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701 brake upgrade

Because I was curious how much of a difference it'd make, and because I like puzzling things out, I decided to fit a radial master cylinder and monoblock caliper to my 2017 Husqvarna 701 Supermoto.

result

Installing the master cylinder

I found a reasonably priced used Brembo PR16x18 master cylinder, which also included a pressure switch for the brake light. A 16mm master is a good choice for a single-disc bike like the 701. I'm not sure of the diameter of the stock master cylinder (13mm I've read somewhere), but this one worked well with the stock brake caliper.

Radial master cylinders use a different location/angle for the banjo bolt, but thankfully there's adapters that allow you to fix that without requiring a new brake line.

radial master adapter
Hel HEL-CFA-01 radial master adapter.

The main annoyance was the fact that the 701 hand guards attach to the brake (and clutch) cylinders, which now wasn't possible anymore. 3D printed parts fixed that issue; I also needed a new part for the clutch side to keep things symmetrical, as the larger radial master meant the hand guards had the be positioned a bit more forward. The 3D print files can be downloaded here.

handguard
handguard
3D printed handguard mounts.

This master cylinder did not come with a clamp with a mirror mount. At first I used an extra mirror clamp, however that was ugly and brought the brake lever inward more. Eventually I splurged on a clamp with a mirror mount all the way from Japan.

mirror
Brembo racing master cylinder mirror clamp.

M40 Monoblock caliper

I found a cheap M40 off a Ducati Hypermotard. Thankfully it was easy to bolt up, no new brake line needed. I chose this caliper not just as it was reasonably priced, it uses the same piston diameter as the stock caliper, so it works well with both the stock master cylinder and the 16mm one I installed. An M50 caliper would require a smaller master cylinder.

mirror
Brembo M40 caliper.

Some nomenclature:

P4
Stock 701 caliper. 4x34mm pistons Not to be confused with the expensive racing P4. 701 uses 4-pad version, 690 Duke uses 2-pad version.
M4.34
The original M4. Caliper that I used. Comes with 4x34mm pistons.
M4.32
Calipers often seen on not-top-end bikes such as the Panigale V2. 32mm pistons.
M50
Also known as M4.30. 30mm pistons. Lighter than the M4.
Stylema
Lighter than the M50. Again 30mm pistons.

Verdict

Brake feel is difficult as it's subjective and you're often replacing multiple parts at the same time (caliper and pads). Here's my impressions:

Created: Jul 24 2020
Modified: Jul 24 2020