The art of braking

Given that my daily is a heap of junk with no abs i have lately been thinking lot about brake systems. For instance is there any commercially available systems that regulate the slip on each wheel in relation to the others as well as front wheel angle?

I assume aftermarked systems would not be easily allowed on the street but how is it for track use and racing? I checked WTAC rules and they did not allow anything unless stock mounted.

http://www.worldtime...ex.php/english/

 

Global Time attack series however does allow complex systems as they are not spesificly mentioned.

 

http://www.globaltim...014-GTA-CCR.pdf

 

I ask because i believe i know a group that combined could develop such a product, with the expertise to valves, machining and programming as well as the the likely ability to do the calculations that this would involve.

 

But surely such a system allready exists in a ready to go package?

 

I would like you to share some info on this and products if you know

Edited by MatsNorway, 18 January 2014 - 22:16.

Brembo, AP, Willwood and many others make street callipers.Mostly 4 piston. Which in turn are essentially a big old Girlock or Kelsey Hayes from the late 60s early 70s made in alloy. And are sometimes less effective too.As they flex something fierce.
A road car calliper has dust seals to prevent dirt, mud and grime getting into the calliper. The seals can cause dramas with piston retraction. Though often more a displacement problem.
With all the hype it is purely a pad of friction material that does the braking and a stiff hydraulic clamp that supplys the pressure [the calliper]

The next thing is ofcourse is making a calliper that does not flex, the pistons do not 'knock off'causing a displacement problem and then the calliper pad and piston transmit as little heat to the brake fluid which will boil and cause a spongy pedal or worse no clamping.

The reason most road car callipers are single piston [or two on one side] is less displacement issues and less pad knock off. Most 'float' causing far less issue.

Race callipers come in 1,2 4 6 8 piston 'spot'. Though really most are 4. The others are too long and often less efficient. Most decent race callipers and aftermarket road ones will come with staggered pistons. The leading is smaller than trailing,that keeps the pads from wearing to a taper as quickly which keeps the pedal 'up' More taper = lower pedal. I currently am using callipers with 1 7/8 and 1 5/8. The other car is 4x 1 3/4. ok for short races and then you turn the pads around to try and equalise the wear. These callipers are simple old Girlocks from a Jag. Big heavy but stiff things which do fry the seals quite quickly. Again ok, in fact great for short races in a smaller car.But pads can only be quite thin. The Wilwood stagger bore callipers are not as stiff, a third of the weight but uuse pads twice as thick. Which if nothing else keeps the fluid cooler. As does the alloy construction. I have to use line pressure valves to keep the pistons in contact with the rotors. The Jags do not have the same issue.

Never use a multi piston calliper on the rear unless you have a floating hub. Live axle cars will just have the axles moving in and out 50 thou Far from ideal! Many so called floaters, live or IRS are in effect little better. IF you can control that a 4 spot on the rear can be an advantage, if nothing else a better supported and clamped pad.

Most of the above happens on a race track or severe driving. This includes big bumps etc that is flexing hubs, stubs and spindles.

All the electronics in the world really are no better on a properly sorted system. And a decent driver. In motorsport personally I would ban all electronics. Motorsport is supposed to be a test of driving skill. Not cheat gizmos that often go wrong. ABS is nice on the street BUT causes grief too when it goes wrong, or a spirited driver gets into a non ABS vehicle and locks wheels everywhere. Which has happened to me. Though I don't panic and crash like the average mugs does. But it does wake you up.

The more expensive brands usually are an improvement over the cheaper for a consistent pedal. Some road car callipers have very little available decent high performance pad material. Or have too small a piston/s to be really serious. Though this can be the case of the latest and greatest that uses a different pad profile.
The more expensive are supposed to use better material for the seals. Though personally I have had a lot of grief with the expensive and used 'cheap as' road car seals with more success.

The initial question though? I suspect that really there is nothing new now. Just making better cheaper.

