[Proctor750]

Originally Posted by doughboy

Also it says to oil the thread and no thread locking compound is used. So the assembly relies on the friction of the hub/gears/crank faces only.

For 99USD plus shipping the VTT bolt fix seems a good start.

Interesting - wonder if some red loctite wouldn't help in combination with the capture plate.

In the M4 section I'm asking the guys there if they have heard of anyone having the hub spin AFTER installing JUST the plate and not a new splined or keyed hub.

Apparently there was a guy who spun his twice before installing the plate only (still on OE hub) and has had no issues since. His car is heavily modified as well. Edit (sorry that's this thread I am getting mixed up between forums)

That's what got me thinking - if VVT created the bolt capture plate years ago and customers who purchased it have not reported failures after installing it - what instigated them to build their spline lock hub? Seems like their cheaper initial solution worked fine.

I would guess market share BUT once a hub does spin with the plate only everything will become clear - it's not just the bolt backing out but stretching OR friction surfaces giving way or combination of all could be additional causes.

I wonder what bimmerworld did with their M4. As someone who intends to track the M2C (high RPM and constant stress/force on hub) I'm getting nervous..


Edit 2: "2. The hub could move against the crank moving the timing gear with it. If the hub turns then this may turn the bolt with it maybe loosening the clamping further" THIS is precisely what worries me.

[doughboy]

Re loctite. The thread needs to be oiled because the torque setting is for an oiled thread as per BMW spec. This then precludes the use of thread locking compounds.

It's a TTY (torque to yeild) bolt which should still be in its elastic range thus still be able to give and take stretch and still pull back tightly each time. Only if overtightened will it stretch permanently.

As VTT say to line up the bolt for the capture just pull it tighter a fraction. Unless it was already FT (technical term for very tight) you'd know something wasn't right. The tech would need a flywheel locking tool for that.

Agree, would be good to get data on m3/m4 with this capture fitted.

[Proctor750]

Originally Posted by doughboy

Re loctite. The thread needs to be oiled because the torque setting is for an oiled thread.

This then precludes the use of thread locking compounds.

It's a TTY (torque to yeild) bolt which should still be in its elastic range thus still be able to give and take stretch and still pull back tightly each time. Only if overtightened will it stretch permanently.

As VTT say to line up the bolt for the capture just pull it tighter a fraction. Unless it was already FT (technical term for very tight) you'd know something wasn't right.

You can actually use loctite instead of an assembly lube, pretty common and even ARP allows it instead of their lube.

As for the VTT instructions - I thought the capture plate could be installed without bolt removal? Or perhaps I am misunderstanding what you are saying.

[doughboy]

No don't have to remove bolt but may need to turn it so it lines up with the capture hex hole.

If you remove the bolt to add loctite then you have to replace the friction washer and timing sprocket and retime the whole engine.

[evolved///M]

Has anyone in the M3/M4 world checked the balance of the damper on a spun hub?

[Proctor750]

Originally Posted by evolved///M

Has anyone in the M3/M4 world checked the balance of the damper on a spun hub?

Ask that here: https://f80.bimmerpost.com/forums/sh...2#post24407562

[M2C_PLUS]

Originally Posted by Proctor750

Interesting - wonder if some red loctite wouldn't help in combination with the capture plate.

In the M4 section I'm asking the guys there if they have heard of anyone having the hub spin AFTER installing JUST the plate and not a new splined or keyed hub.

Apparently there was a guy who spun his twice before installing the plate only (still on OE hub) and has had no issues since. His car is heavily modified as well. Edit (sorry that's this thread I am getting mixed up between forums)

That's what got me thinking - if VVT created the bolt capture plate years ago and customers who purchased it have not reported failures after installing it - what instigated them to build their spline lock hub? Seems like their cheaper initial solution worked fine.

I would guess market share BUT once a hub does spin with the plate only everything will become clear - it's not just the bolt backing out but stretching OR friction surfaces giving way or combination of all could be additional causes.

I wonder what bimmerworld did with their M4. As someone who intends to track the M2C (high RPM and constant stress/force on hub) I'm getting nervous..


