I want to upgrade from front drums to disks, probably 7.5" Is a booster required?

Nah

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nope i upgraded to disk brakes it gives u a really solid pedal but make u use those leg muscles

With 7.5's you don't need one, but I prefer to run with a booster.

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The general consensus seems to be no booster with 8.4", but use a booster with 7.5".

However, there are many who prefer no booster even with 7.5". Without, the pedal is really solid, but you get the feeling you have more control. The boosters tend to make the pedal feel a little more spongey.

The Cooper S came with a booster.
But the Cooper S also came with brake pads designed in the early 60s that were rock hard to last a long distance race or rally without being changed. They needed the booster to stop the car because you couldn't stop the car with those hard pads without a booster.

Brake pads have come a long way since then. You don't really need a booster with modern brake pads.

I prefer a booster but others prefer no booster. It comes down to personal choice.

^^^ Now that's a great answer!

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When I bought my S, the servo (booster) was disconnected. Eventually I did it up and refitted it. I much prefer the feel with it connected but I agree, it is personal choice and could not be considered necessary in any way. There could be a certification problem removing one from a system that originally had one, just one small detail to think about on S's and GT's.

Regards
Al

I agree with everything you all have said.
However one of my clients could not get his mini a 'roadworthy' as the booster was not fitted (as per cooper S spec)
I told him to argue it, but he just fitted one in the end.

-Andrew

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This raises an interesting question, and I understand the view "that's how it came from the factory so that's how it should be" for Cooper S's, but what about garden variety minis that are subsequently fitted with 1275 engines? I think all registering authorities require minis that are fitted with 1275 engines to have disc brakes. There are 2 type of disc brakes available, 7.5" and 8.4". 7.5" when released had a booster, eg, Cooper S. 8.4" when released did not have a booster, eg 1275LS. Just how far are we required to go? Do we have to duplicate the braking system to suit?

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Steve

Hi Steve,
Spec'ing up a new system on a modified car has to be signed off by a compliancing officer and he will decide what is required and must take the responsiblity.

The removal of a component from an factory system should also be complianced but, at the end of the day, how many 'experts" would know? Its usually when something has turned to crap that things are discovered !

Al

The thing is, the booster does not increase the braking ability, so I really don't get how it can be a compliance thing. My old Elf had the booster fitted, but disconnected. I was failed under the rules here cause if it was there it had to be working. SO I took it out, problem went away

I have registered a 1275 in the ACT with Unboosted 7.5 discs (Cooper S).
This was in the old days when the car went over the pits yearly.
As said previously modern pads are a lot better than the old style pads which were very hard and will give good braking though a little heavier than drums.
Try without and update to a booster if you feel you need.
Cheers Rob

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82 BJ42 just completed resto
64 850 Modified(about to start rebuild)

A booster can increase braking ability. A Cooper S is a poor example but a single leading shoe 850 would be a good example of improving the brakes with a booster. You may not be able to approach the point of lock with single leading shoe brakes and wide sticky tyres but if you fit a booster you can.

Try stopping something like this without a booster...

Yes and No.

eg. I have several small trucks, with Hydraulic Brakes, vacuum assisted. There is no way on gods earth you would slow them without the booster let alone try to actually stop. So much so that factory fitted is a reserve vacuum tank and low vacuum warning lamps and buzzers.

Would removal of the booster be legal? I doubt it.

A Booster is a Booster and if it was deemed necessary by the manufacturer, it's removal would require engineering inspection / certification.

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