Chachi

Bit of a weird one this, I've noticed a few time now that my ABS cuts in when really it shouldn't.

First time it happened was in a carpark and slowing gently for a speed hump, abs seemed to cut in and I effectivley had no brakes. Bit Odd I thought. but carried on as everything returned to normal.

Second time was approaching a roundabout at about 55mph, another car enetered the roundabout and caused me to brake slightly heavier than I was already (just cruising remember ... not pushing it) and again ABS cuts in and braking is severly reduced !!! kind of graunching noise (if that makes sense). Was lucky I wasn't going a bit faster as I think I might have modified my bonnet.

I've got EBC drilled/grooved discs up front with Green Stuff Pads, Rears are standard.

I have noticed that I have odd wear on the rear, not all the corrosion gets cleaned when braking .... grooves appear. I'm planning to replace the rear pads and the discs don't feel scored. Could a problem with the rear calipers cause the ABS to falsely activate ???

Any ideas ??

Chachi

Anybody ????

Heeeelllllpppppp !

Miniman

iTrader: (2)

Noticed this on my MY02 and plus I've noticed a few other posts on here saying the same thing.

Usually I've found that the car does it when I've hit a drain cover or slight dip/bump in the road. ABS cuts in and you go skittering over the drain cover.

I haven't worked out yet if this is a good thing or not, I mean I could feel the car wasn't going to skid over the drain, but the ABS thought it was and theoritically once over drain, it will have good tarmac and stop the car ok.

But its very disconcerting.

warrenm2

either that or your ABS sensor has been damaged - havent had the disks or calipers off recently have you?

Chachi

Not recently, Probably a good 18 months since I changed them. Still plenty of meat on the pads (Don't do too many miles these days)

Where abouts is the sensor?

John 37

This is quite a well known characteristic of 4x4 systems.

When you are braking over a wet manhole cover or, worse, a pot hole, the wheel momentarily looses grip. The ABS senses the excesive retardation as being above it's trigger level and removes the braking force from that wheel. It then slowly re-applies the brakes learning the new level of grip as it does. This can result in increased stopping distances.
The biggest problem, as I understand it, is the lack of a free reference wheel that allows the system to know the true road speed. A normal car can tell the road speed from an undriven wheel fairly quickly. Those wheels have little rotating mass and no drive so regain road speed rapidly. A 4x4 wheel has a lot of stuff attached to it making it react slower. The car can also have all wheels spinning. When this happens, and the power is removed, the ABS sees this as a sudden deceleration and removes the brakes. If it were to wait until the wheels had got back up to the previous speed before re-establishing the brakes, well you can imaging the results. As a result, when the ABS triggers, it resets the brakes in a series of steps. That process can take about 1 second, a long time in our case.
I used to drive a road with a cattle grid on a braking point. I always had to be ready for this and brake earlier or jump off the brakes over the cattle grid. Pot holes are even worse.
ABS is not always the Gods gift folks think it is. It's good on a uniform surface but real-world incedents can confuse it.
John

New_scooby_04

iTrader: (4)

Seems a common misconception that ABS will always improve retardation, but what it does do is ensures that you retain the ability to steer the car around the obstacle (if possible) should you not be able to stop in time. I wonder how many people just slam on the brakes and don't steer at all in an emergency though? Amazing what you can forget to do when under pressure.

NS04

ALi-B

iTrader: (1)

My mates MY95 scooby had this problem. The thing was fecking lethal. It had a similar brake setup to yours too (EBC discs and pads)

Everybody (including me, til I tried it) dismissed it as "thats what ABS does mate"

It turned out the front brakes pads were glazed and therefore doing practically nothing - especially when they were cold/cool (cold as in drive at 40mph+ for 10+mins) the rears were biting better than the fronts (rear discs looked manky...basically because they were overheating). The ABS on this particular scoob went into a hissy fit as it couldn't compensate enough for the rears braking more than the front = in a nutshell no brakes when you needed them.

I suggest you pull the ABS fuse one day and do some brake tests on an empty straight flat road on a wet day and see which wheels lock up first. It should always be the front, and usually the front left grabs first (more water/crap on at the side of the road than the middle). If your rears are grabbing first (and you'll know if they do ) then you have a problem...but be careful, you only need to do this test at 30mph

Once your confident that all is ok with the physical braking system can you turn your attention to the ABS system.