Ultimate Spun Crank Hub (SCH) Poll: ALL Members Please Vote!

[JAI///M3]

Looks like your Reddit comments were removed. You’re likely to get better info here anyways. I would recommend starting a new thread here with your details

[jayk_007]

Originally Posted by JAI///M3

Looks like your Reddit comments were removed. You’re likely to get better info here anyways. I would recommend starting a new thread here with your details

it was not the crankhub. It was caused by the catless downpipes and midpipes, as Autozone showed that the car was freaking out because it was amitting too much gas.

[FrankMstein]

Keep in mind this is FAIL DATA ONLY CURRENT as of 7-28-23. 2015 includes 2014 and 2018 is 2018+. I only looked at this 5 ways from Sunday, not 6.
What does everyone think?

[FrankMstein]

I guess not much...

[ellipsis212]

It’s easier to read than the survey but I’m not sure this data shows much of anything. I’d want to know the probability that a car of a single model year and transmission type combination will fail given certain levels of tuning/fueling vs stock/never tuned, and whether that changes over time/mileage.

For all we know forum members are overwhelmingly enthusiast types who know about the kick down function and aggressively drive their cars regularly versus any non-forum driver so again I’m just unsure of the usefulness of this exercise.

[FrankMstein]

Your right it only samples the people here. My take is that they can all do it. No matter the trans/tune/mode/engine temp etc. Understanding what was going on is key before and during and people here will not going to own up to or know what happened.

[Kal_el]

I recently spun my hub shifting into second at a stop light going maybe 10MPH. It just happened. I took my car to Brother's Garage in Alexandria, VA for the Precision Dynamics CHUB.

I was stressed waiting on the leakdown test and thankfully no valves got hit.

It just happens.....

For context: 2016 6MT, FBO BM3 Stage 2 Flex Fuel.

But she's good now, rippin and runnin!

[FrankMstein]

Originally Posted by Kal_el

I recently spun my hub shifting into second at a stop light going maybe 10MPH. It just happened. I took my car to Brother's Garage in Alexandria, VA for the Precision Dynamics CHUB.

I was stressed waiting on the leakdown test and thankfully no valves got hit.

It just happens.....

For context: 2016 6MT, FBO BM3 Stage 2 Flex Fuel.

But she's good now, rippin and runnin!

What were you doing beforehand? Was the engine oil up to temp?

[FriedPiston]

Originally Posted by FrankMstein

Keep in mind this is FAIL DATA ONLY CURRENT as of 7-28-23. 2015 includes 2014 and 2018 is 2018+. I only looked at this 5 ways from Sunday, not 6.
What does everyone think?

Thank you! Adding this to the main post.

[Kal_el]

Originally Posted by FrankMstein

What were you doing beforehand? Was the engine oil up to temp?

I'm military. Drove three miles off installation nothing over 30.

Got right out side the gate at the light, turned green. I didn't take off fast at the light because it immediately dips so I shifted into second and started to hit the gas and it shot. Car turned off immediately

[FrankMstein]

Originally Posted by Kal_el

I'm military. Drove three miles off installation nothing over 30.

Got right out side the gate at the light, turned green. I didn't take off fast at the light because it immediately dips so I shifted into second and started to hit the gas and it shot. Car turned off immediately

Ok, sounds like you just got started on your trip. What was the previous drive like?

[KnighTT]

I just purchased a 2015 F82 DCT. 57k miles. The car is in excellent maintained condition, has full bolt on upgrades, and someone spent a great deal on the upgrades. The vehicle is not tuned from everything I can observe.

I took it on a three day Tail of the Dragon event and the car performed beautifully. Engine runs perfectly. So I do not believe there are any current CH issues.

My question is, before I start going down the path of doing the upgraded CH, is what are some ways to tell if the prior owner may have already had this job done on the car? I do not have access to the prior owner as the car was sold to Carmax, then the dealer I got the car from bought it from Carmax, then me. For the amount of time this issue has been around, and the car was modified by someone who spent a great deal of money, what are some signs to look for?

I plan on many more Dragan Rally's and track days, so I'm going to upgrade the crank hub before I put any kind of tune on the car. I'm just honestly wondering if maybe it already has been done.

[FrankMstein]

Originally Posted by KnighTT

I just purchased a 2015 F82 DCT. 57k miles. The car is in excellent maintained condition, has full bolt on upgrades, and someone spent a great deal on the upgrades. The vehicle is not tuned from everything I can observe.

I took it on a three day Tail of the Dragon event and the car performed beautifully. Engine runs perfectly. So I do not believe there are any current CH issues.

My question is, before I start going down the path of doing the upgraded CH, is what are some ways to tell if the prior owner may have already had this job done on the car? I do not have access to the prior owner as the car was sold to Carmax, then the dealer I got the car from bought it from Carmax, then me. For the amount of time this issue has been around, and the car was modified by someone who spent a great deal of money, what are some signs to look for?

I plan on many more Dragan Rally's and track days, so I'm going to upgrade the crank hub before I put any kind of tune on the car. I'm just honestly wondering if maybe it already has been done.

I would try and see if the previous owner is on here or FB and ask them. If not then there is no outward sign. You could find from the carfax if it possibly had been done. Also with the carfax you can see where the car has been serviced and call shops there and see if they recognize the car or have a record of the CH being done and/or the previous owner. With FBO, some shop likely touched it. 99.8% of the people here are not going to do it themselves and if they had, the car IS tuned.

