[M3_MANN]

Originally Posted by SYT_Shadow

The tabs are breaking due to high cycle fatigue. I'm sure some of them break due to the pump seizing.

The pump is mounted on bearings, it can't move at all. The pistons move up and down but aren't able to vary the position of the pump.

Ah youre right. I didn't think about the bearing. I had the unit completely out of its shell and remember moving the center piece around. But like you said, its a fixed with the bearing. Unless the seized piston slows the speed of the pump and cause the hub to run into the holes. I reckon this can damage the hub tabs as well.
The tab design isnt great, but I still think the material should still be strong enough to withstand the ideal pressure and impact that the hub made to absorb. It must be some sort of a mechanical failure causing a very strong impact that breaks the tabs.

[SYT_Shadow]

Originally Posted by M3_MANN

Ah youre right. I didn't think about the bearing. I had the unit completely out of its shell and remember moving the center piece around. But like you said, its a fixed with the bearing. Unless the seized piston slows the speed of the pump and cause the hub to run into the holes. I reckon this can damage the hub tabs as well.
The tab design isnt great, but I still think the material should still be strong enough to withstand the ideal pressure and impact that the hub made to absorb. It must be some sort of a mechanical failure causing a very strong impact that breaks the tabs.

Some of those bearings fail and of course wreak havoc.

The tab design is horrible from a engineering perspective. It's just begging to break. They should never have a 90 degree angle like that!

While mechanical failure will cause the tabs to snap right off, many times it's simply cyclical loading, the pounding movement, which causes the failure.

I'm quite happy with my 4340 Turbotoy hub. At least if it fails I won't have chunks of metal falling into the engine

[M3_MANN]

Originally Posted by SYT_Shadow

Some of those bearings fail and of course wreak havoc.

The tab design is horrible from a engineering perspective. It's just begging to break. They should never have a 90 degree angle like that!

While mechanical failure will cause the tabs to snap right off, many times it's simply cyclical loading, the pounding movement, which causes the failure.

I'm quite happy with my 4340 Turbotoy hub. At least if it fails I won't have chunks of metal falling into the engine

gotcha.

Did turbotoy figure out the reason why the his hub failed so early? I remember there was a thread about this.

[RedM3/4]

There is endless speculation on failure mode, but I don't find your pump alignment problem to be one of the higher odds theories. Can't PROVE you're wrong, but point this out for others that might see this thread and not look back at some other pretty serious analysis that has been done.

ADS

Originally Posted by M3_MANN

It seems to me that the biggest reason for the hub failure is (1) possibly the uneven contact between tabs and drilled holes on pump putting too much force into one tab and (2) the little spring filled pistons that give the pump some leeway gets partially stuck (for maybe less than a second) and cause the hub to rotate its way into death.

Ill try to post a video or at least pictures of a completely disassembled vanos pump.
To make it a bit clear, the hub is rotating in a fixed area while the pump is capable of moving within the load tension of the spring. Similar to how strut/spring can move up and down. So even the slightest misalignment on the pump can cause the hub to fail. And it fails because the tab rubs against the wall of the drilled holes of the pump. When the alignment is way off, it'll rub hard and might even chip the pump. But if it rubs just slightly, itll still break the tabs and leave the pump not damaged.

[ZkansasZ]

Originally Posted by SYT_Shadow

FWIW, BMW sells the actuator+solenoid for $500. Mind you, the only solenoid that will go into my car is Beisan System's one which is also quite cheap.

Good luck!

is this the one you prefer to?
http://www.beisansystems.com/images/bs023_large.jpg

[SYT_Shadow]

Originally Posted by M3_MANN

gotcha.

Did turbotoy figure out the reason why the his hub failed so early? I remember there was a thread about this.

Material was not hard enough to resist a crack starting in it, so it broke.

The one I'm running now is much improved

[SYT_Shadow]

Originally Posted by ZkansasZ

is this the one you prefer to?
http://www.beisansystems.com/images/bs023_large.jpg

Yes. That part is great. And it's cheap too!

Getting a brand new solenoid is relatively pointless. I got a new one which lasted only 4 months

[M3_MANN]

Originally Posted by ZkansasZ

is this the one you prefer to?
http://www.beisansystems.com/images/bs023_large.jpg

I have beisans installed as well. Works great...i think.

Originally Posted by SYT_Shadow

Material was not hard enough to resist a crack starting in it, so it broke.

The one I'm running now is much improved

I see. Its definitely a good upgrade compared to the oem hub.
If we can find out who manufactured our hubs for BMW, maybe we can order a new design via group buy or similar.

[qualicas]

I'm wondering if the tabs have a very sharp inside corner? If so that could start stress cracking and failure. There should be a slight inside radius, even 0.020" radius would be good. I just bought my M3 as a fix up project. Unfortunately, my list keeps getting longer and longer.

[matthias2280]

I decided to run the Dr. Vanos hub. It's cryogenicaly treated to improve strength and hardness. It's semi proven. Chris from Dr. Vanos has been shipping these things for 2 years now with no failures reported. My car is not my dd so I'm hoping it lasts for at least as long as I own the car. I think the revised clearances between the holes and the hub alone will take care of the issues. OEM clearance is close to 1 mm. That's a lot... With the Dr.vanos machined pump that clearance is cut more than in half. Here's hoping!!!

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