You Won't Believe the Difference: 9, 6.5 & 5 Bar OPV Mod with Flow Rates for Gaggia Classic Pro

Want a better mouth feel and less channeling on your Gaggia Classic Pro? Then follow this simple tutorial for replacing the original 12.5 bar spring of the OPV to a 9, 6 or 5.5 bar spring. We take a look at the measured pressure of each spring, and determine the average flow rate in 4 separate extractions. Then we look at the results of the original 12 bar spring, as well as the 9 bar, 6.5bar and 5 bar springs.

-------------------------------Products used/recommended in this video---------------------------------------------------
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►The Gaggia Classic Pro:

► Springs:

►Bottomless Portafilter:

Spring measurement breakdown:
12 bar spring: 23.6mm long and wire strength of 0.6mm.
9 bar spring: 19.5mm long and wire strength of 0.6mm.
6.5 bar spring: 23.9mm long and wire strength of 0.5mm.
5 bar spring: 20.1mm long and wire strength of 0.5mm

Chapters:
0:00 Intro
0:51 Required Tools
1:35 Factory Spring test
2:08 Puck Preparation
2:41 12 bar Spring Results
3:06 Installing the 9 bar Spring
5:43 9 Bar Spring Results
6:36 6.5 Bar Spring Results
7:19 5 Bar Spring Results
8:08 12 vs 9 bar Spring Extraction

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#gaggiaclassicpro #tomscoffeecorner #opvmod

[TomsCoffeeCorner]

AFFILIATE DISCLOSURE:
Some of the links used in the description will direct you to Amazon, as an Amazon Associate I earn from qualifying purchases at no additional cost to you.. Affiliate commissions help fund videos like this one.

[chriskvikstad]

Hi Tom, I know this is an older video but the topic is very current, especially for those of us with Gaggia Classic Pros and other smaller, vibratory pump espresso machines that are shipped from the factory calibrated to higher pump pressures. I have been feeling disappointed with my spring mod for my Gaggia Classic Pro. I installed the 9 bar spring and it just hasn't made much of a difference for me, so I started really deep diving into what is going on. I found this interesting video from the Espresso TV channel regarding pump pressure differences. In the video, the host visits the Bezzera factory in Italy and he talks about pressure with Luca Bezzera (the grandson of the man who invented the espresso machine). Luca Bezzera says that with small espresso machines using these tiny vibratory pumps, they have to be calibrated using higher pressure at the pump in order to get the proper flow rates and pressure at the group head during extraction. There is significant pressure loss between the pump and group head during the actual extraction process. He said they need to have 12+ bars of pressure at the pump because the pumps are so tiny. In contrast, large commercial machines and prosumer machines using rotary pumps are calibrated at 9 bars of pressure because the pumps are so much larger and more powerful. He's a native Italian speaker, so he's having some language barriers at times going between Italian to English, but he gets the point across. The host of Espresso TV is a German hydrodynamic engineer who used to design large pumping systems at water facilities. He understands the fluid mechanics involved and his English is really proficient, so he does a good job of trying to explain the basic physics in the comments section.

I believe Marc at Whole Latte Love has recreated some of these test experiments. I can't find his video at the moment. To accurately measure pressure loss between the pump and group head during an extraction, there needs to be a device attached to the portafilter that allows water to flow out at the proper extraction flow rate to simulate an actual extraction while the pressure is simultaneously being monitored at the portafilter. If you do your test first, to measure the pump pressure, then you can conduct this second experiment to calculate the pressure loss in your machine during extraction. Then you know with certainty what pressure you are really extracting with. Marc said there is so much pressure loss with the Gaggia Classic Pro that you are not extracting anywhere near 12 bars of pressure with the standard OPV spring.

[SpartacusDog]

Thank you, Tom! Of all the hundreds+ coffee videos on YouTube, on hundreds+ topics, yours are invariably the very best. Your videos are better thought through, they are the clearest, and your explanations are the most informative. You've greatly elevated my coffee brewing IQ and greatly informed my coffee making decisions. All I can add is thanks again.

[lostboy]

Hi Tom, I am another convert thanks to your excellent advice.The 9 bar spring mod which I successfully undertook thanks to your video, the difference is night and day, it is way better, my shot has a far better crema, and the shot now has that wonderful silky appearance that I have come to appreciate in great expresso.I am absolutely delighted in the difference and the results, so thank you so much for dialling me in to near perfection, kudos to you Sir.

[BobMacNeal]

I appreciate seeing the comparison of all the Shades of Coffee spring mods for the GCP. Based on your previous instructional video, I installed the 9 bar spring from Shades. I also do about a 5 second pre-infusion step for my all of my shots (aiming for 1:2 recipe). I've been very pleased with the results. Thanks Tom.

[DrHankVenture]

Hey, I came back to tell you that this was the MOST HELPFUL video for these mods. I put the 5.5 bar in my machine, and I cannot believe how good my shots have become. They're absolutely incredible. Thank you so much for for this!

[Psychoh]

Appreciate the content and the flow comparison :)

My only issue with the taste comparison is that the GCP users need to be careful of temperature surfing. Sure the flow rate had impacted the flavour of the coffee, but at the same time it could be the not perfect temperature surfing (not showed in this video).

