Crank Bolt Capture

[Smee]

can anyone explain to me how this CBC stops the bolt from unwinding?

not a trick question i am looking to purchase one but before i pulled the trigger something in my mind pinged and said no.

[Rotzy]

Originally Posted by Smee

can anyone explain to me how this CBC stops the bolt from unwinding?

not a trick question i am looking to purchase one but before i pulled the trigger something in my mind pinged and said no.

The crank bolt and the hub are two separate pieces. The bolt runs through the center of the hub and is heavily torqued. The faceplate of the hub has 8 threaded bolt holes that the crank pulley is mounted to. In addition, the head of the crank bolt protrudes approximately 3/4" - 1" past the face of the hub.

The Crank Bolt Capture encapsulates the head of the crank bolt and is secured to the faceplate of the pulley/hub using the 8 aforementioned bolt locations. This prevents the crank bolt from rotating independent of the hub (ie. backing out) but does not prevent a failure of the friction disks or possible stretching of the crank bolt. That is why it is only a partial solution.

[Smee]

Originally Posted by Rotzy

The crank bolt and the hub are two separate pieces. The bolt runs through the center of the hub and is heavily torqued. The faceplate of the hub has 8 threaded bolt holes that the crank pulley is mounted to. In addition, the head of the crank bolt protrudes approximately 3/4" - 1" past the face of the hub.

The Crank Bolt Capture encapsulates the head of the crank bolt and is secured to the faceplate of the pulley/hub using the 8 aforementioned bolt locations. This prevents the crank bolt from rotating independent of the hub (ie. backing out) but does not prevent a failure of the friction disks or possible stretching of the crank bolt. That is why it is only a partial solution.

Ok so the bolt can still back out of the crank but now instead of just the bolt backing out the hub and pulley would go with it?

[MR RIZK]

@smee I think you need to look at the etk to see how it goes together as this should clear it up for you along with @rotzy description.

http://www.realoem.com/bmw/enUS/show...diagId=11_5597

[Rotzy]

Originally Posted by Smee

Ok so the bolt can still back out of the crank but now instead of just the bolt backing out the hub and pulley would go with it?

In a way, yes, but the only way the hub and pulley are coming out with the CBC installed is if you spin your crank hub (ie. the friction disks fail/crack or the bolt stretches reducing the clamping torque on the assembly.) In that case, the hub was going to spin with or without the CBC.

Remember, the bolt and hub normally spin as one clamped assembly. It's only when something fails (or the bolt backs out) that they shift (ie. momentarily spin independently), thus throwing off the timing.

[Smee]

many thanks. you 2 are a lot better at explaining than some others

so one more question does the hub get pressure fitted in to the hole in the end of the crank?

i.e if you took the bolt out does the hub simple fall off or do you need a to whack it off or pull it off with an extractor?

[MR RIZK]

I can only assume as have not performed this myself but based on what I have read and the TIS it is a snug fit not a pressure fit. The TIS says just pull it out by hand with two of the damper bolts reattached to get grip.

[ssgm1x]

Originally Posted by Smee

Ok so the bolt can still back out of the crank but now instead of just the bolt backing out the hub and pulley would go with it?

I believe the majority of Spun Hubs occur when the Crank Bolt comes loose. The Capture just prevents the bolt from coming loose, reducing the odds of a Spun hub.
The Capture costs about $450 installed (part included)

[FreeDarko]

Originally Posted by ssgm1x

I believe the majority of Spun Hubs occur when the Crank Bolt comes loose. The Capture just prevents the bolt from coming loose, reducing the odds of a Spun hub.
The Capture costs about $450 installed (part included)

But has there been a case on this forum atleast where the CBC was installed and something related to crank hub failed.

[Smee]

Originally Posted by FreeDarko

But has there been a case on this forum atleast where the CBC was installed and something related to crank hub failed.

Can you get the link please cos I hadn't seen one. Didn't think there was any evidence of a failure with just a capture

[MR RIZK]

Originally Posted by Smee

Can you get the link please cos I hadn't seen one. Didn't think there was any evidence of a failure with just a capture

I think u are mis reading the post and swapping the words "has and there" around. I believe the poster is asking if there are any failures recorded with the CBC installed. Ie the same answer u are chasing.

