Anyone got any metro calipers to hand?
Turbo Mini Forums

Can you measure the diameter of one of the pistons please!

4 pots

Edited by minimark on 12th May, 2004.

Everyone knows that instructions only have to be read if the thing doesn't work....

Metro's are all 4 pots aren't they ?
Minis are 2 ?

Phil.

WWW.TURBO-MINI.COM

thick geordie muppet!..

Talking of Multi pots, Dave, how good where those 6pot mountain bike brakes?..bloody over the handle bar type stuff!

Il measure if i remember tomorow... :)

assume tyhis is 4 the post on mc?

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

yep!

measure mine, not very accurately.

35mm, maybe 34mm

Shouldn't have bothered if I'm not going to get it right.

Wil

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

As i suspected,

Working out the area, two 4 pot pistons ARE almost identical to a single 2 pot piston...

but dont they press on a bigger area of pad ?

9 valves, 4 wheel drive, 3 cylinders, 1 turbo, which got nicked

just measured mine i got 35.93 mm to 36.00mm

no longer a series, but still 1.3 turbo.

Pad contact area is irrelevant - only it's position on the disc is important...

I think pad size is only about wear. i.e. the larger 4-pot pad wil last longer.

Does the larger pad have better heat dissipation so it takes longer to heat up?

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

Forgive my ignorance, what is the advantage of four and six pots then ?

9 valves, 4 wheel drive, 3 cylinders, 1 turbo, which got nicked

A bigger pad has a bigger area so the effective contact patch is bigger

how can that be irrevelent... or are you talking about it being irrevelent for what your working on?

AlexF

Turbodave wrote
Quote "Pad contact area is irrelevant "

???

9 valves, 4 wheel drive, 3 cylinders, 1 turbo, which got nicked

I'm asking what he means by that!!

the amopunt of breaking you get is effected... but if he means that for what he's working out (master cylinder sizes I suppect) its not then thats a different matter!

alex

AlexF

come on guys - co-efficient of friction is dimensionless, hence the actual area in contact has no difference...

or to put it simply, if you apply 1kg over 1cm^2 on a horizontal plane you get the same resistance to movement as if you were to apply 1kg over 2cm^2 - basically, you are increasing the area, hence applying less of a mass over each mm^2...

Pad contact area affects wear more than anything - but heat is also a factor i hadn't thought of untill Wil mentioned it....

Edited by turbodave16v on 13th May, 2004.

I think he means that pad size is irrelevant to how good brakes are. A bigger pad with the same coefficient of friction on the same size disk will not stop the car any quicker.

The Metros used the 4pot callipers and bigger pads (I suspect) because the metro is heavier and will therefore need more pedal/brake pressure to stop than a mini. Thus the wear rate of the pads would be higher on a metro meaning a bigger pad would be needed to make the pads last a reasonable time.

The only reason I run 4 pots is because I couldn't easily find a small 2pot calliper to fit. 4pot alloy one are easy to find.

So, you would use a 6pot calliper purely to have a big pad that lasts longer. I guess if you had a massive pad you could use a 'stickier' material that would wear quicker but stop you quicker.

Sorted

Wil

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

how much are these alloy 4 pots nowadays?

I bought the Minispares one. I think they were about ?250 for the pair.

Wil

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

?260 ish from Minispares

Sure the idea of multi piston calipers is the spread the pressure over the area of the pad more evenly.

Thats what I thought jon

9 valves, 4 wheel drive, 3 cylinders, 1 turbo, which got nicked

can you get alloy 2 pots?

Team Racing

Yes. Wilwood do a lovely set of 2 pot alloy callipers.

Find them here http://www.rallydesign.co.uk/

The problem is fitting them. I think the adaptor plate needs to be a work-of-art. That's why I never bothered.

Wil

Fastest 998 mini in the world? 13.05 1/4 mile 106mph