Yaris cross 2WD electronic parking brake

[Graham47]

16 minutes ago, Roy124 said:

Oh no it won't. If I stop my car outside my garage and unstrap it will not DISENGAGE 

⁰

I didn’t say it would !
I said ….

1) HOLD will NOT engage until SB is fastened

2) SB does not have to be fastened for EPB to disengage.

 I reverse up my drive EVERY DAY, EPB disengaged, without SB fastened.

At the top, I have to fasten my SB before I can engage HOLD.

[MikeSh]

57 minutes ago, Cyker said:

and more expensive

I doubt that. Modern electrics are not expensive and the savings on the production line are significant when you consider all the levers, cables and rigging needed for a mechanical system. The looms are getting put in anyway, so an EPB with a motor on each wheel is almost plug & play.

[Roy124]

9 hours ago, Graham47 said:

 

 

[Roy124]

Cyker, a long time ago.  I know their brake arrangements were unusual.  Two circuits, both front and one rear.  I also know handbrake turns were tricky if not impossible. 

I think the arrangement had something to do with its rally cars.

They had a similar brake issue as Toyota hybrids, under use.   In their case the handbrake drums rusted a d did not benefit from braking scouring.

[flash22]

4 minutes ago, Roy124 said:

Cyker, a long time ago.  I know their brake arrangements were unusual.  Two circuits, both front and one rear.  I also know handbrake turns were tricky if not impossible. 

I think the arrangement had something to do with its rally cars.

They had a similar brake issue as Toyota hybrids, under use.   In their case the handbrake drums rusted a d did not benefit from braking scouring.

It's called brake bias, fronts and rears have their own master cylinder and a balance bar in between them

https://www.mambamotorsport.co.uk/p/a3-cylinder-pedal-box-with-balance-bar-master-cylinders/

[Cyker]

2 hours ago, MikeSh said:

I doubt that. Modern electrics are not expensive and the savings on the production line are significant when you consider all the levers, cables and rigging needed for a mechanical system. The looms are getting put in anyway, so an EPB with a motor on each wheel is almost plug & play.

How are you working that out? The cost of the EPB caliper screw unit alone costs more than all the parts of the handbrake put together, unless you are counting the drum/disc brake as part of that well! It also needs additional code and in most modern cars an ECU module, which a mechanical handbrake won't need.

Electrical cabling would need to be run to the wheels rather than bowden cables, so I imagine that part is probably similar in terms of assembly cost.

[bathtub tom]

6 hours ago, Roy124 said:

My SAABs had disc and drum brakes with the handbrake on the front wheels.   I later had 900s but can't remember if they were front wheels too 

2CVs also had the handbake operating on the (inboard) front brakes. Drums on early models and discs on later IIRC.

[bathtub tom]

I was once blocked in by a Qashqai whose driver had sat in the car listening to the radio with the lights on. Couldn't release the EPB as the Battery was too low. Of course they didn't know how to do it manually and no handbook. Scuffed a wheel on a kerb trying to manoeuvre out.

[MikeSh]

5 hours ago, Cyker said:

The cost of the EPB caliper screw unit alone costs more than all the parts of the handbrake put together,

And the source of that is ... ?

Regardless, as I said previously it's not all about cost. You are likely strong enough (for now) to set the parking brake on a steep hill, but a lot of people aren't. Populations are ageing.

I've had cars that I've had to work at to get a good PB hold and I know for sure my wife hasn't got as much arm power as me (and that was a few years ago - I know I've lost arm power since then and might struggle with those cars now). We all accept power steering and power brakes as normal, even essential, three days ... wtf is the problem with accepting power parking brakes?

[MikeSh]

Just now, MikeSh said:

wtf is the problem with accepting power parking brakes?

Oh, handbrake turns.

Essential motoring skill in 2024 ...

[Roy124]

23 hours ago, Graham47 said:

 

Sorry Graham, it's a glitch in the forum software as I was unable to delete the post.

[anchorman]

12 hours ago, Cyker said:

How are you working that out? The cost of the EPB caliper screw unit alone costs more than all the parts of the handbrake put together, unless you are counting the drum/disc brake as part of that well! It also needs additional code and in most modern cars an ECU module, which a mechanical handbrake won't need.

