Crank Bolt Capture and still spun crank hub?

[byebyev8]

Has anyone with the Crank Bolt Capture still spun the Crank hub? I know for sure I'll be FBO e85 and hoping for 130+ traps. I'm going to be replacing my 11sec e92 i had for 6 years with either a m4, m6 or c7 vette. Leaning towards the m4 since i can drive that year round and get rid of my f10msport.

[jpy1980]

https://f80.bimmerpost.com/forums/sh....php?t=1597456

[ssgm1x]

Originally Posted by byebyev8

Has anyone with the Crank Bolt Capture still spun the Crank hub? I know for sure I'll be FBO e85 and hoping for 130+ traps. I'm going to be replacing my 11sec e92 i had for 6 years with either a m4, m6 or c7 vette. Leaning towards the m4 since i can drive that year round and get rid of my f10msport.

I have heard of Zero incidents of spinning it with Stock Hub and Crank Bolt Capture.
I myself am running E85+Meth with many passes at the strip and many many dragy runs with the Crank Bolt Capture on stock hub.

[Msm1984]

Originally Posted by ssgm1x

I have heard of Zero incidents of spinning it with Stock Hub and Crank Bolt Capture.
I myself am running E85+Meth with many passes at the strip and many many dragy runs with the Crank Bolt Capture on stock hub.

I am considering just doing the cbc and I have a hub upgrade next to me waiting to get installed next week.

I am thinking about making a poll here to find out how many people got a CBC only and how many have spun with a tune and how many miles they have done since installing it.

[papasmurf_m3]

Originally Posted by ssgm1x

I have heard of Zero incidents of spinning it with Stock Hub and Crank Bolt Capture.
I myself am running E85+Meth with many passes at the strip and many many dragy runs with the Crank Bolt Capture on stock hub.

Nice 👍🏻 I'm going to install the CBC before I go e85 600/630 power levels at the wheels.

[Rokoz]

Originally Posted by ssgm1x

I have heard of Zero incidents of spinning it with Stock Hub and Crank Bolt Capture.
I myself am running E85+Meth with many passes at the strip and many many dragy runs with the Crank Bolt Capture on stock hub.

DCT? Do some kick downs for science please

[Azurite_F80]

Originally Posted by ssgm1x

I have heard of Zero incidents of spinning it with Stock Hub and Crank Bolt Capture.
I myself am running E85+Meth with many passes at the strip and many many dragy runs with the Crank Bolt Capture on stock hub.

I know I am resurrecting this from the dead a little bit.. but who did your install ssgm1x? Any issues in the last year? I live in Haddon Heights btw, good to see some more super local presence here.

[papasmurf_m3]

I got a deal for VTT V2 full solution installed that I could not pass up. So, I'm running that since I've been running flex fuel. My kill map is E85 and I send it dig or rolls no issues here. Love it!

[Twistm4]

My car has cbc, traps 134-136 and does a lot of digs.

Think the trans is gonna go before that nonsense slips.

[Hoppyumr]

I actually started a thread earlier today but my phone killed my post, and haven't had time to get back to it; then I found this...

So my concern is that the hub is attached to the crank through the friction rings and sprockets and then through the hub to the harmonic balancer where the crank bolt capture is - assuming the sprockets aren't pinned or the like, the crank bolt capture still only relies on friction, and it seems that adding the attentional rotational mass is technically not a good thing. I understand the thought is that the hub stays in position with the bolt, but that still just relies on friction, and then one of the sprockets is still "loose" (via friction rings). That said, i know one of the sprockets is the timing chain, but I don't know what the other does and technically don't know which sprockets is the timing (inner or outer).

I do, however, like hearing that people running crazy power haven't had trouble, but is that absolute? Also, I like hearing the work is only a few hours to install. Would they FOR SURE have had problems if they didn't CBC it and ran the HP they are, or are we talking coincidence since the failure rather is generally so small anyway??

Clearly the best would be a male/female splined hub to crank interface with splined sprockets slid on the crank hub, and the the crank bolt capture keeping all nice and snug.

Can someone explain to me the splined crank hub solution out there? What are the splines supposed to interface with to keep it from slipping? I'm sure there aren't unused splines in the crank, so is it supposed to just be a mild interference fit that is supposed to be tapped in place?? If so, that's still friction, and I'd much rather see the use of keys or pins as we aren't really taking about power transfer, we're talking about maintaining position for the cams. Have there been any failures of any of the pinned solutions? I still think it's a little funny that people take a hand drill and imprecisely take weight out of the crankshaft on a precision built German engine running at 7500 rpm.

Sorry for the long post.

[Groganrocket]

I only have CBC and went yesterday and did about 10 kickdowns without any issues.

[jpy1980]

Originally Posted by Hoppyumr

I actually started a thread earlier today but my phone killed my post, and haven't had time to get back to it; then I found this...

So my concern is that the hub is attached to the crank through the friction rings and sprockets and then through the hub to the harmonic balancer where the crank bolt capture is - assuming the sprockets aren't pinned or the like, the crank bolt capture still only relies on friction, and it seems that adding the attentional rotational mass is technically not a good thing. I understand the thought is that the hub stays in position with the bolt, but that still just relies on friction, and then one of the sprockets is still "loose" (via friction rings). That said, i know one of the sprockets is the timing chain, but I don't know what the other does and technically don't know which sprockets is the timing (inner or outer).

