S54 vanos diaphragms

[BMWfanz]

Guys, planning to rebuild vanos with anti-rattle kit and new bearings set for gears, already ordered new s62 diaphragms for anti-rattle but now i found some posts on forum that installing s62 diaphragms will increase reaction time and it could be a problem with vanos test passing. Any detailed info? As i saw- there was a one issue with vanos pump with diaphragm set- but no info was the issue were in pump or diaphragms.

[jbfrancis3]

I installed S62 diaphragms 3 years/12k-ish mi ago as part of VANOS overhaul with all Beisan stuff. Just like you, I saw subsequent posts saying the same thing and was always curious. Just last weekend to commemorate ponying up for an genuine ICOM, I ran a VANOS test. Reaction times on the intake were 281ms/218ms and exhaust 198ms/221ms (overall test passed, too). Those reaction times are within spec so hard for me to get concerned with work already done.

Your question is a little different which is should you install them? I believe they are supposed to dampen noise but VANOS is never going to be silent so I question the need, especially if you do the rattle repair. Look for others to chime in but I also wouldn't hesitate to call Beisan and get them to elaborate on the need.

[karter16]

I had reservations about the S62 diaphragms all the way back in 2016 when I did my vanos. From my reading and understanding of how vanos worked I didn't see how the stronger springs weren't going to have an impact on operation. Ultimately I decided to go with what everyone was doing at the time. I was fairly new to the M3 at the time and it was the first work of significance that I was doing to the car. I decided I would do what the recommendation was as it was clearly working okay for a large number of people. My vanos passes the tests, but like others have since reported I've had higher than ideal intake reaction times. I think that this is likely to be due to the S62 springs (although I can't confirm as haven't swapped back to S54 ones). In terms of the original reason the S62 springs were recommended, noise, they've made a huge difference.

All in all, being much more confident with this platform and with my own assessments and decision making, if I was doing my vanos today, and when I do it in the future, I'd use S54 diaphragm springs, but equally don't feel any need to rush to get rid of the S62 springs.

Provided that this is what's causing slightly higher intake reaction times, you're not going to notice the difference either way anyway, only way you'll tell is looking at the results of the vanos test :-)

That's my thoughts anyhow.

[maupineda]

S62 produces more engine torque, these diaphragm springs are a clutch like system, it made sense for the S62 engine to avoid slippage, the S54 produces less torque, and is an inline 6 so the force to break away the torque to rotate the cams will be more compared to a bank of 4. So i am sure that is a main the reason, and also explains why the pressure spec is higher on the S54 v S62. Also BMW design the S54 to be more responsive and higher reving.

these springs make the sprockets and cams to lock, and only the force of the hydraulics make the splines move in and out rotating the cams overcoming the breakaway torque force of these diaphragm springs.

My Z4M went from los 200ms to low 300ms. Like others said, is not like I am rushing to remove them, but definitely is something I want to do. If it wasn’t ideal, BMW would have not changed the spec for the S54 since the S62 came out first.

[sapote]

No reason not to use the stock S54 spring disk. If it's rattling then check for the bearing having plays and rectify the problem. Done.
The spring disk is to eliminate the plays/clearance between the hub and the cam to avoid chattering.

During vanos activation, the cam is moving relative to the hub with the spring disk in between. So the spring force was selected to eliminate the plays but not so much to cause unnecessary high friction between hub and cam.

[BMWfanz]

Received official answer frim beisan: 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

[sapote]

To use the weak springs can leave some rattle from the splined shafts play inside the hub gears

It's safe for them to say this, but many cars including mine don't have the rattle with the stock spring disks. The stronger loading on the S62 disk will cause faster wear on the disk.