 on stock crank hub since the competition and CS can handle the higher horsepower safely? If going stage 2 by all means I support the crank hub fix.

I believe the BM3 numbers push it above what a stock comp or CS is pushing. I think the comp only pushes 20 hp over stock, CS about 40. This is less than BM3 Stage 1. As you can see from other threads, plenty of people on Stage 1 have spun their crank hub. A lot of them report within 24 hours of flashing to stage 1. I am currently on stage 1, but I have CBC installed. I haven't seen any failures under 600 WHP with CBC reported yet that were not money shifted. I would really suggest anything more than a 'GTS' or 'CS' tune at least get a CBC installed for piece of mind. It was only $300 for the installation for me, and I believe the part is about $100. Worth the piece of mind for me at least.

[rmanm4]

CBC is only if the bolt backs out due to vibration.

A full crank hub fix is what is needed when you have high torque. The torque due to kick downs or wild swings is what over powers the friction plates between the bolt and the timing sprockets.

This is also why in the new S58 engine BMW went with a one piece design and not a CBC to fix the issue.

If you are going to be pushing over 550 ft-lbs of TQ you should get a full CH fix.

Now, the bolt can slightly back out over time and make it easier for the friction plate to slip, so this is why a full CH fix is with CBC.

[verruckt]

Originally Posted by rmanm4

CBC is only if the bolt backs out due to vibration.

A full crank hub fix is what is needed when you have high torque. The torque due to kick downs or wild swings is what over powers the friction plates between the bolt and the timing sprockets.

This is also why in the new S58 engine BMW went with a one piece design and not a CBC to fix the issue.

If you are going to be pushing over 550 ft-lbs of TQ you should get a full CH fix.

Now, the bolt can slightly back out over time and make it easier for the friction plate to slip, so this is why a full CH fix is with CBC.

Not necessarily true. Vibration isn't the only mechanism for the crank bolt to back out. No one has substantially tested WHY the crank hub fails. We can't say with certainty that the friction plates are what's failing. Until someone puts it on a test rig, fully bolted together and testing to failure repeatedly, we will never know. It's all a guess.

Now, the crank hub bolt can also back out with shock load - the exact type of situation a lot of people are describing when the CH fails...

Personally (and this is all a guess...) I think this is all due to the CB backing out after repeated shock loads. The CH assembly is compressed in place by the CHB, and affixed to the harmonic damper. The CHB is right hand threaded - the same direction as the rotation of the engine (or crank) in this case (clockwise from front). If it takes a shock load its going to loosen because of this, not tighten.

I believe what is happening is people are driving their cars in a certain way (which is exacerbated by tunes) that is causing a load on the CH. This load is then transmitted to the harmonic damper, which is connected to a bunch of parasitic load. The damper, which has substantial mass on its own takes a shock and something has to give - and I believe its the bolt due to how its threaded into the crank. Slowly over time and repeated shock, the bolt backs out, the hub assembly falls apart and boom.

Also, guess what the approximate torque to break the bolt is when removing it? 450ish ft/lbs...

The CBC is enough to hold the bolt from backing out, or at least loosening. The problem is the bolt can still back out from the back end where it bolts into the crank (if a bunch of other shit goes south - extremely rare) , but this issue will still occur even with a keyed crank hub. If my hypothesis is true, then the bolt is the core issue here. Not the hub design.

Now, is the CH replacement overkill? Yeah probably. Is it retardedly overpriced? Oh yeah. What is its failure mechanism? Same as above - if the crank bolt backs out.

What I'd really like to see is S55 owners group together and hold BMW's feet to the fire, start a campaign of emailing BMW M / GMBH nonstop as a group, and forcing them to acknowledge the problem and come up with a solution. Something such as the one piece crank / hub integration OR their own fixed crank hub.

[paulo_f80m3]

Originally Posted by verruckt

What I'd really like to see is S55 owners group together and hold BMW's feet to the fire, start a campaign of emailing BMW M / GMBH nonstop as a group, and forcing them to acknowledge the problem and come up with a solution. Something such as the one piece crank / hub integration OR their own fixed crank hub.

