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Old 16th February 2008, 01:53   #1
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Default Swift Vxi - ABS has started to kick in too early when braking

I own a mid 2006 model Swift Vxi ABS which has done around 17k kms. The car is doing pretty good. Recently however I feel that there is some problem with braking.
I feel that the ABS kicks in way earlier than it should leading to very bad braking distance. Even with not so hard brakes, ABS kicks in multiple times causing larger braking distance.
I gave the care to the Service Center. Bloddy ppl convinced me to do 4th service with brake cleaning etc costing 2.5 k but the problem was not solved. Gave the car again and yet the problem was not fixed. They say that the problem does not exist and its just in my head. However I have driven the car 17k kms, I can exactly feel the difference.
Anyone else has faced this problem and any idea what is causing the problem and how to get it fixed.
Thanks ppl,
Anand
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Old 16th February 2008, 11:09   #2
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ABS is not supposed to kick-in AT ALL under normal braking. The ABS will act (one can feel the shudder in the brake pedal when it does) when at least one wheel-speed sensor indicates zero-speed (wheel lock). This happens only when one brakes really hard - not expected in normal driving - and there is loss of friction with ground. There is a deceleration formula used there, which tracks the rate of change of wheel speed (one does not measure ground speed to know if there is wheel lock, i.e. wheel lock if ground speed > 0 AND wheel speed ~ 0).

Are you getting that shudder? If so, you can take a service person along for a drive and show him the conditions under which you get the shudder - irrefutable proof. There is not much that can go wrong with ABS sensors, and if any sensors IS bad, the ABS ECU will show error on the dash display.

If not, perhaps there is a mismatch between expectation and actual happening. This may be the reason why you are saying ABS is acting and the service guys are saying it is not. What exactly are you expecting / observing that makes you say that ABS is actually acting?

There are a couple of other braking-improvement functions in some ABS systems such as EBD (Elctronic Brake-force Distribution) and BFM (Brake Force Multiplication; increases brake force proportional to rate of pressing the brake pedal), which are not provided by the Swift ABS.
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Old 16th February 2008, 12:27   #3
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Thanks for the informative post.
I am a very enthusiastic driver. Whenever I see a patch of free road I speed up even if I need to brake later. I do try to avoid hard braking, but I do have a fair idea of the behavior of the car under braking.
The issue I am facing is that since past month or so, almost always when I end up pressing the brake more than half, I feel that while decelerating the the braking suddenly stops and the car seems like moving forward without deceleration (almost giving a feeling like it is skidding). This happens even if I am at a speed of 40 and applying brakes before a speed-breaker. However if I apply brakes gradually there are no issues.
The services guys say that it is normal, however I haven't seen this behavior in more than an year of driving.
Any ideas :(

Quote:
Originally Posted by DerAlte View Post
ABS is not supposed to kick-in AT ALL under normal braking. The ABS will act (one can feel the shudder in the brake pedal when it does) when at least one wheel-speed sensor indicates zero-speed (wheel lock). This happens only when one brakes really hard - not expected in normal driving - and there is loss of friction with ground. There is a deceleration formula used there, which tracks the rate of change of wheel speed (one does not measure ground speed to know if there is wheel lock, i.e. wheel lock if ground speed > 0 AND wheel speed ~ 0).

Are you getting that shudder? If so, you can take a service person along for a drive and show him the conditions under which you get the shudder - irrefutable proof. There is not much that can go wrong with ABS sensors, and if any sensors IS bad, the ABS ECU will show error on the dash display.

If not, perhaps there is a mismatch between expectation and actual happening. This may be the reason why you are saying ABS is acting and the service guys are saying it is not. What exactly are you expecting / observing that makes you say that ABS is actually acting?

There are a couple of other braking-improvement functions in some ABS systems such as EBD (Elctronic Brake-force Distribution) and BFM (Brake Force Multiplication; increases brake force proportional to rate of pressing the brake pedal), which are not provided by the Swift ABS.
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Old 17th February 2008, 01:59   #4
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Quote:
Originally Posted by talk2anand View Post
Thanks for the informative post.
I am a very enthusiastic driver. Whenever I see a patch of free road I speed up even if I need to brake later. I do try to avoid hard braking, but I do have a fair idea of the behavior of the car under braking.
The issue I am facing is that since past month or so, almost always when I end up pressing the brake more than half, I feel that while decelerating the the braking suddenly stops and the car seems like moving forward without deceleration (almost giving a feeling like it is skidding). This happens even if I am at a speed of 40 and applying brakes before a speed-breaker. However if I apply brakes gradually there are no issues.
The services guys say that it is normal, however I haven't seen this behavior in more than an year of driving.
Any ideas :(
Ah.
That does not sound like ABS to me.

