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Old 20th October 2020, 14:21   #151
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Default Re: Brake failure issues in the Kia Seltos

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Originally Posted by ashokabs View Post
ABS can increase distance in some cases like gravel and ice but in these conditions it provides greater control of the steering keeping the car on line. However, when ABS is used on surfaces like normal macadam roads or concrete roads ABS will reduce distance as the wheels will not lock or skidding. Skidding increases distance of stopping on such roads besides one losing control of the car.

A lot has been said on ABS on this thread already. It is intended to keep directional control of the car under braking.

Whether ABS does or does not reduce braking distance is an ongoing debate.
ABS monitors your four wheels and if any of them lock up (due to less friction) it releases the brake pressure to that respective wheel. It does so at a very high frequency (those are the pulses or vibration you feel in your brake pedal when applying the brakes hard).

So in essence it prevents the wheel from locking up. Because if it does you lose directional control and start skidding.

Certainly modern ABS on many cars are very good. Whether ABS does or does not increase the braking distance is related to how good the driver is when it comes to brake control. Most of us, are not very good. Over the years I have taken many driver courses.

You would be surprised how easy it is to learn, on a test track, with an instructor, how to outbrake most ABS systems. You need to learn and get a feel for applying the brake in one hard push, so you get maximum momentum and weight on the front wheels and then coming off just a tad so they don’t lock up. If you know how to do that, you will end up with a shorter braking distance than with ABS.

I have done it on a multitude of different cars on test tracks where you could disable the ABS at the flick of a switch. And (nearly) all of my fellow test track students managed to do so as well. Most can learn this trick in less than 5-7 attempts.

Fairly easy and great fun to do on a test track.

The problem is real life.

Although we all like to think we are pretty hot shot drivers, very few of us would have the skills to replicate these braking skills in day to day situation. If anything these very hard stops don’t happen to often. And if they do, most people will just stomp on the brake pedal as hard as they can. Which, if you have ABS fitted is the best thing. Relying on human skills to outperform the ABS is left best to some real fancy driver that can do these emergency stops, without ABS and without locking up the wheels.

Nearly all of us are almost hardwired: Emergency, stomp on the brakes as hard as you can. Under those circumstances ABS is simply the best. Whether in theory one could brake a little shorter is simply not relevant. Because very few of us could make these braking techniques are default technique.

It is the same with rear wheel driven cars. It is relatively easy to learn how to apply the throttle, rather than to hit the brake when the rear steps out. On a test track that is! But if it happens unexpected, in the dark, on a wet road, almost all drivers will hit the brake, rather than the throttle. Because for nearly all of us, that is the natural thing to do.

There is a big difference what humans can do, under controlled conditions, and how most of us will respond in real life. A lot of it is down to conditioning and experience. Normal driving experience teaches us / conditions us to apply the brake in a certain fashion. On the one off occasion where it needs to be done differently you are unlikely to do so.

So I for one rely on ABS, rather than my ability to outperform ABS.

Jeroen

Last edited by Aditya : 20th October 2020 at 23:02. Reason: Minor typo. Thanks.
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Old 20th October 2020, 15:26   #152
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Default Re: Brake failure issues in the Kia Seltos

What scares me the most is when A.S.S doesn't see anything when they scan the car for defects / faults / errors because it's that computer embedded within that acts cranky like a 2 year old and behaves like one throwing tantrums randomly that could prove fatal to anyone inside / outside the vehicle! Should they take a manual approach rather to see for any defects as the reliance on computers are increasing by discarding the eye-for-detail approach that was done years back by most of FNGs?

We all have seen Tata & Mahindras' cars not meeting the quality levels of these korean giants. But, do we really have to be worried with Tata / Mahindra's QCs or the lack of attention to issues like this from the relevant companies to these mass complaints posted by the customers with the most successful cars?

I do not think India will ever step up in terms of tightening the laws guarding the women against rape or guarding the consumers against these issues!

I only hope Kia looks at this considering how greatly India has accepted them with open hands making their products a great success!

Last edited by gururajrv : 20th October 2020 at 15:27.
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Old 20th October 2020, 15:39   #153
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Default Re: Brake failure issues in the Kia Seltos

Help me out here. The note says 'unfortunately for petrol engines there is no pump'. Is this true? My 20 year old Zen has a booster pump. Don't the newer petrol cars use it?
Quote:
Originally Posted by sv97 View Post
I don't know if something similar has been posted before but this is what a user in the Seltos Owner's group on facebook posted. Hope this helps resolve the issue and concerns raised on the thread to some extent.
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Old 20th October 2020, 15:56   #154
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Default Re: Brake failure issues in the Kia Seltos

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Originally Posted by sv97 View Post
I don't know if something similar has been posted before but this is what a user in the Seltos Owner's group on facebook posted.