Edit 2: "2. The hub could move against the crank moving the timing gear with it. If the hub turns then this may turn the bolt with it maybe loosening the clamping further" THIS is precisely what worries me.

Are you trying to get a cure for as cheap as possible? It you are going to rag your M2C get the full fix, exactly what I did. Owners spend more on carbon....l would rather protect my engine first.

What I can tell you is everyone focuses on the damper end but they should also focus on the dual mass flywheel end too. For example, during testing, 2 S55 engines each spun an OEM crank hub using the same gear box, fly wheel and tune. The only way it stopped spinning OEM crank hubs was swapping The Flywheel to the second engines flywheel. Crank vibration plays a massive part in the issue.

The crank spinning is the leading force in slipping the crank hub/destroying the friction ring. You can see this when you look at the "direction of damage" on the friction rings and timing sprockets. The crank can moves faster than the timing sprocket not the other way round. (of course once timed they move "together" unless it spins a crank hub and the crank keeps moving while the crank hub slips out of time).

Hope that all makes sense, it is not meant to teach you to suck eggs

[Proctor750]

Originally Posted by GreatWhiteM2

Are you trying to get a cure for as cheap as possible? It you are going to rag your M2C get the full fix, exactly what I did. Owners spend more on carbon....l would rather protect my engine first.

What I can tell you is everyone focuses on the damper end but they should also focus on the dual mass flywheel end too. For example, during testing, 2 S55 engines each spun an OEM crank hub using the same gear box, fly wheel and tune. The only way it stopped spinning OEM crank hubs was swapping The Flywheel to the second engines flywheel. Crank vibration plays a massive part in the issue.

The crank spinning is the leading force in slipping the crank hub/destroying the friction ring. You can see this when you look at the "direction of damage" on the friction rings and timing sprockets. The crank can moves faster than the timing sprocket not the other way round. (of course once timed they move "together" unless it spins a crank hub and the crank keeps moving while the crank hub slips out of time).

Hope that all makes sense, it is not meant to teach you to suck eggs

Makes perfect sense to me - very interesting about the testing rigs spinning hubs. It seems like a lot of manufacturers are doing this friction fit garbage - must be a money saving thing or speed of production.

I have no interest in anything besides longevity first which is why my first "aftermarket" item I have installed is the metal oil cooler guard aka booby trap 1 of 4 diffused. Hub (or capture plate in the interim) is next. The charge cooler after that thanks to people hydro locking from the core leaking internally. Lastly a twin ear diff mount.

The car has come from the factory with booby traps folks.

[doughboy]

Originally Posted by GreatWhiteM2

Are you trying to get a cure for as cheap as possible? It you are going to rag your M2C get the full fix, exactly what I did. Owners spend more on carbon....l would rather protect my engine first.

Yes I want the cheapest cure, who wouldn't - if it's a cure of course! Why spend 3k on a fix if £100 will do? And don't forget the very act of fairly major engine surgery carries risks of other damage, (accidental) or consequential damage caused by factors unknown.

I'm just going through a thought / discussion process rather than just dive into this weeks latest fix (not suggesting you have done that of course)

I also won't be spending money on any carbon till this is fixed for sure!! Carbon is no good on a car that doesn't run.

And I fully see where you're coming from, and yes it's all to do with crank vibrations, that's what the damper is for so it has to deal with all those stresses.

[M2C_PLUS]

Originally Posted by doughboy

Yes I want the cheapest cure, who wouldn't - if it's a cure of course! Why spend 3k on a fix if £100 will do? And don't forget the very act of fairly major engine surgery carries risks of other damage, (accidental) or consequential damage caused by factors unknown.

I'm just going through a thought / discussion process rather than just dive into this weeks latest fix (not suggesting you have done that of course)

I also won't be spending money on any carbon till this is fixed for sure!! Carbon is no good on a car that doesn't run.

And I fully see where you're coming from, and yes it's all to do with crank vibrations, that's what the damper is for so it has to deal with all those stresses.