You might want to check out the analogue A-B systems on the big sporting/high performance M-B's..

 

From ~20 years ago - pre computerisation..

 

- they are fairly expensively engineered, are  effective, & should be available inexpensively from scrap yards.

 

 Their disc rotors & pads (consumables) are not too pricey either..

You might want to check out the analogue A-B systems on the big sporting/high performance M-B's..
 
From ~20 years ago - pre computerisation..
 
- they are fairly expensively engineered, are  effective, & should be available inexpensively from scrap yards.
 
 Their disc rotors & pads (consumables) are not too pricey either..

probably not in Oz. Europe most probably.

I recently replaced the ones (discs & pads) on mine with Aussie brand units ( I don't like the dirty Euro pads) fairly inexpensively..

 

4 piston ( dual opposed ) front & 2 piston opposed rear calipers..

This is all you ever need...
http://www.ebay.com....7c872348&_uhb=1

Typical 'contribution' again there C-P,

 

& ' fancy -faux ' covers are of no value to the thread question..

Thank you Lee Nicole. Allways nice to learn a thing or two about brakes as well as given some reminders about flex. Info on this Analoge system and it claimed abilities would be nice JAW.For instance i doubt that they had gyros in the mix? And i still hope someone knows something about existing systems being available. There really is alot of time to get from this. Say for Global Time Attack and Pikes peak events++

Edited by MatsNorway, 19 January 2014 - 15:52.

Why not use a good oem system 

This is all you ever need...
http://www.ebay.com....7c872348&_uhb=1

We use these when all else fails

 

http://www.ebay.co.u...=item1e62edca23

" For instance is there any commercially available systems that regulate the slip on each wheel in relation to the others as well as front wheel angle?" What do you mean by this Matt?

" For instance is there any commercially available systems that regulate the slip on each wheel in relation to the others as well as front wheel angle?" What do you mean by this Matt?

I understood the question as him asking for an aftermarket ABS system..

It kinda is.. but with focus towards racing.. Hard to explain. Slippage is ok as long as its even and is enough to keep the vehicle in stable state, adjustable and adapts to gyro input, wheel angle..

 

i have no clue about modern abs systems. The ones i have experienced is crude and judders on/off far more than it should for being a decent system in racing outside of rain.

 

To continue first line. Ducati have a traction control system being able to work even when the bike is in a wheelie. I recon it can only do that with gyro input. I wonder if there are traction systems for brake that are that well developed++

Edited by MatsNorway, 19 January 2014 - 22:12.

Bikes run in pitch/yaw/bank angle changes true, but the traction control sensors compare front/rear wheel speed differences, AFAIR..

We use these when all else fails

http://www.ebay.co.u...=item1e62edca23

Simple and effective, the downside is the variable performance on different road surfaces.

You seem to be after something that lives in the combination of ESC and ABS. They certainly exist on modern production cars, where side to side braking of the rear axle (most often) is used to bring the yaw and yaw rate of the vehicle into line with the steering wheel angle. At least one moderately successful racer switches his production cars electronic assists off and on as he goes around the circuit (Baruth at TTAC).

 

Once you have 4 channel ABS the rest is just sensors and programming, Fortunately the nice people at Bosch like the sound of your wallet...  http://www.bosch-mot...2/html/3720.htm

modern ABS systems know about the "ideal" slip% and will even adjust it according to the surface type/condition...

 

as was pointed out, there are race ABS systems available..

Knowing how long it takes to tune an ABS system for an OEM I don't know how much I like an aftermarket system. I am wondering how refined it can be. Real hard on a race car with different pads and tire compounds. If they give the end user control of the software I can see it being pretty useful in a panic mode but for out and out brake distance there is some fine tuning there.

We use these when all else fails
 
http://www.ebay.co.u...=item1e62edca23

Now come on! That is the park brake!

