Re: [T3] MPS observations

["Jim Adney" <jadney@vwtype3.org>]

On 9 Aug 2008 at 8:49, Phil Hof wrote:

> That will be a very difficult job.  The flexing properties entirely
> determine the response of the MPS, which directly controls the
> injection.  It can be correct geometrically, but not act the same
> under vacuum.  It is surprising therefore to find two different
> materials!  Perhaps one was original, one was rebuilt by Bret?  This
> will be a key part for making these VWs "last forever." 

Your position on the material is the same as found here:

http://members.rennlist.com/pbanders/manifold_pressure_sensor.htm

But I'm not sure I agree with that position. The diaphram is quite 
flexible, but the other springs in the MPS are quite stiff. My 
feeling is that the stiffness of the other parts make the spring in 
the diaphram pretty negligible. Things would be different if the 
diaphram contributed the lion's share of the forces, but that's not 
the case.

My main concern is with durability, which means I'm worried about 
things like corrosion, chemical compatability, and fatigue life. I'll 
still try to make any replacements as flexible as possible.

The Rennlist writeup is pretty impressive, and I've taken most of it 
to heart, but I get the impression that he's more comfortable in the 
electronic realm than in the mechanical aspects of the problem.  

-- 
*******************************
Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA
*******************************

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