Take your car to an open road, go at 30km/h. Make sure there is noone around / behind you, and press the brakes as HARD as you can. Dont be gentle. You will feel a vibrating in the brake pedal, accompanied by a metallic tak-tak-tak-tak noise that will probably scare you a little. That is ABS.

Is that anything like what you are experiencing and considering to be ABS?

How many kms has your car run ? What tyres do you have? How much tread to they have left on them?

Since its hard to get a guage of how hard you are breaking over an online discussion - Do you think that its possible that your car is actually skidding silently?

If not - then it could be some other braking related issue, but i dont think its the ABS.

cya
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Old 17th February 2008, 02:08   #5
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If you are running on stock 165/80/R14s, after the 17k kms, they could have lost the "grip" and hence the ABS is kicking in earlier. This is purely theory that could be true.
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Old 17th February 2008, 06:01   #6
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I feel that the car just skids forward. I mean I press the brakes, the cars decelerates at first and then suddently I feel that the brakes got released and the car seems like moving forward without deceleration.

My car has done 17k kms and I have 185/70 R14 Bridgestone GIII Tyres (upgraded right after purchase). The front two tyres are brand new tyres (older ones got couple of punctures, to bought a new tyres on one side and replaced with stepni on the other last month). So two brand new tyres on front and two 17k run tyres on the back.

I would love it if some ppl in bombay, esp ppl who own ABS (swift) car take a test drive and help diagnose the problem.

Thanks
Anand

Quote:
Originally Posted by Rehaan View Post
Ah.
That does not sound like ABS to me.

Take your car to an open road, go at 30km/h. Make sure there is noone around / behind you, and press the brakes as HARD as you can. Dont be gentle. You will feel a vibrating in the brake pedal, accompanied by a metallic tak-tak-tak-tak noise that will probably scare you a little. That is ABS.

Is that anything like what you are experiencing and considering to be ABS?

How many kms has your car run ? What tyres do you have? How much tread to they have left on them?

Since its hard to get a guage of how hard you are breaking over an online discussion - Do you think that its possible that your car is actually skidding silently?

If not - then it could be some other braking related issue, but i dont think its the ABS.

cya
R
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Old 17th February 2008, 11:29   #7
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i am sure its not the ABS.it may be some thing related to the booster.you can have checked at any of the dealer service centres and please dont say to them that-i feel some thing iis wrong with the abs.let them decide on whats the problem and just inform them what is happening while you are braking.
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Old 17th February 2008, 13:10   #8
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This is exactly what I did. Problem is that they are maintaining that there is not problem with braking at all :(

Quote:
Originally Posted by ram_hyundai View Post
i am sure its not the ABS.it may be some thing related to the booster.you can have checked at any of the dealer service centres and please dont say to them that-i feel some thing iis wrong with the abs.let them decide on whats the problem and just inform them what is happening while you are braking.
ram
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Old 17th February 2008, 18:39   #9
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@talk2anand, from your description it looks like you are experiencing brake fading, i.e. your pads need replacing. ABS is not the culprit - you cannot miss the loud drrrrrrr or trrrrrrrr coming through the pedal to your foot, when it does act. As Rehaan said, it can be scary to the uninitiated.

When braking hard, other than an initial jerk, the disk / drum is not being retarded enough by the pads, giving you the feeling of slip. But when gradually braking, you are retarding the car gradually. The difference is that you DID NOT expect the car to slow down fast, even though the same slip is happening in gradual braking also.

To prove it to yourself, try double-braking: in the same condition as earlier, try pressing the brake pedal twice or thrice rapidly, instead of one hard push. Kind of press-release-press, chak-chak, and kick hard. This is likely to lock your wheels and make the ABS act. Try this, as Rehaan said, at 30kmph, and do it when driving in a straight line - don't turn the wheel.

