Well, I got a master cylinder when I bought the kit and its pieces, but it was left open and as such, I'm unsure of it's condition. I decided that a new one was definately in order.

Now I've done the trawling of ebay, motor factors and the like, and I can't find a direct replacement for mine. It has three outputs; 2 individual for each of the front calipers, and a single (t'd off) to the rears.

I'm running Sierra callipers, all brand new, with discs all round. Question is, does anyone know where I can get hold of one from? Some people have suggested using twin master cylinders with a bias bar, something I've never done before, so have no idea. I get the principle behind it, and know that for IVA I have to weld the bar in a fixed position, but was under the impression that the front/rear split in a 2-way manner wasn't acceptable when Mr. Tester inspects it?

Hunting around, I looked at Rally Design as they seemed to be mentioned and raved about a lot, and discovered this as a possibility: Balance Bar Box thingy

Thoughts? Never used a non-standard setup like this so any advice thrown at me can only be good....

The master cylinder issues has been pretty well covered in the past, a Sierra or Mondeo mastercylinder or one any other similar car isn't really suited to the car you are building anyway.
For decent brakes without having to push the brake pedal too hard you need a tandem master cylinder from a car not fitted with a servo
Cars without servos used mastercylinders with a smsller diameter than those with servo assistance.

In the standard models Caterham and Westfield both use a 17mm dia tandem master cylinder and this or something close to this diameter is what you require.
The caterham and Westfield cylinders are shown on theier online parts shops --- at price.
But MK1 Fiesta or MK1 Polo (both from models without servo) will fit the bill try Ebay other locoster have had success there.

Note the mounting bolt pattern for cylinders without servo is different but this shouldn't be a problem.

[Edited on 18/5/09 by britishtrident]

http://www.westfield-sportscars.co.uk/shop/product.asp?numRecordPosition=17&P_ID=173&strPageHistory=cat&strKeywords=&SearchFor=&PT _ID=73
Rescued attachment 173.jpg

So the tandem system would cover it, yes? The current M/C from the sierra didn't have a servo unit attached when I bought the car, but that's not to say it shouldn't have one.

Aside from the cost difference between the Rally Design box and using a Polo/Fiesta unit, are there any real benefits? Bearing in mind I'm going to be using the car mainly on the road, with a handful of track days every year?

A bias bar system gives you the ability to adjust the front/rear brake balance which can be handy on a track to match braking to conditions. However, on the downsides it's a more complex system, IVA don't like them (you have to permanently lock the adjustment to make it pass), and you tend to get a harder pedal.