S54 Diaphragm Springs and Exhaust Hub

[Slideways]

That was my initial thought too. This is an interesting topic, I will likely trade out my S62 springs to see what happens, but it'll be a little while. The question will be do I put a set of used ones in (to simulate reusing them) or a new set...

Throw a used set in a parts washer. They'll look brand new

[George Hill]

The S54 VANOS had higher forces to overcome. More valves and cylinders in a give bank, higher revving engine also, that can explain why BMW did not use a newer revision of the part if it was better, also the pressure is 15% higher.

So maybe they started with the same I6 spring constant on the V8 and then realized that they could get away with a higher spring constant because of the reduced friction of the shorter cams. S54 still has the longer cams, so they kept the original springs there.

That was my initial thought too. This is an interesting topic, I will likely trade out my S62 springs to see what happens, but it'll be a little while. The question will be do I put a set of used ones in (to simulate reusing them) or a new set...

[heinzboehmer]

I think this could easily be a case where there was already stock or an order in place that it didn't make sense for BMW to change them just because on the S54. Maybe the questions is why did they change them on the S62? I'm just thinking that if they are better on the S62 doesn't mean they are on the S54.

Potentially too far fetched of a theory, but BMW did introduce the diaphragm spring style VANOS on pre-S54 inline sixes.

So maybe they started with the same I6 spring constant on the V8 and then realized that they could get away with a higher spring constant because of the reduced friction of the shorter cams. S54 still has the longer cams, so they kept the original springs there.

Just daydreaming mostly, but sounds plausible to me.

[maupineda]

The S54 VANOS had higher forces to overcome. More valves and cylinders in a give bank, higher revving engine also, that can explain why BMW did not use a newer revision of the part if it was better, also the pressure is 15% higher.

the Overall stack is a bit smaller with the B springs, which may result in chatter of there was play, but by design the springs are always under compression, so I am not sure it was noise, there maybe more to it.

[lemoose]

That was my understanding too have never been able to tell a difference though.

I had forgotten about that noise! I haven't heard (or even thought about it) it actually since you did my VANOS overhaul so maybe it can help? Mine was particularly bad around 3-4k I want to say.

[George Hill]

50ms is definitely not perceptible, even more if you imagine that the VANOS is constantly adjusting and probably never makes such a "large" movement as in the VANOS test, so in the real world it'll be a % of that 50ms even...

That's my point does even matter if the add 50ms?

My logic would be; since the 98-01 S62 engines were delivered with the "A" spring that the S54 uses, and BMW TIS for the S62 states that those can be replaced with the newer style "B" spring, by that logic the same could apply to the S54.
Perhaps it is that simple, but on the other hand 09/2001 was still VERY early into S54 production, so if BMW deemed the "B" spring universally "better", why not use it on the S54 onwards, that is what bothers me the most.

I think this could easily be a case where there was already stock or an order in place that it didn't make sense for BMW to change them just because on the S54. Maybe the questions is why did they change them on the S62? I'm just thinking that if they are better on the S62 doesn't mean they are on the S54.

Also look at it this way, even if the end conclusion is that there's (virtually) no difference in performance between the "A" and "B" springs, that just means that no one should care to remove their existing S62 springs.
But it also means that going forward there is no point installing them, so we still learned something.

I agree, I don't think anyone should take their car apart JUST to remove them. And if it was apart for another reason then I'm not sure I would replace them either.

But if there is not operational change and I can save my customers $80 that's a win in my book.

They were supposed to reduce noise.

That was my understanding too have never been able to tell a difference though.

[Slideways]

50ms is definitely not perceptible, even more if you imagine that the VANOS is constantly adjusting and probably never makes such a "large" movement as in the VANOS test, so in the real world it'll be a % of that 50ms even...


Unfortunately we can't ask him anymore :/

My logic would be; since the 98-01 S62 engines were delivered with the "A" spring that the S54 uses, and BMW TIS for the S62 states that those can be replaced with the newer style "B" spring, by that logic the same could apply to the S54.
Perhaps it is that simple, but on the other hand 09/2001 was still VERY early into S54 production, so if BMW deemed the "B" spring universally "better", why not use it on the S54 onwards, that is what bothers me the most.


