[F87source]

Originally Posted by chris719

This is pure speculation, it is most likely not as simple as the bolt backing out over time. Listen to F87source on this.

I have alot to say about the bolt backing out theory as well, but first let me say I just watched the video about the precision dynamic crank hub and I still don't know how I feel about it. I like how beefy the key is so that is really nice and it is supposedly a bi directional lock on two axis because of how it cuts, but it only has one key. This combined with the fact that the key can be cut bigger has me worried for a few reasons:

1) If you rely on its ability to "mushroom" in a bigger hole you have regions of high pressure and low pressure due to uneven contact. This can cause material fatigue and failure over time. Also I am not totally clear on how it locks in but I am worried about play, and any play at all means timing failure because timing is very very precise. But that is why the pinned hubs have exact drill bit to pin diameter.

2) It is not symmetrical, and with the fact that you cut a bit more material out than you need it could cause imbalances. This also concerns me.



Now in regards to the bolt backing out, I put alot of fricken time and thought into this after talking to Megator this summer and here is what I think:

like I said before every RPM increase from downshifts etc causes a counter clockwise torque to be applied on the hub from the inertia of all the things that the hub drives (oil pump, timing components, water pump - for the s55, and all the serpentine belt driven components). This acts over a short period of time so the effect (impulse) is even bigger essentially acting like an impact driver which uses this concept to break high torque bolts easier.

Now since the only contact between the hub and the crank bolt is by the head of the bolt (there are no threads inside of the crank hub) the only way for the bolt to be backed out is if the hub spins, because that is the only way friction can be applied to it. Maybe the fact that the crank speeding up can also apply a torque to the bolt due to its own inertia while it too speeds up but that would be so small it wouldn't be a concern. So what I think is it is more likely for the friction disks to break loose compared to the bolt coming loose, because if the bolt were to come loose the whole hub would have to spin too.

So that is a reason why I sold the CBC to my friend who wanted one, and I never bought another one after that. Also with a CBC if the hub spins and it would normally not loosen the bolt (maybe not enough friction with the head of the bolt and the surface of the hub idk) the CBC would actually spin the bolt loose because now it is all one piece. So that was another concern of mine. Paired that with the fact that the n55 really doesn't see many issues with spinning crank hubs (again due to less stuff being driven off of the crank hub - aka electric water pump vs. mechanical, and less load on the crank hub due to the chain driven vaccum pump as there is only 1 hpfp attached to it) I am not too worried.


But we do see S55 guys who have experienced alot of spun crank hubs over and over again see it stop with a CBC so I am not sure what to really think about the bolt coming loose. But all in all since I have an N55 I am not too too concerned.

[doughboy]

I though about it a lot too and also posted an analysis about the counter clockwise torque reaction on downshift / rev increases only.

But if this was the only cause then tuning would have no bearing on it. A 800hp M3 doesn't downshift any quicker than a stock one. So the rate of change of RPM would be the same, unless they changed the clutch / flywheel etc for a lighter one but that's a whole different can of worms..

So there must be other vibrations / oscillations at play related to power output.

But anyway, i had similar thoughts to you about the CBC (which i have the UK Litchfield one fitted on my S55).

I had a different theory. As you say if the hub slips the bolt doesn't, but if the hub slips it only moves a small amount still under enormous friction from the clamping arrangement. The bolt is incredibly tight and requiring over 600nm to undo so I'm hoping the cbc will just hold the hub to the bolt if that makes sense?

[F87source]

Originally Posted by doughboy

I though about it a lot too and also posted an analysis about the counter clockwise torque reaction on downshift / rev increases only.

But if this was the only cause then tuning would have no bearing on it. A 800hp M3 doesn't downshift any quicker than a stock one. So the rate of change of RPM would be the same, unless they changed the clutch / flywheel etc for a lighter one but that's a whole different can of worms..

So there must be other vibrations / oscillations at play related to power output.

But anyway, i had similar thoughts to you about the CBC (which i have the UK Litchfield one fitted on my S55).

I had a different theory. As you say if the hub slips the bolt doesn't, but if the hub slips it only moves a small amount still under enormous friction from the clamping arrangement. The bolt is incredibly tight and requiring over 600nm to undo so I'm hoping the cbc will just hold the hub to the bolt if that makes sense?

I can't remember what you said about this issue before so could you tag me in that post or summarize it?

