[adneo]

Originally Posted by Jeroen

I doubt that very much. I did a bit of googling and there are some documents out there showing pretty detailled braking requirements. Much more than just braking distance by the way. Also, I noticed the braking distance was not given, but specified in decelerations time, which is probably a much better criteria anyway. (https://law.resource.org/pub/in/bis/...852.8.2001.pdf) But it is dated though.

Would love to hear somebody who could really dig up the most recent versions of these Indian documents and lets do the math.

But for lack of anything concrete lets take the UK highway code. Which does specify braking distance. (not to be confused by stopping distance). See https://www.rac.co.uk/drive/advice/l...ing-distances/

Attachment 2086335

If I compare these table to the stopping distance tables you posted earlier you will see that nearly all cars in your table comply with current UK Highway Code!

You really think you need more stringent requirements? Almost all your cars comply with modern Western European Brake Distance requirements. What is the problem?

Jeroen

Yes regulations will always be there , so the one you are searching for is IS 11852, but its thenlaws there which will be skewed inspite of all the details. Juat like our Constitution btw which is the most voluminous in the world. Yet our law and order issues are a different topic.


Firstly if there is anything, we actually need more aggressive braking distances because our road planning and traffic management isnt as organised as any western country like the UK. Our rowdy crowds are a different level itself and you have you have to be ready to tackle odd cow or idiot jumping onto the fast lane any moment.

Inspite of the UK highway code mentioning 55m the Polo in the UK went from 60 mph to 0 in around 35m!

https://www.team-bhp.com/forum/attac...ngdistance.jpg

Whereas the same Polo depending on trim went from 100 to 0 in any distance between 56 to 46m. Its legal u wud argue but is it the same as the UK car? NO!

I would rather kick the touchscreen and get the UK spec brakes.

[IP_Man]

Drum brake has one advantage, requires less force to brake due to inherent servo action. That is why they were common in non assisted braking system. But, drum brake tends to lockup. Disc brakes don't have tendency to lockup but requires more force for effective braking hence require some sort of braking assist.

I'm wary of any automation in the braking system such as automatic radar brakes. They are useless in India. I'm OK of getting audible warning of close proximity but don't want any automatic action.

[TheHelix0202]

Originally Posted by ajaiD

Now this difference could be because of the rear setup or the fact that the 1.5 NA does not come with a booster.

Brake Booster as in Brake Assist (BA)??

[Voodooblaster]

Originally Posted by RoadMonkey

have you not seen the people who cross the road regardless of traffic condition and just stretch out their hand in front of you as if casting a spell that'll make you stop?

How many times have you seen cars or bikes slowing for hapless pedestrians ? Unless and until the pedestrian puts his body in harm's way, no driver even thinks of slowing.

I live in a small town along NH66 in southern Kerala. Crossing the busy 2 laned road is a nightmare. There is a zebra crossing near KSRTC bus stand in this town. I tried to cross along with a 3 other unknown people when a car was approaching almost 500 metres away. The gentleman (the forum rules prevent me from using the right words) flashed his lights and blared his horn and kept barrelling towards us. The other people raised their hand to request the guy to allow them to cross but to no avail. Finally they sprinted across the road, since traffic from the other side was sedate. Seeing the maniac, i simply waited for him to pass, noted the vehicle number and informed the traffic cop stationed nearby.

And the cop simply shrugged and said he couldn't do anything about it.

I could cross the road only after a good 5 minutes after that. The cop did stop the traffic near the pedestrian crossing once a couple of more pedestrians queued up on both sides.

Nb: the particular point has no traffic signals. Just a cop

[SS-Traveller]

Originally Posted by adneo

Hi All,
One of my biggest grief when it comes to Indian Car manufacturers is how every single one of them try to skimp on important safety features and provide more gizmos and toys instead.

The feature which i want to highlight is Rear Discs.

That's a mythical lack of safety in Indian cars point. As Jeroen correctly points out...

Originally Posted by Jeroen

Drum brakes at the rear is not necessarily a problem at all. Lots of modern cars still have them.
...
Stopping power, or stopping distance if you like, is not necessarily related to having drum or disc brakes as such. Many other factors come into play.

And drum brakes are way more powerful and efficient than discs, for the amount of hydraulic / pneumatic force being applied. Just think about this: a 20-tonne truck uses drum brakes to stop, not discs.

Originally Posted by adneo

Verna came with rear discs but Hyundai took them off saying passengers complained of the aggressive braking!

Aggressive braking depends on the quantum of servo boost, not on whether the actual stoppers are drum or disc. In fact, discs need boosting more than drums do.

For me 0-100 is luxury but 100-0 is a bare necessity and there should be absolutely no compromise around it.
...
Safety cant be a single dimensional approach like plugging in airbags into a structure which can stand up to an impact. It has to be addressed holistically, where all the pieces give us absolutely all options to keep us safe.

Don't depend too much on brakes to stop safely at the last moment. Safety begins from good driving, not over-servoed brakes. But that's a topic for another sub-forum / thread.

Originally Posted by Jeroen

In case anybody still thinks drums are inferior to discs. They do have their use!

Indeed - most truck and other heavy vehicle manufacturers think so!

[thehacker]

Having all 4 disc brakes is definitely better. But having said that, I have 2 points to make:

• I believe that the confidence-inspiring part has more to do with the brake bite rather than with the brake setup(as you have already mentioned about Vento vs Rapid). Off course, all disc brakes reduces stopping distance and should inspire confidence, but I strongly feel that the brake bite is more effective in making us believe that the brakes are stronger. I have owned/driven multiple cars with different brake setups - all drums(M800), front discs rear drums(Liva, Brio, Celerio, WR-V, City, Rapid) and all discs (Corolla, Abarth).
• Just curious - is there any empirical evidence that just by changing the rear brakes from drum brakes to disc brakes, how much of an improvement it makes in stopping distance?

