I've ripped out a few articles on braking here and all say the benefits of
multi-piston callipers is generally a larger pad area, a much more even
braking force and a general lack of flexing. Sometimes the real wolrd
doesn't follow theory. I know i had rebuilt 1600 brakes and they were shit
and faded fast, i upgraded to 240k which were as i got them off the wreckers
vehicle and ive loved them ever since. My brothers has 200b brakes and i can
make them fade too quickly but with better pads as terry knows they are
quite capable. In the shed we have a set of struts with unknown but large
and very heavy brakes on that i will identify soon and hopefully chuck onto
one of the 1600s and ill let you know how they go.
regards chris
>From: "Daniel Kroehn" <[EMAIL PROTECTED]>
>Reply-To: [EMAIL PROTECTED]
>To: <[EMAIL PROTECTED]>
>Subject: Re: RE:sec: unclassified Brakes - Long
>Date: Mon, 8 Jan 2001 16:53:00 +1000
>
>I agree with scott. I know jack shit about all the physics involved but
>what most of the posts have said I can kinda get my mind around. Anyway if
>sliding calipers are "SO GOOD" why is it that the V8 touring cars all use 6
>pot BREMBO/WILLWOODS/whatever brakes on the front and 4/6 pots(not sure
>which ones) on the rear. I'm sure if the "sliding caliper brakes were just
>as good if not better then the multi-piston, non-sliding variety then they
>would use them. From what I've been told by many a person, big buck
>motorsport is the proving ground of high performance gear!
>
>Daniel Kroehn
>Recommending DATRATS, supplying quality Datsun performance parts.
>www.Datrats.com.au
>
>----- Original Message -----
>From: McEwan, AC Scott <[EMAIL PROTECTED]>
>To: <[EMAIL PROTECTED]>
>Sent: Monday, January 08, 2001 4:15 PM
>Subject: RE:sec: unclassified Brakes - Long
>
>
> > Here's my two bits. Take a dinner plate and clasp it in one hand ( like
>a
> > single piston slide calliper) and get a mate to try and pull it out of
>your
> > hand. He should find that pretty easy to do. Now. Take the plate and
>clasp
> > it with one hand on each side( yes, that's right. Just like a twin or 4
> > piston calliper). Get your mate to try and pull the plate out of your
>hands.
> > Note how much easier it is for the person holding the plate to hold it
>with
> > more force with less effort? Conclusion. I may not know physics but I
>know
> > what works. Twin or 4 piston callipers produce equal or more clamping
> > pressure than a slide calliper with far less effort. Hence. They kick
>ass!!
> > Scott......
> >
> > -----Original Message-----
> > From: Pooley, Trevor [mailto:[EMAIL PROTECTED]]
> > Sent: Monday, 8 January 2001 16:23
> > To: '[EMAIL PROTECTED]'
> > Subject: RE: Brakes - Long
> >
> >
> > Sorry nick but I don't agree with what your saying about single piston
> > calipers and clamping force. My reasoning would be about 1000 words and
> > would still make me confused. Sorry but I'm no engineer and my physics
>is
> > not to flash!
> >
> > My basic logic is as follows:
> > two pot simitomo (ie 2 x 4.8cm diameter pistons) - each piston pushes
>one
> > pad independantly on either side of caliper towards disk by X force.
> >
> > Theroretical Single pot sliding caliper with 4.8cm dia piston and same
>pad
> > area as above. Ok so given that piston is pushed out of caliper in one
> > direction by X force. The force at the pad is then halved though as the
> > caliper is a sliding arrangement.
> >
> > What I mean is that the pad clamping force in this case is shared
>equally
> > between the two pads. Where as the twin pot clamps each pad individually
>so
> > the force is greater.
> >
> > Regards
> > Trev
> >
> > -----Original Message-----
> > From: Andrew Greenbury [mailto:[EMAIL PROTECTED]]
> > Sent: Monday, 8 January 2001 15:09
> > To: [EMAIL PROTECTED]
> > Subject: RE: Brakes - Long
> >
> >
> > I agree with zac: if you exert force on one side obviously there will
> > be an equal and opposite force on the other side - this doesnt
> > equate to twice the effective force/pressure.
> >
> > if you put scales on a table with 10kg on them, do the scales show
> > 20kg because the table is exerting a 10kg reaction on the scales
> > too??
> >
> > andrew
> >
> > > imagine the disk was "u" shaped so that the a brake piston acted
>inside
> > the
> > > "u" shaped disk, a single piston could be aranged to operate
>internally,
> > > pushing outwards against the inside of the "u" and thus the effective
> > > pressure would indeed be doubled, the piston pushes against one side
>and
> > the
> > > floating cylender pushes on the other side.
> > > in real life it works the same way but with "levers and brackets" used
>to
> > > transfer the pressures against the outside of a disk.
> > > make sence?
> > >
> > >
> > > -----Original Message-----
> > > From: [EMAIL PROTECTED]
> > > [mailto:[EMAIL PROTECTED]]On Behalf Of Zac Campbell
> > > Sent: Sunday, January 07, 2001 8:43 PM
> > > To: [EMAIL PROTECTED]
> > > Subject: Re: Brakes - Long
> > >
> > >
> > > I'm not entirely convinced that one piston can create the pressure of
>two
> > > pistons just by having it push two pads. To me this would mean the
> > opposite.
> > > I think that it would then create only a percentage of it's full
>potential
> > > pressure on each pad, whereas an opposing twin piston caliper would be
> > able
> > > to push 100% on each side.
