So today I was driving along and had to apply a little extra pressure to the stop pedal.

As I did, ABS kicked in, but the car DIDNT slow down at all, instead it felt as if the front brakes didnt bother holding and the rears did all the work.

Got to work and borrowed a Snap On Scan Tool from one of the repairers that was visiting and no codes came up regarding ABS or anything of the sort.

Any ideas..?

SuFz :ninja:

Brake line blockage or leak? Perhaps the master brake cylinder? It could also be the vacuum lines that go from the block to the intake as I believe they have something do to with brakes.

Or possibly brake pads or even disks.

If ABS kicks in, you're actually slowing down less because the wheels are locking - optimal braking is that fraction just prior to ABS.

I actually down shift like a mad man (tiptronic) whenever I have to brake suddenly. I find the car pulls up much quicker than with brakes alone but that's probably an AWD thing.

One day when a light changed right in front of me, I pulled up hard but there were some bumps just before the intersection. The abs kicked in and it only just pulled up in time. If it was a smooth road it would have pulled up a car length earlier.

Were you on a bumpy road?
Maybe you can wet down the road in front of your house (or find somewhere nice and quiet) and do some brake tests? (it's safer in the wet because you don't have to go as fast to lock up the wheels ). If you can get someone to watch from outside, they can check that the wheels are locking & releasing quickly.

One thing that might cause the ABS to cut in sooner is if there's any damage on the ABS trigger - a toothed wheel on the CV joint I think. Or maybe dirt/grease in there or it's sensor might cause a mis-read ?

I hope it's nothing - or maybe it's time for some ~320mm 4-pot kido brakes?

What are the tyres? Age, wear, etc

Maybe explain the actual situation with more detail because you indicate that a situation arose where you had to "had to apply a little extra pressure to the stop pedal" and then "As I did, ABS kicked in, but the car DIDNT slow down at all".
From this I would read that a dangerous situation occured which made you apply the brakes hard, but then the ABS kicked in yet the car didn't slow down.....what was the end result?....did you steer avoid the hazard or what?
Also the actual road conditions - wet/dry/loose gravel/speed.

Road - Tar
Conditions - Dry
Outcome - Swerved and Avoided (Including downshifting like a mad man)
Speed - 60-65km/h

I've had ABS kick in previously and its happen a few times.. I had a mate drive my car and I sat in the passengers seat, so he could see if he noticed it and he did too. Although, he said when he turned left slightly they would play up.

SuFz :ninja:

With brakes, take it to a specialist. Stopping is of primary concern. I should know! I have not stopped in time this week.

They will know where to look and what to look for.

Mike

With brakes, take it to a specialist. Stopping is of primary concern. I should know! I have not stopped in time this week.

They will know where to look and what to look for.

Mike

Have you had another misfortune Mike.

Check the abs sensors are clean and not cover in road grime and stuff.

Have you had another misfortune Mike.

Car is ok (bumper will need a bit of a respray for a 50c sized paint chip) but the other object faired much much worse. This is all I will say on the subject.

Anyway, the car has EBD as well. So maybe the system could have cocked up? But I doubt it as if there is less people in the car it makes the front brakes work harder. There could be somethign simple like a rock in the caliper preventing it from clamping down on the disc. Who knows. take it to a specialist.

Mike

I'll drop it off to the mechanic during the week..

I've pulled the calipers off and nothing I can see..

SuFz :ninja:

Are you sure that the brakes failed to work completely? I know that with our cars (Pajero and Magna), when the ABS does kicj in, it seems as if they brakes are failing. I am of the old school, and when a wheel locks up, you ease off the pedal a bit until the wheel starts rolling again. Nowadays, on the rare occasion that the ABS does kick in, I think it does so far too early. I have to accept that because the system thinks a wheel is about to lock up, and it probably is abot to, and I am sure that teh ABS is more sensitive than my bum and my brain. All I know is that when it happens, it scares hell out of me and the first thing I do when the pedal starts pulsating is to lift my foot off. That is the last thing I should do, but it is the way I was brought up.