Also on the HP/TQ display (please post a pic of it) it will indicate a higher than stock power levels indicating it has a tune. If the previous owner had a tune you can likely get it transferred to you. It is very unlikely that it is untuned since FBO = downpipe and there will be a CEL on and the only way to get it turned off is with a tune.

[sargodlike]

Assume the SCH issue primarily affects tuned f8x’s or should I be conferred with a stock car?

[KnighTT]

A follow up on my last post.

So I went and inspected the crank pulley on my F82 for evidence of any replacement of the crank hub.

It does not have a CBC device, or anything that looks aftermarket, but I did notice something different. The CH bolt and the pulley bolts are very clean for the 58k miles the car has BUT what caught my eye is on the tip of each of the pulley bolts is a green mark made by a marker or paint. Like the kind of mark I would dab on a bolt after torquing it down. As my brain forgets. It doesn't look like a machine paint mark. Each one looks like a human dabbed it on there.

Did BMW ever have a blue mark on these bolts or is this a sign that perhaps these bolts have been replaced in the past? Which may be an indication that the CH has been replaced.

[n8dgr84]

2019 M2 Comp 6mt SCH on E60 550whp after 500 mi.

[FrankMstein]

Originally Posted by sargodlike

Assume the SCH issue primarily affects tuned f8x’s or should I be conferred with a stock car?

It can happen to anyone at anytime. It's user error.

[E46G07fanatic]

Originally Posted by KnighTT

A follow up on my last post.

So I went and inspected the crank pulley on my F82 for evidence of any replacement of the crank hub.

It does not have a CBC device, or anything that looks aftermarket, but I did notice something different. The CH bolt and the pulley bolts are very clean for the 58k miles the car has BUT what caught my eye is on the tip of each of the pulley bolts is a green mark made by a marker or paint. Like the kind of mark I would dab on a bolt after torquing it down. As my brain forgets. It doesn't look like a machine paint mark. Each one looks like a human dabbed it on there.

Did BMW ever have a blue mark on these bolts or is this a sign that perhaps these bolts have been replaced in the past? Which may be an indication that the CH has been replaced.

I'm in the exact same boat as you. I bought a bore scope to inspect the hub and witnessed the exact same picture. That leads me to believe it is 100% stock. I have a 2017 COMP. DCT. 82k miles.

I might do the CH for peace of mind but I don't plan on driving the car hard. Interestingly found out the car has been tuned, which is interesting. Must have a stage 1 tune because everything else is stock.

[N1rve]

Originally Posted by FrankMstein

It can happen to anyone at anytime. It's user error.

You’re joking right? lol User Error?

[FrankMstein]

Originally Posted by N1rve

You’re joking right? lol User Error?

I track have tracked my 514 RWHP 8+ times for two years and no SCH. So yeah, no joke.

[KnighTT]

So here is something interesting I found. These are the instructions provided by VTT for installing the spline hub but there is a specific part that I find interesting.

"Using the proper crank or flywheel holding tool, recheck the bolt tq is at 75 ft/lbs. Once verified, using a very long breaker bar, put 360 degrees of stretch for N54, and 270 degrees for N55/S55."

Why would the N54 crank hub be torqued to a higher value than S55? Same crank hub. I can't imagine the crank itself is weaker and wouldn't handle the higher torque for the bolt.

I wonder what the OEM torque spec is for the S55 crank bolt versus the OEM spec for the N54. Now the N54 is not without a few people spinning a crank hub here and there but it such a smaller issue that no one talks about upgrading the hub before shoot for crazy HP numbers.

Another interesting tid bit. I fully built my N54. During the process I ran across the "updated" crank hub design from BMW and put that in for the build instead of the new one. Not only did it have an updated design, the cogs had updated friction discs. A few people even did a side by side comparison to the OEM prior style and they had much rougher surface area and changes to provide "more friction". I also remember that entire 360 degree torque value because that was a ^%#&!!

Was the S55 torqued to a lower value from factory than the N54?

[FrankMstein]

Originally Posted by KnighTT

So here is something interesting I found. These are the instructions provided by VTT for installing the spline hub but there is a specific part that I find interesting.

"Using the proper crank or flywheel holding tool, recheck the bolt tq is at 75 ft/lbs. Once verified, using a very long breaker bar, put 360 degrees of stretch for N54, and 270 degrees for N55/S55."

Why would the N54 crank hub be torqued to a higher value than S55? Same crank hub. I can't imagine the crank itself is weaker and wouldn't handle the higher torque for the bolt.

I wonder what the OEM torque spec is for the S55 crank bolt versus the OEM spec for the N54. Now the N54 is not without a few people spinning a crank hub here and there but it such a smaller issue that no one talks about upgrading the hub before shoot for crazy HP numbers.

Another interesting tid bit. I fully built my N54. During the process I ran across the "updated" crank hub design from BMW and put that in for the build instead of the new one. Not only did it have an updated design, the cogs had updated friction discs. A few people even did a side by side comparison to the OEM prior style and they had much rougher surface area and changes to provide "more friction". I also remember that entire 360 degree torque value because that was a ^%#&!!

Was the S55 torqued to a lower value from factory than the N54?

Or was there a change of bolts? That is what would dictate the different angle, bolt yield. That also is another factor however I tend to believe the friction washer variation failure before the torque/angle/bolt yield direction from the factory