> > > Also are we taking into account even pad pressure from both sides
>created
> > by
> > > an opposing piston setup?
> > > What about pad area!?
> > > I'm not doubting Terry's setup his obviously works a charm for the
>reasons
> > > that Brad Hallett pointed out.
> > >
> > > zac
> > >
> > > ----- Original Message -----
> > > From: Ken Abraham <[EMAIL PROTECTED]>
> > > To: <[EMAIL PROTECTED]>
> > > Sent: Saturday, January 06, 2001 5:52 PM
> > > Subject: Brakes - Long
> > >
> > >
> > > > Errol, Terry, Trevor et. al.
> > > >
> > > > Some Notes and questions about brakes resulting from my field trip
>to
> > the
> > > > Wreckers,
> > > > (some of my recent posts on this have been rejected by the server,
>so
>I
> > > > don't know how much has already got through).
> > > >
> > > > 1. Sumitomo twin piston calipers
> > > > Readily available (i.e choose a good pair and don't pay more than
>$20
> > > each)
> > > > on some Toyota Corona's and Mark 2's (6 cylinder sports coupe), all
>have
> > > > braided lines.
> > > > There are 3 main types, they differ in where the brake line attaches
>to
> > > the
> > > > caliper.
> > > > The Sumitomo caliper bolts straight onto an early 200b Strut, and I
> > assume
> > > > it goes straight onto the 270mm brake-disc 240K struts.
> > > >
> > > > 2. Single piston versus twin piston, and four piston - IMPORTANT
> > > > Previously, we have calculated the effective piston area of a single
> > > piston
> > > > caliper as the area of the piston. However, actually the effective
>area
> > is
> > > > slightly more than double the area of the piston since the force
>exerted
> > > on
> > > > the medial chamber wall (the inner face, opposite the piston) is
>used
>to
> > > > press the lateral (outside) pad against the disc.
> > > > With this new view, compare various calipers below...
> > > > (Note the greater the effective piston area - the greater the force
>on
> > the
> > > > pads for a given brake line pressure, Pressure=Force/Area)
> > > > Porsche 993 Turbo caliper has 2x 44mm pistons and 2x 36mm pistons
>giving
> > a
> > > > total area of 50.7681cm sq.
> > > > By my reckoning the stock 1600 caliper would have 2x 20.43cm sq. =
> > 40.86cm
> > > > sq.
> > > > The big 200B caliper would have 45.80cm sq.
> > > > The poor old Sumitomo would have 36.19cm sq.
> > > > The Rover 3500/AP Twin pot would have 51.04cm sq.
> > > > Volvo & Hilux 4 spots 28.27cm sq.
> > > >
> > > > As I see it there is no difference in the surface area to volume
>ratio
> > > i.e
> > > > caliper cooling ability) between 1, 2 or 4 or even 10 piston
>calipers.
> > > > Perhaps the advantage of 4 spots is that they distribute the
>clamping
> > > force
> > > > over the length of the pad better, hence reducing disc warp and pad
>hot
> > > > spots.
> > > > Perhaps single piston sliding calipers are more prone to flex and
>pad
> > > knock
> > > > off than the opposed-piston fixed type caliper.
> > > >
> > > > 3. Sources for brake mods and further research,
> > > > The Nissan Urvan has large single piston sliding calipers on vented
> > > rotors,
> > > > the calipers have the Datto 90mm bolt spacing, but with ~M20 (i.e
> > large)
> > > > bolts, and would fit on Bluebird or R31 Struts with slight
>modification.
> > > > Approx piston size is 55mm, eff. area = 47.51cm sq.
> > > > BMW 3.0S calipers are 4 spot vented at the front and twin piston
>vented
> > at
> > > > the rear have 90mm spacing and may fit on Datto 200b, 1600 etc...
>strut,
> > > > don't know what type of disc to use though. E28 also has 4 spots and
> > twin
> > > > spots. E30 has twin spots up front.
> > > >
> > > > 4. Bluebirds/R31
> > > > The Bluebird is not an 'orphan' or black sheep as people have
>suggested,
> > > > parts from it can be good for swaps.
> > > > The disc brake rear (TRX, LX) is an early version of the R31 rear
>and
> > the
> > > > calipers are interchangeable (internal handbrake on Bluey though),
> > > similarly
> > > > up front, the Bluebird brakes are just non-vented R31's
> > > > There are DBA sport rotors available for the R31.
> > > > The disc brake rear is basically what is fitted to the VN
>Commodore!
> > > > I would like to find a swap for the rear caliper though. I hoped to
>fit
> > > > Bluebird front calipers to the rear and fit a Mini pressure
>regulator,
> > > > however the bolt and pin spacing is different, any ideas?
> > > >
> > > > 5. I made a tactical decision and went for the R31 250mm vented
>front
> > > > struts, rather than the 270mm solid 240K struts, I'll just hang onto
>the
> > > > Sumitomo's until The brake issue is resolved.
> > > > I will have to change the spring seat though, or swap all the bits
>into
> > my
> > > > Bluey struts.
> > > > BTW the R31 struts with vented rotors and finned calipers look
>SWEET.
> > > > What car did I get the struts from, it was an R31 skyline, but it
>was
>a
> > > > sports model in Two-tone grey - Not a GTS, they have 270mm discs. A
> > > > silhouette maybe?
> > > >
> > > > Regards,
> > > > Nick
> > > >
> > > >
> > > >
> > > >
> > > >
> > >
> > >
> >
> >
> >
> >
> >
>
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