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Brake splash shields

freddofrog said:
found an interesting article on the MVX250 http://www.mcnews.com.au/honda-mvx250f-with-phil-hall/

Same picture in the article of four of the bikes (note that someone has removed the shrouds on one bike)
[img=http://www.mcnews.com.au/wp-content/uploads/2015/04/Honda-MVX-250F-Trio.jpg


"There was another reason for the comet-like life of the MVX. The main competition for the MVX came from Yamaha’s brilliant LC model, a bike with style, clout, a racing pedigree a mile long and a raft load of companies producing hot-up bits to make it go even faster than it already did. It really was no contest.
And so the brilliant little MVX, Honda’s first two stroke road bike, came and went and its passing went virtually unnoticed"
[/QUOTE]All shrouds seem to be present, though some tea leaf has nicked the engine from the bike at the back.

The NS400R took the same engine technology and ran with it. Apart from a full reversal of the race bike engine, the pedigree is there. I can't remember if ****logising was the reason for a road going version though, ala the other manufacturers.

Engine detail from about five minutes in.

https://youtu.be/WK1vUduVAVw

The con-rod issue was unforgivable to a consumer product though, and Honda had the VT250 as a worthy alternative, making a triple 250 stroker a design exercise rather than a serious new line. I wouldn't have minded trying one out though.

By virtue of the cylinder porting and captive piston rings, the two stroke is always going to be higher maintenance than the nearest four stroke power plant, and to leave any multi-cylinder block parked up for any length of time with fluids inside kills them stone dead.

But I digress, Honda spent many months working on enclosed discs for bikes, stuck it on a few models for a year or two, the public went meh when presented with bills for periodic servicing, and it was dropped.
Click to expand...
 
These large aircraft brakes work like multi-plate clutches. The pressure plate seems to protect the disc ***embly from foreign objects.

These brakes can soak up huge amounts of heat, but do so in a single action so cooling to prevent fade is not a design parameter.

A 747 mechanic once told me they can't go near the brakes for a while after they have been used as they radiate so much heat!

edit: this post was in response to #60
 
Richard B said:
These large aircraft brakes work like multi-plate clutches. The pressure plate seems to protect the disc ***embly from foreign objects.

These brakes can soak up huge amounts of heat, but do so in a single action so cooling to prevent fade is not a design parameter.

A 747 mechanic once told me they can't go near the brakes for a while after they have been used as they radiate so much heat!

edit: this post was in response to #60
Click to expand...
If you read the patents they're mainly heat shields (to protect the wheels from catching fire while passengers use emergency chutes)

QED (747 heavy brake test)
https://youtu.be/Mr4V680UQ-k?t=20s


Airbus brake test on a rig
https://www.youtube.com/watch?v=m1dv_y_3EK0

A380-800 Brake test in overweight landing situation.
Dynamometer energy: 125.2 MJ
Brake application speed: 90.07 m/s
Stop distance: 1120 m
Mean deceleration: 3.62 m/s/s
Energy absorption rate: 5.04 MJ/s
 
So ......getting back to Brake Splash Shields (on cars) .....

It looks like they're there to prevent a vortex of water being thrown inboard during heavy rain.

The vortex is produced by a combination of
1. the rotating brake disc forms a vortex localised on the disc
2. the air-flow under the car draws the vortex inwards (Bernoulli principle/Venturi effect)

On the Honda Accord, is this something to be concerned about if the shields are removed, back or front ?
 
By the time you find the answer is yes, you will probably feel very silly for thinking no.


Test track
motorway speed
puddle
good tyre tread
1. emergency brake distance with shields
2. emergency brake distance without shields

End speculation.
 
Richard B said:
By the time you find the answer is yes, you will probably feel very silly for thinking no.


Test track
motorway speed
puddle
good tyre tread
1. emergency brake distance with shields
2. emergency brake distance without shields

End speculation.
Click to expand...
Brake pad technology is designed to cut through the surface water immediately after application and the sintering of the material is there to provide abrasive heating, to vapourise the road dirt and grease through friction.

Whilst I would concur that the less water thrown on the axle, suspension joints and bearings is beneficial for long term corrosion, what goes onto the disc is unlikely to make an appreciable difference even when emergency braking is required.

