ABS kicking in alot 172

[woodleadam]

Last few days noticed that my abs seems to be kicking in quite a bit. When i brake and go over bumps i can feel the abs through the brake pedal. Dont think it ever kicked in as much as it is recently. What could it be.

Would ABS kick in more if brake pads needed changing.

Does it sound like a fault with the abs or that a sensor needs changing.

Need help and advice please people, milage 12K.

 

[telford_mike]

Mine does that at the moment, and it does seem to get worse as the pads wear. No idea why though.

Of course it could be that the roads are getting worse and your brakes are fine

 

[woodleadam]

Am just finding that if i brake fairly hard i can feel abs is kicking in abit. Got paranoia that the abs is kicking cos the front drivers wheel is skidding abit. Maybe its just my imagination.

How long do the front pads normally last anyway, roughly.

 

[telford_mike]

The standard pads last a long time - I think I got 18,000 out of mine, including a lot of trackdays. Changed them for Tar-ox fast road pads which are a lot better on the track (dont fade).

 

[woodleadam]

cheers for help mate

 

[Pete]

Does it pull to either side under braking? Could be tire wear!

 

[woodleadam]

nah not tire wear. Have fairly new rainsports on there. Took hands off wheel at 40 and braked hard to see if she stayed straight, and she did stay fairly straight.

 

[Lee]

Ive noticed mine has started to snatch a little recently. I suspect the pads will want changing at the next service. Its currently on 19k so not long to go.

 

[Scribbler]

Has anyone had the feeling that the brake pedal disapears as you press it as if all resistance goes until near the end of the travel scared me to death the other day i thought the pedal had dropped away or something. Think this may be the abs .

 

[Smokey]

ABS is anoying me too but know it will save my skin a few times so im grateful for it lol

 

[entjm]

on mine it seems a bit sensitive, almost as if it wouldnt have skidded but the abs cut in pre-emptively.

mine did get a bit better after having the pads changed, though i dont see a reason why that should be the case... surely new pads, bigger braking force, morelikely to lock up so more ABS...?

also on ice... put the brakes on and just carried on rolling forwards... scary sh*t. abs just let it roll!



then my car is only a humble 1.4 so maybe the ABS is not as good as on a 172?

 

[Rory]

I find that aswell, the combination of ice abs and braking, I was left with 3 wheels and a bill for £4,300 (insurance covered thanks f*ck!!)with my 1.2 16v!!

The car has only done 6000 miles so I doubt it would be the brake pads wearing!

 

[JAY172]

the pedal will feel to drop up and down due to the fluid pressure being released and then the pump refilling the system.

1,brakes pressed,wheels skid

2,inlet valve on the braking circuit with the skidding wheel closes,computer rechecks if the wheel is still skidding-if yes then...

3,outlet valve opens on the braking circuit on the wheel that is skidding to release pressure and so reduce braking to prevent the wheel skidding. outlet valve closes when skidding is no longer detected.(when this valve opens this is the point where the pedal feels to drop)

4,the fluid that was released down the outlet valve goes into a accumalator chamber. when the outlet valve closes the pump replenishes the lost fluid from the inlet side by sucking the fluid out of the accumalator and back into the inlet side of the braking circuit.(this is where the pedal feels like it kicks back up again as the pump forces the fluid back into the inlet side)

5,inlet valve re-opens reapplying the brake and then it goes back to step 1.

the abs computer rechecks wheels speeds and so skidding after each point. if your not braking that hard then sometimes step 2 will prevent the skid and no other action is nes.

each wheel/caliper has its own set of inlet/return valves so each wheel can be operated seperatly as reqd. worn pads could create more abs operation if one side is more efficient than the other so one wheel potentially skids first. abs is useless on ice as it is trying to prevent the wheels skidding when its impossible for it to do so due to the wheels having virtually no grip. in good conditions though abs will slow a car a lot quicker than conventional brakes especially as new abs systems have an emergancy braking mode as well.

 

[telford_mike]

Remember, ABS is there to allow you to steer - it doesnt guarantee to stop you!

 

[JAY172]

well nothing can totally compensate for driver error or sudden eventualities on the road. yes the main part of abs is to stop wheel skid which will allow you to steer/make evassive manuvoures for example.

 

[entjm]

what about tyres too actually...

if theyre not gripping then more likely for abs to intervene. thinking about it that may be my problem.

 

[Loki]

erm seems to be a bit comon mine does it aswell the cars on 18000 only had it 3 wks and done 2000 already lol but yea i think it must be a clio thing ill ask fordy if his had done it yet bein as he lives 2mins away from me his is on 14000

 

[JAY172]

Quote: Originally posted by entjm on 24 April 2004


what about tyres too actually...

if theyre not gripping then more likely for abs to intervene. thinking about it that may be my problem.

are all the tyres the same brand and near enough have the same amount of tread left.

 

[entjm]

different brands i think, and almost needing to be changed, probably about 2-3 mm tread left. MOT next month so will get new ones for then

 

[JAY172]

different brands of tyres could have different levels of grip so in some situations may possibly cause the operation of abs. even so though this isnt a fault with the abs as all its doing is detecting skidding and rectifying it.