Yes it is a grey area. As long as your insurance company is happy and it gets through rego every year.

In ACT we don't have yearly inspections, so my main concern would be a random roadside inspection - where it may be difficult to convince them that your car is legal. This is where an engineers certificate may make life easier. And whilst you are at it, you could also engineer all the other grey areas on a Mini, like adjustable suspension, aftermarket seats, etc.

Shame engineering is quite expensive!

I believe the issue is that you will in theory drive a higher BHP motor faster and harder than a smaller motor. It's not that you can do the same 100 - 0 braking test once or twice; rather that under spirited driving, a larger motor will accelerate faster and consequently have to brake harder. Leading to more stress (heat) in the brakes.

Minis are a bit of an anomaly, in that drums (by modern standards and assuming they're maintained by the average owner) are marginal. In other words, the legislators had to make a cut-off somewhere with the result is that 1275 minis are generally regarded as requiring disk brakes. That's not to say the well maintained drum brakes aren't sufficient, but across all owners, their performance can be marginal in modern traffic conditions.

Im going to go have a chat with my mini mechanic, vicroads and my insurance company about the legalities out of curiousity. im confident driving my car with drums for now but only untill i get disks. im not letting anyone else drive it tho. by the looks of it all the disk brake conversions ive seen only turn out a couple of hundred cheaper then the really thing so im saving for that. is a brake booster required aswell?

_________________
Enjoy Chris

Brake booster is not 'needed' its personal choice - I like the feel of un-boosted brakes but some love boosted. There are arguments that boosted actually improve stopping distance - but thats not entirely true, it actually improves the 'reaction' time because the booster adds to the braking instead of you having to push the pedal as much.

Short answer - no not a requirement to have booster...

For all those wondering, Drum brakes out stop disks first time, the issue with drums is brake fade... a set of perfectly setup drums will stop fine, its the driving conditions and fade that make drums 'worse' than disks.

Pete

_________________

Click here for the Turbo Conversion Thread!

BMC and Leyland fitted discs to all cars with 1275 engines. (except export Mokes) So the rulemakers require discs with a 1275 for the reason that the manufacturer made the cars that way.

A booster can make a car stop better. It is quite simple. It is the same thing as fitting bigger discs. You get more braking performance.
But to take advantage of the greater braking performance you may need tyres with more grip.
So wider, stickier tyres and a booster may make the car stop shorter than with just the wider, stickier tyres.

Really? I was lead to believe all it did was lower the effort at the pedal. The brakes stopping performance is a factor of disk size, pad material and caliper design, surely?

So the weight of the vehicle and the grip of the tyres don't make any difference to stopping distance?

Ok, it lowers the pedal effort. So you can stop just as well by only using about half the pedal pressure. So what happens if you use the same amount of pedal pressure?

No, the weight of the car, the tyres, the road surface and so on play a part. In terms of braking performance, an unboosted braked car will stop in exactly the same distance as a boosted braked vehicle (all other variables the same). The pedal effort will be less with a booster, as discussed.

But a boosted drum brake car will not stop better than an unboosted disk brake car.

So why do people fit bigger discs? Why 4 spot calipers? By your reasoning they will make no improvment.

Is this the right room for an argument?

In terms of pure mechanics, vented and slotted disk won't improve your brakes' performance. They will help to reduce brake fade by allowing the heat to dissipate better. The size of the wheel will make a difference. The pad material will make a difference. Brakes' performance is a factor of converting kinetic energy to heat, so it's leverage and friction, controlled in a car's brakes by leverage (pedal), the grip of the pads against the disk and the distance of the braking point from the wheel's axis.

A brake booster helps you push the lever down, but doesn't do anything else.

Try taking the booster off a truck then.

Oh, I am in the right place.

You could, but your car wouldn't stop any better. You would feel like you only needed to touch the lever to get a lot of brakes, but the brakes will still do exactly the same work.

Actually, your car would stop a lot worse since you've increased the weight of your vehicle.

Incidentally, since kinetic energy is a function of the square of speed, (1/2 mass x velocity x velocity), it takes the same amount of energy to slow a car from 70km/h to 50km/h as it does to slow it form 50km/h to 0. Or something like that.

If you decide to go with the 'S' discs, you can get very different results with different pads - I have used some in competition that have cracked through the compound while others have been almost fade free.

Carbon metallic pads are great for competiton but can feel very wooden for normal road use if they do not have any heat in them.

So it becomes hard to judge whether 'S' discs will meet your need depending on how you want to use the car and the pads you choose.

i have standard unboosted 7.5 discs with my s/c 1360.

i have a booster but i have been told not to fit it as you lose feel.

i can see the advantages of having one on a road car so i might fit it.

My last mini had unboosted S Disks, as will my current one. I prefer the feel rather than the easier push. BUt that's my preference. See if you can drive one of each...

Dicko