The Grimeca semi-hydraulic kit installed on a Vespa PX.
The front drum brake on vintage Vespas has never been celebrated for its stopping power. But there are a couple of things you can do about it. But first a little history:
When Piaggio re-introduced the Vespa PX to the US in 2004 (and prior to that, upgraded in Europe in 1998) they did so with a couple of modifications. Arguably most important among which was the addition of a hydraulic front disc brake by Italian manufacturer Grimeca bringing the stopping power of the machine in line with modern standards. The Genuine Scooter Company’s PX clone The Stella introduced around the same time uses the same set-up.
Prior to this Grimeca spent several years providing an after-market semi-hydraulic upgrade. The upgrade proved popular with Vespa enthusiasts and was no doubt a considerable factor in Piaggio’s decision to include the brake as standard on the newer machines.
So what’s the difference between hydraulic and semi-hydraulic braking?
Hydraulic (AKA fully-hydraulic)
On a modern Vespa, the front baking system consists of a hydraulic hose that directly connects between the front brake lever on the headset and the brake caliper itself hugging the braking disc. Pulling on the brake lever immediately puts pressure on the hydraulic fluid inside the hose, transferring the applied force of the rider directly through the hose to the brake. This set up is considered fully hydraulic.
On a modern Vespa, the front baking system consists of a hydraulic hose that directly connects between the front brake lever on the headset and the brake caliper itself hugging the braking disc. Pulling on the brake lever immediately puts pressure on the hydraulic fluid inside the hose, transferring the applied force of the rider directly through the hose to the brake. This set up is considered fully hydraulic.
All hydraulic braking systems use a reservoir for the brake fluid called a master cylinder. In the reintroduced PXs (and the Stella) this cylinder is immediately noticeable as a small black box attached to the front brake lever. On modern Vespas including the ETs, LXs and so on, the master cylinder is incorporated inside the headset with a visible site glass near the brake caliper.
Semi-hydraulic
A semi-hydraulic set up is not considered as efficient a braking system but it does allow vintage riders to upgrade their bike without needing to modify their existing headset and it does offer a vast improvement over the stock drum brake. Here’s how it works:
A semi-hydraulic set up is not considered as efficient a braking system but it does allow vintage riders to upgrade their bike without needing to modify their existing headset and it does offer a vast improvement over the stock drum brake. Here’s how it works:
Instead of requiring modifications to the scooter’s headset, the upgrade mounts the master cylinder reservoir on the front fork with a short hose of only a few inches feeding the brake caliper on the disc. The master cylinder in turn is remotely operated by the existing front brake cable that feeds (as normal) from the front brake lever, through the headset, down the steering column and out of the fork. Thus the brake is semi-hydraulic, or to put it another way, semi-cable.
Converting to fully-hydraulic
Since the reintroduction of the PX, many vintage P series owners have chosen to invest in a fully hydraulic set up by replacing the lower half of their existing headset with the post ’04 version which is cast with mounting holes for the master cylinder/brake lever unit on the right handlebar. This is the ideal solution, removing any potential cable related problems from the system (cable break, stretching) but it is more expensive and more labor-intensive requiring not only a new disc operated hub, but also a partial headset replacement.
Since the reintroduction of the PX, many vintage P series owners have chosen to invest in a fully hydraulic set up by replacing the lower half of their existing headset with the post ’04 version which is cast with mounting holes for the master cylinder/brake lever unit on the right handlebar. This is the ideal solution, removing any potential cable related problems from the system (cable break, stretching) but it is more expensive and more labor-intensive requiring not only a new disc operated hub, but also a partial headset replacement.
Converting to semi-hydraulic
Vespa owners who’s bikes pre-date the P-series, or P-series owners looking for a more cost-effective and less labor intensive solution can still purchase the Grimeca semi-hydraulic upgrade directly from Germany’sS.I.P. Scootershop or imported in-turn through USA’s own MotorSport scooters.
Vespa owners who’s bikes pre-date the P-series, or P-series owners looking for a more cost-effective and less labor intensive solution can still purchase the Grimeca semi-hydraulic upgrade directly from Germany’sS.I.P. Scootershop or imported in-turn through USA’s own MotorSport scooters.
The kit is available in versions that fit both 16mm and 20mm forks. And the 20mm version is available in the original front-hub casting and a newer “Millenium” version that uses a five spoke front hub used on contemporary Vespas. The advantage of the spoke version is that it is about half-a-kilo lighter, and allows the rider to be able to use a disc brake lock through the aperture in the spokes.
To identify whether your Vespa has 16mm or 20mm forks, Scooterhelp.com shares a comparison.
Next steps
In part two of this posting we’ll walk you through the 20mm semi-hydraulic upgrade on my 1985 PX.
In part two of this posting we’ll walk you through the 20mm semi-hydraulic upgrade on my 1985 PX.
1 comments:
Hello, I am Brazilian and I have a Vespa PX 200E 1990, manufactured in Brazil. It originally came with front drum brake and canvas, but I want to adapt disc brakes. In Brazil found no alternative. Can you help me indicating a kit. Even more, how much it costs and whether it is possible to send to Brazil. Thank you. Roney. email: roneyw@terra.com.br
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