If you are running more grip (wider tyres, softer compound, downforce ,etc.) you may find that you can stop quicker with a booster without locking the wheels.

Don't quite follow your logic there.

The reason everybody is talking about locking the wheels is because if they lock, you have shown that no more braking force/ability is available, the force applied to the disk has overcome the friction between wheels and road. Therefore no amount of boosting that force will allow you to stop any sooner. Ideal breaking force in emergency (or racing) is just less than required to lock - that's your maximum force available.

I drove my metro vented set-up with the servo disconnected (couldn't be bothered hooking it up). WoF guy failed me and said because it's certed with servo I had to hook it up. I did so, went back, and he says "Huh. It was better without it wasn't it?" What he's talking about though is pedal feel, and for that it's simply personal preference. The car I'm building now will be using the metro disks but no booster. If you like a softer pedal, stick one in *shrug* Just be aware it will only allow you to stop faster if you are unable to reach maximum force without one.

Well do exactly that. Run it without booster and hook one up if you feel you need one...

_________________
Lillee - 1969 Morris Mini K

Thats what I plan to do

_________________
No more Minis!......For now.

sorry to hijack buts, do u really need to change the brake master cylinder?? why would that be?? they look all the same to me.. this is the one the pedal operates not the rears

_________________
Potato

Because a shitty (as in crappy and old and leaking) master brake cylinder aint worth having on ure car when you have just spent $1000 on brakes.

Best to just do it all in one hit and know that everything will be able to take the pressure.

_________________
No more Minis!......For now.

Standard Cooper S master cylinder is 0.700" bore.

So were just about all Minis produced here until the end, 1978...
exceptions being 850 and 997, 998 Cooper.

So, in most cases the standard one you have will do. Good idea to replace it though if old, or at least put a kit in it.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I've always had a booster on my Minis with 7.5 Cooper S brakes. For a road car I think they are a good idea. Only problem on a Mini is space to fit them inside the engine bay. I don't particularly like seeing them under the dash on a road car though it's ok for a competition vehicle.

My solution is to recess the (remote) booster into the right hand engine wall (inner guard). I can easily haul the engine out or change the clutch without moving the booster. Not for the purists, but it makes maintenance a bit more easy going.

_________________
Slide
1965 Mini Van (1360)
1970 Mk2 Cooper S (1310)
1978 Rover SD1 V8 (4.6)
1996 Land Rover Discovery V8 (4.0)

I just picked up the Mini K after having new master cylinder and rear cylinders fitted, it has S discs.
On the trip home from the mechanics the brakes were good but the pedal effort required was just more than I want to know about.
It goes back on Monday to have the booster fitted.

_________________
Mini K, 1310, Jet Red/Crystal White Roof, Rover Interior

75 Clubman

To the comment about ABS, ABS was designed to regain drivability under emergency braking. Ie. As to no lock the wheels enabling the driver to still swerve (ie. wheels are still spinning, giving manouvarability) whilst heavily braking.

the maximum pressure with a booster is far in excess of the maximum pressure you could attain with your foot without one

Which just means the front brakes will lock sooner! It'd stop quicker, if they don't (quite).

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

To quote http://www.howstuffworks.com:

"A skidding wheel (where the tire contact patch is sliding relative to the road) has less traction than a non-skidding wheel. If you have been stuck on ice, you know that if your wheels are spinning you have no traction. This is because the contact patch is sliding relative to the ice. By keeping the wheels from skidding while you slow down, anti-lock brakes benefit you in two ways: You'll stop faster, and you'll be able to steer while you stop."