Master Cylinder Updates
Back in 2016, for nothing else other than curiosity I started to think about reducing pedal travel.
There's nothing wrong with the system as it stands but most modern cars have very little travel and switching between them is disconcerting for the first couple of miles. I became obsessed with the idea, even to the extent of measuring the amount of movement for the pads (hence pistons) at the callipers and calculating the expected movement.
If you're interested the theory came in as 3.8cm at the pedal, in practice I seemed to be getting between 3.5 and 4cm, the range probably down to my own measuring accuracy.
But apart from pressure bleeding and installing residual pressure valves I seemed to be at the end of the line. So that's it, as far as I can go until something changes.....
2016 : All Systems Change
Towards the end of 2016 I changed the brake system completely and that threw the master cylinder debate back on the table
Bigger brakes meant less pedal pressure to stop the car so perhaps we can increase the bore of the master cylinder to reduce travel without making pedal pressure too uncomfortable ?
Over the winter of 2016 I did a comprehensive brake system overhaul on the Elise S1. A couple of things came out, firstly the Elise uses the same diameter rear caliper pistons but slightly smaller fronts to my Europa.
Secondly it uses a 19mm (0.75”) bore master cylinder with no servo and gives a very good brake pedal with little travel which I really like.
So to set the scene, this is how the system is arranged on the S1 Elise.
Elise S1 Master Cylinder Arrangement
The Elise set up uses the fluid reservoir mounted directly atop the master cylinder and that also feeds the clutch cylinder. There’s another problem in that although the bolt mounting centres are the same on the Elise as Europa, the Elise m/cylinder has the mounting flange at an angle.
So whilst using the same master cylinder might be attractive, there are problems to be addressed first.
Fiat X/19 8mm Plastic Connectors
The first is how to mount the fluid reservoir, which on the Europa is currently a remote reservoir with fluid level alarm in the cap.
That’s an easy one, we need some 8mm plastic fittings and by happy coincidence those used on the Fiat X19 / Lancia Montecarlo will fit very nicely. Fiat use a couple of designs for this fitting, either 90deg as shown here, or at 45deg.
They are easily available and IIRC the Elise master cylinder is also used on a Fiat, so perhaps it’s not surprising that they fit.
Now for the elephant in the room, the simple fact that both master cylinders have completely different mounting arrangements.
Comparison of Elise and Triumph Spitfire Master Cylinders
The upper image is the master cylinder removed from the Elise, the lower the 0.7” master cylinder as fitted to the Europa, complete with a shield above the rear inlet to protect it from any possible interference from the steering rack bellows.
The obvious problem is the angle of the mounting flange.
Close examination shows the hole centres are close enough as makes no difference so we have two options. The first is to make up a 1/2” spacer plate with two holes to match the chassis and two studs to match the new master cylinder.
This is a tried and tested route which I’ve used before so it will certainly work and be strong enough.
The second option is to simply mount the master cylinder directly to the chassis, which will obviously mean that both the inlet and outlet connections will be approximately 45 degrees to the horizontal.
This might give us problems at bleed time if it allows bubble retention in the master cylinder.
Hmmm, what to do ? Well, theorising isn’t going to give a definitive answer so the easiest thing is to just bolt it on and see if it works. So I did, and it does.
This shows the first installation, complete with a few drips of brake fluid as this was taken just after connecting up all the pipework to see if it would fit and bleed properly. It now has clips securing the rubber tubing to the plastic connectors and hence no more drips. :)
So it fits and using a pressure bleed there were no problems with air retention, it cleared first time around.
And that’s all there is to say really, the modification looks strange to start with but once you get your head around it there’s no logical reason as to why it shouldn’t work is there ?
Installation on the Europa
The end result is that yes, the pedal travel is reduced and no, the effort hasn’t made me panic and think I’m not going to stop the car. In fact the theoretical added pedal pressure was a bit of a non-event. I suppose if you drove two cars back to back you’d notice a difference but I can’t honestly say it’s a big deal.
But pedal travel reduction, albeit small, is very noticeable because your right foot is more sensitive to travel than you might think.
I can easily go back to a 0.7” bore cylinder because I have the parts available. But I won’t, this is an improvement for me.
Costs:
I think this is a Fiat part if you want to look around, but even from Lotus specialists this is not an expensive cylinder, in fact it’s cheaper than the Triumph Spitfire Tandem clyinder.