With an ABS system you have a very sophisticated system watching each wheel and as soon as one starts to lock up, it eases the pressure on that wheel so it doesn't. It is like having 4 separate brake pedals controlling 4 separate wheels. I know that it is good, but I still say that I can do better IN MOST SITUATIONS. In most situations, I drive so that I don't need to brake that hard, but sometime you do get caught out, and that is exactly why I insisted on ABS for both our cars. FOrtunately, we rarely drive in close proximity to other cars, so we normally are not exposed to such situations.

Are you sure that the brakes failed to work completely? I know that with our cars (Pajero and Magna), when the ABS does kicj in, it seems as if they brakes are failing. I am of the old school, and when a wheel locks up, you ease off the pedal a bit until the wheel starts rolling again. Nowadays, on the rare occasion that the ABS does kick in, I think it does so far too early. I have to accept that because the system thinks a wheel is about to lock up, and it probably is abot to, and I am sure that teh ABS is more sensitive than my bum and my brain. All I know is that when it happens, it scares hell out of me and the first thing I do when the pedal starts pulsating is to lift my foot off. That is the last thing I should do, but it is the way I was brought up.

With an ABS system you have a very sophisticated system watching each wheel and as soon as one starts to lock up, it eases the pressure on that wheel so it doesn't. It is like having 4 separate brake pedals controlling 4 separate wheels. I know that it is good, but I still say that I can do better IN MOST SITUATIONS. In most situations, I drive so that I don't need to brake that hard, but sometime you do get caught out, and that is exactly why I insisted on ABS for both our cars. FOrtunately, we rarely drive in close proximity to other cars, so we normally are not exposed to such situations.

I've been driving ABS equipped cars for over 20 years and can honestly say that I've never had the ABS kick in. I also trust the ABS syatem to operate quicker and more efficiently than I will ever be able to do in my wildest dreams should a panic situation occur. I think it's called "defensive driving". Remember mechanical brakes?

ABS takes some learning if you never driven with it before. Lifting off when the ABS cuts in is a natural response to prevent wheel lock up on a non ABS car. My suggestion is - learn to trust the ABS. Find a nice quiet street, and practice. Slam the brakes on hard, and keep the foot down hard, and see what the car does. It's the only way.

@Hako: Never had ABS cut in? R U sure? Modern cars have ABS working so well that you don't notice. I thrashed a rental 380, couldn't make the tyres squeal with either full acceleration or mashing the brake pedal. I was stumped, until I worked out it has traction control and ABS. Not noticeable when the electronics cuts in under either acceleration or braking.

Ive had ABS in the last few 3rd Gens ive had.. Ive checked the front calipers and the pistons, pads and rotors are fine..

I might do fluids.. Hoping its not a major issue.

I knew it wasnt the fronts because the rear was locking up then releasing as per ABS.. Where as the front wasnt.. We did a few tests yesterday with my neighbour and we noticed the fronts seem to be giving up on braking when ABS kicks in.

SuFz

Again, what state are your tyres in? Are they ling longs or golden shower brand?

Again, what state are your tyres in? Are they ling longs or golden shower brand?

Kumho - 90% Tread

i am not quite sure on how the abs systems work on magnas, but when i go 4wding in the forester, i remove the abs fuse, because trying to stop in the mud or soft sand with abs is literally impossible as the brakes do nothing. perhaps a good way to eliminate mechanical error from electrical error would be to remove your abs fuse on a quiet dirt road, or paddock and see if all 4 wheels lock up. if they do, this will rule out mechanical issues and will tell you that it is in your abs system somewhere.

"I might do fluids.. Hoping its not a major issue."

Brake fluid is hyroscopic ie it absorbs water. In doing so, it lowers the boiling point of the fluid. When this happens, the fluid boils in the calipers and your foot goes to the floor. Scary stuff. This will only happen if you really flog the brakes. Further, if you have water in your brake fluid, you will get corrosion and that leads to leaks. If neither of these events are happening, I would tend to rule out brake fluid, although changing the fluid can do no harm, if done correctly.

