Handbrake "failure"

[Nookiebear]

Almost as if its a marketing move to make the electric ones seem more reliable and secure.

 

So… on that basis there's the notion that Skoda would deliberately (at the behest of their Marketing department  :wonder:) manufacture hundreds of thousands of vehicles knowing that one of the most vital safety systems is ineffective/defective, alienating their customers, the media and industry regulators, severely damaging the brand name and the parent company's reputation, and giving rise to numerous possible injury, damage and other claims, not to forget recall expenses - just to highlight what they believe to be (to a public group who probably couldn't be more disinterested in the subject) the perceived benefit of electromechanical over mechanical ...

 

Sorry… pointless commentary!

 

There are many possible reasons for any failure on an individual or group basis, but they're unlikely to be as a result of a major manufacturers wish to commit business suicide. 

[Huskoda]

Not very good marketing if it hits the news when some woman with a pram gets killed by a big estate car rolling down a hill....

Yes and the VW with its electric one didn't  Though, I think Passats were well known for doing that.

 

It wasn't a serious comment, just casual cynicism  Relax guys.

[Phildmill]

I may be old, learnt to drive in an old Austin mini, handbrake was a gesture not a fact so have always left any vehicle since in gear

[hobbie2k]

I have never trusted handbrakes. Where I'm from the temp can drop so low that an engaged handbrake cable will stretch (thermal expansion) then when it warms in the morning, the brakes release.

I always leave the car in gear and only use the handbrake on inclines.

Even in gear, though, it's not guaranteed to stay put. My brother's Mazda3 rolled on a slight incline while parked in gear. It was his spot at work and he had parked there every day for years. But one day it just let go...

Why would a person be taught to press the button when lifting the brake? I would assume that it would cause failures...

Edited 13 August, 2014 by hobbie2k

[SC03OTT]

So you're not wearing out the ratchet each time you apply. The wear would probably be minimal anyway, but might as well prevent it as good practice.

However, you have mentioned the possibility of the handbrake failing by doing this. I suspect that's exactly what's happening in these cases and not an actual mechanical failure.

[gadgetman]

I'd still raise with Skoda and cc VOSA in case someone is injured as a result

[Mort]

So you're not wearing out the ratchet each time you apply. The wear would probably be minimal anyway, but might as well prevent it as good practice.

 

I've never understood this argument?

 

Doesn't that defeat the point of actually having a ratchet system?

 

Why not just have something like the chair sliders, where you push the button to release the mechanism, move to the point you want, release and it clicks and locks in place?

 

A ratchet only works in one direction, to say good practice is to not use the ratchet in that direction kinda makes the whole thing redundant?

[V6Jules]

I press the button in ever since I had to change a handbrake lever on a previous car due to the ratchet being worn out. I've never had one unlatch before but then I always keep the rear brakes in good service so I don't have to hang off the lever. If it was drop a tooth then the brakes should still hold the car.

I can only imagine that the ratchet would jump from not being properly engaged if there was enough pressure on it for the pawl to catch on the very edge of a tooth, possibly from pulling the lever up too high to start with

UNLESS its just badly designed or made which could well be the case here.

[fabdavrav]

I have always put car in 1st gear, unless facing downhill, then put in reverse................don't care if the handbrake fails................this "problem" has been known about since the invention of the handbrake I recon........

 

Next car (on order) has an electronic handbrake..................will still put in gear..........

[neiln]

I always press the button ( I also always leave a car in gear). On applying the hand brake the other day, I released the button and let go of the lever, hand was just inches from the lever when Bang! It released. It dropped one tooth only, clearly it had not quite latched the tooth as I released the button, but the ratchet worked as it should and caught on the next tooth.

 

Best practice might be to pull the lever up one more click after releasing the button, if you press the button at all that is.

[Geek42]

Best practice definitely to use the button but then pull one extra click on the ratchet to make sure that it's not settled 'in between'. Interested by the people saying that they leave it in first or reverse gear depending on direction of slope though, I would have thought it made no difference. If you leave it in first facing down a hill and gravity manages to turn the engine then leaving it in reverse isn't going to fair any better, surely? I use 2nd, irrespective of slope direction.

 

What actually locks the engine position when it's all turned off anyway (I'm not disputing that it is locked, just wanting to understand the mechanics of it a bit better).

[hobbie2k]

Nothing actually "locks" the car when it's in gear. It just increases the resistance to rolling. When the car is in gear, in order to roll not only do the wheels have to turn, but so does the engine. That means all those extra parts with all their mass and friction have to move, as well as the air that has to be pumped through a closed throttle.

It's the same force that you feel if you let off the accelerator and then downshift a couple gears. The car will start slowing down a lot faster.

Lastly, to get the most firm hold, you should be in highest gear ratio (Most engine turns per wheel turn). Usually that's reverse. I prefer first, however, because that way my reverse lights don't come on before I'm ready to back.

Maybe if I have some time tomorrow I'll give a little physics lecture.

[V6Jules]

Best practice definitely to use the button but then pull one extra click on the ratchet to make sure that it's not settled 'in between'. Interested by the people saying that they leave it in first or reverse gear depending on direction of slope though, I would have thought it made no difference. If you leave it in first facing down a hill and gravity manages to turn the engine then leaving it in reverse isn't going to fair any better, surely? I use 2nd, irrespective of slope direction.

What actually locks the engine position when it's all turned off anyway (I'm not disputing that it is locked, just wanting to understand the mechanics of it a bit better).