But the thing is even if an 800 horse power m3 doesn't down shift quicker it will definitely be able to rev faster and more agressively than a stock m3 and in any gear once boost kicks in. This will also be a factor in spinning the hub. So now you also have the factor of every acceleration causing more stress along with every down shift.

In terms of vibrations compared to stock there probably will be more but I don't know how much in regards to the harmonics that's capable of shaking the bolt loose. There also shouldn't be any (or too much) detrimental harmonics because that would damage the engine, and the inline 6's natural balance + the damper should stop all of this.


Yes that makes sense I understand what you're saying, but I don't like the idea of having the bolt hold the hub via the CBC. My thoughts would be if you rely on the bolt holding the hub via the CBC one of the following could happen:

1) the hub spins and loosens the bolt (via the CBC as it is all one unit now), because the spin is just so agressive due to a heavy down shift of multiple gears from a very low rpm (1-2k high way crushing) to a high rpm (near redline) due to kick down.

2) the crank bolt just gets rounded by the capture. Let me clarify this, since the crank bolt already has rounded edges over time the hammering if the cbc could damage it and round it out. I doubt this is a high possiblity because the bolt itself can take so much torque and the CBC fits quite nicely but who knows, maybe when it starts rusting it'll be a higher possiblity.

3) the bolt is tight enough to stop the spin but now the hubs friction disk is compromised and the timing gear spins.

4) the bolt is tight enough to stop the spin and the friction disk is strong enough to stop the timing gear from slipping. But now everytime the force that would cause the hub to spin is being transmitted to the bolt like an impact driver which over time will loosen the bolt and the failure would be even worse than just having the hub or gear slip on its own.

[chefczyk]

I'm in the "its really fast stock" camp - don't know about you all but speed limits are usually 45-70 on roads in VA. I rather have "that feeling" for a longer period of time (e.g. slower car) as I speed up on a highway off-ramp, etc.

My opinion would be to tackle some suspension / tire mods and enjoy it on a track? It already loses so much traction (stock) - the add'l power honestly seems useless on the street (and I'm not good enough on the track to harness it).

[M2_MEDUSA]

Sad part is, I take delivery in less than a week so in all honesty I’ll do everything to not void the warranty. By the time I’m ready roughly 40k miles I’ll go ahead and toss on a upgraded crankhub. By that time there will be enough R&D with the precision dynamics hub for me to fully decide. Also @f87source what’s your take and opinion on the VTT spline lock v2? What’s a spline lock and how does it differ from the upgraded drilled crankhub. Much cheaper and ive gotten quoted 2,000$ Thanks !

[F87source]

Originally Posted by SpecialEdition_F87

Sad part is, I take delivery in less than a week so in all honesty I’ll do everything to not void the warranty. By the time I’m ready roughly 40k miles I’ll go ahead and toss on a upgraded crankhub. By that time there will be enough R&D with the precision dynamics hub for me to fully decide. Also @f87source what’s your take and opinion on the VTT spline lock v2? What’s a spline lock and how does it differ from the upgraded drilled crankhub. Much cheaper and ive gotten quoted 2,000$ Thanks !

Well my take is that the v2 with striaght splines are much better than the v2, and there is now proof it cuts into the crank shaft.

My next thoughts are that splines are designed to take torque hence why transmission input shafts, half shafts, etc are splines and not pinned. So straight off the bat I lresdy like the spline lock concept more. However I do not know if the crank shaft material is cut deep enough so that the splines will not deteriorate if it needs to be used, so far vtt has said it has broken a crank shaft before it slipped and no v2 had failed. So I'm confident enough it works well. So if it was my car I'd go with a SPLOCK over all other options.


There was a guy online that made a SPLOCK with pins as a hybrid setup, and that would be even better imo. But he was an unknown guy so I don't know if that's even trustworthy. But the best solution imo would be to have a tool to cut deep splines that would match the SPLOCK, and also have pins.

[M2_MEDUSA]

I’ve weighed out my options and only going with a CBC considering it’s only about 500-700$ installed. Also there’s been zero issues with any CBC failing under 600whp. If you plan to go upgraded turbo then spline lock v2 is worth it for me I won’t be going over 600 so it makes no sense to drop 4k. Crank bolt capture is all you need under 600. Just do it quick enough preferably low miles because you’ll only be stopping it at the point of where it’s currently at. But no failures under 600 is a strong buy for $700 installed

[F87source]

Originally Posted by SpecialEdition_F87

I’ve weighed out my options and only going with a CBC considering it’s only about 500-700$ installed. Also there’s been zero issues with any CBC failing under 600whp. If you plan to go upgraded turbo then spline lock v2 is worth it for me I won’t be going over 600 so it makes no sense to drop 4k. Crank bolt capture is all you need under 600. Just do it quick enough preferably low miles because you’ll only be stopping it at the point of where it’s currently at. But no failures under 600 is a strong buy for $700 installed

Why don't you self install it? Then it would only be $50 with the CBC going on sale during black friday.

