Ad: VTT "Spline Lock" Crank Hub Solution Now Available!

Oct 24, 2016
1,111
Scottsdale, AZ
Some of you guys are really not understanding how this works. If it were to spin it would have failed. The design turns twisting force into increased clamping force, drastically decreasing the incident of spinning in the first place. You'll break things before it slips.
 
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Panzerfaust

Lieutenant
Jul 3, 2018
634
Chicago
Some of you guys are really not understanding how this works. If it were to spin it would have failed. The design turns twisting force into increased clamping force, drastically decreasing the incident of spinning in the first place. You'll break things before it slips.
I think the initial wording definitely just confused some people. They aren't getting that the whole point is this would *stop* the slip, not allow it to slip but actually dig itself in deeper - just like any other crank fix
 
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SlowE93

Lieutenant
Jul 2, 2017
517
Yeah, the explanation and analogy used was the confusing part. I was imagining similar to dropping in a distributor. Gear at end of shaft turns as distributor gets dropped into place. As it does this, the more the rotor will turn on top and timing will be shifted.
No big deal.
 

SlowE93

Lieutenant
Jul 2, 2017
517
It captivates the crank bolt stopping it from vibrating loose, which is one of the two major causes of SCH. The spline lock addresses they other.
But if the hub has no key or grooves to lock in place, how does "capturing" the head of the bolt and locking it to the hub / pulley keep it in place ?
Ok, say a wall with a threaded hole in it. Install 2 large washers and put a bolt through the center and tighten it. Tack weld the head of the bolt to the washer. This is kinda what im picturing. The bolt even though tacked to the washer can still be backed off, it will just spin the washers with it and still be able to be removed since they are not locked to anything, just like the hub and sprockets etc.
Or am I thinking this wrong ? I want to buy one but want to understand how this works.
 
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GreyNBlueE92

Corporal
Oct 3, 2018
154
OH
Any reason it cant just be tacked to the crank or something. Obviously it would have to be broken to be taken apart... Similar to the nut on E46s M54
 

SlowE93

Lieutenant
Jul 2, 2017
517
See what I mean ? Locks it to the crank hub. The
20190401_190708.jpg
hub itself is NOT locked which is why it spins in the first place. How does locking it to a slipping hub "lock" the bolt in place ???
 

SlowE93

Lieutenant
Jul 2, 2017
517
Whats stopping it from spinning back WITH the hub all together ?? It only takes a little bit, then the sprockets are free because the friction disc wont do its job and all hell breaks loose STILL. Im not knocking the product, just want clarification before I purchase. Thanks in advance
 
Oct 24, 2016
1,111
Scottsdale, AZ
The friction discs and the torque on the crank bolt is supposed to stop slip from happening.

The crank bolt (jesus bolt, lol, love that term) holds the hub to the crank. There are two main ways the hub slips. The first, is that the bolt vibrates itself loose. When it does that, it no longer is worth of being called the jesus bolt, clamping force goes from "meh" to "not nearly enough" and you can expect the hub to slip as a function of the crank bolt not being tight any more -same as you'd expect if you didn't install the crank bolt properly when building the motor.

The CBC stops the bolt from vibrating out. This does not add clamping force to the assembly, it just stops clamping force from falling off via the bolt vibrating loose.

The spline lock is the counter-part to the CBC, which increases the hub clamping capability and ultimately the capacity of the hub before slip can occur. The flip side of that coin is that the spline lock does nothing to stop the bolt from vibrating loose.

The CBC was never intended to stop hub slip via increased hub torque capacity. It's just a method of making sure the bolt doesn't loosen itself via vibrations.

Clear as mud?

Chris
 
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SlowE93

Lieutenant
Jul 2, 2017
517
The friction discs and the torque on the crank bolt is supposed to stop slip from happening.

The crank bolt (jesus bolt, lol, love that term) holds the hub to the crank. There are two main ways the hub slips. The first, is that the bolt vibrates itself loose. When it does that, it no longer is worth of being called the jesus bolt, clamping force goes from "meh" to "not nearly enough" and you can expect the hub to slip as a function of the crank bolt not being tight any more -same as you'd expect if you didn't install the crank bolt properly when building the motor.