You seem to be after something that lives in the combination of ESC and ABS. They certainly exist on modern production cars, where side to side braking of the rear axle (most often) is used to bring the yaw and yaw rate of the vehicle into line with the steering wheel angle. At least one moderately successful racer switches his production cars electronic assists off and on as he goes around the circuit (Baruth at TTAC).
 
Once you have 4 channel ABS the rest is just sensors and programming, Fortunately the nice people at Bosch like the sound of your wallet...  http://www.bosch-mot...2/html/3720.htm

Greg, as far as I am concerned you have to do that to drive to the shops. On Top Gear last week Clarkson was trying to spin the tyres on wet grass. The dumb traction control had him creeping like an old lady in a sidevalve Anglia.
The driver drives the car,, not the ECU!

modern ABS systems know about the "ideal" slip% and will even adjust it according to the surface type/condition...
 
as was pointed out, there are race ABS systems available..

Yeah, I have seen quite a few crash too. Bozinjak at Amaroo. Huge. John Nicholls nearly took me out at Mallala when it failed and locked all the wheels. There was some major problems last year with the big time Porsches too I was told.
Again, the driver drives the car,, not the ECU. And motorsport is supposed to be about driver skill. Not the ECU!

Knowing how long it takes to tune an ABS system for an OEM I don't know how much I like an aftermarket system. I am wondering how refined it can be. Real hard on a race car with different pads and tire compounds. If they give the end user control of the software I can see it being pretty useful in a panic mode but for out and out brake distance there is some fine tuning there.

What difference do the pads and tyre compounds make?

 

Maybe I am being too simplistic here, but isn't the ABS just concerned with wheel behaviour (speed)?  Is it not indifferent to whether the wheel is being slowed by my $50 pads, or your $250 high temperature race pads, or is shod with my wooden Chinese pseudo tyres, or Mr Dunlop's finest racing slicks?  Isn't the aim to monitor the rotation of the axle/wheel, and determine when the rotation speed approaches a predetermined level, at which point line pressure is adjusted?  How does my choice of tyres/brake pads get into the ABS data set, and what is the ABS response to this choice? 

 

This is of more than passing interest to me, as a club racer who has been party to a number of debates on whether to retain/fit ABS, and who currently runs an ABS equipped car.  FWIW, these debates have generally resolved down to 'I can brake more heavily without ABS', versus 'I can brake more effectively and consistently, without lockups, with ABS', and ne'er the twain do meet .

Edited by GreenMachine, 21 January 2014 - 05:44.

You seem to be after something that lives in the combination of ESC and ABS. They certainly exist on modern production cars, where side to side braking of the rear axle (most often) is used to bring the yaw and yaw rate of the vehicle into line with the steering wheel angle. At least one moderately successful racer switches his production cars electronic assists off and on as he goes around the circuit (Baruth at TTAC).

 

Once you have 4 channel ABS the rest is just sensors and programming, Fortunately the nice people at Bosch like the sound of your wallet...  http://www.bosch-mot...2/html/3720.htm

 

You pretty much got the idea. I never tought of it initially as a device for altering the behavior and turn the car. Just a tool to monitor slippage, Keep the tail stable and deny komplete locks. By doing this alone you get the maximum out of the brakes in the back. By say allowing more slippage at the back than in the front (by driver preference) you can make the car dance a bit more going into the corners. Or less understeery if thats what it does in its natural state.

 

So what is the price of that Bosch device? it looks so simple. Can it possibly do all the things i want as quick as i want? I havent looked at the data sheet and so on yet. Been a bit busy today.

Knowing Bosch?  A pretty penny I expect.

I looked.  Big mistake    Five or six big ones from memory. 

 

You could go the the local junkyard though.  The risk there is that you get one that needs to talk to its engine (for want of a better expression) ECU in order to work, or worse, for all I know these days all the ABS electronics are in the ECU.

