Quote:
Originally Posted by F87source
I kept saying that....
Here's reality:
1) the chance of a spun crank hub is already really low
2) a majority of spun crank hub bmw owners aren't on the forums.
3) the chance of an owner being on the forum with a cbc and experienced a spun crank hub is low. Because it's a factor of 3 really improbable events having a cbc, being on the forum, and having a failure.
4) the chance of a stock car with a cbc is even lower because most stock guys don't mod, and most cbc owners have heavily modded cars.
So the probability of you seeing a stock car with a cbc reporting a failure on the forum is almost 0%. So saying it's a fact that the cbc is a guaranteed solution is statistically false.
The only way to say it's a fact is to have a proper control group and test group then determine via a chi squared test if the difference is statistically significant or sheerly due to chance. But that's impossible in this scenario, and the physics did of things still show that the friction disks can still be over come so the cbc is not a full solution, that much is clear unless your judgment is just deluded for a miracle solution due to fear of a pretty rare case of spinning your crank hub.
Imo if you're stock don't do anything let it spin (chances are it won't since it's pretty rare), and let warranty fix it for you.
Post warranty I'd still leave it stock sub 600 whp, at that power range spins are still rare and even if it does spin the chance it causes damage is so rare as well. So when it does spin get an upgraded hub, then add some blue loctite to the bolt and that guarantees there will be no vibrating loose (which is still unproven).
Personally I'd never get a cbc ever again even with an upgrade hub, I don't personally believe it does anything helpful. I believe it could add more detriments in that if the hub spins counter clockwise (again like I said earlier unlikely if the spin is timing chain induced because the friction disks likely can't exert that much force to the hub from the timing gears before it slips, but it can still happen if the serpentine belts exert the torque directly to the hub) then no you risk the cbc exacerbating the damage by loosening the crank bolt. Also every time the torque is exerted counter clockwise onto the hub it'll act like an impact wrench due to the high torque in a small time period, and if you have a cbc it'll transfer that impact effect to the crank bolt and over time can loosen the bolt. At least in theory that can happen.
So imo the added risks of a cbc is not worth it, especially since it is still unproven that the bolt vibrates loose.
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This was really informative. Thanks