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M/cyl To Brake Caliper Piston Ratio Formula?


threepot900

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I have an old (1981) Triumph Bonnie I am playing with. One of my plans is to change the front cast iron 2 pot caliper for something a bit more modern. I have a pair of 4 pot calipers off a TT600, and a M/cyl to match. I only plan to use one caliper on the front with the M/cyl. which is designed to cope with two 4 pots. Will this work? Will the brakes be like hitting a brick wall? - good. Or will they be softer than a pensioners turd?- bad.

Is there a formula to work out M/cyl piston size in relation to brake caliper piston displacement?

The two 4 piston calipers weigh about the same as one of the cast iron AP-Lockheed calipers, and as it is all unsprung weight, the change looks a good idea.

I had thought about using the other on the rear wheel, but I'm certain the TT600 rear M/cyl won't cope, so I will have to get a std TT600 caliper or a similar brembo etc: for the rear.

If I can find a lower R/H fork leg for less than £250, I'd convert to twin front discs and live with the fact it is overkill, but at least the calipers will be Triumph branded!

Any advice?

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find out what the mc cylinder diameter is and work out the area in mm2

find out the complete caliper piston areas too.

ratio is one to the other.

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Will this work?

I once bought a Fazer 600 from the kind of person who shouldn't be allowed motorbikes (or spanners :eusa_wall: ), and one of the front disks was badly* bent.

Being a skint student, I just pulled the offending disk off, pumped the lever until the pads on that side met in the middle, and carried on riding** until a cheap replacement appeared on eBay. I would describe the braking available as 'adequate', unless an emergency stop was required in which case it was more of an emergency with less of the stopping. Probably not recommended then.

Easily solved though, pick up a 13-ish-mm M/C designed for a single 4-pot caliper (plenty of Ducatis, SZR660, Cagiva Mito, various TZR/FZR/CBRs, load of dirt bikes) for a couple of quid and flog the Trumpet M/C for a profit B)

* It jammed against the caliper

** Dodgy, me?

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Thanks for the links to the vintage racing page. Thats the info I was after.

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