Electrical cabling would need to be run to the wheels rather than bowden cables, so I imagine that part is probably similar in terms of assembly cost.

I can just see the top of your head now Cykes.  That’s some hole you’re in.  They don’t fit disc brakes on the back for convenience, they do it because some models with enough weight and speed won’t meet the braking regs for Type Approval or their own internal specifications.  Drum brakes are pretty good at normal temperatures and they provide quite a good parking brake with moderate input on a lever because they have a self servo action which wraps the shoes into the drum - a bit like throwing a wedge under a door.  A disc parking brake with a lever needs a gorilla on it to have the same effect because it relies entirely on clamping force and in any case, they are good dynamic brakes but not good static brakes.  That’s the disc brake parking aspect but now go back to the motor driven cables.  To this day, globally, there are hundreds of accidents where cars roll away because while you might be able to haul on that lever, little old Ethel (who used to ride round on starmer’s bus to keep warm) can’t and frankly she’s a menace because occasionally she drives an Avensis Touring with that motorised cable and the only reason it doesn’t end up through the Post Office window is because someone has recognised the danger for her and for you.  The same applies in this so called emergency where you reckon she might need to stop the car with the handbrake.  Have you tried it?  If you go on a quiet lane and do so at LOW SPEED, you’ll find it waits two seconds just to make sure you’ve not got your knicker elastic caught in it then it will bring the car to a stand with the ABS - something a manual brake won’t.  Now as for cost, you are probably comparing what you pay rather than what the vehicle builder pays because like anything else, when the volume goes up, the price comes down and it isn’t what it was.  It is for you at the parts counter but they are only usually needed if they’ve been mishandled.  Also, they speed up production because some poor Derek doesn’t have to thread it all through and adjust it.  In service, they often end up being over adjusted which stops those drum brake manual adjusters working because they need to return all the way to the stop in order to work and then when the cable fails and it will (go and pose the question on the RAV4 section) they are often a b itch (have to do that for the snowflake filter in case a cable gets offended) to change and need the back seats out and the fuel tank dropped and and…..  I’ll quite happily take the disc parking brake even if in the very unlikely event it needs working on.  

[Tommy X]

An old school mechanic many years ago advised pressing the footbrake hard and apply the handbrake for maximum effect. 

[anchorman]

38 minutes ago, Tommy X said:

An old school mechanic many years ago advised pressing the footbrake hard and apply the handbrake for maximum effect. 

It does work, you can feel the pedal go down as you pull on the handbrake but that’s too much effort for some. 

[Cyker]

All good points!

I will say that the whole reason the handbrake lever is so long and on a ratchet is for mechanical advantage - You shouldn't need to be Eddie Hall to engage it to a safe level of clamping force; If you do, there may be something wrong with it and/or it needs checking/adjusting!

I found this with my Fiesta - It needed a fair pull to lock it solidly, but being my first car I thought that was normal. When I got my Yaris it would lock up really easily with much less force required, but when I got my 2nd Yaris it was more like my Fiesta, which I thought was weird - Got my mechanic to look at it, thinking maybe the shoes needed replacing, but it just needed a bit of adjustment and it was back to being as sharp and easy as it was on the first one. My mech did say it was a common problem as hardly anyone checks their drum brakes these days!

I suspect part of the reason EPBs are so prevalent now is the proliferation of rear brake discs - As you say, manufacturers quickly discovered a mechanical handbrake can't provide enough force to safely lock a brake disc - A big reason we moved to brake discs is they are much harder to lock up, which allows much more braking force to be applied without locking up the wheels!

That's why they were trying all sorts of things - The most common seems to be a drum-in-disc, although I recently became aware of some quite clever attempts at alternatives, e.g. a cam system to greatly multiply the clamping force, similar to what's used in competition archery bows.

With an EPB, you can eliminate a lot of that without having to use rear drums, although ironically some EVs have gone back to using drums as they have some big advantages over discs (e.g. Less static drag, sealed against the environment, reduced corrosion from low use, reduced dust) which fit EVs very well, so we might see the return of the physical handbrake in EVs! 

