[Venkatesh.H]

I am a Seltos GTX plus diesel AT owner and clocked around 1400KMS.

Following are my observation:
- Never faced any braking issues.
- Last few days I am testing brakes at different speed and inclined surfaces and working perfectly alight.
- Brakes working fine in diesel engine probably due to presence of separate pump and same is missing in petrol engines as explained by kia Service engineers in FB post.
- Surprised to see Kia going on shortcut by not providing pump for petrol engines.
- It is understood as explained by Jeroen sir that by disconnecting vacuum line to booster will replicate wooden feeling of brake.
- Kia charges 15 - 20L for Seltos and why can't they provide 2nd booster fitted parallel with 1st booster. So there will be more redundancy. Even if one booster fails there won't be complete failure of brakes or wooden feeling of brake.
- Brakes are min basic in every car and car manufacturers should pay close attention in designing fail safe technique in braking systems.
- How Tata, Mahindra and others are providing correct braking systems or too much electronics in latest cars is sabotaging brakes ??

[vsrivatsa]

Originally Posted by a4anurag

It is the similar 'feeling of the pedal' that I have felt whenever in the past the pedal went hard during braking.

Originally Posted by Jeroen

Again, if the engine (petrol) does not produce enough vacuum with the engine idling, or any RPM for that matter, I think that is an incorrect design.

I think it is pretty normal response to a situation where your brakes don’t feel ’normal’, people tend to pump then. So again, a design issue.

Happy to see that this issue seems to be narrowing down. So, in terms of validating my understanding and to ensure everyone also has a summary would it be correct to say that:

1. Can we conclude that as stated by Kia Service Engineer, this issue affects Petrol Based Kia Seltos Cars only? If this is true, then we need to change the title of this thread to reflect "Petrol Only" ensuring that the people planning to buy or owning Diesels do not get worried.

2. This also means there is every potential for the same issue to be present on 2020 Creta, Sonet and Venue Petrol cars as well.

3. The last point which possibly needs further research would be if the same issue exists with Automatics or do they have some RPM setting which ensures that the minimum RPM is maintained hence preventing this issue from occurring. And this behavior maybe different for IVT and DCT as well possibly.

[Motard_Blr]

Originally Posted by vsrivatsa

...

1. Can we conclude that as stated by Kia Service Engineer, this issue affects Petrol Based Kia Seltos Cars only? If this is true, then we need to change the title of this thread to reflect "Petrol Only" ensuring that the people planning to buy or owning Diesels do not get worried.

...

Both petrol and diesel cars have vacuum-operated brake boosters. The way vacuum is produced is different: petrol engines create vacuum between the throttle and the cylinder, whereas diesel engines use an engine-driven vacuum pump. In both cases the engine needs to be running to get brake assistance.

This means that both diesel and petrol cars may be equally affected.

The easiest way to demonstrate the vacuum booster effect is to drive to a sloping road, press and hold down the brake and stop the engine. With the clutch pedal pressed, the brake is released and the car should start moving down the slope. As the brakes are pumped when the car is moving down the slope, each subsequent application should become harder until a maximum is reached after about 3 applications.

Each time the brake is applied some vacuum is used up. The reserve quantity is generally good for only about 2 or 3 brake applications.

[Venkatesh.H]

Originally Posted by vsrivatsa

Happy to see that this issue seems to be narrowing down.
3. The last point which possibly needs further research would be if the same issue exists with Automatics or do they have some RPM setting which ensures that the minimum RPM is maintained hence preventing this issue from occurring. And this behavior maybe different for IVT and DCT as well possibly.

Hello Srivatsa,

Following observed on my seltos diesel AT box:

- In torque converter AUTO gear box, Engine RPM is constantly maintained around 1800.

- Hard acceleration momentarily crosses 2000 RPM and again RPM drops below 2000 and maintain at 1800 RPM.

- This is also one of the reason why AUTO boxes have good breaking capability.

- Yet to experience breaking and RPM details on seltos manual gear box.

Thanks

[deepakdograbhp]

Hey guys, I'm expecting delivery of my Creta 2020 Petrol IVT in few days and thus was following this thread. I'm not acquainted with mechanical/technical know-how of brakes. So please pardon me if my way-around sounds too naive.

