Now, I’d like to ‘do-a-LeaUK’ and summarize where we are. Note that I am only going to discuss LeaUK and JimF VFCs and their respective bms.
Abbrev: 119 200 00 22 = “00” ; 119 200 01 22 = “01”
JimF tests:
I have tested two (2) VFCs with “00” and “01” part numbers in
water. Both results showed that they locked up around 100C. Both of these parts
never locked up on the car in
air . . ever! This was in their ‘stock’ configuration; they did lock with modification.
Have inspected
many bms and have NEVER seen a bms that was marked different than the two that I tested. Yet, documents ‘claim’ that there are different bms in some of the various VFC assys. Still unresolved.
LeaUK tests:
He has an
operational VFC on his car that locks up at yy C degs. I say ‘yy’ degrees because I think that the indicated temperature (85C) in the IC, may be low. But if the gauge is correct, then he
definitely has a low temperature bms.
This conclusion stems from three (3) facts. 1) his bms has different markings (“1577” vs “1577A” for JimF); 2) it appears to be made of a different amalgam than the ones that I tested; 3) it actually locks up when mounted to the car.
Remaining Tests:
To
prove that the LeaUK bms is different, it should be tested in water. It would be informative if a JimF bms could be tested at the same time. By doing this, you would see the different “bends” and these would be immediately visible.
Remember as shown in MENU#21, the two bms bent exactly the same. I suspended both of them ON THEIR SIDE with separation so you could see slight bends and could see different amounts of bend. No such thing happened; they bent the same. Based on the part number, “01”, it should have been different.
Testing Methods:
I’ve included this so as to point out that WATER is the preferred test medium because the properties and environment that the bms being tested can be easily controlled. We all should know this by now, but based on some posts, it seems to be missing.
A small vessel of water, big enough to contain a bms and/or VFC + bms is relatively easy to heat to a ‘homogeneous’ temperature. As such then the bms (or multiple bms) being tested will not be subjected to different temperature gradients is would be in “air”.
If testing of the LeaUK VFC on a MB car shows that it locks up at 85C, you can be assured that the bms in the VFC will show
more bending than a JimF bms. So testing them side-by-side would make a ‘great’ picture and clearly show the different bends.
Also, you do NOT have to remove them from the water to take a picture if you use my technique; suspend the two in a small metal ‘pick’ that has small notches to keep each bms separate AND each on its side. Then take the picture from the top (straight down), the diffraction would not be a factor. And whatever it is, it would be the same for both.
Quote:
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Originally Posted by LeaUK
How may the viscosity of silicone fluid affect the temperature of operation? Theory ONLY, but a possibility:
For the purpose of this explanation I will assume the BMS bends 1mm at 90C, with this movement MAYBE the valve behind the pin allows (leaks) a minor volume of fluid into chamber 2. With an original clutch containing original silicone fluid this MAY NOT be enough to achieve lock. But now increase the viscosity of the fluid significantly (me adding something I think is about right) and with this same volume of leaked fluid MAYBE the clutch will lock.
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My comment is ‘could-be’! But remember that the
higher the viscosity of the ‘gel’, then the bigger the opening needs to be to get it to migrate. Little opening, high viscosity gel = little gel migration; little opening, low viscosity gel = more gel migration. Kind of a double edge sword.
BMS bend vs Pin Clutch engagement:
In one of the posts, you may recall that I modified a ‘stock’ pin clutch and removed about 0.030” from the end. It should be obvious now that I’m trying to see
how much NEEDS to be removed, so that it will engage (lock-up) at “xx” C temperature. Trying to see what “xx” is versus pin clutch length. And make “xx” about 95C coolant temperature if possible.
So for a total pin clutch ‘travel’ of 0.080” or so, removing 0.030” inches has not helped; it has not locked up. The car’s coolant temperature showed 95C max.
Since the bms bends “a little bit” at 90C, that’s
not enough bend to start lock-up. As I said before, the bms
must bend quite a bit to engage the clutch; just a little bend is not enough to start gel migration. This is an almost new VFC w/ 'stock' gel.
Plans are to continue to test and hopefully the weather will get warmer, maybe even ‘hot’! If it still doesn’t lock, I will remove 0.010” more and then test it again.