S54 Diaphragm Springs and Exhaust Hub

[maupineda]

I have taken measurements of the sprockets, and the surface that nests against the retainer plate is 2.5mm proud from the mating surface for the hubs, the depth of the cavity for the diaphragm spring assembly is 7mm, this means that...

For "A" parts there will be 1.5mm of spring compression
For "B" parts there will be 1.25mm of spring compression

I have made some quick math, but will do it fully tonight, however, there is at least 40% more preload force on the "B", or S62 items. So the delta is not some, is quite significant.

[sapote]

I did not know there was an issue changing pump discs. Is it more that with a higher mileage engine you could get a mismatch of wear with the pistons? Or is it that the recommendation now is to change the hub rather then the disc?

I just changed out the disc for a drilled one as a preventative measure, low mileage engine thoguh, 35k. Never occurred to me that the disc would likely be out of a much higher mileage engine. No issues I noted on reassembly. Now, of course, Beisan has my original disc.....I feel like an idiot for not thinking of this.

The original disk is matched to these critical dimension for a proper oil pressure delivery:
1. Its center hole to the vanos shaft. If not matching and the set has a little loose clearance here, then oil leaking and cause low pressure
2. Disk 4 holes to pistons clearance: too tight leads to piston seized up and not pumping, too loose leads to low pump efficiency.

I redrilled my disk, but if one can't access to have the disk re-drill, then best option is to change the hubs with larger driving tabs as OP did.

[maupineda]

I am not sure is correct to assume they are "matched", they are simply made to spec, and any new component off the shelf would meet design intent. the issue comes from interchanging parts from engines with different wear and tear levels, then the deviation from spec is completely unknown. the only "matching" aspect is the A and B markings, which can be found on pump discs, pump shafts, and diaphragm springs assemblies. No one in a high volume production line will be matching anything, they just grab from the parts dispenser and put it on.

[sapote]

Beisan answer on s62 diaphragms:
To use the weak springs can leave some rattle from the splined shafts play inside the hub gears

I don't think the stock spring is a common rattle noise source as the compressed spring is strong to eliminate all clearances during active cycles. It removes the plays between the hub and the cam sleeve, and has nothing to do with the splines vs hub clearance.

[maupineda]

I have calculated the load to compress the spring washer 1mm

"A" = 628N = 142lb
"B" = 1022N = 229lb

That is +60% delta.

Also, we need to keep in mind that the S54 is an I6, so the Vanos needs to fight all the valve springs actuating at any given time. whereas the S62 is effectively an I4 since each Vanos units only handles 4 cylinders

[sapote]

I have calculated the load to compress the spring washer 1mm

"A" = 628N = 142lb
"B" = 1022N = 229lb

That is +60% delta.

Also, we need to keep in mind that the S54 is an I6, so the Vanos needs to fight all the valve springs actuating at any given time. whereas the S62 is effectively an I4 since each Vanos units only handles 4 cylinders

How do you find the spring disk's Spring Constant K where the compression force is F = deltal D * K; delta D is the compression distance.

[maupineda]

You can look up Belleville springs formulas in the net. I assumed steel

[bigjae46]

I have the S62 springs with an OEM hub and OEM pump disc that I drilled myself. I milled the holes for a slight interference fit so you have to lightly pry the disc off the hub tabs. I've only had one timing related fault and that was a bad solenoid pack - too many rough curbs at COTA shook the shit out of it.

Are you using the VAC hub? Its thicker but what is the centerline and how does it match up with OEM. If the backside is thicker then you'll have less spring compression as it presses against the sprocket. A heavier hub will require or generate more force as it rotates. Possibly that could have an effect on how quickly the VANOS reacts.

[maupineda]

Yes, I will use the VAC hub. The hub is a circular part and all its features are concentric to the hub, just like OE. The depth of the pocket for the diaphragm spring and plate are 7mm on both, VAC and OE, so that difference on thickness of the main core is not important. About the weight delta and the impact to operate the splines, I have no way to calculate it, I could probably calculate the PMI as a comparable point, but I am sure the spring load is way more influential.

that said, I wonder why Beisan passed on the opportunity to enlarge the tabs on their design. It really is a missed shot. Also, VAC could have drilled several smaller holes around to lower the weight, at the cost of strength, but this part has low forces acting on it, is just a carrier for the splines to operate the cams. Hardness and impact resistance are the mail attributes for durability on this part.

[jayjaya29]

The Beisan hub does have thicker tabs then stock though.

https://nam3forum.com/forums/forum/main-forum/e46-2001-2006/604-beisan-s54-exhaust-sprocket-hub-solution

[maupineda]

The Beisan hub does have thicker tabs then stock though.

https://nam3forum.com/forums/forum/m...t-hub-solution

Thicker, not wider

[sapote]

Thicker, not wider

I'm confused:
He said:

1. a thicker wall and tabs
2. The Beisan hub tabs are the same width as the BMW hub tabs.
3.increased width of the Beisan hub tabs

In (2) he said the tabs have the same width, but in (3) he said the tab width was increased. Can someone verify that the tabs have thicker wall, or wider width?

https://nam3forum.com/forums/forum/main-forum/e46-2001-2006/604-beisan-s54-exhaust-sprocket-hub-solution/page4#post273994

[sapote]

The Beisan hub does have thicker tabs then stock though.

But it is not for mating with a used stock pump disk, because: he profiled his new hub tabs the same as the stock tabs (as compared to VAC with a half cylinder tabs which contacts more bearing surface on the disk holes) with four 90* corners. The used disk has 4 indentation wear from the tabs, and this will cause Beisan new tabs to be loose in the old disk holes. This is why he said it's best to be used on a new disk with virgin holes.

[jayjaya29]

Correct, the Beisan hub is intended to be used with their drilled disc (using the smaller holes they drill) or a brand new OE disc.

[sapote]

Correct, the Beisan hub is intended to be used with their drilled disc (using the smaller holes they drill) or a brand new OE disc.

This makes no sense to me.
His new disk has smaller holes and the OE disk has larger holes, so the same hub tabs cannot fit well to the two disks.