TR2/3/3A TR3 Brake Proportioning Valve?

[karls59tr]

On the 59 TR3A the brake line goes from the master cylinder to the top of the proportioning valve. Brake lines then split to the front and rear brakes.Isn't the function of the PV to provide 60/40 braking front/rear? If so why wouldn't the proportioning valve be placed only on the outlet that goes to the rear brakes?What am I missing here? CK

 

[Andrew Mace]

I'm not aware of any proportioning valve on a 3A, just the residual pressure valve that keeps just the slightest pressure on the front caliper pistons to keep the pad near the rotors.

 

[TR3driver]

If you mean that gizmo on top of the 5-way union, it's a RPV. And while it's function is for the front brakes, it keeps pressure in both front and rear.

The concept is that, under hard cornering, the front spindles flex enough to move the rotor sideways relative to the caliper. Without the RPV, the outside piston pushes fluid back into the MC reservoir and the pedal is low the next time you use the brakes. With the RPV, the fluid pushes the inside piston out instead.

But some people (like me) don't like having the brakes drag that much, so we disable the RPV (by removing the plunger inside).