I am more inclined to think shields may be a throwback to drum systems, where water and dirt may find their way though the gaps between hub and moving drum owing to the vortice effect since many marques were built with options of discs all round only on the elite models.
 
OK, so definitely maybe, with a touch of perhaps.

I'm not taking mine off. What if my engine suddenly explodes and my tail gate stops working? Then I'll be sorry.
 
Richard B said:
By the time you find the answer is yes, you will probably feel very silly for thinking no.


Test track
motorway speed
puddle
good tyre tread
1. emergency brake distance with shields
2. emergency brake distance without shields

End speculation.
Click to expand...
Public test_track, motorway_speed, puddle_depth, good_tyre_tread, emergency_brake_distance_with_shields, emergency_brake_distance_without_shields

Sub macro1()

test_track = ""
motorway_speed = ""
puddle_depth = ""
good_tyre_tread = ""
emergency_brake_distance_with_shields = ""
emergency_brake_distance_without_shields = ""

MsgBox (speculation)

End Sub

Function speculation()

If test_track = "" Then
speculation = "Daft" 'test track is unknown
Else
speculation = "shields cause overheating" 'test track = track day
End If

If motorway_speed = "" Then
speculation = "Daft" 'motorway speed is unknown
Else
speculation = "shields cause overheating" 'same as track day
End If

If puddle_depth = "" Then
speculation = "Daft" 'puddle depth is unknown
Else
speculation = "shields don't stop splash" 'splash from a puddle is horizontal
End If

If good_tyre_tread = "" Then
speculation = "Daft"
Else
speculation = "not relevant" 'tyre tread depth has no relevance to function of splash shields
End If

If emergency_brake_distance_with_shields < emergency_brake_distance_without_shields Then
speculation = "speculation"
Else
speculation = "Daft"
End If

End Function 'end of speculation

---------------------------------

edit:
forgot to say, the computer says your speculation is "Daft" :lol:
 
Channel Hopper said:
Brake pad technology is designed to cut through the surface water immediately after application and the sintering of the material is there to provide abrasive heating, to vapourise the road dirt and grease through friction.

Whilst I would concur that the less water thrown on the axle, suspension joints and bearings is beneficial for long term corrosion, what goes onto the disc is unlikely to make an appreciable difference even when emergency braking is required.

I am more inclined to think shields may be a throwback to drum systems, where water and dirt may find their way though the gaps between hub and moving drum owing to the vortice effect since many marques were built with options of discs all round only on the elite models.
Click to expand...
Absolutely
 
Richard B said:
OK, so definitely maybe, with a touch of perhaps.

I'm not taking mine off. What if my engine suddenly explodes and my tail gate stops working? Then I'll be sorry.
Click to expand...
Well stick to driving your Accord and that situation won't arise
 
The vehicle would need to be on a wet rolling road in a wind tunnel to prove or disprove the cone theory.
 
Channel Hopper said:
I am more inclined to think shields may be a throwback to drum systems, where water and dirt may find their way though the gaps between hub and moving drum owing to the vortice effect since many marques were built with options of discs all round only on the elite models.
Click to expand...
None of the motorbikes I've ridden had splash shields and didn't suffer from poor braking in the wet because of that. So that supports what you say there; when it comes to water, brake calipers quickly squeeze that off the disc surface. Motorbike tyres splash water away from brakes though, so brakes mainly see water from rain or spray from other vehicles. My commuter bike which saw a lot more wet roads than the more pampered Ducati, did go through the original set of discs rather quickly.

But every car I have driven that had disc brakes also had splash shields and I am inclined to think car manufacturers don't add unnecessary parts to cars. Brake discs on cars sit closer to the road cars are designed to not just deal with sealed roads, but also surfaces that contain puddles of mud. I've done a fair bit of wet mountain biking, and muddy (disc) brakes are less effective than dry or just water wet brakes. And mud wears out brake pads and discs. One race, one set of pads.. Splash shields do protect against this effect on cars.

So perhaps we can modify the speculated outcome a bit. If all your car sees is tarmac and wet weather type water, you can probably do without splash shields. But if you then chamge to regularly driving unsealed roads, or sell the car to a driver who does, the lack of splash shields can become an issue. This is why I think most car manufacturers continue to include splash shields as a standard part of the brake set up.
 