"I might do fluids.. Hoping its not a major issue."

Brake fluid is hyroscopic ie it absorbs water. In doing so, it lowers the boiling point of the fluid. When this happens, the fluid boils in the calipers and your foot goes to the floor. Scary stuff. This will only happen if you really flog the brakes. Further, if you have water in your brake fluid, you will get corrosion and that leads to leaks. If neither of these events are happening, I would tend to rule out brake fluid, although changing the fluid can do no harm, if done correctly.

I get where you're coming from..

But this will tell me if i've got an issue with a fluid leak, bad fluid etc.

Cant hurt.. Done many a brake fluid flush.. so should be fine there.

SuFz :ninja:

Beltto probably has the answer - disconnect the ABS and see if you still get funny things happening. If you do, it is not the ABS system. If they go away, then check for stuff like gunked up sensor rings on the axles, damaged cabling (although that would probably bring up a fault code)...

Also check all brake line connections, especially where the brake lines enter the ABS unit near the bulkhead

Bled Brakes
Cleaned ABS sensors
Roughened up pads

Its fixed!!!

Supposedly dirty ABS sensors.. Did a quick few tests on a wet road and happy days!

SuFz

Again, what state are your tyres in? Are they ling longs or golden shower brand?

ROFL!

Happy to hear it's fixed - don't need anything going wrong at the wrong time.

I'll have to have a look at my ABS sensors when I'm putting the coilovers on :)
Where abouts is the sensor? back of the hub or something?
While I've got the front end apart, I'll probably spray the calipers too.
Hmm, maybe I should be typing most of this in my own members ride thread. Oh well :)

Supposedly dirty ABS sensors.. Did a quick few tests on a wet road and happy days!

Yeah dirty ABS sensors can cause all sorts of heartache. They can make the ABS module think the wheels are about to lock up when they're far from it. Basically the sensor mis-reads the wheel speed.

Its back!

I turned into a driveway this afternoon and as I applied the brakes, the car didnt stop and continued rolling with my foot WELL to the floor.

Luckily I wasnt going quick and parked the car.

I will be contacting the mechanic tomorrow, just to see if he can have a squizz at it.

SuFz :ninja:

Sounds like it is losing all brake pressure or something? so odd.

Sounds like it is losing all brake pressure or something? so odd.

I know.. Scared the bajeesus outta me.

She'll be getting dropped off to the mechanic tomorrow..

I'll ask him to do a flush and check the lines etc.

SuFz :ninja:

That is very bizarre. I suspect this must be a large singular point of failure to have no brakes AT ALL. Modern braking systems have built-in redundancy to ensure that braking power can be maintained front to rear even when there is a fault. Master cylinder and ABS unit would be good places to start

im no mechanic but it could be some air keeps getting into the system?

maybe a split brake like or something or rooted Pump

When you installed the coilovers you used a home made brake line mount bracket didn't you?
Positioning of the mount is critical, did you check the brake lines (and abs lines) aren't kinking throughout the turning range of the strut, especially at full lock?

Oooh good call.

When you installed the coilovers you used a home made brake line mount bracket didn't you?
Positioning of the mount is critical, did you check the brake lines (and abs lines) aren't kinking throughout the turning range of the strut, especially at full lock?

Yes..

Confirmed it upon full lock left n right..

This car was ok when I last drove it.

The brakes were a bit grabby (noise) when the car came to a stop, but that is probably a bedding issue. I did not drive it to require a large amount of braking force, but the car was fine.

Mike

Still could be dud ABS sensors then. Pull the ABS fuse and drive around for a bit. I believe it's fuse #13 - but check to see what else that fuse does just in case it deactivates something else.

Has the car been left parked for a prolonged (1 year or more) period of time? The brake booster can actually play up due to lack of use. OR you might have to bleed the brake lines. There might be an air-bubble in there from a loose bleed nipple.

No issues are coming..

I'll bleed the brakes a second time and use a slightly better brake fluid..

SuFz