Dual Circuit Brakes
So, with the larger calipers and discs installed, it was time for phase 2, remove the servo and move to a dual circuit system.
The current system wasn’t standard, it had a 0.75” bore m/cyl with a Lockhead servo which had given a very firm pedal. All in excellent condition and if I’m honest, if felt fine.
The only reason to change was to get rid of the servo and see if I could get more feel to the brakes.
So, the shopping list started with a 0.7” bore dual master cylinder, as used on the later Triumph Spitfire 1500s.
Girling/Triumph Spitfire Master Cylinder fits neatly
This is smaller than the old one and could be expected to give more pedal travel as not only is the bore smaller, but we now have larger bore pistons on the front calipers.
Too much movement ? The sums say not, but only time will tell for certain.
So, the dismantling started and it wasn’t long before I hit the first “doh” moment; the new m/cyl had Metric connectors and everything else was Imperial. Off to buy some Metric fittings and we’re back in business.
Remote reservoir with Low Level Indicator
As you can see from these shots, the new m/cyl fits easily under the webers. There is room enough for a reservoir immediately on top of the cylinder but I’m fed up with the hassle of bleeding brakes with it hidden away, so I fitted a remote reservoir on the inner wing, complete with a fluid level warning light.
The warning light wiring is spliced into the handbrake warning light circuit, the dashboard light serving both systems. It works fine and keeps the dash board original.
The only other modification was to remove the servo and replace the old 5-way junction with 2 separate 3-way junctions, the hydraulic stop light switch being on the secondary (rear) circuit.
I don’t know if that’s legal or not, something I’ll find out at the next MoT I suspect.
So, does it work ? Well yes, amazingly the sums were right. Pedal travel is longer but within reason and feels less than our more modern MR2. It is a modern system with a hidden benefit, I found you get a lower pass mark on the handbrake. (that's after I've fixed it of course)