Which piston seals?

Al James

I am planning to fit new piston seals later today and have discovered I have an 'old set' and a new (proper fit) set. Can anyone tell me if I should be using the type in the top or bottom of this picture please.

Attached files

Reiss Gunson

hi al

im not sure if I'm answering your question, but if you are asking which are the new seals;

the new seals look like this:

Attached files

Al James

Thanks Reiss,
That answers it - the seals at the bottom of the picture are the new ones...

Many thanks

Martin ismail

So excuse me for asking what is the difference between the two


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Reiss Gunson

for reasons only known to the group manufacturer they fit a piston seal that is not the same height as the seal groove

this works ok on a traditional italian dose of 14g as the pressure presented on the seal by the coffee puck (via the water & air between the puck and the piston) is less, but on larger modern doses the piston drives downwards and the seal slips upwards in the seal groove by about 1mm and this results in the high lever grab

we now machine our own seals that exactly match the thickness of the seal groove

sorted; https://londiniumespresso.com/store/espresso-machine-parts/one-londinium-custom-piston-seal

pity it took us so long to get to the bottom of the matter, it still makes no sense to me; i can only assume 7mm seals were more readily available and therefore less expensive

reiss.