rmofsen wrote:Hi all,
I found this on Amazon (https://www.amazon.com/gp/product/B087C ... UTF8&psc=1)and received it today. It's a bit pricey and requires a small amount of filing but fits perfectly.
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espressotime wrote:The piston rod wants to move from front to back by each pull. You can see in my video my it is actually doing that.Hence the knock you hear and the movement you see in the video.
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The piston 6 inches down in the group isn't you regular piston with three seals.Only a teflon ring of app. 3 mm wide makes contact with the piston wall .Of course the one seal also but that thing is flexible.
Vilt = felt
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Also that felt seal is a big thing.

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Once that isn't installed you create a lot of movement in the top.And with each pull the piston rod is wearing that piston tube in the upper housing down.
And the force it does that with is high.
Now take into account that I also do heat up pulls and cleaning pulls.
In 8 years that makes 8x356 x45 = almost 130000 scraping movements of the rod against that tube. That will wear that thing down.
I once destroyed a big end bearing of my old harley in 20 seconds of idling without any oil flow from the tank.
That thing idles at 900 rpm. That bearing was shot.
Metal on metal without any kind of lubrication is killing.

drH wrote: So how long will that felt piece last? Won't it need regular replacement?

Poor Cremina goes back on the shelf?