This.

[CalinSez]

Originally Posted by verruckt

What I'd really like to see is S55 owners group together and hold BMW's feet to the fire, start a campaign of emailing BMW M / GMBH nonstop as a group, and forcing them to acknowledge the problem and come up with a solution. Something such as the one piece crank / hub integration OR their own fixed crank hub.

I second the motion!

[j2dad5389]

Originally Posted by aamirani

I believe the BM3 numbers push it above what a stock comp or CS is pushing. I think the comp only pushes 20 hp over stock, CS about 40. This is less than BM3 Stage 1. As you can see from other threads, plenty of people on Stage 1 have spun their crank hub. A lot of them report within 24 hours of flashing to stage 1. I am currently on stage 1, but I have CBC installed. I haven't seen any failures under 600 WHP with CBC reported yet that were not money shifted. I would really suggest anything more than a 'GTS' or 'CS' tune at least get a CBC installed for piece of mind. It was only $300 for the installation for me, and I believe the part is about $100. Worth the piece of mind for me at least.

thank you for the insight. would you consider it to be a lot safer to tune to CS or GTS tune than the Stage 1 with bm3?

[maddmatth]

Originally Posted by verruckt

What I'd really like to see is S55 owners group together and hold BMW's feet to the fire, start a campaign of emailing BMW M / GMBH nonstop as a group, and forcing them to acknowledge the problem and come up with a solution. Something such as the one piece crank / hub integration OR their own fixed crank hub.

But how do we argue that it's BMW's responsibility when it only seems to be a significant issue when exceeding factory power levels?
Or do we have many known cases on factory tunes?

[verruckt]

Originally Posted by maddmatth

But how do we argue that it's BMW's responsibility when it only seems to be a significant issue when exceeding factory power levels?
Or do we have many known cases on factory tunes?

It's apparently happened on bone stock cars too.

[Suds]

Done it three times on a S55, still own two of them.
2015 M4 BPM stage 1, tuned at 27k miles sold at 52k miles with 3500 track miles.

Current:
2019 M4 BM3 stage 1, tuned at 9k miles now at 22k miles with 3400 track miles.
2019 M2c BM3 stage 1 tuned by previous owner. Currently stock tune until his license is transferred.

Paying for a new engine doesn’t bother me, as a mechanical design engineer I am not sure any of the fixes really fix the problem.

[maddmatth]

Originally Posted by verruckt

It's apparently happened on bone stock cars too.

So rare though, could be assumed to be a crank bolt that wasn't tightened correctly from factory, and the ones I've seen have been fairly low mileage and taken care of under warranty
Whereas many have had this failure shortly after flashing a tune.

[Silverlining_m2]

Originally Posted by maddmatth

So rare though, could be assumed to be a crank bolt that wasn't tightened correctly from factory, and the ones I've seen have been fairly low mileage and taken care of under warranty
Whereas many have had this failure shortly after flashing a tune.

"Many" is starting to feel like a subjective term in regard to the crank hub on these forums. So many thousands of tuned m's in this world, so few with a spun hub. And even fewer with a catastrophic failure... That said my cbc is being shipped as we speak.

[Boostd4]

Originally Posted by maddmatth

So rare though, could be assumed to be a crank bolt that wasn't tightened correctly from factory, and the ones I've seen have been fairly low mileage and taken care of under warranty
Whereas many have had this failure shortly after flashing a tune.

I think it's a mix of this as well as driving habits. You have the manual guys who can money shift the car and the DCT guys that abuse the kick-down feature. Then you have the drivers who hammer the pedal at very low RPMs. All things that will lead to mechanical failures in a turbocharged engine that can make ridiculous amounts of torque at very low RPMs.

From what I've been able to gather, it seems like one of the most common reasons why the crankhub fails is that the bolt backs out. Once you lose that mechanical tension, the friction disc can't do it's job. Now, BMW has had this design for many years (there is another thread that shows the actual designs of the past few generations) and the CH hasn't really been a factor.

