Break suddenly applies hard when decelerating

[Pyrotik]

Hey guys, When rolling to a stop when I hit around like 15 mph the car breaks pretty hard. I don’t think that’s a warped rotor and it’s not downshifting.... any idea why that could be? In comfort mode. Catches me off guard every time especially passengers

 

[G70 Owner]

Hey guys, When rolling to a stop when I hit around like 15 mph the car breaks pretty hard. I don’t think that’s a warped rotor and it’s not downshifting.... any idea why that could be? In comfort mode. Catches me off guard every time especially passengers

are you sure its not the downshift from 3-2? You said its not downshifting, but thats just about the speed it would normally downshift. And I have this issue in my G70, can replicate by coasting down from 20-25mph

 

[Pyrotik]

are you sure its not the downshift from 3-2? You said its not downshifting, but thats just about the speed it would normally downshift. And I have this issue in my G70, can replicate by coasting down from 20-25mph

I just had my wife drive it to watch the RPM's and stuff and no it's definitely not that. It's not a warped rotor either, it's almost like the break suddenly gets easier and while your foot is applying the break it just activates more? Lol weird to describe. Could it be break fluid???

We tested it by breaking a bit harder too, like not trying to coast to a stop, and it stopped fine. It's only when slowly applying break and it'll just suddenly be like, WAPAM.

 

[MerlintheMad]

These electronically monitored brakes are of course "complexticated" by the interface. Maybe a "reflash" of the entire system would slap the brake sensors awake.

If it isn't mechanical, it has to be electronically induced sudden "grab".

(By the way, there is no such thing as "warped rotors"; only uneven rotor surface from pad deposits and even cementite, which attracts heavier pad deposits; but cementite is very rare.)

If you don't experience this at any other speed, I think that almost guarantees an electronic issue.

 

[Pyrotik]

These electronically monitored brakes are of course "complexticated" by the interface. Maybe a "reflash" of the entire system would slap the brake sensors awake.

If it isn't mechanical, it has to be electronically induced sudden "grab".

(By the way, there is no such thing as "warped rotors"; only uneven rotor surface from pad deposits and even cementite, which attracts heavier pad deposits; but cementite is very rare.)

If you don't experience this at any other speed, I think that almost guarantees an electronic issue.

I bet you it is electronic. I swear it didn't do it just now when I was driving so it like went away for a bit I guess? It did it back to back two drives in a row earlier, so weird. Brake fluid is fine, I dont see any deposits on rotors either.
Thanks buddy for the info

 

[sym]

Are you using adaptive cruise control or auto hold? My brakes are always more sensitive for a few moments after either of those turn off. It takes a bit for all of the pistons to retract which can make braking after using either of those features feel very "grabby".

Somewhat aside but I've also noticed what might be some electronic assistance when going in reverse down a steep incline.

 

[Pyrotik]

Are you using adaptive cruise control or auto hold? My brakes are always more sensitive for a few moments after either of those turn off. It takes a bit for all of the pistons to retract which can make braking after using either of those features feel very "grabby".

Somewhat aside but I've also noticed what might be some electronic assistance when going in reverse down a steep incline.

No, both of these were turned off. Just regular comfort mode driving. My wife kept fussing at me for breaking so hard and I was like I swear it's not me! So she drove it and we had the same issue. So weird.

I just bought the car last week with 15k miles on it so not sure if the previous owner did something weird to it.....

 

[SafetyPilotCal]

It's not the brakes, it's the transmission downshifting. If you let off the brakes it'll still happen on decel. Some cars are more aggressive about it, so I assume it's something quirky about how the ECU adapts shifts since people have reported the problem goes away after disconnecting the battery and resetting everything.

 

[Avon]

You are not alone. My wife yells at me all the time for same reason. I tell her it is just downshifting.

 

[oddball]

It's downshifting.

 

[Pyrotik]

In reference to everyone saying it's downshifting, it's interesting that I don't really see the tachometer moving at all but I believe it must be that or just something electronic based on what I'm hearing.

 

[G70 Owner]

In reference to everyone saying it's downshifting, it's interesting that I don't really see the tachometer moving at all but I believe it must be that or just something electronic based on what I'm hearing.

Easy to test. Does it happen when you’re coasting down with no braking at all

 

[Pyrotik]

Easy to test. Does it happen when you’re coasting down with no braking at all

Hmm I haven’t tried that yet actually...

 

[oddball]

It's downshifting.

The reason you don't see the revs change is why it feels so ... thrusty? Something about how Kia set up the shift timing, engine tune at low RPMs and torque converter stall that the engine really, really holds onto that low RPM, causing the torque converter to soak up the shift, thus the sudden slowdown.
Most engines will rev up pretty freely when downshifting while slowing down. This one, not so much. No idea why or how, but that's how it is.

 

[Pyrotik]

It's downshifting.

The reason you don't see the revs change is why it feels so ... thrusty? Something about how Kia set up the shift timing, engine tune at low RPMs and torque converter stall that the engine really, really holds onto that low RPM, causing the torque converter to soak up the shift, thus the sudden slowdown.
Most engines will rev up pretty freely when downshifting while slowing down. This one, not so much. No idea why or how, but that's how it is.

That's interesting and makes since as to why the car has power pretty much whenever you want it.
Is this like actual facts or just your guess on what's going on?

 

[87and66]

I agree with everyone saying its a downshift. When I'm leaving work, there is a stop sign half way up a hill and i usually coast to a stop. when it shifts from either 3rd to 2nd, or 2nd to 1st (not sure which), it feels like the brakes were applied. Its a rough downshift in certain situations and its amplified uphill.

 

[leecm]

This is one of the things that kept me from falling in love with my Stinger, unfortunately.

 

[G70 Owner]

This is one of the things that kept me from falling in love with my Stinger, unfortunately.

When I sell my G70, this will be the reason. Just a matter of timing now

 

[5tinger]

I vote for downshifting too.
Typical Kia trait wIth automatics is that they really aim to keep the torque converter locked as much as possible.
It's the same as the Forte 1.6 Tgdi

I prefer it this way to the slushy and massive amounts of coasting you get on Toyotas

 

[oddball]

That's interesting and makes since as to why the car has power pretty much whenever you want it.
Is this like actual facts or just your guess on what's going on?

Well, I build engines, I build transmissions, I build rear ends and complete suspensions rebuilds, I've done transmission swaps and custom supercharger installations, and, for kicks, I've done custom interior work and paint.... I'm pretty serious about this hobby.
So IMO it's a pretty damn good guess.
I've felt the same torque converter drag in different cars in different scenarios. Every automatic will do it to one extent or another. It's just pretty pronounced in the kia, especially in the lower gears while coasting. There's literally nothing else it could be unless the brakes are actually applying. And that's wildly unlikely.