I do, however, like hearing that people running crazy power haven't had trouble, but is that absolute? Also, I like hearing the work is only a few hours to install. Would they FOR SURE have had problems if they didn't CBC it and ran the HP they are, or are we talking coincidence since the failure rather is generally so small anyway??

Clearly the best would be a male/female splined hub to crank interface with splined sprockets slid on the crank hub, and the the crank bolt capture keeping all nice and snug.

Can someone explain to me the splined crank hub solution out there? What are the splines supposed to interface with to keep it from slipping? I'm sure there aren't unused splines in the crank, so is it supposed to just be a mild interference fit that is supposed to be tapped in place?? If so, that's still friction, and I'd much rather see the use of keys or pins as we aren't really taking about power transfer, we're talking about maintaining position for the cams. Have there been any failures of any of the pinned solutions? I still think it's a little funny that people take a hand drill and imprecisely take weight out of the crankshaft on a precision built German engine running at 7500 rpm.

Sorry for the long post.

Thoughtful post and I’m not one to usually say this on the forums, but please try searching for some crank hub threads as what you’re asking has been discussed ad naseum on this board. There are a couple of threads that come to mind but As I’m away from my comp, I can find it easily on my phone. Be warned as they are long threads but read it and see what conclusions come to mind after reading.

One key point in the splined hub is to message Chris at Vargas. They are the only company to make a splined hub and he can explain everything to you, more thoroughly than any of us.

I personally just run the CBC myself but I’m only tuned with the BM3 CS tune. There are no definite answers on which one is best and what exactly causes the issue, so you won’t find a satisfactory answer.

[MisterF80M3]

I wish we can pin this thread with 10+ pages of CBC discussion. This should be the master thread of CBC.

https://f80.bimmerpost.com/forums/sh....php?t=1597456

Went from BM3 stage 2 FBO to BM3 E30 to Cary Jordan E85 S2+ with just a CBC. Hub is still holding up fine.

[///BMW Junkie]

Installed CBC 12K miles ago before going custom 93 and full E85, plenty of 50-150 pulls - no issues. Upgraded to PS2+ and running just 93 past couple months, essentially same power as my stock turbo E85, still going strong!

[fiveohwblow]

Originally Posted by MisterF80M3

I wish we can pin this thread with 10+ pages of CBC discussion. This should be the master thread of CBC.

https://f80.bimmerpost.com/forums/sh....php?t=1597456

Went from BM3 stage 2 FBO to BM3 E30 to Cary Jordan E85 S2+ with just a CBC. Hub is still holding up fine.

Same journey, same results. I second this post on all accounts.

[jpy1980]

Originally Posted by fiveohwblow

Same journey, same results. I second this post on all accounts.

Yup! That’s the thread I posted on the initial response to this thread!

[White340]

I wonder how it could even spin when the crank bolt itself seems prevented from turning given the bracket that is surrounding it which is bolted on with 8 different bolts and the whole unit is spinning at the same speed. Can someone explain this to me?

[fiveohwblow]

Originally Posted by White340

I wonder how it could even spin when the crank bolt itself seems prevented from turning given the bracket that is surrounding it which is bolted on with 8 different bolts and the whole unit is spinning at the same speed. Can someone explain this to me?

The theory, because that’s all we have at this moment, is not the bolt or any extremity that spins, but rather the rapid speed of torque introduced causes the friction discs inside to spin just enough to allow it to lose alignment. It is a three piece, outside or pulley, oil pump gear and timing chain gear. The friction discs between the oil pump and timing chain gear “slip” thus causing the timing to be out of spec.

The value to the cbc is that it also relies on the theory that if the bolt, or high pressure from the high torque of the crank bolt loosens ever so slightly, it allows the friction discs to slip. Others such as myself have chosen to “risk” this theory being accurate and so far, despite he said she said they said stories, no one has come forward with legitimate prood the cbc hasn’t been suffice.

Someone please correct me if I am not stating it correctly.

[ckendri]

4400 miles, custom E85 from Cary Jordan, and a CBC only. Same story as the other guys.

[Gunzy]

I mean everyone who hasn't spun is going to post up and basically boast about not spinning. It's a chance happening with no rhyme or reason, I was stock ona. 6 speed and spun at 3k. It's not a, it's not gonna happen, it's a, it CAN happen. Just take it with a grain of salt.

[MisterF80M3]

Originally Posted by Gunzy

I mean everyone who hasn't spun is going to post up and basically boast about not spinning. It's a chance happening with no rhyme or reason, I was stock ona. 6 speed and spun at 3k. It's not a, it's not gonna happen, it's a, it CAN happen. Just take it with a grain of salt.

We aren't talking about stock. We are talking about if crank bolt capture will prevent spun crank hub.

[ckendri]

Originally Posted by Gunzy

I mean everyone who hasn't spun is going to post up and basically boast about not spinning. It's a chance happening with no rhyme or reason, I was stock ona. 6 speed and spun at 3k. It's not a, it's not gonna happen, it's a, it CAN happen. Just take it with a grain of salt.

Not all of us are boasting. I am just adding a data point to the scatter plot, and I completely agree that there is no conclusive evidence to the "why" it spins. There is a chance that anyone's hub will spin, and the only thing known for sure is that there is a chance a hub will spin. The CBC debate is a highly interesting one though. Personally, I think I would like to have a VTT splined hub and a CBC. However, I am testing the CBC theory. The scientific method requires repeatability, right?