S54 Diaphragm Springs and Exhaust Hub

[BMWfanz]

Beisan answer on s62 diaphragms:
There are no reports about problems with the stronger springs that BMW introduced 2001 to all S62.
Of course the resistance is higher for adjusting the vanos, but only milliseconds. So you won’t notice it when driving. To use the weak springs can leave some rattle from the splined shafts play inside the hub gears

[Cubieman]

Just to be clear, you had a new Beisan disc and not a Beisan redrilled OE BMW disc?

Correct.

[Slideways]

I had an issue with the Beisan disc not creating enough pressure due to excessive clearance between the disc and shaft.
I would agree it's a good idea to try to have your original pump disc machined instead of one out of another vehicle.

Definitely do a test before and after working on your vanos, mine was well within spec before I installed the beisan pump disc and very much out of spec after.

I likely would not have know there was an issue for some time as just drving around town it didn't really feel all that different to me.

Just to be clear, you had a new Beisan disc and not a Beisan redrilled OE BMW disc?

[Cubieman]

I had an issue with the Beisan disc not creating enough pressure due to excessive clearance between the disc and shaft.
I would agree it's a good idea to try to have your original pump disc machined instead of one out of another vehicle.

Definitely do a test before and after working on your vanos, mine was well within spec before I installed the beisan pump disc and very much out of spec after.

I likely would not have know there was an issue for some time as just drving around town it didn't really feel all that different to me.

[Slideways]

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.

There are many engines out there with the Beisan exchange redrilled disc. No issues that I recall with the genuine BMW discs being redrilled and exchanged with another. There was only an issue a while ago where Beisan decided to make there own discs because not enough people were sending back the cores. I believe OP and one other forum member had issues with the new Beisan disc where the piston holes were undersized, which caused the pistons to get stuck. It required some light machining by the DIYer similar to the anti rattle procedure. Beisan discontinued the new discs.

[1bluemcm]

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.

[bmwfnatic]

Your measurements are close to the BMW ones.

The official measurements are 0.85mm and 3.55mm.
And 1.25mm and 3.20mm.

Early (up to 09/2001) S62 came with the A (S54 style) springs, then BMW changed them for the later models to the B springs that we now refer to as S62 ones.

Interestingly BMW also wants you to install the new style S62 springs with the smaller side of the spring towards the hub, not towards the eared retaining plate like on the S54.

However since BMW did this change from 09/2001 going forward, which was still quite early in S54 production, I think they would have also applied it to the S54 if it were deemed necessary.

I am looking forward on someone doing a VANOS test and a video of noise before and after with the only change being the A vs the B springs.

[maupineda]

I measured the weight of the hubs, unsurprisingly, stock is lighter. Springs sets are the same weight

[maupineda]

I have compared the diaphragm spring sets and is interesting, the S62 individual items are thicker. However, the complete stack is taller on the S54 items, but being thinner, the spring washer will have less preload force.

S62, the retaining plate is 3.16mm and 1.2mm thick.




The S54 retaining plate is 3.5mm and the sping washer is 0.85mm




However, the stack of the two, is taller on the S54

S54



S62



Once seated in the hub, the S62 stack is a bit more recessed, you can see that when compared with the chamfer around the edge of the pocket. this is only 0.25mm.

The plate is almost flush with the chamfer's edge.



The S62 stack is a bit recessed, you can see the "step" from the retaining plate and the chamfer. however, the spring will have higher preload force as the spring washer is significnatly thicker.

[sapote]

• Address only the issues that are proven to be such
  • loose sprocket screws
  • address slack between the exhaust hub tabs and disc holes.

.

I think you meant Loctite the cam-sleeves 12 bolts.

[sapote]

I joined the forum late and didn't see the article about why Beisan suggest to use S62 spring disk. I never believe in this and always suggested people not to use it and not exchange their stock pump disk, but keep the stock disk and 4 pistons together as they are matched parts.

The only think I did on my car is to re-drill the disk with smaller holes for the driving tabs, new upper chain guide, loctite the 12 bolts for cam-sleeves.

[karter16]

I will post for reference the test results of my VANOS with the S62 hubs, and change to S54 items and see the effect on the Vanos testing.

As much as this has been an expensive exercise for you I do want to thank you for taking the time to document this and finally provide us with a before/after comparison of the S54/S62 springs. I encountered the slow response issue directly after rebuilding my VANOS in 2016 with S62 springs (which as you note was the cool thing to do at the time). At the time on the forums you pretty much got your head bitten off for suggesting that Beisan might be wrong in some way (especially as the newcomer I was at that point) so I stayed pretty quiet on my suspicion that the S62 springs were to blame. I'm very much looking forward to seeing a direct comparison between the two.

[maupineda]

Photos

As you can see the tabs are not only larger in diameter, but also in width









Also, there is a draft needed for manufacturing, which the VAC items does not have, this makes possible to have the width of the tab increased





Another observation is the thickness, VAC is 0.1mm thicker. this does not matter, but a nuance non the less.





I measure the depth and height of some surfaces and there are some variations as well but those could be due to measuring method

[maupineda]

A bit of context, about 4 years ago I "bullet proofed" my VANOS, and that sent me down a rabbit hole unnecessarily. so word of caution is, do limit the scope of your work to what is actually needed addressed, and avoid following internet advise blindly.

For me, the key learnings from that experience are simple:

• Before any VANOS work, do a test pressure and VANOS testing using ISTA, INPA, DIS (depends on your car)
• DO NOT mess with the unit if your tests are successful
• DO NOT change diaphragm springs to S62
• DO NOT change / exchange your oil pump disc
• Address only the issues that are proven to be such
  • loose sprocket screws
  • address slack between the exhaust hub tabs and disc holes.

I learned the above the hard way as my car had no issues, and created some by jumping on the internet band wagon

• My VANOS had no issues whatsoever, but I caused pressure issues by changing the disc with a faulty one
• I changed the diaphragm springs and as a result slowed down the response time of adjustment, this is not a problem per se, but causes the system to be slower and without proper testing, is not possible to tell what the effects are.

From the issues above, I was able to address the pressure problem by going back to an OE setup (expensive), and now I am going back to the correct S54 diaphragms springs. These springs preload the hubs, S62 items are thicker so the preload is higher, which will increase the friction needed to rotate the hubs and ultimately adjust timing. This items make the hubs effectively a clutch type system.

I will post for reference the test results of my VANOS with the S62 hubs, and change to S54 items and see the effect on the Vanos testing.

I also chose to install a VAC hub as a way to prevent those driving tab from breaking.