Over sensitive ABS?

[KevH]

Hi all

I picked up a brand new ES F sport a few month ago and noticed something funny with it and was wondering if anyone else is seeing the same thing.

 

If I hit a pothole (pretty hard not too now a days!) whilst braking the ABS kicks in ! The potholes are not huge and I’m not braking hard and it’s happening quite a lot. It didn’t happen with my old mk3 GS or my wife’s CT so wanted to check before heading to the dealer.

 

Thanks

Kev

[peniole]

19 minutes ago, KevH said:

Hi all

I picked up a brand new ES F sport a few month ago and noticed something funny with it and was wondering if anyone else is seeing the same thing.

 

If I hit a pothole (pretty hard not too now a days!) whilst braking the ABS kicks in ! The potholes are not huge and I’m not braking hard and it’s happening quite a lot. It didn’t happen with my old mk3 GS or my wife’s CT so wanted to check before heading to the dealer.

 

Thanks

Kev

On a downhill? One particular pothole near my work, not too bad either, ABS will kick in. It's actually a feature of newer ABS systems to prevent the wheel slamming into the other edge of the pothole while locked, but rather by continuing to rotate. It does feel a bit more sensitive, but it is performing as designed.

[KevH]

11 minutes ago, peniole said:

On a downhill? One particular pothole near my work, not too bad either, ABS will kick in. It's actually a feature of newer ABS systems to prevent the wheel slamming into the other edge of the pothole while locked, but rather by continuing to rotate. It does feel a bit more sensitive, but it is performing as designed.

There are two that I cant avoid and trigger the ABS, one is on a flat T junction and the other is entering a roundabout on a slight downhill slope. 

Kev

[peniole]

Turned wheels (are you turning at the junction?) and downhill slopes increase ABS sensitivity.

[KevH]

24 minutes ago, peniole said:

Turned wheels (are you turning at the junction?) and downhill slopes increase ABS sensitivity.

yeah, im turning right from a 40 mph main road into a side street

[Mincey]

On 12/27/2021 at 7:14 PM, peniole said:

On a downhill? One particular pothole near my work, not too bad either, ABS will kick in. It's actually a feature of newer ABS systems to prevent the wheel slamming into the other edge of the pothole while locked, but rather by continuing to rotate. It does feel a bit more sensitive, but it is performing as designed.

Betsy did this to me earlier today on a downward slope towards a mini roundabout in Stamford. Luckily thanks to your post, I knew exactly what she was up to. I may write to South Kesteven District Council and tell them to get their roads in order.

[The_Doctor]

There is a hill near my home (approx 1:10 gradient) and my ES does this every time I pass over a particular feature in the road (a drain cover I believe) going downhill while lightly applying the brakes to hold speed back. I'm not an expert in vehicle dynamics but I am given to understand front wheel drive vehicles are more prone to this.

[peniole]

FWD RWD 4WD nowadays make no difference when it comes to braking and ABS, unless one has a foot on the gas and the brake at the same time or is applying heavy downshifting while braking. No modern cars have much engine braking nowadays anyway. Also, with EBD (electronic brake distribution) front and rear brake bias is a thing of the past and takes into account where downshifting (or in our case for hybrids regen) is helping and applies less brake force to that set of wheels maximizing and equalizing brake force. It's why newer cars don't dip their nose as much as older ones. Now really nose heavy cars may struggle more with that (think pickup with empty bed), EBD really goes hard on the rears for heavy braking to counter the weight and prevent dipping but struggles with the lack of weight on the rears, ABS will then have to kick in. Again most newer cars aim for as close to 50/50 front to back weight distribution as possible. ES300h is 59/41 GS300 54/46. Not much in it to make a discernible difference.