The install is relatively easy, so it would make sense.


Also a CBC is not a fool proof solution, it can still spin regardless of CBC or not. We have not seen a spin with a CBC but that does not mean it cannot happen.


You also simply cannot put a power level on when a CBC will fail or not, because the friction disk can easily give out and you will have the timing gear slip.

[M2_MEDUSA]

Originally Posted by F87source

Why don't you self install it? Then it would only be $50 with the CBC going on sale during black friday.

The install is relatively easy, so it would make sense.


Also a CBC is not a fool proof solution, it can still spin regardless of CBC or not. We have not seen a spin with a CBC but that does not mean it cannot happen.


You also simply cannot put a power level on when a CBC will fail or not, because the friction disk can easily give out and you will have the timing gear slip.

Negative so I’ve talked with vtt and they are in the field seeing things we don’t see in the forums and they’ve mentioned although not a complete solution they’ve never seen a single CBC fail below 600whp. That to me is data that is tried and true.

Your best bet is like I said do it low miles. If your low miles you’ll be installing the CBC on a crank bolt that hasn’t moved at all or very minimal amounts. The fact that there’s guys with high miles doing CBC and still after all this time not a single hub spun under 600 tells me yes! Yes absolutely we can put a power number on it !

[Megator]

Originally Posted by SpecialEdition_F87

Negative so I’ve talked with vtt and they are in the field seeing things we don’t see in the forums and they’ve mentioned although not a complete solution they’ve never seen a single CBC fail below 600whp. That to me is data that is tried and true.

Your best bet is like I said do it low miles. If your low miles you’ll be installing the CBC on a crank bolt that hasn’t moved at all or very minimal amounts. The fact that there’s guys with high miles doing CBC and still after all this time not a single hub spun under 600 tells me yes! Yes absolutely we can put a power number on it !

Aftermarket companies will tell you whatever you want to hear so you buy their stuff.. VTT has a mixed reputation at best so not sure how much I would trust them.

Here is a CBC that failed on a stock turbo car. I think people need to realize that for stage 0/1/2 a spun crankhub is a royal flush level of un/luck not a pair level of un/luck. Doubly so to have catastrophic damage from a SCH.

CBC is unproven either way. all we have are speculaiton and companies selling us stuff telling us "it works!". I have to think that if the solution was this simple BMW would have implemented it already, as it would cost them peanuts and save a ton on warranty costs.

For these reasons I am not touching the crank hub.

Let others with crank hub fixes pile on the miles and lets hope they come out with thier positive and negative stories and that the negative stories don't get buried by companies that won't accept fault.

[NathObeaN]

Originally Posted by Megator

Aftermarket companies will tell you whatever you want to hear so you buy their stuff.. VTT has a mixed reputation at best so not sure how much I would trust them.

Here is a CBC that failed on a stock turbo car. I think people need to realize that for stage 0/1/2 a spun crankhub is a royal flush level of un/luck not a pair level of un/luck. Doubly so to have catastrophic damage from a SCH.

CBC is unproven either way. all we have are speculaiton and companies selling us stuff telling us "it works!". I have to think that if the solution was this simple BMW would have implemented it already, as it would cost them peanuts and save a ton on warranty costs.

For these reasons I am not touching the crank hub.

Let others with crank hub fixes pile on the miles and lets hope they come out with thier positive and negative stories and that the negative stories don't get buried by companies that won't accept fault.

Interesting pictures although the damage would suggest the capture plate did prolong the life... those wear marks would be a result of repeated high-torque of the bolt attempting to spin out, in turn pushing the smaller bolts around it. If the plate wasn't in place, no doubt it would have spun a lot sooner and potentially more damaging?

[AmooManiak]

Originally Posted by Megator

Aftermarket companies will tell you whatever you want to hear so you buy their stuff.. VTT has a mixed reputation at best so not sure how much I would trust them.

Here is a CBC that failed on a stock turbo car. I think people need to realize that for stage 0/1/2 a spun crankhub is a royal flush level of un/luck not a pair level of un/luck. Doubly so to have catastrophic damage from a SCH.

