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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