Some posts mentioned that this problem may arise due to engine running at very low RPM. If I choose to drive in Sports mode which tries to keep engine running at higher RPM, will it help in avoiding such instances? Also, will it cut down engine's life?

If engine life is not impacted, I suppose a trade-off between safety and mileage is pretty easy to decide.

Some posts also mentioned that at lower RPM, it may be better idea to press clutch first before brake. How about IVT variant??

[a4anurag]

Originally Posted by vsrivatsa

1. Can we conclude that as stated by Kia Service Engineer, this issue affects Petrol Based Kia Seltos Cars only?

A couple of Creta 1.6L CRDi owners including me are facing the issue of hard pedal sometimes. The issue could be more in number owners of petrol-powered ones than diesel IMHO.

Originally Posted by vsrivatsa

2. This also means there are every potential for the same issue to be present on 2020 Creta, Sonet and Venue Petrol cars as well.

I have ended the 2020 Diesel Creta for a fair bit of distance and found the braking much better than my model. Could be because it has discs all-round.

Originally Posted by vsrivatsa

3. The last point which possibly needs further research would be if the same issue exists with Automatics or do they have some RPM setting which ensures that the minimum RPM is maintained hence preventing this issue from occurring. And this behavior may be different for IVT and DCT as well possibly.

I have read reports of Seltos IVT owners who have reported the hard pedal issue. I was puzzled reading it as RPM would hardly reach stalling stage.

[amol4184]

I don't have a horse in this race but a very fascinating and frustrating read, this thread. Fabulous work done by various members putting out smallest details.
What truly baffles me is that braking issues on Hyundai (and now Kia) are known for years and are still continuing as seen in this thread but they have refused to acknowledge.

I truly wish with enough outcry and noise generated over such forums might ring some bells in manufacturers' ears - here's to hoping.

Forum members with their absolutely limited resources are doing RCA and have almost zeroed down the cause. How amazing is that? While Hyundai with their billions and unlimited resources has pretty much shown a certain finger to (Indian) customers.
I believe "sab chalta hai" attitude that we see everywhere in the society has been very well adopted by the companies too. How do they get away with it? Lack of rules cannot be the sole factor here.

[Jeroen]

Originally Posted by amol4184

Forum members with their absolutely limited resources are doing RCA and have almost zeroed down the cause. .

Sorry, we did not do a RCA, neither have we even begin to zero in on the real cause. All we have done is to verify that with no vacuum the force to operate the brakes is substantially higher than with the vacuum on and thus booster operating.

Whether the vacuum was causing the problem and if so, what caused the vacuum to be affected, remains on both counts to be seen.

I still see some remark from members who appear to believe that petrol engines should also be equipped with vacuum pumps, like diesels. As I explained earlier, diesels do not create vacuum on the inlet manifold, therefor there is a need to equip them with a vacuum pump. The vacuum created on petrol engine is perfectly capable of producing the vacuum needed for the brake booster and even other ancillary equipement. For instance on my Mercedes the same engine vacuum also powers the central locking system, the adjustable head lights and in case of an automatic, also the shifting on the auto box.

When properly designed and implemented, manifold vacuum is a great resource. Dead cheap, super simple, extremely reliable and virtually maintenance free. On the other hand, a separate vacuum pump takes power from your engine, cost a lot, wears and will need maintenance over time.

Both work extremely well, when properly designed for its intended purpose.
There is absolutely no need for a seperate vacuum pump on a petrol engine. There are literally hundreds of millions of cars out there with perfectly fine vacuum, drawn from the engine manifold. Guess what, it has been implemented like this for many, many decades. And it is such a great design there has never been a need to change it!

Simply put; the petrol engine manifold vacuum is vastly superior to a vacuum produced by a separate vacuum pump.

Jeroen

[srini1785]

Originally Posted by Jeroen

Simply put; the petrol engine manifold vacuum is vastly superior to a vacuum produced by a separate vacuum pump.

Vacuum produced by a manifold is by a Venturi and is high vacuum in terms of percentage but low flow volumes.

Vacuum produced by a pump is by a rotating vane and is low vacuum in terms of percentage but high flow volumes.