 

The two advantage of paying all that money are that you get adjustability and the ability to program it.  If you know what you are doing, that could be worth it - if you want those sheep stations badly enough

" The risk there is that you get one that needs to talk to its engine (for want of a better expression) ECU in order to work, or worse, for all I know these days all the ABS electronics are in the ECU."

 

I'd say that risk is 100%, but you may be able to fudge the necessary inputs.

 

I'm pretty sure the ECU is separate from the ABS controller in most cars, as the ABS controllers are typically black or dark gray boxes to the OEMs.

" The risk there is that you get one that needs to talk to its engine (for want of a better expression) ECU in order to work, or worse, for all I know these days all the ABS electronics are in the ECU."

I'd say that risk is 100%, but you may be able to fudge the necessary inputs.

Certainly not 100%. My experience with Mazda ABS (looks like any other Bosch 3 or 4 channel ABS of the early - mid 2000s) is that it wants to know about the hand brake light, and maybe (I can't recall exactly) something else, but nothing from the ECU per se (or is this what your 'fudging' was referring to?).  Wiring diagrams will tell the story, but if it is on a CANBUS it may not be so readily discernible or manageable.

 

I'm pretty sure the ECU is separate from the ABS controller in most cars, as the ABS controllers are typically black or dark gray boxes to the OEMs.

 

Thanks for that Greg - that has been my observation, but then I only observe older cars.  I am also interested in your comment on the colour of the boxes - does this mean that the ABS is acting largely/completely independent of the vehicle ECU?  Or that there is some limited data exchange between the two?

A black box is supplied to the OEM by the Tier 1 supplier and the OEM is not responsible for what goes on inside the box, does no tuning, and basically just writes a large check and a hopefully ironclad spec and contract. Typically the tuning is done by the Tier One's team, the OEM may get a seat in the car. Tires, shocks, and some steering systems and a lot of ABS stuff is like this.

 

Grey boxes have some tunable elements but much of the details are still not shown to the OEM. Almost all EPAS and ESC systems have parts that are exposed to the OEM, and others that are not. For example in the EPAS we are currently tuning there are 4 layers of access. The top layer is just a few gains and damping knobs. Most OEMs have access to that The next layer is lookup tables and switches for various features. Some OEMs have access to that. Then under that is a layer that interfaces the first two and then adds safeguards so you can't damage the motor. OEMs have no direct access to that but can ask for changes. Finally underneath it all is the actual motor drive software. That just translates all the digital stuff into usable voltages.

 

White boxes are fully specified by the OEM (usually in consultation with the tier 1, but not always) and the tier one just makes them to print.

 

There are very big differences in the level of access to internal tuning between OEMs, At least one manufacturer has an unbelievably 'hands off' attitude to black and grey systems, and also freezes some aspects of the car that we regard as tunable very early in the program.

 

As to the ABS talking to the engine, not much, I think, but from the engine or vehicle computer you'd get battery voltage, engine running, and from ABS to the vehicle would be vehicle speed if the manufacturer has a clue. Obviously if TC is installed then the TC module interfers directly with the engine.

Yeah, I have seen quite a few crash too. Bozinjak at Amaroo. Huge. John Nicholls nearly took me out at Mallala when it failed and locked all the wheels. There was some major problems last year with the big time Porsches too I was told.
Again, the driver drives the car,, not the ECU. And motorsport is supposed to be about driver skill. Not the ECU!

 

the problem I saw on some porsches, and on my car too, was that if you have ripples in the tarmac in the brake zone, and we sure do have them on our not very maintained track, the ABS will mistake them for wheel splippage and go into some crazy ICE mode or something and you are left with no brakes..  happend to me more than once..will do the same in the winter on rough snow/ice surfaces too... that is why I know where the ABS fuse is..

that is why I know where the ABS fuse is..

Just pull the handbrake on one click, or until the warning light just comes on, if you want a short term 'off' switch ...

 

Works for me, ymmv though.