CBC is unproven either way. all we have are speculaiton and companies selling us stuff telling us "it works!". I have to think that if the solution was this simple BMW would have implemented it already, as it would cost them peanuts and save a ton on warranty costs.

For these reasons I am not touching the crank hub.

Let others with crank hub fixes pile on the miles and lets hope they come out with thier positive and negative stories and that the negative stories don't get buried by companies that won't accept fault.

I like this. Coming from having multiple N63 platform cars, I can tell you that you only hear from the 0.0001% of owners that have some sort of issue. You will never see a random post about how reliable a car is. Chances are higher that something else will break before you even have to think about the crank hub.

BMW engineered these cars, and if a fix was as simple as a redesign, they would have already implemented it a long time ago. Just drive it like it's meant to be driven. I feel a lot more confident with these engines than with the N63 (which has a higher failure rate), and I barely had any issues with that engine over multiple cars and over 8 years.

[Megator]

Originally Posted by NathObeaN

Interesting pictures although the damage would suggest the capture plate did prolong the life... those wear marks would be a result of repeated high-torque of the bolt attempting to spin out, in turn pushing the smaller bolts around it. If the plate wasn't in place, no doubt it would have spun a lot sooner and potentially more damaging?

Well, I am not so sure about that.

The circle imprint on the plate is likely from it being soft aluminium and a hard steel bolt with ribs digging into it uppon initial assembly.

Its hard to tell if the ovaled part of the bolt imprints occurred progressively or instantly when it failed.

The bolts seem to have a mix of straight up sheared bolts and some that have shoring marks (left most in the row of 4 for example) indicating flexing on the bolts before they sheared. Without seeing the bolt in person its hard to tell if this happened over a ton of cycles or 4-10 cycles.

All in all, its hard to tell if it went in one go or progressively.

In any case the only way to get the CBC bolts to rotate relative to crank bolt is if the crank bolt is no longer holding the crank hub in place.

This would indicate that the preload on the crank bolted joint had already gone before the CBC bolts broke. Remember that the CBC does nothing to fix the crank bolt to the crank. The crank hub is still only held onto the crank by the friction between the various hub components. The friction force is a factor of the preload generated by the crank bolt. The only thing a CBC does is make the crank bolt not rotate with respect to the crankhub. The crankhub is in no way keyed to the crank (hence all these aftermarket alternatives).

Why the preload on the crank bolted joint decreases till it could loosen itself is unclear.

My theory is that the parts + assembly tolerance stack up creates a (rare) situations where one gets insufficient preload in the crank bolted joint, allowing the friction disks to rub and wear, leading to SCH. This is a difficult to analyse and remedy situation.

Coming back to the CBC, in this case the guy said it led to total engine damage. I am not surprised as once the preload in the crank bolt is gone, the crank hub is free to spin with respect to the crank. The crank hub is running all the accessories which "brake" the crank hub.

As the crank hub goes "backwards" the CBC also starts to undo the crank bolt, further reducing preload, causing more backing out, etc to the point where everything can move "freely”, and valves meet pistons.

Without the CBC, you don’t have all this mass undoing the joint and the shock will be smaller. Meaning that the crank hub joint might survive a little slip without it being catastrophic (but defo needing to be fixed). Multiple people have had SCH with the car only needing a retime.

[F87source]

Originally Posted by Megator

Well, I am not so sure about that.

The circle imprint on the plate is likely from it being soft aluminium and a hard steel bolt with ribs digging into it uppon initial assembly.

Its hard to tell if the ovaled part of the bolt imprints occurred progressively or instantly when it failed.

The bolts seem to have a mix of straight up sheared bolts and some that have shoring marks (left most in the row of 4 for example) indicating flexing on the bolts before they sheared. Without seeing the bolt in person its hard to tell if this happened over a ton of cycles or 4-10 cycles.

All in all, its hard to tell if it went in one go or progressively.

In any case the only way to get the CBC bolts to rotate relative to crank bolt is if the crank bolt is no longer holding the crank hub in place.

This would indicate that the preload on the crank bolted joint had already gone before the CBC bolts broke. Remember that the CBC does nothing to fix the crank bolt to the crank. The crank hub is still only held onto the crank by the friction between the various hub components. The friction force is a factor of the preload generated by the crank bolt. The only thing a CBC does is make the crank bolt not rotate with respect to the crankhub. The crankhub is in no way keyed to the crank (hence all these aftermarket alternatives).