Attachment 2070074

Hope this helps resolve the issue and concerns raised on the thread to some extent.
Thank you for sharing this post. I dont recall anyone in the previous posts talking about this connection. Can someone confirm?

In my case (2018 diesel Verna owner), I havent faced any issues but I distinctly remember my father in-law complaining about brake performance of 2016 Creta (1.4 diesel) over rumblers during the initial days of ownership but not anymore (1.6+ lakh kms). Probably because he got used to it now.

On a side note, we also own a Grand i10 nios and the brakes are significantly sharper in the mornings (after a long rest) for this car for the first ~200 meters. I am not 100% on this because the AMT box also lunges forward in the mornings and because of that, we could be using more force instinctively. Any owners on the forum who can pitch in on this?
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Old 20th October 2020, 16:24   #155
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Default Re: Brake failure issues in the Kia Seltos

Quote:
Originally Posted by gururajrv View Post
What scares me the most is when A.S.S doesn't see anything when they scan the car for defects / faults / errors because it's that computer embedded within that acts cranky like a 2 year old and behaves like one throwing tantrums randomly that could prove fatal to anyone inside / outside the vehicle!
I doubt very much these issues are related to computers. It rarely is

Quote:
Originally Posted by Sebring View Post
Help me out here. The note says 'unfortunately for petrol engines there is no pump'. Is this true? My 20 year old Zen has a booster pump. Don't the newer petrol cars use it?
(Most) Petrol engines rely on a vacuum on the air inlet manifold (so called manifold vacuum). So that very same vacuum is used for the brake booster, which also works on vacuum. On older cars, you might come across carburators vacuum used to the same purpose.

Actually most engineers will tell you that it is a very neat solution. Using an existing vacuum to power something else. Very simple, it is just a piece of hose, with at best one little check valve build in. Very effective, very cheap, no maintenance.

Anorak fact: In the early days of cars, manifold vacuum was also used to power for instance window wipers. Which made for some interesting wiping as the wipers would respond to changes in the vacuum. E.g. if you would come of the throttle at high RPM, that would create a high vacuum and your wipers would go bonkers!

In that respect, diesels and the odd petrol engine that does require a separate pump is much more complex, more can go wrong, more maintenance etc.

Jeroen

Last edited by Jeroen : 20th October 2020 at 16:28.
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Old 20th October 2020, 16:25   #156
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Default Re: Brake failure issues in the Kia Seltos

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Originally Posted by sv97 View Post
I don't know if something similar has been posted before but this is what a user in the Seltos Owner's group on facebook posted.
.
This means that the brakes may not work when applied under panic when one may not be able to apply foot/ downshift.... is this a generic problem for all brands?
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Old 20th October 2020, 16:55   #157
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Default Re: Brake failure issues in the Kia Seltos

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Originally Posted by ramradcliff View Post

On a side note, we also own a Grand i10 nios and the brakes are significantly sharper in the mornings (after a long rest) for this car for the first ~200 meters. I am not 100% on this because the AMT box also lunges forward in the mornings and because of that, we could be using more force instinctively. Any owners on the forum who can pitch in on this?
This is a separate problem that is not to be confused with the original problem here. Grand i10 twins face this initial sudden brake bite from the launch days itself. My 2014 Xcent SXO AT does it even after 26k kms and 6 years. You will see mention of this in most ownership reviews of i10 twins. There is no solution for this. Learn to adjust in the first few minutes. It goes away after a few meters.
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Old 20th October 2020, 17:14   #158
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Default Re: Brake failure issues in the Kia Seltos

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Originally Posted by sv97 View Post
Hope this helps resolve the issue and concerns raised on the thread to some extent.
Sorry to go off topic, but this reminds me of the Boeing 737 MAX issue. If there is a problem (that to, life-threatening) then FIX IT. No workaround is going to address this. Not every owner will have access to this information or discussion. Brakes are an integral part of an automobile and it cannot be compromised, NO MATTER WHAT.

Let Kia and Hyundai hear this, loud and clear.
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Old 20th October 2020, 17:43   #159
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Default Re: Brake failure issues in the Kia Seltos

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Originally Posted by sachinayak View Post
Not every owner will have access to this information or discussion. Brakes are an integral part of an automobile and it cannot be compromised, NO MATTER WHAT.

Let Kia and Hyundai hear this, loud and clear.
Lot of owners will not even be aware of this braking issue, knowing how to deal with it by adapting your driving style (which is not a solution!) will be known by even fewer owners. Does their manual specify in bold that this is how people should be using the brakes to avoid accidents?
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Old 20th October 2020, 17:47   #160
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Default Re: Brake failure issues in the Kia Seltos

I never knew braking on a Seltos is this technical and complicated !.

I never knew a Seltos owner needs to know so much to just brake!.

I have driven many petrol/diesel, Sedans/SUVs/MUVs, with ABS/without ABS and just braked normally and all of them reacted as they are supposed to!

