Hello,
I am working on a Zacconi Riviera lever machine and have run into a problem. I changed the piston seals and have attempted to use the Ponte Vecchio spring which is basically the same dimensions but 0.5mm thicker. I can't seem to get the original piston travel, and when I switch back to the Riviera spring, I still cant get the right travel. It seems to hit pretty hard and forcing it did not help.
- 45mm portafilter
- 3 seals (I installed the lower seal the wrong way and still need to correct this)
- These seals are a pain to change!. Definitely soaked them in boiling water which helped.
- Using Dow Corning Molykote 111 for assembly.

1st attempt:
I was able to install the piston assembly with the PV spring, but the piston will not rise high enough (6mm short). My assumption was that the spring was too long when fully compressed.
- I fully compressed the stock Riviera spring and the new PV spring, and then ground the PV spring down until the compressed length was the same.
2nd attempt:
Reinstalled and the piston will still not rise high enough (4mm short)
- Also reinstalled the piston assemble without spring and confirmed that it was able to travel freely all the way up.
3rd attempt:
Installed again but spent some extra time to ensure the spring was fully seated at the top of the group. Same results
4th attempt:
Re-Installed the Riviera spring back in and cant get the piston to rise up enough (about 4mm short)
- I discovered that I installed the bottom seal (1st) in the wrong direction. I will correct this issue, but don't think this is my problem

Zacconi Riviera with 3 seals piston
- The last comment on this HB thread has the same problem but no resolution.

Any idea's?

The machine was working quite well before I decided to up the spring pressure. Hopefully I can get it reassembled.

I have tried multiple more times and corrected the lower seal orientation, no luck. I pulled the group off to better inspect the top spring seat and look for wear patterns. I have also fully assembled the piston and lever without spring, and the piston travels freely for the entire stroke. I have been more cautious about ensuring the spring is fully seated in the top of the group and on top of the piston, but always end up roughly 4mm short (piston does not clear the water inlet). It seems to be an issue with the spring binding, really puzzling that I am unable to get the original spring to work, especially since I have removed and reinstalled the piston assembly before without issue (2 weeks ago).

The good new is I am getting very fast at removal/installation of piston assembly and seals! I have re-purposed a cam puller that was for a VW TDI. Looks like it's back to pour overs until I can get this resolved.

This may or may not be relevant, but for my Arrarex machines, small variations in the shape of the piston seals make a huge difference.
The height at which the actual sealing takes place is different for different seals.
When the piston is all the way down, some seals allow water to enter above the piston and others don't. In my case, the seals on which the lip is "not tall enough" are bad.

Perhaps your new seals have longer outer lips than the old ones and that is why the inlet hole is now blocked when the piston is up.

When I had the lower seal reversed, I was still able to get water through, but not as quickly. I pulled a shot and the first 1/3 or 1/4 of the lever felt like air or like it was not sealing. It was probably not sealing correctly due to the reversed seal. New seals fit well within the deep grooves and do not extend beyond the piston.

I can confirm that the rod is not travelling its full stroke anymore, but does with no spring installed. I have been measuring the rod extruding above the group with a caliper. Even without caliper measurements, the piston does not rise above the inlet hole like it used to. I had also taken this measurement weeks ago when I was calculating the volume per lever pull.

Appreciate your thoughts.

My next moves:
1. Pull group off for the third time and better inspect the spring seating. Will take measurements to confirm it is seating.
2. Paint all the parts or cover in blue layout dye. Then re-assemble/dismantle and inspect wear patterns. Hoping to find where the spring is binding.

Running out of ideas

Is the handle installed upside down? Sometimes this messes with the travel.

Tried both directions on handle and both directions on piston. Just tried reversing the handle again now.

I have taken some measurements and have determined that there is currently not enough room for the original spring.

When lever is up, piston is flush with bottom group lip.
Max lever is capable of raising piston from lip: 23.15mm (measured with no spring, I measured roughly the same thing when machine was working properly)
Old piston stroke measurement with working machine: 23.4mm (This compares well to the 23.15mm, this was measured from the rod displacement above the top of group. I still know how much the rod should stick up above the group and can confirm that I am not getting it anymore)
Max lever is actually raising piston from lip (with spring): 20.4mm (This is not enough!)
23.15mm-20.4mm = 2.75mm (this is how short I am from max piston travel)
Top group spring seat to bottom lip: 87mm
Piston height: 34.85mm
Fully compressed original ZR spring: 31mm (I did not spend the time to measure the thickest location so this might be on the smaller side)
Fully compressed spring + Piston: 65.85mm (adding two measurements together, this may be on the small side)

This is how much room I need for the spring and piston:
87mm - 23.15mm = 63.85mm (This is longer than my compressed spring + piston measurement, wtf)
This is how much room I need to have for the spring:
87mm - 34.58mm -23.15mm = 29.27mm
Theoretical max piston height:
87mm-65.85mm = 21.15mm (this compares reasonably well with the 20.4mm measurement)

Ideas:
- spring has grown (Doubt it)
- Spring can compress more in a certain orientation (the seats are flat on the top and bottom, I also tried multiple orientation)
- Piston has grown (Not a chance and I have measurements)
- Rod has unthreaded from piston (Have measurements to prove to confirm this has not occurred)
- Thin brass sleeve inside group has pushed up group 2-3mm (This doesn't add up because the rod used to extend 25mm above group and now it extends about 22.2mm (unless I remove the spring, then its back to 25mm))
- Someone messed with my spring in an attempt to drive me insane
- I want the smoking gun answer to my problems

Side note: when I flipped my lower seal I damaged it a little, hopefully it still works!

I am not sure if anyone is going to understand this nonsense but its helping me to flush things out on here and maybe it will help someone else in the future. At this point I am going to grind my new PV spring down about 2-3mm and I am fairly confident its going to work, not sure why but probably wont care anymore once I get my spro

So first off, the spring only controls pressure, not piston travel. And the piston travel is set by the location of all the holes and connecting links, it looks from the pictures I found that its a very simple design with no levers, just 2 pivots. So from the top, the only way to adjust travel would be to turn the handle over and it's not clear from the pictures that that should do anything unless the holes or shafts are worn. Other than that, if it doesn't clear the fill hole, then the seals have to be wrong or somehow the piston and shaft assembly has increased in length. If you ever took those apart is there any way you could have put them back together so they are slightly longer, like by the thickness of a washer?

So I guess I'm saying, you should work without springs installed till you find the issue as they shouldn't be necessary for figuring that out and it's a lot easier to see what's happening without the spring there.

Ira

Appreciate the response.

The spring can control piston travel if its too long, adding a washer to the top of the spring would have the same impact. I doubt my original spring has grown so I must be missing something... I am installing the PV spring for greater pressure.

There is no washer or change in mechanical parts (pins, roller, lever, spring, pistons, group, etc). I have been very carefully about knowing which spring is going into the machine. The spring seats are flawless, i see no reason for anything to hang up. My lever is symmetrical and I get the same results either way, holes are drilled in centre.

I have installed the lever with no spring several times now and get the correct stroke. I agree that this is a good place to do more experimenting and to triple check all of my measurements.

I have ground down my new stiffer PV spring about 2.5mm, and now I clear the hole. I did not want to grind the original in case I sort out what the issue is.

Dawson

I put everything back together and it seems to be working, i am now getting proper flow again. Had to dial in the grind a little finer which makes sense for the stiffer spring.

The PV spring is now 2.2mm shorter than stock ZR spring when fully compressed.

I am still not sure what went wrong, but am throwing in the towel for now.

Thanks for reading through this nonsense.