Also look at it this way, even if the end conclusion is that there's (virtually) no difference in performance between the "A" and "B" springs, that just means that no one should care to remove their existing S62 springs.
But it also means that going forward there is no point installing them, so we still learned something.

They were supposed to reduce noise.

This video does not mention the S62 springs, but it is a before and after -

[bmwfnatic]

I'm still curious what this affects. I mean lets say they do slow the change down say 50ms is that even something perceptible? "Spec" is 300ms and it doesn't set a fault until 500ms (IIRC).

50ms is definitely not perceptible, even more if you imagine that the VANOS is constantly adjusting and probably never makes such a "large" movement as in the VANOS test, so in the real world it'll be a % of that 50ms even...

I feel like Raj @Beisan Systems was the one who came up with this idea. What is this supposed to fix?

Unfortunately we can't ask him anymore :/

My logic would be; since the 98-01 S62 engines were delivered with the "A" spring that the S54 uses, and BMW TIS for the S62 states that those can be replaced with the newer style "B" spring, by that logic the same could apply to the S54.
Perhaps it is that simple, but on the other hand 09/2001 was still VERY early into S54 production, so if BMW deemed the "B" spring universally "better", why not use it on the S54 onwards, that is what bothers me the most.

Its just always "what we've done" but if there is a better option than I am willing to give it a try.

Also look at it this way, even if the end conclusion is that there's (virtually) no difference in performance between the "A" and "B" springs, that just means that no one should care to remove their existing S62 springs.
But it also means that going forward there is no point installing them, so we still learned something.

[George Hill]

True, I meant more so to leave out the S62 springs, as the other items likely do not directly relate to the adjustment times.

If I do this, it'll be with new springs, no way I have the originals, scrapped years ago.

I'm still curious what this affects. I mean lets say they do slow the change down say 50ms is that even something perceptible? "Spec" is 300ms and it doesn't set a fault until 500ms (IIRC).

I feel like Raj @Beisan Systems was the one who came up with this idea. What is this supposed to fix?

Its just always "what we've done" but if there is a better option than I am willing to give it a try.

I had a client stop by today and I ran the Vanos test on his car. I don't have a before, but I do have an after. His car got everything plus the rattle kits for the splined shafts. These two tests span about 30k miles.

2020:




2024:

[Slideways]

When swapping these back, can you reuse the original S54 springs and plates that came out of the engine? I can't remember if I saw a wear pattern on them and figuring out which side was intake and exhaust is probably going to be impossible. This is for future reference if installing cams.

[bmwfnatic]

Unfortunately I think that is highly unlikely to get someone who just wants to do that as I would want to go back in and replace all the parts we normally do. Maybe I'll take them out of my car, no other changes.

True, I meant more so to leave out the S62 springs, as the other items likely do not directly relate to the adjustment times.

I have switched 2 engines back to S54 springs, but one of them doesn't even have a car to go in to yet, and the other definitely wont run before spring...

[George Hill]

George HillGreat data points, could you at some point see if a customer with a similar relatively low mile vehicle is willing to do “just the seals”, so we can see if the slowing in reaction time is related to the S62 springs, or to the seals being new.

Unfortunately I think that is highly unlikely to get someone who just wants to do that as I would want to go back in and replace all the parts we normally do. Maybe I'll take them out of my car, no other changes.

Here's some more data, this is my car. I lost the initial tests due to a hard drive failure but I have these, unfortunately no mileage stamps but I'd wager at least 5k miles between them. Same as all the cars above but with the rattle kit. This is after the initial break-in which I think is what is causing the slower times on freshly serviced Vanos units.

5-18-21:



1-21-22:



9-27-24:

[bmwfnatic]

George Hill

Great data points, could you at some point see if a customer with a similar relatively low mile vehicle is willing to do “just the seals”, so we can see if the slowing in reaction time is related to the S62 springs, or to the seals being new.

[maupineda]

Thanks for adding those data points!

[sapote]

Here's another one:
The car had 55k on it and looks like the Vanos has not been touched.

On this car the highlights are:
Beisan seal kit
Beisan oil pump disk
S62 diaphragm springs
No rattle kit, splines are original

[/URL]

It's clearly the vanos moving time before is less than after.
Before average = 240 IN, 211 EX
AFter average 260 IN and 245 EX

Also I wonder why the EX total travel is about 48 deg instead of 45 as spec?