Multi Piston disc brake Calipers
Multi Piston disc brake Calipers
(OP)
Good day all,
I have just joined your group and have a question or point I would like clarified.
In multi piston, ie. 4 or 6 spot disc brake calipers, is there a ratio or formulae for the difference in piston diameters that is prevlent in some of the OEM and aftermarket sets available.
I have posted this in 2 other forums, with no response yet.
Thanks in Advance
Paul
Brisbane
OZ
I have just joined your group and have a question or point I would like clarified.
In multi piston, ie. 4 or 6 spot disc brake calipers, is there a ratio or formulae for the difference in piston diameters that is prevlent in some of the OEM and aftermarket sets available.
I have posted this in 2 other forums, with no response yet.
Thanks in Advance
Paul
Brisbane
OZ





RE: Multi Piston disc brake Calipers
Kevin
RE: Multi Piston disc brake Calipers
I am sort of fishing for something I don't think really exists.
I am aware of the master cyl dia relationship, but in our case master cyl diameters is not an issue for this application, we can change both of them as the need suits.
We want to replace some heavy castiron 2 spot calipers with some aluminium 4 or 6 spots (semi race application) units. All the overpriced commercial calipers seem to have piston diameters that suit stock bar sizes rather than a specific ratio or formula.. ie. 1 3/4", 1 1/4" & 1" or 1 1/2", 1 1/8" & 7/8" and a few metric size of similar value.
These are just a sample of the assemblies we have considered.
The suppliers all qoute "special" design parameters for their piston sizing, but I beg to differ.
I/we ( I am part of a small design group) now want to machine our own caliper bodies to suit commercially avail pads, a new lightweight rotor assy as well.
This is what prompted my initial posting.
Thanks Again
Paul H
Brisbane OZ
RE: Multi Piston disc brake Calipers
I think the piston sizing on the centre piston will be the maximum size that can fit in the avaliable space with consideration to maximum rotor size within the practical avaliable rim sizes.
on a 4 spot design, I think the 4 pistons should be the same size, and if they are not, I agree it is to get the required area from stock size raw materials. Not a good enough reason in my unqualified opinion.
On a 6 piston design, the smaller leading and trailing pistons will be about pad and caliper flex. I would like to see a finite element analysis of the structure before deciding on final dimensions.
Regards
pat
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Multi Piston disc brake Calipers
I guess I will research a little more, if no obvious corelation or ratio shows up, then I'll probably follow the current experts and go with OEM/non genuine spare part piston & seal kits..and fit these into my design housings to suit an "off the shelf" type pad that fit my design hat & floating rotor.
Thanks again,
Paul H
RE: Multi Piston disc brake Calipers
Jakub
RE: Multi Piston disc brake Calipers
This would prevent the backing plates to bend. This would also produce more even brake pad wear.
RE: Multi Piston disc brake Calipers
i would say
1 find the limitation of pedal length
2 select a caliper resonably sized for the application
3 select a mastercylinder to provide the appropriate pedal pressure and throw to operate the system