Working up a head of steam

First time I've noticed this but on the way in to work yesterday in
the heavy rain, when I used the front brakes hard I could hear a
distinct hissing from them presumably as the rain water boiled off
them.

I assume this because clearly the pads are going to sweep the actual
contact area clear of water and so the only way water will boil off is
if the heat generated is sufficient to raise the surrounding area of
the disk to boiling point. Which I presume only happens under heavy
braking.

 

Normal for drilled discs.

Nope, they make that lovely zizzy hiss normally.

Your pads virtually ride on the disc all the time, this keeps the majority
of water off.

Try it for yourself next time it pisses down. Ride for a mile then pull in
at the side of the road without using the front brake. Now see how wet the
discs are.

Modern sintered pads. Marvellous invention.

 

I've only noticed it in the rain and it was tipping it down yesterday
morning all the way in, but I have to say my hearing's not quite as
good as it was. I blame be a helicopter passenger too often. Nowadays
I'd sue.

Which would be pointless without the equally marvellous modern tyres

 

I dunno if this is all urban myth or not, and I am certain in my own mind I
read about it from a usually reliable source ( ie, NOT MCN ). Please
correct me if I am wrong here.

Drilled discs came about thanks to BMW when a test rider complained that
brakes were 'letting off' when used hard. The issue turned out to be
generation of gas at the pad surface as its surface temperature rose. Gas
not being noted for its braking ability. By drilling holes in the disc, the
gas had somewhere to go. This also helped with wet weather braking.

Early motorcycle disc brakes, even up to the early Eighties were not always
brilliant in the wet. Problem one was the disc material used, problem two
was the pad material. The problem was in part addressed by using discs that
actually wore out instead of stainless steel[1]so the surface was regularly
sloughed off, the second was the adoption of better pad material that
incorporated fine metal particles and strands, ie, sintered pads. These two
developments gave us the brakes we know and love today. The rest is just
refinition.

Sadly, it took a few years for tyres to catch up. Catch up they did though.
I'm sure my wet braking distance on the Bandit is shorter than the dry
distance on the X7 on organic pads. On Goldfren sintered pads the Bandit
still outbrakes it, but the difference is nowhere near as marked.

I await the flaming.

[1] I'm sure they are still basically stainless steel, just less stainless.
My XJ discs never rusted even though it spent the last four years of its
life stood out in the open, never moving, those discs never rusted at all.
The Bandit gets a fine surface coat within a few days. The EBC Iron discs
on my 600f rusted solid within two days.

 

My front brakes suddenly started doing that. Turns out that the LHS
caliper was binding like a **** and had gone through the friction
material and was grinding the metal pad sleve against the brake disc.

However, I'm sure yours is fine...

 

It may be urban myth, but I've heard it too, now that you mention it.

Understatement alert! Ever ridden an XS750 in the wet? No need for ABS
on those bikes.

EBC Pro-lites are Almost-But-Not-Quite-Stainless. With EBC sintered
pads they rust slightly all over, but mostly under the pads and the
pad-shaped rust patch doesn't wear off. PITA they are when that
happens.

 

I see you're keeping on top of the bike maintenance thing Nick


--
Beav

VN 750
Zed 1000
OMF# 19

 

Mr. Suzuki Mean Dealer sorted it out for me in return for pennies. My
LHS front foot peg hanger should arrive tomorrow so that I can
actually ride the effing thing again.

 

This is bollocks. I remember tests at the ime - some drilled discs even
made wet weather braking *worse* because the holes acted a sreservoirs
for the water. Kawasaki drilled early discs, in an assymetric pattern,
and said it stopped squeal.

Mostly true. Discs in the 1970s were horrendous in the wet - I had an
SOHC Honda CB750 with discs at either end, and in cold wet weather you
could count to two before the bloody things bit.

Cast iron discs (as used on Italian bikes) seemed to work better. But
yes, sintered pads solved the problem. Sintered pads work quite happily
on old 1970s stainless steel discs, which never seem to wear out at all
(possibly because the calipers were on the feeble side).

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, BGN

If you don't get yourself to WUNderland for the free "Bike Maintenance
101" course very soon, I am going to get very, very shouty at you.

