Brake Master - look familiar?

[1200 JOTA]

My rear master is occasionally seizing (or not returning properly) ... so replace or service - but what is it?

Only markings are 3J9. On a 1200 Jota America with standard calipers.

 

[Dellortoman]

Here's my solution ...

 

[1200 JOTA]

Here's my solution ...

... and that's standard OE? Brembo?

 

[Dellortoman]

The master cylinder is standard Brembo fitment. I could tell you the additional return spring is a Brembo option, but I'd be lying.

I changed the lever ratios on my system and the M/C internal return spring wasn't quite up to the job of returning the pedal to the rest position, so I gave it a bit of help by adding the external spring.

 

[Legs]

Neat adaption. In the old days we used rubber bones for that sort of thing (inner tube cut into rubber bands).

 

[sfcpiet]

My rear master is occasionally seizing (or not returning properly) ... so replace or service - but what is it?

Only markings are 3J9. On a 1200 Jota America with standard calipers.

Standard Brembo PS15 rear.  Uses the same seal kit as the front M/C.

With the RH brake, there should be a pretty strong return spring at the brake pedal, unless you are using those, imho, rather dodgy stock rear sets.

piet

 

[1200 JOTA]

Standard Brembo PS15 rear.  Uses the same seal kit as the front M/C.

With the RH brake, there should be a pretty strong return spring at the brake pedal, unless you are using those, imho, rather dodgy stock rear sets.

piet

PS15 it is! Thanks ... I'll hunt down a kit.
The pedal is returning fine (original spring to the brake lever - with no resets) but the gallery in the MC may be contaminated and not getting a fresh touch of fluid, so time to pull it down.

 

[Dellortoman]

... rather dodgy stock rear sets.

I'll second that opinion. The factory rearset system (at least in respect to the brake) is a poor design. It almost seems as though it was cobbled together in a hurry without giving much thought to its functionality.