Richard B said:
So is that the answer then?
Click to expand...
It is to anyone who still believes that a "splash shield" prevents water from splashing the disc, but see next



To recap, I believe that, in #37, I have found the earliest reference to a "brake shield", which was filed in 1951 when disc brakes were just about to be used on cars (they were already being used on aircraft). That patent shows the disc being fully enclosed so as to prevent dust and dirt getting onto the disc on a road car. By the fact that this type of setup was never implemented, implies that it did not become an issue. Note that that would mean they are called "brake dust shield".

On the Accord, they are referred to as "Brake Splash Guards" ....item 13 here ...... https://www.lingshondaparts.com/honda_car_parts_selection.php?block_01=17SED01&block_02=B__2200&block_03=529&block_05=hcr

But, in #45 I found a patent for a type of splash shield that is not adjacent to the disc, the reason given in the patent is that adjacent to the disc causes heating issues, and the patent states that the shields (all of them) are there to prevent "an oblique cone" from being thrown inboard (my wording, see #65 for the way I describe it).


I know that this has been a very long thread, but I believe that the reasons for these shields are shrouded (pun intended) in mystery. Not deliberately, but it is the case that the reasons are known only to a few tens or hundreds of engineers (at the most).

I have tried to find the patents for the brakes on the Accord, which are Nissin. From the attempts I have made, they are filed in Japan in Japanese.
 
Ned said:
The vehicle would need to be on a wet rolling road in a wind tunnel to prove or disprove the cone theory.
Click to expand...
at least some one else is also following the thread ;)

(my quota of "likes" is used up btw)
 
Richard B said:
None of the motorbikes I've ridden had splash shields and didn't suffer from poor braking in the wet because of that. So that supports what you say there; when it comes to water, brake calipers quickly squeeze that off the disc surface. Motorbike tyres splash water away from brakes though, so brakes mainly see water from rain or spray from other vehicles. My commuter bike which saw a lot more wet roads than the more pampered Ducati, did go through the original set of discs rather quickly.

But every car I have driven that had disc brakes also had splash shields and I am inclined to think car manufacturers don't add unnecessary parts to cars. Brake discs on cars sit closer to the road cars are designed to not just deal with sealed roads, but also surfaces that contain puddles of mud. I've done a fair bit of wet mountain biking, and muddy (disc) brakes are less effective than dry or just water wet brakes. And mud wears out brake pads and discs. One race, one set of pads.. Splash shields do protect against this effect on cars.

So perhaps we can modify the speculated outcome a bit. If all your car sees is tarmac and wet weather type water, you can probably do without splash shields. But if you then chamge to regularly driving unsealed roads, or sell the car to a driver who does, the lack of splash shields can become an issue. This is why I think most car manufacturers continue to include splash shields as a standard part of the brake set up.
Click to expand...
Car manufacturers don't design the braking mechanisms, they have a close relationship with a chosen supplier. Honda uses Nissin.

But, not all brake manufacturers fit shields, so it just depends on the reason for them. From what I have found from looking through US patents, they are there to reduce water from being thrown inward, they are not there to protect the disc.

"Splash shield" is a semantic that is clearly misunderstood, the shield is an attempt to reduce inward splash, not splash onto the disc itself. Imagine you are driving down a motorway at 3am in pouring rain, you've been cruising at 70mph for an hour, then suddenly you come upon a lorry (you haven't seen one in ages). By pure coincidence that lorry has a blow-out and jack-knifes. Do you think that the shields adjacent to the discs on your car have kept the discs dry ?

The shields are there to reduce the amount of water that would be thrown inboard, not a safety feature.
Maybe a long-term corrosion feature ?
 
Ned said:
The vehicle would need to be on a wet rolling road in a wind tunnel to prove or disprove the cone theory.
Click to expand...
Does it need to be proven or disproven though? Tyres more or less splash the same volume of water on both sides, however the inside has a car and deflected turbulent air interfering wit the splash. A car at speed creates a considerable splash pattern around each tyre, and it is unthinkable that brakes aren't continuously subjected to water in wet weather.
 
