Early 2 litre disc brake conversion

[mikebro]

Originally Posted by David C

I am now wondering whether it is necessary to fit a vacuum tank with a newer servo. Not having vacuum wipers or washers and now using a slightly more modern servo with built in non return valve I can't immediately see the need.

Also I'm interested to know what ratio servos others use with disc brake conversions. I have a 4.25:1 on my 403. It balances the light throttle pedal pretty well but it's probably more assistance than necessary. I fitted a 3:1 on my 401 and that seemed ok for the short distance I drove it prior to sale. I think the 401 had a 406 pedal box fitted so it would have had more mechanical advantage than an original 401.

All this leads me to the decision that 4.25:1 will probably fit the bill for a 400 with original pedal box. Opinions, please!

I have a 403 with a factory fitted Dunlop disc brake conversion, done in 1958.

Vacuum tank - a very knowledgeable friend pointed out that the vacuum on a 400/401/403 is produced by only the front two cylinders, not the whole engine, as these cars have no full engine installed manifold. I've (so far) dispensed with the vacuum tank, but my 403 is not on the road yet, so I don't know whether this will work. Easy to put the tank back if it doesn't,

Servo ratio - Powertrack matched my Bristol fitted servo as a 1 : 1.9, and they have supplied me with a modern equivalent. Seems that a disc braked car needs less assistance than a drum braked one. Time will tell once I get the 403 back on the road.