[PaddleShifter]

To add my 2 cents, my current car (S-cross) has all 4 disc brakes and while braking is excellent with them, my Punto with drums at the rear offered equally good braking (if not better).

So I agree with forum members who feel that having drums at the rear is not always a disadvantage.

One added advantage of cars haing good braking capability even with rear drums is that you have 2 less brakes to maintain, haha. Discs need periodic inspection/attention every 4-5k Kms to check for rate of wear and time their replacement.

[Jeroen]

Originally Posted by thehacker

Just curious - is there any empirical evidence that just by changing the rear brakes from drum brakes to disc brakes, how much of an improvement it makes in stopping distance?[/list]

No, you simply can not make that comparison. Because it really depends on the size of the discs, the caliber, the pad and the set up. You can make it worse, better or equal. Both drums and disc brakes come it many different sizes and variants. So making general statements on the effects of replacing drums with brakes are vice versa are simply nonsense.

Please read the earlier posts in this thread to get some notion on the difference and how they materialise.

Jeroen

[RoadMonkey]

Originally Posted by Voodooblaster

How many times have you seen cars or bikes slowing for hapless pedestrians ? Unless and until the pedestrian puts his body in harm's way, no driver even thinks of slowing.

I live in a small town along NH66 in southern Kerala. Crossing the busy 2 laned road is a nightmare.

..

I could cross the road only after a good 5 minutes after that. The cop did stop the traffic near the pedestrian crossing once a couple of more pedestrians queued up on both sides.

Nb: the particular point has no traffic signals. Just a cop

The situation I'm talking about isn't at a crossing but throughout the entire road. And if you do cross, it should at least be when the car's a bit away, giving driver the time to notice. It's not like I don't have to cross roads myself. I just wait a bit and an empty stretch always comes along even on the busiest of roads. If not, at least a calmer one.

Most of the crossings where I live have MASSIVE speed breakers as well as traffic lights, nobody seems to follow them. I would pick up speed when the light goes green only for a pedestrian to cross me without EVEN LOOKING while raising the hand. We all have to be in most of the situations, the pedestrian crossing the road, the two wheeler driver, the four wheeler driver. What we can do is not make the mistakes we bemoan on this forum. I *do* slow down for crossing pedestrians, especially for the elderly. That's all that's in my powers.

[Kosfactor]

Imagine a wet road, there is a bit of sand and mud on the road. Your 4 wheel disc brake equipped 5 star rated whatever car, you think it is going to stop at the same distance as when the road is dry?

[IP_Man]

Originally Posted by Kosfactor

Imagine a wet road, there is a bit of sand and mud on the road. Your 4 wheel disc brake equipped 5 star rated whatever car, you think it is going to stop at the same distance as when the road is dry?

Whether disc or drum, ABS will increase braking distance slightly in the above mentioned situation. What is important to note here is that car will stop without any drama due to ABS action.

IMO, ABS is more suited to disc brakes due to simple operation and progressive linear braking force.

In old time, Fiat and Ambassador use to have front drum brakes. Locking front wheel is more dangerous than locking rear wheels in hard braking. Maruti 800 launched with front disc brakes, after that automobile scenario changed from front drum to disc brakes. Now a days motorcycle come with front disc brake as standard and in premium motorcycles rear brake is also disc.

In short, passenger cars and bikes are slowly moving from drum to disc brakes but drum brakes are going to stay for heavy vehicles.

[Kosfactor]

Originally Posted by IP_Man

Whether disc or drum, ABS will increase braking distance slightly in the above mentioned situation.

I don't think ABS is bad here,Let's leave the ABS aside, Why dint it stop? Is it due to lack of traction?

The solution as most of you experienced drivers know is to drive slowly. But you know that because of some instinctive knowledge of physics, you carry more speed and less traction - Slide all over the place.

Increasing the 'bite' therefore is of no use, you may as well paint the calipers red.

[IP_Man]

Originally Posted by Kosfactor

Why dint it stop? Is it due to lack of traction?

If we go to very basics of braking, to stop moving car, kinetic energy of the car must be converted to other form that is heat.

Non ABS car on dry road, if you brake hard, wheels lock up, it is friction between car tyre and road will stop the car. Kinetic energy is dissipated to heat between tyre and road.

On wet road, friction (or traction) between car tyre and road is less. So if ABS is not in picture, on hard braking (wheel lock up), car will slide for long distance without any control. Dangerous situation.

If ABS is in picture, it will not allow wheel to lock up, so kinetic energy is dissipated as heat in controlled manner across disc brakes.

In short ABS makes sure braking is done only by disc (or drum) brakes for which they are made for and not by the friction between the tyre and road.

[R2D2]

Originally Posted by IP_Man

In short, passenger cars and bikes are slowly moving from drum to disc brakes but drum brakes are going to stay for heavy vehicles.

Volvo buses use disc brakes at the front, but I am not sure about the rear wheels. I have seen the brake calipers myself when the bus my wife and I were travelling in had a flat front tyre at 1:30 am and I was providing the conductor and driver much needed light using my LED torch to change the flat.

For that matter even some high speed railway wagons and locos have shifted to discs brakes. Disc brakes are easier to maintain, self cleaning (drum brake system rust when if the vehicle wades through water and also traps debris) and dissipate heat faster than drums (especially ventilated discs) making them far more effective when stopping from high speeds.

Given a choice between drum and disc it's the latter that wins overall IMO.

[Kosfactor]

Originally Posted by IP_Man

In short ABS makes sure braking is done only by disc (or drum) brakes for which they are made for and not by the friction between the tyre and road.

Wrong! Ultimately your car stops because of the friction between tyre and road. (Apart from crashing into something, of course).