[whips333]

Originally Posted by whips333

To the OP...are these Dr. Vanished hubs or your own modified hubs?

Sorry I meant Dr. Vanos.

[SYT_Shadow]

they're his modified hubs, not Dr Vanos' cryo hub

[turbotoy2791]

Originally Posted by thestigCLT

Something is definitely not right here. In Post #16 it appears the failure region has a cup like shape in the hub and has a mostly brittle fracture mode I have a hard time understanding why this tab failed this like or at all for that matter. It might be that the part requires more ductility than strength.

Going to 4340 with such a high yield strength (186 ksi) is going to make the material even more brittle especially in the presence of any stress concentrations. I recall that these materials can be very susceptible to cracking due to certain sealants or lubricants, moly difsulfide comes to mind.



Just for reference:

Metals Handbook, Volume 1, Properties and Selection: Irons, Steels, and High-Performance Alloys, p. 195 – 199, 430 – 448, and 609, ASM International, Tenth Edition, 1990.

http://www.asminternational.org/cont...81G_Sample.pdf
Well they make connecting rods and cranks from 4340, sealants and lubricants should not be a problem.
If only Nikola Tesla was still alive he could give us some insight.

I have a few guys I need to talk to about this one is a gear maker and the other works at a heat treating shop. It will be Tuesday before I have more information.
I am going to try the 4340 see how long it last if it makes it past 50000 miles it will be acceptable to me since when the tabs fail they do not escape and fall in the engine. If it does not make it to 50000 I will take the pump out of the engine and use an external hydraulic pump ran off a belt for the vanos.

I could also tighten up tolerances between the pump and hub but, If they are not in perfect alignment this may also cause a problem, it may work in one engine but in another it may bind and cause the pump bearing to fail. I don't know how close this alignment is from car to car.
They are other ways to fix this buy putting some kind of absorber in the pump or on the hub. As you ad parts you have more to fail and more to wind up in the timing chain.

[thestigCLT]

Originally Posted by turbotoy2791

http://www.asminternational.org/cont...81G_Sample.pdf
Well they make connecting rods and cranks from 4340, sealants and lubricants should not be a problem.
If only Nikola Tesla was still alive he could give us some insight.

I have a few guys I need to talk to about this one is a gear maker and the other works at a heat treating shop. It will be Tuesday before I have more information.
I am going to try the 4340 see how long it last if it makes it past 50000 miles it will be acceptable to me since when the tabs fail they do not escape and fall in the engine. If it does not make it to 50000 I will take the pump out of the engine and use an external hydraulic pump ran off a belt for the vanos.

I could also tighten up tolerances between the pump and hub but, If they are not in perfect alignment this may also cause a problem, it may work in one engine but in another it may bind and cause the pump bearing to fail. I don't know how close this alignment is from car to car.
They are other ways to fix this buy putting some kind of absorber in the pump or on the hub. As you ad parts you have more to fail and more to wind up in the timing chain.

Thanks for the paper. What's bothersome to me is the how the tabs failed. There are no signs of fatigue at least not that I can see at least on one tab. The other tab might have some ductile tears. Just very surprising especially after seeing your hammer test. Oh and are connecting rods made of extremely high strength 4340?

[Obioban]

Interestingly, other BMW engines don't have the loose tolerance between the hub and pump... At least the M54 and s50b32. I wish we knew the reason they felt the need to add the slop on the s54.

I wonder if there's some SLIGHT cam shaft slop at 8000rpm that they were trying to allow for.

[CybrSlydr]

I'm subbing to see what happens - this is quite surprising!

Turbo doing this like he has makes me feel a lot better about buying a hub from him if/when I ever need one.

[MahCBCNe46]

Aww man this sucks

[MahCBCNe46]

Originally Posted by SYT_Shadow

Hi everyone,

It was my hub which broke. The engine is still operable, although the tabs fell inside so I'll have to fish them out.

I put 15k on them. Hard driving, but I did not track the car.

Yesterday I did a DIY of how to remove the entire vanos, valve cover, etc (so you all can update your bolts and check on your tabs) and when I removed the vanos they were both gone.

The welds were inmaculate... the tabs were ripped clean off.

I expected the oil pump to be seized causing the hub failure, but it was perfectly fine and spins around very well.

SYT

Did the tabs fall into your engine while you were taking them out? or did they fall in there by themselves when they sheared?
Where you taking the engine apart because of the broken tabs (SES light?) or just found them in the process of just making that DIY?

[SYT_Shadow]

Originally Posted by MahCBCNe46

Did the tabs fall into your engine while you were taking them out? or did they fall in there by themselves when they sheared?
Where you taking the engine apart because of the broken tabs (SES light?) or just found them in the process of just making that DIY?

A great thing about Turbo's design is that it's not possible for the tabs to fall into the engine. They fell in when I separated the vanos assembly from the engine. I heard a ticking sound when they fell and didn't understand what had happened until I saw the missing tabs.

I took my engine apart because I was doing a DIY for the forum. I did have a SES light but was convinced it was a dirty vanos actuator or the solenoid.

Had I not been doing the DIY I would have replaced the solenoid and the vanos actuator with a brand new unit that just arrived and found that the problem was still there.

I'm going to have to dismount the oil pan to get the tabs out... I'm not looking forward to it

[SYT_Shadow]

Originally Posted by deadlysyns

Wow, that took alot of force to sear both tabs off.

Scott,

Have you considered trying to do a 4 tab design instead of two? This would require drilling two extra holes on the pump though. We all can learn something from this and try to pin point why the tabs are breaking off. I am curious if one tab broke off first then the 2nd tab broke off.

Also on the 4340 material, you may have this metal austenitized, oil quenched, and tempered at 850°F per AMS-H-6875 to get a high strength part.

My thoughts exactly... with 4 holes and 4340 that thing should be indestructible.