Richard B said:
Does it need to be proven or disproven though? Tyres more or less splash the same volume of water on both sides, however the inside has a car and deflected turbulent air interfering wit the splash. A car at speed creates a considerable splash pattern around each tyre, and it is unthinkable that brakes aren't continuously subjected to water in wet weather.
Click to expand...
the water is thrown inboard from the disc, the water is already on the disc, the shield is there to prevent/reduce the water from being thrown off the disc inboard into the suspension etc, it is not a safety feature
 
I removed a post up there that was probably a bit more of a knee jerk than it should have been, but Freddo then quoted the entire thing back for prosperity, thereby proving that nothing ever truly goes away on the internet.

I did appreciate the code response though. It was kind of funny in its own right. For me it is has another layer to it, as part of my job is to make sure that programmers' work translates to outcomes that non-programmers can understand. I'm forever complaining that coders narrow things down too much, and they complain that I shy away from educating the end user to think more logically. The end users ultimately pay the programmers wages so they win.
 
freddofrog said:
"Splash shield" is a semantic that is clearly misunderstood, the shield is an attempt to reduce inward splash, not splash onto the disc itself. Imagine you are driving down a motorway at 3am in pouring rain, you've been cruising at 70mph for an hour, then suddenly you come upon a lorry (you haven't seen one in ages). By pure coincidence that lorry has a blow-out and jack-knifes. Do you think that the shields adjacent to the discs on your car have kept the discs dry ?

The shields are there to reduce the amount of water that would be thrown inboard, not a safety feature.
Maybe a long-term corrosion feature ?
Click to expand...
What do you think of the "mud" approach though? Cars are designed and tested to operate in a huge amount of conditions, and there are some atrocious roads out there.
 
Richard B said:
I removed a post up there that was probably a bit more of a knee jerk than it should have been, but Freddo then quoted the entire thing back for prosperity, thereby proving that nothing ever truly goes away on the internet.

I did appreciate the code response though. It was kind of funny in its own right. For me it is has another layer to it, as part of my job is to make sure that programmers' work translates to outcomes that non-programmers can understand. I'm forever complaining that coders narrow things down too much, and they complain that I shy away from educating the end user to think more logically. The end users ultimately pay the programmers wages so they win.
Click to expand...
I've edited it out of my reply now ;)

indeed, if the window of opportunity was there, I'd probably get rid of that code, but it was a bit of a joke (the last "if" will always dictate the function return, so the first 4 ifs are redundant LOL)

copy and paste it into a VB module in Excel, then run it from an Excel sheet. It's micky-mouse code, but I couldn't think of any other way of "redacting" the text in #68
 
Richard B said:
What do you think of the "mud" approach though? Cars are designed and tested to operate in a huge amount of conditions, and there are some atrocious roads out there.
Click to expand...
well even in mud, I can't see that a shield that is adjacent and parallel to a disc, it going to do much. From what I've also read on a couple of off-roading threads, they usually remove the shields because they get in the way and cause too many problems.

I'm only about 70% sure, but, I do think that "brake splash guards"/"brake splash shields" are there to reduce/eliminate the "impact" of a vortex of water onto suspension components.
 
I would imagine it's more a case of preventing grit and debris from being lodged between the pad and the disc.

Either way, my tourer only has one splash shield at the rear, and I've not yet pirouetted into a tree in the rain.
 
Goodluckmonkey said:
I would imagine it's more a case of preventing grit and debris from being lodged between the pad and the disc.
Click to expand...
kind of, in #45 there is that 1968 patent that refers to "cone patterns emanating from a wheel on one side of the vehicle toward the brake unit of a wheel on the other side of the vehicle". I see no reason to doubt that this is a real phenomenon, and there is grit in road-water.

Honda do call them "Brake Splash Guards" so it depends on what is being "splashed" , where it goes, and the fluid mechanics involved in throwing the stuff around from the wheel and brake disc.

I'd like to talk to an engineer who is involved in the design of disc brakes for cars, preferably one who does not speak just Japanese or German LOL
 
45140-333-000 Cover , comp , disc.

In reference to brake shields on bikes. This was those godawful trailing calliper units as installed on fours, twins from the early 70's which used stainless steel rotors. (there was also a cable operated version on their smaller singles that made the one leading drum shoe look good in the wet..........)

To be honest it didn't make a blind bit of difference when removed, but Honda must have put it on all their first generation non drum bikes for a reason.
 
I'm beginning to think that Honda are the most paranoid company when it comes to brake discs LOL


What about Scoobies, do they bother with shields ?
 
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