Thanks Greg, that is very interesting.

Just pull the handbrake on one click, or until the warning light just comes on, if you want a short term 'off' switch ...

 

 

can't as the handbrake switch will also disable the central active diff lock..

the problem I saw on some porsches, and on my car too, was that if you have ripples in the tarmac in the brake zone, and we sure do have them on our not very maintained track, the ABS will mistake them for wheel splippage and go into some crazy ICE mode or something and you are left with no brakes..  happend to me more than once..will do the same in the winter on rough snow/ice surfaces too... that is why I know where the ABS fuse is..

Both of the above where failures. Racing ABS that was dangerous. The Nicholls car was 3 days old!
Though my comments again are proof that it should be banned.
Any street system would make you a good bit slower than any decent driver. OK for the towcar,, maybe.
My first experience with ABS was on a ED Ford,, where the pedal went away under your foot. That inspired confidence,NOT

As for centre diff locks! real race cars do not have centre diffs! Just the towcar. And even then the drivetrain sometimes will fool the ABS as everything chatters on a rough road.

Edited by Lee Nicolle, 22 January 2014 - 09:54.

As for centre diff locks! real race cars do not have centre diffs!

 

 

WRC racers would not agree with you..

 

agree with you on the need for deletion of ABS..

Mats,

The Bosch ABS system (sensors, harness, etc) is €6302 or €7415 +tax depending on what connectors you want.

However, as far as I can tell, it does not use front wheel angle as an input so if you absolutely need that, you are out of luck.

http://www.bosch-mot...4_Manual_en.pdf

Thats a mad price! I for some reason was converting it to dollars and was thinking okay.. thats a lot of money!

 

My thought was to make the device/devices modular so you could buy only one thing at a time and so on to fit it with a budget, rules or the learning curve. Not sure if that is possible as a design but..

Edited by MatsNorway, 22 January 2014 - 16:48.

If you go to a wreckers and buy an ABS from the days when it was optional then you have a good chance of it having a stand alone controller. Of course it will also be relatively unsophisticated.

 

 

As to Lee's point, in a straight line a good, relaxed, driver will beat the ABS in a controlled environment. That of course is NOT what ABS is intended to do, what it does is allow anybody to steer effectively while braking heavily and panicing. That shows a triumph of optimisim over experience, most people fixate on the glowing brake lights ahead of them and more or less gracefully impale their radiator on the towball. On a freeway that may actually be safer than having people change lanes while braking.

WRC racers would not agree with you..
 
agree with you on the need for deletion of ABS..

Rallying is not racing. It is one car at a time motorsport. And WRC cars now and in the past bear no connection to the road going version. If they did there would be more makes and often the AWD cars would be blown away. While far from my favourite car a Porker would make mincemeat of near production Lancers and Rexes on many of those stages. Dirt or bitumen. And so would many other production 2wd cars. Far more interesting too though probably a good deal slower.

well porkers have been run in modern rally.. along with astons and lambos... elfers are quite spectacular to watch, sound incredible, and are favourite among the spectators and most of the drivers... Francois Delecour is quite outspoken about it...

 

sad thing is,... Lancers make mincemeat of them most of the time... One more thing... those 911's are really expensive to run... we should switch all amateur and semipro racing to crate LS engines..

 

Is rallycross racing?

well porkers have been run in modern rally.. along with astons and lambos... elfers are quite spectacular to watch, sound incredible, and are favourite among the spectators and most of the drivers... Francois Delecour is quite outspoken about it...
 
sad thing is,... Lancers make mincemeat of them most of the time... One more thing... those 911's are really expensive to run... we should switch all amateur and semipro racing to crate LS engines..
 
Is rallycross racing?

I am talking near production events. WRC is not that. WRC cars cost millions to run. The Japanese seem to have given up.
And yes Rallycross is racing, there is a group of cars all starting at once. Though it will always be suited to smaller cars ideally as the venues are generally pretty tight.