Last edited by DerAlte : 17th February 2008 at 18:40.
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Old 17th February 2008, 23:18   #10
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Quote:
Originally Posted by talk2anand View Post
I feel that the car just skids forward. I mean I press the brakes, the cars decelerates at first and then suddently I feel that the brakes got released and the car seems like moving forward without deceleration.

My car has done 17k kms and I have 185/70 R14 Bridgestone GIII Tyres (upgraded right after purchase). The front two tyres are brand new tyres (older ones got couple of punctures, to bought a new tyres on one side and replaced with stepni on the other last month). So two brand new tyres on front and two 17k run tyres on the back.

I would love it if some ppl in bombay, esp ppl who own ABS (swift) car take a test drive and help diagnose the problem.

Thanks
Anand


hay dude i think that you you break is not making proper pressure thats why you are having the problem there are some problems with abs cars like these it can be taken care off dont worry

Last edited by Rehaan : 18th February 2008 at 00:32. Reason: thts = thats. Please type in full words as per Team-BHP rules.
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Old 18th February 2008, 00:38   #11
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Some good points here...

I guess the first thing to do is to indeed confirm there is a problem.

Quote:
Originally Posted by talk2anand View Post
I would love it if some ppl in bombay, esp ppl who own ABS (swift) car take a test drive and help diagnose the problem.
Where in Mumbai do you live?

If you have time to spare, PM Dippy or any of the other TBHP guys who hang out regularly on weekend-nights and see if you can meet up and get one of them to check out what it feels like to them.

If there is something noticably wrong, try again at the service station (talk to a different service rep / mechanic).

cya
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Old 18th February 2008, 01:44   #12
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Yes! Get in touch with some Mumbai team-Bhpians who hang out together in weekends.
They'll make sure what is the problem with your car's brakes. In return, you can pay the bill!

If possible, get the car test driven by some good mechanic and You'll be able to point it out when the problem occurs.
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Old 18th February 2008, 13:36   #13
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The service station guys did a full service of the brakes and opened it up and oiled everything. They claim that brake pads etc have no issues at all.

I will try what you have mentioned over here. I think one of the best things would be to attend of the meets in mumbai over the weekend. Will PM Dippy

Thanks
Anand

Quote:
Originally Posted by DerAlte View Post
@talk2anand, from your description it looks like you are experiencing brake fading, i.e. your pads need replacing. ABS is not the culprit - you cannot miss the loud drrrrrrr or trrrrrrrr coming through the pedal to your foot, when it does act. As Rehaan said, it can be scary to the uninitiated.

When braking hard, other than an initial jerk, the disk / drum is not being retarded enough by the pads, giving you the feeling of slip. But when gradually braking, you are retarding the car gradually. The difference is that you DID NOT expect the car to slow down fast, even though the same slip is happening in gradual braking also.

To prove it to yourself, try double-braking: in the same condition as earlier, try pressing the brake pedal twice or thrice rapidly, instead of one hard push. Kind of press-release-press, chak-chak, and kick hard. This is likely to lock your wheels and make the ABS act. Try this, as Rehaan said, at 30kmph, and do it when driving in a straight line - don't turn the wheel.
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Old 18th February 2008, 22:42   #14
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i am not sure if this could be of help:

Try and locate the fuse for ABS, Remove it and see if the braking response is different. If there is a problem with the ABS, you should get a better response with fuse removed.

From the discussion,seems any problem with the ABS has been ruled out. But you can try this out to single out the cause of the problem.

PS: If you are not sure of the fuse thing, PLEASE dont try it yourself. Get the help of your friendly neighbourhood MASS!!!
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Old 19th February 2008, 03:22   #15
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Quote:
Originally Posted by talk2anand View Post
The service station guys did a full service of the brakes and opened it up and oiled everything. They claim that brake pads etc have no issues at all.

I will try what you have mentioned over here. I think one of the best things would be to attend of the meets in mumbai over the weekend. Will PM Dippy

Thanks
Anand
I too feel its a Brake Fade issue as mentioned by DerAlte

What did the service guys lubricate? How did they know that the pads in question that look fine has not suffered from brake fade. Usually caused by rapid heat build up in the pads, for which most cars meant for repeated heavy braking come with ventilated rotors. Again as DerAlte mentioned, the intermittent braking might be able to generate better retardation.
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