Now what is all this technical stuff now?

Note: It is good to know technical stuff and that is one of the highlights of this forum. But at leisure at home and not when in the driver's seat!.

Last edited by Nalin1 : 20th October 2020 at 17:49. Reason: typo
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Old 20th October 2020, 18:24   #161
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Default Re: Brake failure issues in the Kia Seltos

I have been driving the Seltos (D) for almost 8k kms and I have come across this issue number of times. I have kept myself mentally prepared on what to expect when I brake. Below are my observations :
1. This has not happened with me on tarmac. 90% of my driving has been on highways. I have done some hard braking and thank God, this one did not crop up.
2. I have encountered this multiple times on bad patches or the ones with loose gravel.
3. I don't recollect getting this while I press 'only' the brake ( light or hard ), however if I keep the clutch half pressed and apply the brake completely on a rough patch, I can hear something like a tin can being rattled from the front right side and it takes a bit more time to stop.
I did not get the feeling that the brake is hard. It stops but with all those grind-clank noise. I believe those noises are audible enough because I can see people around, looking at the bottom of the car, as if I ran over something.

I did reach out to different service centres in two states and they check the braking system and both of them said it is because of the ABS and how it performs.

I have my doubt if there is any link between the abs/brakes with the engine rpm. Professionals on this thread please comment on this. It feels like there is a tug of war between the engine and the brake system. Next time I will monitor the rpm when this happens.
Is there some diagnostic log that can be pulled to correlate the engine rpm and the same time stamp as the ABS kicked in.
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Old 20th October 2020, 19:10   #162
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On a lighter vien, there is no stopping of the Kia Seltos. Of course, the obvious pun intended!
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Old 20th October 2020, 19:58   #163
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Default Re: Brake failure issues in the Kia Seltos

Somewhat related question -

In this kind of scenario where you are unable to engage the brakes using the pedal, would an electronic parking/hand brake work the same as a manual lever ? Most modern cars are moving to a button operated handbrake, so I dont know if you can engage it while driving at speed.
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Old 20th October 2020, 20:24   #164
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Default Re: Brake failure issues in the Kia Seltos

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Originally Posted by sv97 View Post

Hope this helps resolve the issue and concerns raised on the thread to some extent.
But this is hog on multiple counts, let me tell you why.

1) The car should be generating vacuum at idle rpm too, I am sure the idle rpm of a Kia is 800 rpm + and a little more with AC. If you do go below the idle rpm say you put yourself in 3rd instead of second (Hypothetically) either there is enough torque and the anti-stall will immediately increase the rpm and get you in the range of the idle rpm or you will stall.

2) Even if you stall, there is vacuum inside the booster which is good for 2-3 brake attempts before the pedal becomes rock hard. You can try this yourself, switch of the car when you are standing and press the brakes 1-2 times, the pedal will be light, it will keep getting harder after that and turn into a stone in say 3rd attempt or progressively get harder in the 3rd and 4th attempt.

3) Also if you must experiment, press and release the brake pedal fast in a car which is switched on, after a few tries it will become hard because the rate of refilling the brake booster chamber is lesser than the rate at which its passing onto the pressure chamber. Keep your foot on this hard pedal when the car is on and when it has got hard, it will start going down slowly in a second when the vaccume chamber is filled and air is passed onto the pressure chamber.

4) I am sure people who are braking in these Kia cars are not going bam bam bam bam on the brakes when driven at 40-50 kmph in 3rd-4th gear as per their less than X rpm theory because if they were, the car would stop much before the 2nd-3rd bam, its pittance speed.
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Old 20th October 2020, 20:26   #165
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Default Re: Brake failure issues in the Kia Seltos

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Originally Posted by a4anurag View Post
For an experiment sake, BHPian interc00led and I took my Creta to a road with 'NO traffic' and then removed the ABS-related fuse (40A) from the fuse box in the engine compartment. Drove the car at various speeds like 10kmph, 30 kmph, 50kmph and tested the braking performance at each of these speeds. The car did manage to stop but experienced wheel locking on gravel road since ABS was not functioning but on smooth tarmac, it was stopping normally with no pedal feel. Also no hard pedal feel issue was experienced during the tests at all.

I still have a hunch that is it the Brake booster that is to be blamed here. Mando is the manufacturer of the part of the ABS unit.
Thanks for sharing your experiment.

It is obvious that ABS system is fail safe i.e. in case of power cutoff (fuse blown), ABS hydraulic valve remain open to allow brake fluid to pass through albeit without ABS operation.

My point was ABS system malfunction i.e. hydraulic valve stuck close (because of unknown reason) for brief period instead of operating normally i.e. it open/close several times in a second to modulate pressure on the brake pads to prevent wheel lockup. When it is stuck close, brake fluid is trapped inside that makes brake hard to press and obviously there will be no braking.
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