The difference? Torque and sudden changes in torque. Now I'm sure there have been modified previous generation engines that have probably had the CH fail...but you're talking about a very small number since most of those cars stayed NA.

I guess what I'm trying to get to is that the CH issue isn't necessarily a design flaw, it just that it wasn't a design meant for high TQ engines...which is why the B58/S58 platform has this issue addressed.

[masab321]

I am in a similar situation with my stock 18’ F82 DCT. Sitting at 31k miles. I plan to keep the car. Warranty expiring next month. I have two options:

Should I keep the car stock and skip CH fix or just go ahead with stage 1 and CH upgrade. I am actually satisfied with stock performance but I am getting the “itch” to add stage-1 especially after listening to people who have tuned the car.

[rmanm4]

Originally Posted by masab321

I am in a similar situation with my stock 18’ F82 DCT. Sitting at 31k miles. I plan to keep the car. Warranty expiring next month. I have two options:

Should I keep the car stock and skip CH fix or just go ahead with stage 1 and CH upgrade. I am actually satisfied with stock performance but I am getting the “itch” to add stage-1 especially after listening to people who have tuned the car.

It is only a matter of time before you scratch that itch!!

Plan for the move before its too late!

[TopJimmy]

Originally Posted by masab321

I am in a similar situation with my stock 18' F82 DCT. Sitting at 31k miles. I plan to keep the car. Warranty expiring next month. I have two options:

Should I keep the car stock and skip CH fix or just go ahead with stage 1 and CH upgrade. I am actually satisfied with stock performance but I am getting the "itch" to add stage-1 especially after listening to people who have tuned the car.

If you suspect the power itch will grow past Stg1 then do the hub fix and CBC. If you have E85 nearby just do it now.

If you know Stg1 93 is your limit then a $100 CBC Plate is enough.

[Silverlining_m2]

Originally Posted by TopJimmy

If you suspect the power itch will grow past Stg1 then do the hub fix and CBC. If you have E85 nearby just do it now.

If you know Stg1 93 is your limit then a $100 CBC Plate is enough.

Having just tuned my car to stage 1 I'm very interested in this thread. Only doing the cbc and not the entire fix, but staying stage 1 91 oct, on 93 oct fuel. I'm dct but instead of "kick down" I just shift down sequentially 2-3 gears. And I don't dig race typically. I guess we will see what happens but bmw is installing my cbc from VTT as soon as it arrives.

[masab321]

Originally Posted by F82spaceship

Having just tuned my car to stage 1 I'm very interested in this thread. Only doing the cbc and not the entire fix, but staying stage 1 91 oct, on 93 oct fuel. I'm dct but instead of "kick down" I just shift down sequentially 2-3 gears. And I don't dig race typically. I guess we will see what happens but bmw is installing my cbc from VTT as soon as it arrives.

How much has bmw quoted for cbc?

[Silverlining_m2]

Originally Posted by masab321

How much has bmw quoted for cbc?

3-4 hours labor. My dealership charges $150/hr so the quote including tax was $666. They told me thats the high ball amount and they have always charged me less than the quote. I expect about $450-500.

[BzsBimmer]

BMW is installing it? Didn’t think they’d want the liability. Interesting.

[Silverlining_m2]

Originally Posted by BzsBimmer

BMW is installing it? Didn’t think they’d want the liability. Interesting.

Our local dealership if pretty mod friendly, as none of my bimmers have been in warranty. They have installed spacers and done an alignment together for me, and they are aware of my cars being tuned. I actually traded in my stage 2 435i (lowered on bilstein b14) to them when I got the m4, and they SOLD it as is! Catless and all to a young enthusiast who was looking for a jump start to the modding. They are definitely cool, and the SA i use is a master mechanic. He doesn't bs me, and they always come in under quote price. I read all these " stealership" stories and I'm definitely thankful for my place.