A part from that, flow comparison is great and I switched just last week from the standard to the 9Bar

[SunriseLAW]

After significant experimentation, imo the best results from my GCP come from the original spring (13 bar?) and the Dimmer Mod. That allows me to ramp up the pressure and taper it off. I was watching a vid (I think it was the "Decent" machine) and it automatically ramped it up/down such that it peaked at 17 bar (?). That gave me the idea to try it on the GCP and put the original spring back in, and I think the results are better.

[j.t.]

Ha ha!! I am learning well! I first thought, why on earth would we use that stock basket when Tom recommends the IMS (for my Delonghi)? Then, you answered my question. Glad that this video came up today.

[tomaszdrgas]

I like the wideo but result was what i expected (vs unbelievable title) even though i have heard first time about any spring being involved.. still very helpfull informations

[jmsaffroy]

Last year I got an older (used) Gaggia Classic, with the adjustable OPV. The previous owner had left the OPV at factory setting, so I knew had to reduce the pressure. But I didn't want to spend the extra money for a pressure gauge (not so early in my espresso journey), so I measured the OPV output flow (with a blind filter) and adjusted until the flow suggested that the pump was operating closer to 9 bars (there is a table for Ulka EP5 pumps linking pressure to flow).

Then I pulled shots for months, with increased success over time as I refined my technique (puck prep, better grinder), though problems were not rare.

Eventually I bought a pressure gauge (and a portafilter that could accomodate it, as mine could not). Turned out the pressure was actually 11 bars (so the original pressure might have been well over 12 bars, maybe 13 or 14!). I tuned the OPV again, this time to 9 bars really (on the gauge).

Now my espressos taste better, in general "rounder", with less harshness, which I think is a sign of less channeling (I do have a bottomless PF, so I know to look for visible defects). Eventually I'll have to try lower pressures, but going down from 11 bars to 9 is already quite an improvement!

To me, installing a PID and adjusting pressure are essential mods, so much so that I cannot recommend the Gaggia Classic without them (PID comes first though).

[phyxs]

You don't need to order the new spring. Just use the standard spring (and make it shorter) and loosen the brass screw (with the silicone hose). This loosens the spring and lowers the pressure. You can use some gas-sealing tape on the thread to prevent any leakage. There is no water pressure in the silicone hose. But you will need a pressure meter.

[areyouarobotz]

Coffee machine companies are missing out on selling this feature like it needs to be higher up so everyone can see the bottom like you show in the video. I would just make coffee all day to see that trip thing

[HannesNitzsche]

Thank you for putting this video together. I would be interested in a follow-up where all the shots have been properly dialled in for each pressure setting.
Over the last 6 months I’ve also experimented with all four springs and personally I love the 6.5 bar OPV. I only drink long blacks so steam pressure is not an issue but I want the best flavour. The 6.5 bar spring affords me the most consistency and best flavour in my opinion and I found the 5 bar spring lacking body.
Contrary to other comments here I actually had to grind slightly finer as I went from 9 to 6.5 bar, and finer again from 6.5 to 5 bar.
I’d be interested in a deep dive comparison of all the springs and to see if you would recommend a specific brew ratio for the lower pressure springs.
Cheers from Australia!

[wakeawaken]

Nice video Tom

Experimenting with my rancilio Epoca that comes from the factory with 12.5 bar, I found out that everything under 11 bar static pressure was unacceptable
Coffee flat, no taste, no acidity, very bad aftertaste, all coffees same bad taste
Only a very dark roast was acceptable but nothing special

Seems that the pressure at flow is much lower, maybe 4 bar less, at MY machine, but I don't have a scase to test it

What I saw is that as the pressure drops, the acidity drops too, but the good acidity, the acidity we want

That's why my machine is now set at 13 bars static pressure
Taste comes first, I really don't care if there is some channeling

[damonm]

So I ordered a 3 spring combo off of ebay. Shipped 10 days ago and for some reason isn’t here yet. Was hoping to have it now! I look forward to playing around with times/ratios with the 9 and 6.5. I almost always do a 2:1 ratio and find the closer to 30 seconds the better. I’m using the bst 18g basket and a screen and grind 18-21g of coffee depending on the roast. I like lighter roasts most and they’re more dense so 20-21 g and fit a screen in too. I like strong too obviously 🏆

[enesvekshari]

Nice one Tom. I have only tasted 12bar and 9bar ones, I think the lower the pressure more acidic it gets and its definetly not for my taste. Shame the spring mod doesnt work on the dedica though :/

[TheWillHargrave]

I have seen this mod in so many places and never fully understood it. You released this video like 2 days later and it was everything I wanted to know about the OPV spring mod. Thank you Tom! Thank you for being more thorough and 'scientific' than a lot of other channels.

Quick note on your video production. Your voiceover audio sound amazing! But your talking head/live audio could use a little upgrading.

And the video is a little long with a lot of transitions. If you tightened up your pacing and made the transitions a little more unique/quick to add to your video style I think you'll really find some good success. I love your "quick time lapse" style while working on the machine. Very helpful and visually interesting.

Overall Great job man! You need to start a Patreon and start building a following. You're well on your way to full fleged YouTube sidegig.

[Moreno_Cubanito]

depends on the roast though Light roast you need more of an extraction to remove the sourness because it needs more time to extract the flavor and more heat and for dark roast over extraction will give a bitter taste and you may want to lower the heat. I have a flow control to play with different bars of pressure with different roast types. So its more to it than bars of pressure. Roast type and temperature of water is just as important.

[DelReiRock]

Wow! Please make a video how to create this volcano extraction… 😮