Indeed,

No way I would trust the crank capture alone after seeing and testing first hand. The hub needs keying to the crank.

That said, high power M4/3s run like clockwork with stock crank hubs! Its just Russian roulette

[F87source]

The thing is, that in some cases the crank spins due to the force exerted on the crank hub being greater than the friction washer can hold so it doesn't matter if the bolt backed out or not it'll still spin. So that's probably why VTT made their "SPLOCK" crank hub.

[doughboy]

Thing is the friction washer is only between hub and timing sprocket.

There is no friction washer between hub end and crank face or between oil sprocket faces.

So as the timing load is constant then it's the damper forces that change so the likely slip point would be hub to crank, taking timing sprocket with it.

Rather than timing sprocket moving relative to hub.

[F87source]

Originally Posted by doughboy

Thing is the friction washer is only between hub and timing sprocket.

There is no friction washer between hub end and crank face or between oil sprocket faces.

So as the timing load is constant then it's the damper forces that change so the likely slip point would be hub to crank, taking timing sprocket with it.

Rather than timing sprocket moving relative to hub.

Yeah I'm not too sure about this issue. But that's what the guys who make solutions for the crank hub issues said, so I'm just repeating it.

[doughboy]

I don't disagree with what these guys are saying, just good to throw different angles in to the discussion.. seems that no one knows exactly what is going on except these parts arent staying put!

[F87source]

Originally Posted by doughboy

I don't disagree with what these guys are saying, just good to throw different angles in to the discussion.. seems that no one knows exactly what is going on except these parts arent staying put!

Which really does suck. It seems like the curse of the m3 is still alive, with the E46 m3 and subframe issues, the E92 M3 with rod bearing failure, and the F80 M3 with intercooler leaks and spun crank hubs.

I wonder why bmw chose not to key the crank hub.

[Rod 69]

What has happened from last comments till now, planning to buy a new M2C and preoccupied with crank hub issue. I plan to leave it stock, should I stop my buy?

[JoeP]

Originally Posted by Rod 69

What has happened from last comments till now, planning to buy a new M2C and preoccupied with crank hub issue. I plan to leave it stock, should I stop my buy?

The failure among cars that are stock is very rare. You will also have the full warranty to cover you should something happen. Once the warranty is up you can either get rid of it or get the issue fixed with a proven solution.
It is a great car in my opinion.

[Got f1?]

Originally Posted by F87source

Which really does suck. It seems like the curse of the m3 is still alive, with the E46 m3 and subframe issues, the E92 M3 with rod bearing failure, and the F80 M3 with intercooler leaks and spun crank hubs.

I wonder why bmw chose not to key the crank hub.

See the very first post on this thread regarding BMW's intention to have a sort of fuse.

[F87source]

Originally Posted by Got f1?

See the very first post on this thread regarding BMW's intention to have a sort of fuse.

There's a few things that come to mind when I reread this comment.

1) Who is this bmw engineer or person from BMW OP spoke to? As far as I know this could be pure speculation or an untrained tech.


I personally think the "fuse" theory is uninformed and incorrect:

1) Yes OP is right the bolt can vibrate loose, but the friction disc can also fail but it supposedly is more prone to failure at high horse power. Also the crank bolt does NOT hold the vibration dampener in anyway shape or form. There is a huge hole in the middle of the vibration dampener that clears the crank bolt, i believe on the n55 it may sit or barely touch the crank bolt but on the s55 I believe it completely clears the bolt (hard to tell from pictures). The only real contact the dampener has is to the hub itself via the 8 bolts.

2) OP said the bolt vibrates loose from vibrations from the damper or from any other unbalanced source. Vibrations from normal engine operation causing the bolt to come loose - yes. But vibrations coming from an unbalanced source? Unless your engine is flawed the rotating assembly is supposed to be balanced quite well - so no. Remember the bolt is on the center line of the crank shaft which is a balanced source.

3) Yes op is correct if the bolt comes loose your timing is screwed. But the bolt is torque to yield which means you really cannot keep tightening the bolt yearly as a precaution as you will damage the bolt. You also cannot make adjustments to the bolt unless you have the timing lock tools.