[FreeDarko]

Originally Posted by Smee

Can you get the link please cos I hadn't seen one. Didn't think there was any evidence of a failure with just a capture

Sorry that was a question.

[Smee]

Originally Posted by FreeDarko

Sorry that was a question.

was early in the morning lol sorry

[Rotzy]

Originally Posted by FreeDarko

But has there been a case on this forum atleast where the CBC was installed and something related to crank hub failed.

Nothing that I’ve seen yet, and that gives me hope, but that doesn’t mean we’re 100% safe with just the CBC.

There is at least one user who had 2 SCHs before installing the CBC and has been good since.

There is also another user that posted not too long ago who was doing a preemptive crank hub upgrade. The shop found a deformed and broken friction disk during disassembly. His hub was a ticking time bomb that would not have been saved with a CBC.

[Beemerm3]

I just got my cbc installed at svbimmer. Haven't drove the car since then. Stock zcp. Out of warranty.

[tanzm4_]

How much did they charge you guys (sv bimmer)

[Beemerm3]

About 600$ forgot. I had to get an alignment too. Which was expensive lol.

[techlogik]

Originally Posted by Bmwlmr99

They run these cars hard for an hour or more , some 24hr events....downshifting and upshifts constantly...no issues with sch

Yes, and they can just put another engine sitting in the crate in the garage in after each race if they want. Or did they say they run the same engine forever and the entire season?

[techlogik]

The problem with the spline setup IMHO is the spline is supposed to "tighten" and hold better if the crank and gears experience spin. If that is the case, then the timing will then be off as it tightens. There is micro slippage and movement. Thought that was their design explanation instead of a key?

Many engine builders will suggest keyed shaft setups. Better than what BMW did for whatever stupid reason. Engineers should be fired for that dumb idea.

But still, that works sort of like a shear pin. It can shear and fail. Just ups the limit it takes to do it. Better idea when running ok mods and higher power. Some insurance there. But 4k for that and hours? Ouch.

I think the inexpensive plate with reasonable boost stage 1 this is a good reasonable solution. If you are going to run Stage 2 and up and drag racing, launching with DCT, then you should reinforce with something better than the plate. But wow, again, the cost for something that shouldn't have been an issue to begin with is hard to swallow and understand.

So either be prepared for the worse case and have $$$, or just move on to another car....sad.

[Beemerm3]

My car is going to have 200k miles mpe exhaust. Bm3 stage 1 tune. Only cbc. Ftw. Lol

[Chris@VargasTurboTech]

Originally Posted by techlogik

The problem with the spline setup IMHO is the spline is supposed to "tighten" and hold better if the crank and gears experience spin. If that is the case, then the timing will then be off as it tightens. There is micro slippage and movement. Thought that was their design explanation instead of a key?

Many engine builders will suggest keyed shaft setups. Better than what BMW did for whatever stupid reason. Engineers should be fired for that dumb idea.

But still, that works sort of like a shear pin. It can shear and fail. Just ups the limit it takes to do it. Better idea when running ok mods and higher power. Some insurance there. But 4k for that and hours? Ouch.

I think the inexpensive plate with reasonable boost stage 1 this is a good reasonable solution. If you are going to run Stage 2 and up and drag racing, launching with DCT, then you should reinforce with something better than the plate. But wow, again, the cost for something that shouldn't have been an issue to begin with is hard to swallow and understand.

So either be prepared for the worse case and have $$$, or just move on to another car....sad.

Spline lock V2 is straight cut splines, pressed in. Zero reported failures or slip, it's far more aggressive than the original spline lock.

https://f80.bimmerpost.com/forums/sh....php?t=1621073

Chris

[ASRman]

VTT said V1 wouldn't slip. And took people's money on the basis it was a crank hub fix. Plenty of V1s have now slipped. Why should anyone trust that V2 will be any different. Gintani or Max PSI all the way.