GSX-R calipers- Why 2 sizes of piston?

Dibble · Scooby Slapper Joined: 17 Jul 2007 Karma :

I'm fitting some calipers from a 1996(?) GSX-R 600 to my Moto Guzzi V50 and the pistons seem to be 2 sizes i.e. each caliper has 2 large and 2 small pistons.

Does anybody know why and will "running them backwards " have any effect?

The Guzzi has its calipers in front of the forks not behind so the disc rotates past the big piston then the small rather than the GSX-R where it runs small then large.

I can swap the forks over to a more conventional set up if needed and no I don't know why the calipers are in front Smile

cheers

Dibble

MaybeGuy · Super Spammer Joined: 12 Mar 2007 Karma :

i know some of the SRADs used 4 pot and others (the 750) used 6 pot? obv the 6 pot would be smaller pistons.
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Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

Dibble · Scooby Slapper Joined: 17 Jul 2007 Karma :

Gawain · Nitrous Nuisance Joined: 06 Dec 2008 Karma :

Its probably something to do with balancing the braking force at the leading and trailing area of the pad. I think most modern sport bikes have that type of setup.

lonner · Spanner Monkey Joined: 09 Jan 2009 Karma :

it was all about giving more feel to the brakes and pad wear when this different size pistons started many moons ago Thumbs Up

think you will be fine however you fit them Thumbs Up

hth

G · The Voice of Reason Joined: 02 Feb 2002 Karma :

Yea, I think it was worked out that due to the way the wheel was spinning etc that one part needed more force than the other.
However I suspect they'll still be a decent upgrade and that the way they are mounted (the 'wrong' way) will probably be more of a general disadvantage than the individual pistons being the wrong way around.

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Gawain is right. The leading edge of the pad has more braking effect. So to even it out the leading piston is smaller to apply a bit less pressure and even out the braking effect.

Not sure there are any braking disadvantages to having the calipers forward of the forks. Should get more airflow over the calipers to keep them cooler. However with the different size pistons expect the pads to wear oddly at least.

All the best

Keith
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Marmalade · World Chat Champion Joined: 28 Apr 2009 Karma :

If your brakes are linked, as in if you hit the front it applies the back a little as well, the smaller pistons would be for the secondary action.
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