4) OP says that the bolt acts like fuse to protect your crank against imbalanced parts and vibrations. No this is absolutely ridiculous, the crank shaft is protected from imbalanced parts because it in itself is a highly balanced part with counter weights to ensure it is balanced. Then the rotating assembly (pistons, rods, rob bolt etc) is carefully assembled so they are all within a weight range to ensure the engine is balanced. That is how the crank is protected against imbalanced. Vibrations are dampened by the vibration dampener not a bolt.... This is how engines were always designed and bmw motors are no different. To say that you designed a bolt that comes loose to protect the motor from vibrations is asinine, if this were the case then all S55's have issues with the engine being balanced improperly which clearly is untrue as the engine would shake apart as you rev. Also alot of individuals say it is a design to protect the car from money shifts which I think is incorrect, clearly a motor is not designed to be money shifted but there is no way bmw would make the hub this way to protect the engine from money shifts. Because as a result you now have an engine that can slip at any time money shift or not, so solving an issue (money shifting) that really isn't an issue that needs to be solved because if you money shift and the engine breaks that's on you not the motor, now introduces the issue of the engine failing on its own.

5) OP then states if you fix the bolt it can't come loose and it risks damage to the crank shaft and bearings. what the heck does that even mean? If the bolt doesn't come loose no damage. That is what you want, timing won't slip if the bolt won't come out.

6) When OP says everything is constructed by bmw for a reason and follows with you can't adjust timing with a fixed wheel implying that a fixed wheel design won't work, OP was uninformed about what is really going on with the hub design. YES bmw made the hub split for a reason - because the engine is designed to not have a separate timing case to likely avoid leaks (abr houston explaining this:

) this means to get the timing chain set and be serviceable the hub needed to be split. The flaw was bmw using a friction disc instead of a keyed design. This is the reason why bmw made the hub like they did, not to integrate an inbuilt fuse but to make servicing the timing components easier.

7) OP says bmw doesn't recommend a fixed hub design - clearly they wouldn't. OP then says you risk more damages doing so, well clearly you don't if the hub is a good design. You eliminate the possibility of spinning the hub at high power levels or even stock which prevents damage. Not sure how it could cause more damage - you should also have a cbc so the bolt still doesn't vibrate out.

8) OP says most issues are just slipped timing - yes because the car's crank sensor can detect the slip fast enough and limp the car. Doesn't mean the hub is supposed to fail from the factory.


Overall I believe OP is misinformed in this post (sorry I don't mean to bash), but it is simply incorrect to say the bolt was meant to fail to protect against imbalances, vibrations, or even money shifts as to what others would say.

[doughboy]

Yeah i thought it was BS too...

[F87source]

Originally Posted by doughboy

Yeah i thought it was BS too...

Yeah unfortunately his post did not make any sense (sorry if i am being harsh), but that is why I did not comment initially.

Oh and to add on, even if bmw designed this hub to be a "fuse" for money shifts (because vibrations and imbalances should not be occuring to such an extent in the motor that you would need a fuse for it) - which it isn't, then bmw made a defective fuse. Sure it may offer some protection against money shifts (tbh there is no real guarantee your pistons still don't contact the valves) it now opens up failures everywhere else because now the hub can fail at any time under any condition. So that is a defective "fuse" imo.


Edit- but to be fair OP was right that the main issue seems to be the bolt coming out. Alot of S55 guys with just the VTT CBC seemed to have eliminated their hub failure even with turbo upgrades and making 700whp+, even the guys with multiple hub failures prior to the cbc install have had all their issues solved with the CBC.

That is why I have purchased a VTT CBC and will install it when I get the chance. It is a very nice piece of machined aluminium and I can't wait to install it. It is also extremely light and symmetrical so there should be zero balance issues.

[Thescout13]

Originally Posted by doughboy

Yeah i thought it was BS too...

Gotta love the British (assuming you are since from the UK, but apologies if you're a Scot or Welsh) and their concise use of language to get right at the point.