--
Wicked Uncle Nigel - Podium Placed Ducati Race Engineer as featured in
Performance Bikes and Fast Bikes

WS* GHPOTHUF#24 APOSTLE#14 DLC#1 COFF#20 BOTAFOT#150 HYPO#0(KoTL) IbW#41
SBS#39 OMF#6 Enfield 500 Curry House Racer "The Basmati Rice Burner",
Honda GL1000K2 (Falling apart) Kawasaki ZN1300 Voyager "Oh, Oh, It's so big"
Suzuki TS250 "The Africa Single" Yamaha Vmax Honda ST1100 wiv trailer

 

Wicked Uncle Nigel says...

The offer is open here too, if you're away taking care of business in
the colonies.

--
Lozzo
Triumph Daytona 955i SE (Black with added black bits)
Suzuki Bandit 600S (Green with added shit bits)
Yamaha SR250 Delusion (It's "Special")
I'm a modern man, I don't mind buying tampons, but apparently they're
not a proper Valentine's present

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, Lozzo

I fear we are wasting electrons, Brother Lozzo.

--
Wicked Uncle Nigel - Podium Placed Ducati Race Engineer as featured in
Performance Bikes and Fast Bikes

WS* GHPOTHUF#24 APOSTLE#14 DLC#1 COFF#20 BOTAFOT#150 HYPO#0(KoTL) IbW#41
SBS#39 OMF#6 Enfield 500 Curry House Racer "The Basmati Rice Burner",
Honda GL1000K2 (Falling apart) Kawasaki ZN1300 Voyager "Oh, Oh, It's so big"
Suzuki TS250 "The Africa Single" Yamaha Vmax Honda ST1100 wiv trailer

 

Wicked Uncle Nigel says...

Oh well, at least when it all goes tits up there's a nicely recovered
seat on it to sell.

--
Lozzo
Triumph Daytona 955i SE (Black with added black bits)
Suzuki Bandit 600S (Green with added shit bits)
Yamaha SR250 Delusion (It's "Special")
I'm a modern man, I don't mind buying tampons, but apparently they're
not a proper Valentine's present

 

Wicked Uncle Nigel says...

Ooh, is that the time - I have to be up early tomorrow to doss some
more.

--
Lozzo
Triumph Daytona 955i SE (Black with added black bits)
Suzuki Bandit 600S (Green with added shit bits)
Yamaha SR250 Delusion (It's "Special")
I'm a modern man, I don't mind buying tampons, but apparently they're
not a proper Valentine's present

 

As opposed to him showing up, jamming screwdrivers in allen bolts, using
mole grips on nuts, and you getting only mildly shouty?

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, ginge

No, then I'd laugh.

--
Wicked Uncle Nigel - Podium Placed Ducati Race Engineer as featured in
Performance Bikes and Fast Bikes

WS* GHPOTHUF#24 APOSTLE#14 DLC#1 COFF#20 BOTAFOT#150 HYPO#0(KoTL) IbW#41
SBS#39 OMF#6 Enfield 500 Curry House Racer "The Basmati Rice Burner",
Honda GL1000K2 (Falling apart) Kawasaki ZN1300 Voyager "Oh, Oh, It's so big"
Suzuki TS250 "The Africa Single" Yamaha Vmax Honda ST1100 wiv trailer

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, ginge

Ah, but he wouldn't get access to my nuts, y'see.

Certainly not on the first lesson.

--
Wicked Uncle Nigel - Podium Placed Ducati Race Engineer as featured in
Performance Bikes and Fast Bikes

WS* GHPOTHUF#24 APOSTLE#14 DLC#1 COFF#20 BOTAFOT#150 HYPO#0(KoTL) IbW#41
SBS#39 OMF#6 Enfield 500 Curry House Racer "The Basmati Rice Burner",
Honda GL1000K2 (Falling apart) Kawasaki ZN1300 Voyager "Oh, Oh, It's so big"
Suzuki TS250 "The Africa Single" Yamaha Vmax Honda ST1100 wiv trailer

 

Can anyone remember when BMW introduced drilled discs?
ISTR that Italian bikes had them in the late seventies and,
according to Wikipedia, cars had them in the sixties.

 

The first Beemer with discs was the R90S from '73, drilled from '75.

--
platypus

"Merely corroborative detail, intended to
give artistic verisimilitude to an otherwise
bald and unconvincing narrative."

 

Cue joke about a Nissan Main Dealer and a certain S.A. president
getting car parts delivered to his house.