The retro-fit PX hydraulic brake from ScootRS. Time will tell, but in theory, following a small incision, this will fit my bike.
Last Spring I took the warmer weather as an opportunity to address the front brakes on my 1985 Vespa PX. At that point, the bike still had its stock drum brakes – a set up that has never had a great reputation for stopping power. Even following new brake shoes, a thorough cleaning of the inside of the hub and a generous greasing of the moving parts, the drum brakes just weren’t giving me a satisfactory (or safe) stop.
It’s no surprise then that later iterations of the PX (and similar scooters like the Stella) moved over to a hydraulic front disc brake solution and in the intervening years a number of after-market manufacturers have provided replacement disc brake solutions for Vespa owners looking for a little more stopping power.
Perhaps the most popular of these was/is the Grimeca disc brake kit, so in May last year with the kit in hand from Germany’s renown SIP Scootershop I spent a morning hooking it up to my bike.
The kit accommodates two set ups. First, what’s known as the semi-hydraulic set up which is the option I went for: The first half of the solution is a brake fluid master cylinder that’s bolted to the front fork to feed the hydraulic disc brake caliper. The second half of the solution (and what makes it semi-hydraulic) is the existing brake cable coming down from the front brake lever, through the steering column and connecting to the master cylinder. The benefit of this set up is that it doesn’t require any modification to the look or operation of your existing handle-bar set up. You pull the lever, this pulls the cable, which pulls the master cylinder actuator which depresses the brake. At least, that’s the theory.
At the time I installed the beast I declared the solution better than the stock brake set up, but not miraculous, which is the general consensus of the wrenching community.
Over the course of the last twelve months however, the stopping power has continued to nose-dive (and not in the right way.) Various wrenching sessions to keep the brake cable as tight as possible following stretching as part of natural riding, and keeping air out of the brake fluid have had me pulling my hair out on a number of occasions.
At the time I decided to plump for the semi-hydraulic set up, more than one experienced scooterist claimed that the semi-hydraulic set up can be, “the worst of both worlds.” Twelve months in, I concur.
After replacing both the cable inner and outer this weekend, and bleeding the brakes I still couldn’t get a decent brake. The problem is further compounded by the fact that my PX has an in-line front brake switch part way along the length of the brake cable which operates the brake light. This switch adds further unnecessary mushiness to the operation. Even by-passing the switch entirely (the DOT would not approve) I could only either get the brakes to lock-on but not get the brake lever to spring to return (dangerous to say the least) or I could get the brake lever nice and springy but the brakes barely braking. I’ve therefore declared mission “Semi” over and have decided to upgrade to the full-hydraulic set-up before attempting any serious riding on the wasp this year.
A full-hydraulic set up (as recommended by experienced scooterists) is the one used by contemporary scooters and motorcycles with disc brakes. A dedicated brake lever at the headset actuates a brake fluid master cylinder. This in turn feeds to the hydraulic brake caliper at the front wheel by way of a hydraulic hose running down alongside (or through) the steering column. Pull the brake lever and you pressurize the hydraulic fluid at the headset and, in turn, all the way down to the brake. No cable. No cable to stretch over time. It’s the set up that all modern Vespas have – be they PX, LX, or otherwise.
Joint owned UK/Vietnamese ScootRS.com out of good old Ho Chi Minh City have a decent reputation for after market parts in a sea of questionable ones. In particular ScootRS have built a solid following for their Lambretta (and later) Vespa disc brake kits. I’ve order two important pieces from their catalog needed to complete my fully-hydraulic set-up: A combination brake lever/master cylinder that’s designed to retro-fit to PX headsets that were never originally designed to accomodate one and a hydraulic hose to connect this to the disc brake caliper already in place on the wheel of my bike.
Providing the parts arrive before the weekend and the weather holds up, with Dremel in hand, I’ll be reporting back in a few days with how the conversion goes. Stay tuned.
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