Why the preload on the crank bolted joint decreases till it could loosen itself is unclear.

My theory is that the parts + assembly tolerance stack up creates a (rare) situations where one gets insufficient preload in the crank bolted joint, allowing the friction disks to rub and wear, leading to SCH. This is a difficult to analyse and remedy situation.

Coming back to the CBC, in this case the guy said it led to total engine damage. I am not surprised as once the preload in the crank bolt is gone, the crank hub is free to spin with respect to the crank. The crank hub is running all the accessories which "brake" the crank hub.

As the crank hub goes "backwards" the CBC also starts to undo the crank bolt, further reducing preload, causing more backing out, etc to the point where everything can move "freely”, and valves meet pistons.

Without the CBC, you don’t have all this mass undoing the joint and the shock will be smaller. Meaning that the crank hub joint might survive a little slip without it being catastrophic (but defo needing to be fixed). Multiple people have had SCH with the car only needing a retime.

I think it was a clockwise spin not counter clockwise as judged by the shear marks on the cbc. So I think it was just a sudden spin of the crank hub which caused this. In this case it wouldn't have loosened the crank bolt but since the whole hub spun likely damage was inevitable, compared to just the friction disk spinning a bit.


Oh and also I think the only way to make the CBC unbreakable is to have it made of titanium (so corrosion doesn't get to it unlike steel), and have grade 12.9 bolts or maybe even titanium bolts. But at that point the crank bolt might get rounded and the hub itself might break due to the forces from the bolts. Who knows...

But if I had a say in designing a hub it would be splined and pinned (with a spline tool to cut deeper splines and a tool that has a longer drill bit guide so there would be no way that a shop can drill the pins in crooked). This would make it bullet proof and even if the bolt came loose it wouldn't be able to spin.

[F87source]

Originally Posted by SpecialEdition_F87

Negative so I’ve talked with vtt and they are in the field seeing things we don’t see in the forums and they’ve mentioned although not a complete solution they’ve never seen a single CBC fail below 600whp. That to me is data that is tried and true.

Your best bet is like I said do it low miles. If your low miles you’ll be installing the CBC on a crank bolt that hasn’t moved at all or very minimal amounts. The fact that there’s guys with high miles doing CBC and still after all this time not a single hub spun under 600 tells me yes! Yes absolutely we can put a power number on it !

Like megator said, I wouldn't trust what vendors say fully. And there are many other CBC's available with only a small fraction of CBC users being on the forum you don't know how many people out there still had failures with a CBC in place.

Also VTT themselves said the CBC is not a full solution, it will only prevent one potential part of the problem which is the bolt coming loose, but if the friction disk fails and the timing gear spins or the whole hub spins then it won't matter if you have a cbc or not.




BTW a better method to monitoring your bolt for spinning is to make a witness mark on it just like you would do after torquing a bolt. You can use the cross check torque seal stuff that forms a line that will break if the bolt moves. This is way better than constantly touching the bolt.

[M2_MEDUSA]

Originally Posted by Megator

Aftermarket companies will tell you whatever you want to hear so you buy their stuff.. VTT has a mixed reputation at best so not sure how much I would trust them.

Here is a CBC that failed on a stock turbo car. I think people need to realize that for stage 0/1/2 a spun crankhub is a royal flush level of un/luck not a pair level of un/luck. Doubly so to have catastrophic damage from a SCH.

CBC is unproven either way. all we have are speculaiton and companies selling us stuff telling us "it works!". I have to think that if the solution was this simple BMW would have implemented it already, as it would cost them peanuts and save a ton on warranty costs.

For these reasons I am not touching the crank hub.

Let others with crank hub fixes pile on the miles and lets hope they come out with thier positive and negative stories and that the negative stories don't get buried by companies that won't accept fault.

Hey look it’s the crank bolt capture that failed on a car that was revved to 9k and money shifted that doesn’t count and Nope not at all, VTT was fighting that you need a CBC and a spline lock for months. VTT actually corrected their mistake over a year later stating they’ve never seen a failure under 600whp. Which they wouldn’t admit before. No sale here if anything VTT only wants to sell their high dollar products which I don’t believe is neccasary. The only failures so far have been cars over 600whp and money shifted cars. If your under 600 your good to go.

