Totally agree with that the others have said - I recently got a 7.5" kit across from Minispares UK. All standard stuff except for the alloy 4 pots, and it works superbly. I thought I was going to need a booster, but not the case. For me, the landed price was so good I was happy not to have to spend hours and hours sourcing and fixing up second hand stuff. If you're keen, you can upgrade to slotted/vented discs, which I imagine would suit just about any application (except maybe racers like sports sedans).

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'68 Deluxe w/Metro engine

On this topic- has anyone who has fitted discs in place of their drums had to modify/change the master cylinder at all?

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1975 Clubman
1152cc, 40dcoe weber, RE83 cam, GRed head.

I belive that drum master cylinders have a check valve in them to maintain a small line pressure. A car fitted with discs doesn't need this, but I'm not sure if that guarantees you to have a problem with it. Others will know more of the story; I don't think it means you will need a new master cylinder, perhaps at worst, you'll need to put a kit through it. On the other hand, if your current m/cyl is old or of unknown age, it might be a good opportunity to replace/recondition it.

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'68 Deluxe w/Metro engine

I fitted MiniSpares alloy 4-pot calipers, and didn't change the master cylinder.

Having 4 pistons instead of two in each caliper means that these "consume" more fluid per pedal stroke to push the same distance, but the standard drum brake master cylinder is (just) big enough. I get pad engagement after about an inch or so of pedal travel, rather than the pedal being rock hard at the top of the stroke.

If you're used to 2 piston AP calipers then you'd initially feel less confident in my brake pedal, it's almost as if it feels like it needs the drums adjusting. But once the pads bite there's no doubt

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Simon

The adventures of an owner builder in the Tallarook Ranges

There's no problem using a standard drum master cylinder with disc brakes. I've used them with both Cooper S calipers and Metro turbo 4 pot, for many years.

Tim

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1951 Morris Commercial J Type Van
1955 BSA C11G
1961 Morris Mini Traveller
1969 Triumph TR6R
1977 Leyland Moke Californian

Same here. I have a Mk2S MC on my car and Barney had an LS tandem one. With 7.5" discs and greenstuffs both cars stopped the same.

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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.

It is the residual line pressure from the check valve that is meant to be the issue- essentially holding the pads on the discs a small amount as you drive.
Is this a simply thing to pull out?
Kev, I think this would be the restrictor valve you spoke of?
Is rebuilding/putting a kit through a master cylinder hard? (Always apprehensive to mess with a critical component such as brakes!)

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1975 Clubman
1152cc, 40dcoe weber, RE83 cam, GRed head.

Residual pressure valve sits in the top of the MC behind the spring. Easy to get out on a single line MC, but please fit a new seal kit whilst you're in there.
The only tool you need is a pair of internal circlip pliers.

If it's a Clubby tandem cylinder I'd take it to a brake shop, they are a PITA to overhaul.

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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 don't believe its a tandem- looks exactly the same as the clutch master?
I have 1 line out that goes into a T piece below the firewall.

How much residual pressure is this bad boy putting out? It certainly wasn't noticable, I was simply told about it by someone. I.e.....should I mess with it? As it will obviously also need a full rebleed of the system I only did a few weeks ago. (Lillee, if you're reading this-drop that new bleeder over? )

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1975 Clubman
1152cc, 40dcoe weber, RE83 cam, GRed head.

Come borrow it anytime...

When I drove your car the brakes were fine?? why the new worries??

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Lillee - 1969 Morris Mini K

My drums were rubbish from the beginning and master seems brand new-
could it be I never had a check valve? Do new cylinders not come with check valves? How would you know?

The pads could move to and for within the caliper- suggests to me there would be no residual pressure...........


SORRY FOR THE HIJACK ZULU!
(This info will assist you when you convert to discs, I promise )

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1975 Clubman
1152cc, 40dcoe weber, RE83 cam, GRed head.

When Lillee beat Dorris I presumed my brakes must just be stuck on, only plausible explanation

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1975 Clubman
1152cc, 40dcoe weber, RE83 cam, GRed head.

Wise guy I have a stock new MC, if it has the residual pressure valve in there (big doubt), then mine are stuck on too.

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Lillee - 1969 Morris Mini K

I'm just loving the discussion!

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Zulu...

1967 mini Cooper S

FWIW, I didn't do anything to my master cylinder when I fitted the discs. If it had a check valve in there, it's still there.. to no ill effects.

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Simon

The adventures of an owner builder in the Tallarook Ranges