I will admit I don't know what the comparative cost of installing a mechanical brake system vs an EPB is, but it must be really smegging difficult if putting in a bit of cable and a lever still comes out more expensive than 2 weather-sealed screw motors, associated wiring, sensors, ECU etc.!

That said, it may be filtering down if the parts cost has dropped massively from what I know - I've seen costs for a single EPB unit range from £300 to £2000, but that was a long time ago; If they've dropped to double digits then that would remove a lot of the cost penalty, but you experts would have to give me figures for that!

 

7 hours ago, Tommy X said:

An old school mechanic many years ago advised pressing the footbrake hard and apply the handbrake for maximum effect. 

I used to do that on hills in my Fiesta, as well as put it in 1st gear and turn the wheels to the curb, after I once saw someone's old Ford Cortina roll very slowly down said hill and into a lamp post  

 

[Rhymes with Paris]

On my old Yaris, I think that the handbrake is on the rear discs.

It doesn't really matter though, as I have arms like steam hammers, and could pull the lever out of the floor if I wanted to.😉

It does seem to hold ok though, we have a fairly steep hill here, and due to numbskull drivers forcing their way into one lane at the top on a sharp left bend, this results in all the traffic coming to a stop on the steep hill.

It is funny though watching them all trying to do hill starts that they don't know how to do, which I assume is part of the current driving test, even with all the modern tech, which I again assume includes epb's.

 

 

[Rhymes with Paris]

And of course J turns on Sundays.

[bathtub tom]

3 hours ago, Cyker said:

A big reason we moved to brake discs is they are much harder to lock up, which allows much more braking force to be applied without locking up the wheels!

Really? I thought discs were adopted because they provided much better braking due to better heat dissipation and reduced fade, hence their use on aircraft and Le Mans D types. I've had a couple of cars with front discs and no servo which could esily lock the wheels. Drum brakes have an amount of 'self servo' effect (except for twin leading shoe, in reverse!)

[Cyker]

5 hours ago, Rhymes with Paris said:

And of course J turns on Sundays.

Is that what the J in J Sainsburys means??  

It would explain all the circular tyre tracks in the car park...

 

3 hours ago, bathtub tom said:

Really? I thought discs were adopted because they provided much better braking due to better heat dissipation and reduced fade, hence their use on aircraft and Le Mans D types. I've had a couple of cars with front discs and no servo which could esily lock the wheels. Drum brakes have an amount of 'self servo' effect (except for twin leading shoe, in reverse!)

Yes, really, but not just that - I wasn't listing every reason brake discs are used!  

The reasons you give are also why they are more favoured, as is their more linear braking force vs brake drums more unpredictable engagement as you approach the limit, and they work better with the rapid-pulsing of ABS and the independent individual braking of traction control.

I'm sure anchs will give us a list of pros and cons of both if he gets bored and/or annoyed enough  

 

[anchorman]

13 hours ago, Cyker said:

Is that what the J in J Sainsburys means??  

It would explain all the circular tyre tracks in the car park...

 

Yes, really, but not just that - I wasn't listing every reason brake discs are used!  

The reasons you give are also why they are more favoured, as is their more linear braking force vs brake drums more unpredictable engagement as you approach the limit, and they work better with the rapid-pulsing of ABS and the independent individual braking of traction control.

I'm sure anchs will give us a list of pros and cons of both if he gets bored and/or annoyed enough  

 

Who remembers Mr Angry on the Steve Right Show.  “I’m so angry, I’m going to throw the phone down”!!

 

you’re close enough Cykes 😉

[Cyker]

It's okay, my phone is a Nokia! (A real one, not these new re-branded HMD ones  )

All meant in jest and tongue firmly in cheek mate!  

 

[anchorman]

1 hour ago, Cyker said:

It's okay, my phone is a Nokia! (A real one, not these new re-branded HMD ones  )

All meant in jest and tongue firmly in cheek mate!  

 

All taken as such 😉👍

[MikeSh]

4 hours ago, Cyker said:

It's okay, my phone is a Nokia! (A real one, not these new re-branded HMD ones  )

OMG. How old is that? (How old is you? 😛 )