I’ll say it again, VTT fought us for months on why just a crank bolt capture is wrong. They could never provide us with proof and everytime we’d ask it would be “ we’ve heard “ never any results just upsale talk. They kept trying to tell us we needed both. Show me where they backed their products? They didn’t they only attempted to upsale to an un needed spline locks.

Still no proof of any car failure on under 600 and not money shifted everyone just says I know a guy for me CBC is all I need and after over a year VTT finally admitted it as well because data showed true.

Let me say if you put a CBC on a car that’s about to go it’ll only hold it’s position where it’s currently at. Which is why I’m doing CBC after break in and calling it good.

[chris719]

I know it's boring, but for my money, I'm leaving S55 stock until its out of warranty. I'd never put CBC on a stock car, you're just asking them to deny any engine warranty claim. If you're going to tune it then I might consider it, sure.

[F87source]

Originally Posted by chris719

I know it's boring, but for my money, I'm leaving S55 stock until its out of warranty. I'd never put CBC on a stock car, you're just asking them to deny any engine warranty claim. If you're going to tune it then I might consider it, sure.

Also a cbc is designed to prevent the crank bolt from coming loose, that would imply that any pinned hub solution would have failed over time (as more and more stress gets put onto the pins which were not designed to hold the entire hub but just add extra retention strength to the friction disk like a keyed hub would) because the crank bolt would eventually loosen. This hasn't happened so it's a counter to is a cbc really effective?

Imo it could even add risk because it can loosen the crank bolt if it spins because now they are one fixed unit. I know on another forum when vtt was asked that question they couldn't answer it. So that's what left me with the doubt that prevented me from buying another one last year.

[M2_MEDUSA]

Originally Posted by F87source

I can't remember what you said about this issue before so could you tag me in that post or summarize it?

But the thing is even if an 800 horse power m3 doesn't down shift quicker it will definitely be able to rev faster and more agressively than a stock m3 and in any gear once boost kicks in. This will also be a factor in spinning the hub. So now you also have the factor of every acceleration causing more stress along with every down shift.

In terms of vibrations compared to stock there probably will be more but I don't know how much in regards to the harmonics that's capable of shaking the bolt loose. There also shouldn't be any (or too much) detrimental harmonics because that would damage the engine, and the inline 6's natural balance + the damper should stop all of this.


Yes that makes sense I understand what you're saying, but I don't like the idea of having the bolt hold the hub via the CBC. My thoughts would be if you rely on the bolt holding the hub via the CBC one of the following could happen:

1) the hub spins and loosens the bolt (via the CBC as it is all one unit now), because the spin is just so agressive due to a heavy down shift of multiple gears from a very low rpm (1-2k high way crushing) to a high rpm (near redline) due to kick down.

2) the crank bolt just gets rounded by the capture. Let me clarify this, since the crank bolt already has rounded edges over time the hammering if the cbc could damage it and round it out. I doubt this is a high possiblity because the bolt itself can take so much torque and the CBC fits quite nicely but who knows, maybe when it starts rusting it'll be a higher possiblity.

3) the bolt is tight enough to stop the spin but now the hubs friction disk is compromised and the timing gear spins.

4) the bolt is tight enough to stop the spin and the friction disk is strong enough to stop the timing gear from slipping. But now everytime the force that would cause the hub to spin is being transmitted to the bolt like an impact driver which over time will loosen the bolt and the failure would be even worse than just having the hub or gear slip on its own.

The crank bolt isn’t going anywhere near ever rounding with a CBC I’ll tell you that right now lol.

[M2_MEDUSA]

Everyone needs to follow the data on this one. You plan to run aggressive e85 and then eventually upgraded turbos do a spline lock and CBC. You plan to tune on pump CBC all you need. Done deal. Best part about it. CBC job is about $500-600 parts included. When you wanna upgrade your turbos or run aggressive e85 pop on the spline. If you wanna tune aggressive on pump gas and fbo a CBC is more than enough. Data has proven this. Under 600 CBC is all you need.

[jdub486]

One on the m2 competition FB group today where the bolt was fine but the friction disk failed.

[M2_MEDUSA]

Originally Posted by jdub486

One on the m2 competition FB group today where the bolt was fine but the friction disk failed.

Post the link. Let’s see it. What was the power level? What mileage did he get the job done at?

CBC should be done at relatively low miles on 91.

If you get the job done “ after warranty “ or before hell the longer you wait the worse off you are. 200nm is what the bolts at if you install the CBC when the bolt is at 160nm backed out your just holding the bolt from going further. Less force on friction disks.

Send the link let’s see this post