Edited by Lee Nicolle, 24 January 2014 - 09:19.

My idea around the ABS system was to make the wheels go in more even speed (as well as altering the values with steering input/turning) as well as allowing the driver to brake harder on the rear tires without worrying to much about the rear stepping out as wheel lock in the back would be assisted back to preset values.. The system would thought to only lighten the brake pressure on the needed wheel.

 

Lee! 4WD is far superior. And it sadens me that there is so little 4WD in racing. Its way better than FWD as a option. Now that Subies and evos is not in racing they could have gone racing but there is no racing series to support that type of vehicle (sedans with 4WD) FIA you old outdated crappers.

Edited by MatsNorway, 24 January 2014 - 15:29.

Front drive is for shopping trolleys and even then is inerintly dangerous. Cheaper to build, doesn't last as long and on some occasions roomier than a rear drive car the same size.

AWD suffers to with many of the flaws of front drive. AWD is for passenger cars,, 4wd is for Four Wheel Drive vehicles, Landcruiser, Patrol, Landrover etc.Larger offroad vehicles. And they too suffer a bit. Though are rear drive vehicles using a front diff, sometimes with a split diff until locked in proper 4wd. AWD is usually a Front drive platform with a split diff for the rear wheels.
A long time motorsport associate who has raced Sports Sedan, Sports Cars was driving a WRX at a club hillclimb. His comments,, probably the fastest I have been up this hill [in about 50 years!] and also the most boring. And probably the most expensive.
Personally I would not own a front driver as a personal car, may consider a AWD [Subaru Forester or similar] but do drive a Landcruiser. None will ever be a performance car, but mechanised transport. Race cars drive at the rear. Just like F1, World Sports Cars, V8 Thupercars and the like BTCC prams are a snapshot of really how bad front drive is. The main reason they crash so consistently!
The ideal [in theory ] sporty passenger vehicle is like an Alfa GTV. Engine up front and transaxle at the rear. However as most will attest not the most reliable or cheap to produce design. Fun to drive though, BUT I will never own one. Though these days they are all stuffed anyway

As for your idea of ABS, it was done 30 years ago, and is still not perfected on high performance models. And a good driver will outdrive it anyway

Edited by Lee Nicolle, 25 January 2014 - 03:12.

Got to agree there Lee, what M.N. needs  - are true linear non servo-boosted brakes, with an adjustable F/R proportioning valve..

 

If the pedal/hydraulic cylinder ratios are correct, sure it may be a bit firm, - but you know where you are - at all times..

As for your idea of ABS, it was done 30 years ago, and is still not perfected on high performance models. And a good driver will outdrive it anyway

The trouble is when I pull up at the traffic lights I don't always have a good driver behind me.

Which is one good reason why I ride my motorcycle between the cars - inc' to the front of the queue - at red lights..

Got to agree there Lee, what M.N. needs  - are true linear non servo-boosted brakes, with an adjustable F/R proportioning valve..

 

If the pedal/hydraulic cylinder ratios are correct, sure it may be a bit firm, - but you know where you are - at all times..

A F/R proportioning valve++ with some intelligence/dynamic properties as you go would never be bad is what im saying..

 

And stop talking about braking on the street at traffic lights.. totally irrelevant and boring. And it pops out in all threads here.

Edited by MatsNorway, 25 January 2014 - 10:58.

Rear-ender at stop-light in a car ( unless it is a multi-tonne behemoth that collects you)

is annoying, & inconvenient. 

 

But on a bike, it is def' something to be actively avoided, as a general principle..

http://www.racecar-e...gal-at-le-mans/

This is exacly the same as i was thinking about. Only difference is that this system is self adjusting.

 

What i was talking about is not ABS. Its just dynamic brake bias based upon wheel angle, wheelspeed and brake force++

Edited by MatsNorway, 07 July 2014 - 11:16.