When the engine is off its the compression in the cylinders that stop it from rotating. You leave it in a gear for the direction its facing so if it was to roll the engine would not be turned over backwards. Also leaving it in second would mean the car has more mechanical advantage over the engine making it easier for the engine to be turned by the car so you should leave it in a low gear such as first or reverse. This is also why when you bump start a car you do so in a higher gear

[V6Jules]

Ah beaten too it

[Geek42]

Thanks guys, both very clear!

 

I read the previous posts (rightly or wrongly) as people leaving it in reverse facing downhill and first facing uphill, expecting the gearing to work against gravity. What you're actually saying is the opposite is better, not because it makes any difference to the holding capability but if the car does move it will be less likely to cause damage. This is a new suggestion for me.

 

My drive is on a slope, I generally park facing upwards. I also usually leave it in 2nd, but I will leave it in reverse from now on.

[Neily03]

Thanks guys, both very clear!

 

I read the previous posts (rightly or wrongly) as people leaving it in reverse facing downhill and first facing uphill, expecting the gearing to work against gravity. What you're actually saying is the opposite is better, not because it makes any difference to the holding capability but if the car does move it will be less likely to cause damage. This is a new suggestion for me.

 

My drive is on a slope, I generally park facing upwards. I also usually leave it in 2nd, but I will leave it in reverse from now on.

 

It's actually the ratio that holds the car not the direction as the car can still roll forwards when in reverse.  The best gear is reverse as its the lowest ratio making it harder for gravity to overcome the engines compression.

[Geek42]

I know you've been through some pain to get us here Neily, but I just wanted to say 'thank you'. This thread has become genuinely informative!

[hobbie2k]

I was thinking about the engine compression being a factor and I realised that (in a 4-pot, at least), there is always one cylinder on its compression stroke and one on its power stroke.  In theory, the compressed air in the power cylinder (even if it's not ignited) would be trying to force the piston down (thus turning the engine).  This force would counteract any resistance to turning offered by the compression cylinder.  That is why cylinder deactivation works to save fuel, the shut-down cylinders are always conteracting each other).

 

This, however, only applies if the compressed air in the power cylinder stays compressed for a long period after the engine has stopped.  If it leaks out (either past the valves or the piston rings) quickly then there won't be any compressed air to counteract the movement of the compression cylinder.  On the other hand, if it does leak quickly, then the compression cylinder won't work very well as a brake because air will simply seep out of the cylinder.  So how long does it take for a power cylinder to lose its air?

 

I know Mazda was working on a compression-based start/stop system where the engine was spun backwards for about half a rotation till a cylinder was fully compressed, then fuel/spark applied right when the accelerator was pressed to instantly fire the motor.  In that case the system would have to hold charge for at least a minute...

[Barneyrumble]

My two month old Octavia rolled down my drive and crashed into the wall opposite this morning. The handbrake had been on, I can't get out the car with it on the slope otherwise. It wasn't in gear

I was hoping to swop regs with Neily03 if possible and anyone else with a similar problem, to follow this up with Skoda as their first reaction was they have not ever heard of this happening. Like you, I am not expecting the dealer to find a problem and despite half and hour of trying have not been able to replicate it myself

[pipsyp]

Parking nice and close to a kerb and turning in the wheels slightly is good practice as if anything does let go the car should just bump the kerb and go nowhere.

Dont know about others but the handbrake in mine feels quite sticky, I sometimes end up taking it on and off a few times to make sure its on properly. Also i often wait for the hill hold to deactivate, turn.off the engine then reapply the handbrake as I have noticed sometimes that the handbrake doesnr always apply as well as it could if its been applied whilst hill hold is active.

[Gabbo]

I have experienced a similar thing to Neily03 & BarneyRumble with my car, although I am lucky that I had read this thread before I collected my car (and was already in the habit of parking in gear).

 

It seems to me that the handbrake force can be affected by temperature (perhaps its routed close the exhaust system ??)

I was driving last summer (30° ambient) in heavy traffic maybe around 20/30kph for about 30minutes.

After this time the tunnel ahead was closed so I was stationary on a slight incline.

StopStart kicked in & I pulled the handbrake on.

 

After several minutes the engine started, there was a toot behind me & I realised the car was rolling backwards.

Luckily I found the brake in time but then found that the handbrake would rise another couple of clicks before holding the car.

 

During my normal driving & daily comuting since, I have only noticed this a couple of times & always assosiated it with hot temperatures.

(another was arriving in my normal parking place when regen was interrupted. when I returned to the car an hour later the handbrake would rise another few clicks).

[hobbie2k]

Last night we stopped on the side of the road for a break, and I set the handbrake while leaving the engine running (in neutral, of course). A few mins later there was a loud snap sound and we discovered that the brake had released on its own.

We were on flat ground, so nothing bad happened, but it was disconcerting that it let go. I've always parked in gear, but this is the first time I've ever had a brake release, and the car has only 2500km, so it is not worn.

Anyhow, now I make sure to lift it a bit above a click, then set it back down, rather than just pulling it.

[pipsyp]

Sometimes the handbrake can just catch on a notch but only just. Ive experienced this a few times on mine and the bang it makes when it returns to the off position is almighty!

i always check and double check now that its definitely on, I also think that with the miles (20ish k in one year) its improved and I dont recall it having done it more recently.

Its pretty bad on what is supposedly such a safe car that you cant entirely rely on the handbrake. In some respects they should have just adopted the e-handbrake from the Golf, the tech works and auto hold is pretty cool too.

[Greg R]

I had a similar issue with my old vectra (08 model) and eventually vauxhall issued a recall

[steviec]

Read this thread with interest Neil03 you state you have good CCTV of the incident, have you not tried providing that to Skoda? After all it will show you parking up & leaving the car, so if the handbrake was off it would of rolled straight away, then sometime later will show the car roll forward on its own. Is that not enough proof for them there is a problem?