KIA Picanto

BritRael

My missus bought one of these a couple of months ago, and I got to drive it when home at Christmas. Lovely little motor.

However, in the snow (or even on a slightly rough road) there is a violent shudder from the front wheels. I've driven many types of car but not experienced this before so I advised her to contact the garage when it opened after the new year. She did, and they said it was caused by the ABS (which is fitted as standard).

Does this sound right? I though ABS was supposed to make for smoother breaking not the other way around? If correct, I think I'd prefer to just do cadence breaking myself

fb1969

Assuming this happened when your wife was braking it is almost certainly the ABS cutting in when the wheels locked up on the ice/snow.

Essentially ABS works by detecting wheels locking up and briefly taking the brakes off and then reapplying them, that is the juddering feeling that would also be felt through the pedal.

Contrary to popular belief, ABS does not make for shorter braking. What it does do is reduce the chance of a skid, by unlocking the wheels, and allow more steering control when doing so.

Having had this occur on a few cars in the extreme wet or slush I do know how unnerving it is when it happens.

pompeyrich

ABS should only really cut in as a last resort. Ice and snow will cause it to operate more frequently as the wheels will "lock up" at anything more than the slightest attempt to brake. The ABS system will try to stop the skid and replecate the old pedal pumping method and this transfers itself through the brake pedal, which can be quite un-nerving the 1st time you experience it. ABS should make the braking smoother, for the car, if not the driver!! I wouldn't have thought it should judder just on a bumpy road though and if that continues maybe another trip to the dealer will be needed.

Must speed up my typing. Oh well at least both answers are the same !!

BritRael

fb1969 wrote: »

Assuming this happened when your wife was braking it is almost certainly the ABS cutting in when the wheels locked up on the ice/snow.....

er..no
I drove it several times over a couple of weeks, and it happened continually, and was certainly not 'locking up'. I tried just touching the brakes very gently and it still juddered.

BritRael

pompeyrich wrote: »

...The ABS system will try to stop the skid and replecate the old pedal pumping method and this transfers itself through the brake pedal, which can be quite un-nerving the 1st time you experience it. ABS should make the braking smoother, for the car, if not the driver!! ...

Thats the funny thing; there is no skid. If I'd felt a skid I would have naturally cadence braked anyway. Strange
Also, it is transferring through the steering wheel not just the pedal. A very unusual feeling!

Hintza

Still sounds like ABS; but try asking someone else for an opinion (dealer?).

maisy_daisy

I have a Kia Picanto - have had it for 5 years and love it!, and it certainly sounds like my experience of the ABS - the first time it happened I pulled over as I was convinced something had fallen off the car

pompeyrich

BritRael wrote: »

Thats the funny thing; there is no skid. If I'd felt a skid I would have naturally cadence braked anyway. Strange
Also, it is transferring through the steering wheel not just the pedal. A very unusual feeling!

It may have cut in before you noticed the skid, not questioning your ability, obviously been driving a bit if you know cadence braking!! The vibration could well transfer to the steering as well as the brake pedal.

The freaky weather has caused lots of unusual behaviour in cars and people too, if it has settled down now I wouldn't worry but if it continues get back to the dealer and show them.

AdrianHi

BritRael wrote: »

Thats the funny thing; there is no skid. If I'd felt a skid I would have naturally cadence braked anyway. Strange
Also, it is transferring through the steering wheel not just the pedal. A very unusual feeling!

I'm not so sure this is ABS in action. ABS is quite a high frequency vibration only felt through the pedal and only when braking hard enough so that the wheels would lock up if it were not for ABS.

I suspect that the brakes have not been bedded in properly and you've ended up with some brake pad material adhered to the disks which then attracts more brake pad material building up a raised patch in the disk surface causing the judder. This is fairly common and often mistaken for warping of the brake disks (which virtually never happens - even in motor racing).
With new brakes, if you come off a motorway, brake hard to stop and then sit with your foot on the brake the heat concentrated in one spot can cause some of the brake pad material to stick. Once that happens over time more brake pad material builds up even under normal brakling and the judder starts.
More reading: http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

Or I could be completely wrong ?

Fife_Flyer

Not sure if it'll really help, but I've experienced this ABS 'judder' in snow and ice whilst driving two different vehicles, my own Honda CR-V and the company Renault Kangoo van. One of my colleagues reported the same thing happening with his Citroen Berlingo van too. Certainly disconcerting the first few times it happens, but I've been led to believe it's quite normal

BritRael

Although I mentioned that it happens during gentle braking, I forgot to mention a very important bit of info; gentle braking while in 1st or 2nd gear!
So I mean really crawling along, which is why I'm pretty sure the brakes are not locking. I could be wrong, but I thought ABS was supposed to come in during hard braking and perform an auto-cadence (on/off) braking pattern?