Rocket group gasket 8 mm – so the portafilter locks in firmly again
The portafilter slides into the group, turns a little, and then comes that firm, solid lock after which nothing drips anymore. This is down to a slim rubber ring between group and portafilter that holds the full pressure with every shot.
Under heat and pressure, rubber loses its elasticity over time, hardens and shrinks. This item is the 8 mm thick version; we carry the second thickness alongside it, because that is exactly how the two differ when fitted.
When it's due
The first sign is the portafilter handle: it turns further than it used to before it sits tight. If it moves well past the centre, the gasket has shrunk.
Other signs are coffee escaping at the side of the group, a portafilter that can only be released with force, and a gasket that is hard and cracked rather than elastic when removed. If you film the shot, you can also see it at the edge of the portafilter: water escapes there that should actually be going through the coffee.
At a glance
| Type |
Group head gasket, also called group gasket |
| Thickness |
8 mm |
| Installation location |
In the brew group, between group and portafilter |
| Fits |
Rocket portafilter machines. Exactly which series is not documented for us – we check it using the serial number. |
| Version |
We carry the second thickness as a separate item |
| Installation |
Fitting by a qualified professional recommended |
| Brand |
Rocket Espresso |
Our documents do not state a part number for this gasket. We don't enter one that we can't verify – if you have one from a service document, send it to us and we'll cross-check it.
Important for installation
The gasket sits in the group, and the group is hot and under pressure during operation. Before replacing it, the machine must be switched off, unplugged and cooled down; only then is anything loosened at all.
We deliberately do not give step-by-step instructions here. If you're unsure, bring the machine to us or have the replacement done by a qualified professional – it's a small job, but one on a component that holds the full brew pressure.
Who it's for
For anyone with a Rocket whose portafilter turns noticeably further than it used to, or where coffee runs past the side of the group. One of the cheapest parts of the machine with the biggest impact on a clean shot.
What goes with it
The second thickness is the group gasket with 8.5 mm. Which of the two fits is decided by the position of the portafilter handle, not by the model.
The same group also holds the flange gasket of the brew group and the fine filter for the group. Both are inexpensive and belong on the table every time the group is opened.
For cleaning, we carry machine and grinder cleaning products. More can be found in the categories Rocket accessories and spare parts and Service parts.
From our workshop
Whenever we replace the gasket, we always have the fine filter ready alongside it. A new gasket on a clogged filter is only half the job, and the filter costs less than a second workshop visit.
And we check the position of the portafilter handle right after installation: if it sits roughly perpendicular to the machine after locking in, the right thickness has been chosen. If it moves far past the centre, the other thickness is the better choice. This is our routine in Bern and Zurich, not a manufacturer specification.
With it, in Bern and Zurich we like to drink Nutty Delight, Cozy Chocolate and, when it should have no acidity at all, Very Nutty. The full range can be found in our coffee beans.
Returns excluded
Service parts are excluded from exchange and return. They are sourced specifically for each order and cannot be resold after being fitted or test-fitted on the machine. So before ordering, check the model, year of manufacture and serial number of your machine – or drop us a quick message and we'll clarify the fit together. Your rights in the case of defective goods remain unaffected.
Frequently asked questions
Should I take the gasket with 8 or with 8.5 mm?
That is decided by the position of the portafilter handle. If it sits properly with a new 8 mm gasket, stay with this thickness. If it can still be turned far past the centre even then, the 8.5 mm version is the right one.
How do I know the gasket is due?
The portafilter turns further than it used to, coffee escapes at the side of the group, or the old gasket is hard and cracked when removed.
What is the part number of the gasket?
Our documents do not state a number for it, and we won't make one up here. Send us the number from your service document and we'll cross-check it.
How often does it need to be replaced?
That depends on the number of shots, the temperature and the water, which is why we don't give an interval here. We look at the gasket at every service, and you'll notice it at the handle long before anything breaks.
Can I see the part before buying?
Our showrooms in Bern (Gerberngasse 44) and Zurich (Hagenholzstrasse 50b) show a wide selection, but not our entire range – the display changes. Drop us a quick line at [email protected] before your visit, and we will check whether the product you have in mind is currently there.
Unsure about the fit? Write to us at [email protected]. We deliver across Switzerland and to Liechtenstein in 2-4 working days.