The CBC stops the bolt from vibrating out. This does not add clamping force to the assembly, it just stops clamping force from falling off via the bolt vibrating loose.

The spline lock is the counter-part to the CBC, which increases the hub clamping capability and ultimately the capacity of the hub before slip can occur. The flip side of that coin is that the spline lock does nothing to stop the bolt from vibrating loose.

The CBC was never intended to stop hub slip via increased hub torque capacity. It's just a method of making sure the bolt doesn't loosen itself via vibrations.

Clear as mud?

Chris
Yes, its clear and I understand the cbc was not to add clamping force. My question (which seems answered), is that the bolt can still back out even with cbc installed even though its stated "it cannot back out no matter what"
 

The Convert

Captain
Jun 4, 2017
1,343
Perfect, thats what I needed to know.
You brought up an excellent point. The CBC isn’t going to stop anything. The hub is seeing the same vibes as the bolt and will just vibrate loose with the bolt with the CBC kit, as opposed to just the bolt vibrating loose without the CBC kit.

Would have been nice if BMW had just keyed the damn thing, or gave it a bigger flange to accept a bolt circle as opposed to a single bolt.
 
Oct 24, 2016
1,111
Scottsdale, AZ
A little clarity.

SCH is caused by:

- Crank Hub Bolt clamping load reduced: (vibration, incorrect installation torque, or excessive fastener yield)
- Friction areas on hub/timing gear cannot hold on their own or as a result of above

The CBC addresses the crank bolt vibrating loose. The spline lock is the other half of the equation, and locks the assy all together, which is why we keep stating the "complete solution" involves using them together.

For those perhaps a little less familiar with splines, an informal primer might shed some light on why we chose splines over a keyway. This is a pretty solid read: https://gearsolutions.com/features/inside-splines/

We are definitely in agreement that BMW could have done a better job with this aspect of design. I can't imagine how much it's cost them with so many S55's slipped under warranty.
 

The Convert

Captain
Jun 4, 2017
1,343
A little clarity.

SCH is caused by:

- Crank Hub Bolt clamping load reduced: (vibration, incorrect installation torque, or excessive fastener yield)
- Friction areas on hub/timing gear cannot hold on their own or as a result of above

The CBC addresses the crank bolt vibrating loose. The spline lock is the other half of the equation, and locks the assy all together, which is why we keep stating the "complete solution" involves using them together.

For those perhaps a little less familiar with splines, an informal primer might shed some light on why we chose splines over a keyway. This is a pretty solid read: https://gearsolutions.com/features/inside-splines/

We are definitely in agreement that BMW could have done a better job with this aspect of design. I can't imagine how much it's cost them with so many S55's slipped under warranty.
Can you show us a good picture of the broached crank after a splock is installed and then removed? Would be nice to see how deep the splines are cutting. Also, as I’m sure you know, there is more to strength and durability than just the type of joint. The total spline face area vs the total face area on a key being the main one. If a keyed hub has twice the area carrying the load as the splock does, guess which one will hold more power for longer.
 

kayzrx82

Corporal
Apr 4, 2018
110
Can you show us a good picture of the broached crank after a splock is installed and then removed? Would be nice to see how deep the splines are cutting. Also, as I’m sure you know, there is more to strength and durability than just the type of joint. The total spline face area vs the total face area on a key being the main one. If a keyed hub has twice the area carrying the load as the splock does, guess which one will hold more power for longer.
Check
N54 crank hub issue - power level?
Post #89 They added one showing what the spines does to the crank after its been removed. It isnt that great of a photo to make a comparison against a key. Its also shows the material that was removed while the spline cut into the hub. Thats materail ends up wedged between the back of the snout and the top of the splock hub. I would rather see the photo of the one that slipped. I have a good idea of whats going on with the splines on these and I dont think they will work like a spline extractor would in the event enough torque is put at the interface of the spline and snout to cause a slip. I still would like to hear Ghassans thoughts on why he thinks it slipped. Confirmation of the bolt being loose or not would weigh in against VTT saying the exclusion of the bolt capture was to blame. Doesnt seem as if anyone wants to give an update on both ends.
 

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