So it depends on what application it is being used for.

[Jeroen]

Originally Posted by srini1785

Vacuum produced by a manifold is by a Venturi and is high vacuum in terms of percentage but low flow volumes.

Vacuum produced by a pump is by a rotating vane and is low vacuum in terms of percentage but high flow volumes.

So it depends on what application it is used for.

The manifold does not necessarily rely on a real venturi as such. The working of a petrol engine leads to a creation of the vacuum in the manifold. It is essentially the down movement of the respective piston and a restricted inlet (usually throttle plate or similar) that creates the vacuum.

On a carburator there is a real venturi. Often used to power for instance vacuum advance on the ignition. (as for instance on my Mercedes!)

Vacuum pumps can be found with many different designs, not necessarily always vanes. I am looking at a (broken) piston rod of a (dentist) vacuum pump sitting here on my desk right now!

Obviously, the application matters on what is the most optimal type design and in that sense my earlier remarks pertains to the typical use of vacuum on cars.

Jeroen

[Peak2]

Originally Posted by dksv

I have changed my driving habits since that incident and the problem has never recurred. So I can say I “feel” safer. I don’t know what else I can do.

This is how I changed:
1. Be pro-active rather than being reactive, in terms of braking
2. No more clutch first before normal braking
3. Clutch first before panic braking only
4. Never pump brakes, not even twice in quick succession
5. Maintain slightly higher RPMs in low speeds
6. Be ready subconsciously to apply hand brake if all else fails

Thanks for sharing this. Just to understand it well, typically in order to brake in a manual transmission car- we press Clutch and shift to a lower gear while simultaneously pressing the brake pedal to bring the car to a halt. Are you suggesting, we should not do that and instead just press the brake pedal?

Originally Posted by ridehard

I had pretty much decided Seltos to be my next car, to get in the next year or 2. But now, I have to sadly look at something else till there is a concrete solution to this issue.

To be fair, all OEMs have been equally blamed in this thread- whether its MS, Toyota, Honda, Hyundai or anyone else

[dksv]

Originally Posted by Peak2

Thanks for sharing this. Just to understand it well, typically in order to brake in a manual transmission car- we press Clutch and shift to a lower gear while simultaneously pressing the brake pedal to bring the car to a halt. Are you suggesting, we should not do that and instead just press the brake pedal?

Whatever works best for you. The idea here is to NOT press the brake pedal more times than necessary, leading to pumping action. As I found out, even two successive presses in quick succession had made my pedal like 3x times harder.

I had this habit of hitting clutch first and then brake, even for slowing down. This was ingrained in my learning. After the incident and the response from the ASC, with some retrospective thinking I gathered I was using the brake pedal more than necessary when I operated the clutch, sometimes even “pumped”, if you may call it so. It’s now become second nature to press brake first and modulate the force before my left foot wants to reach the clutch. I am surely hitting it lesser “number of times”. Seems to be working for me as the problem never resurfaced. Of course, that and courtesy the slightly higher RPMs I guess.

This is a fascinating thread. Scary, but fascinating to read all the brilliant views, investigations and autopsy of the issue.

[locusjag]

Gentlemen, let's say I were in a petrol Kia Seltos AT and I've had the brake pedal go hard on me. If I were at 60 Kmph and looking to save a puppy on the road a few metres away, will the handbrake save me or will I simply fishtail and broad-side the said pup? I guess my question is - will cars fishtail everytime the handbrake is used?

[AirbusCapt]

Originally Posted by locusjag

Gentlemen, let's say I were in a petrol Kia Seltos AT and I've had the brake pedal go hard on me. If I were at 60 Kmph and looking to save a puppy on the road a few metres away, will the handbrake save me or will I simply fishtail and broad-side the said pup? I guess my question is - will cars fishtail everytime the handbrake is used?

To answer your question, a handbrake can never stop a moving car , forget stopping in a few meters. The handbrake is designed to hold a stationary car, not to stop it.
Besides in a abs/ebd equipped car, the handbrake may be electronically modulated to not offer resistance on a moving vehicle also.

[Sutripta]

The petrols - any of these turbo petrols? What is the vacuum source for these turbo petrols?

Sutripta