Strange ABS behaviour in Fiat Punto

DerAlte · 30th September 2009, 09:47

Quote:

Originally Posted by Crazy_Eddy

... but the interval wasn't that far apart, say about ~5 times a second? ...

That is just about the frequency of grab/release that ABS modulates - can be faster depending on conditions. The brake pedal will softly pulse at the same frequency.

Quote:

Originally Posted by coolboy007

... Tech2 scanner ... I think i read something as Bosch ABS there.

Could be, but it is not certain the way you describe it. The scanner has pre-configured profiles corresponding to different manufacturers' modules to take away the guesswork for the service guy. There is no plug&play in that world! The only way to be sure is either to ask a service manager, or look for the module under the dash.

.anshuman · 30th September 2009, 10:10

Quote:

Originally Posted by abhibh

Does Punto comes with ABS light on the speedo console ? If yes then i guess ABS light should turn on during hard breaking but i am not sure.

Unlike the Traction Control or ESP, ABS light is not meant to turn on when ABS cuts in, It comes on only when the system is at fault. Its applicable for all cars from Marutis to beemers.

Quote:

Originally Posted by sukrit7

@Mclaren- well that certainly doesn't happen?
hmm, linea and punto owners, please clarify?

Best way to check whether ABS is working is by taking the car off the road or a stretch where there is a lot of gravel and try to brake hard (not at insane speeds).

With most cars there is a brief skidding sound before each wheel is released by the system, this happens several times from different tires. More clearly noticable in cars where ABS is tuned to cuts in later.

sudharma · 30th September 2009, 10:42

Quote:

Originally Posted by .anshuman

.

An Indian manufacturer had mechanical ABS installed in their vehicles. Know which?

DerAlte · 30th September 2009, 12:39

Quote:

Originally Posted by sudharma

An Indian manufacturer had mechanical ABS installed in their vehicles. Know which?

Really? Interesting. Waiting for pointers!

.anshuman · 30th September 2009, 12:55

Quote:

Originally Posted by sudharma

An Indian manufacturer had mechanical ABS installed in their vehicles. Know which?

Are you talking about the first gen Scorpio?

Mahindra tried some sort of modifications to braking system to prevent locking of wheels at sudden braking but the results were disastrous with poor braking performance

sudharma · 3rd October 2009, 06:54

Quote:

Originally Posted by .anshuman

Are you talking about the first gen Scorpio?

Mahindra tried some sort of modifications to braking system to prevent locking of wheels at sudden braking but the results were disastrous with poor braking performance

No. Its the Tata Sierra.
The system employed is a steel ball in a chamber set at an angle and connected to the braking system.
Under hard braking the inertia moves the ball forward and this opens a valve in the brake system releasing the pressure in the brake cylinders. Then it sets back. This works the brakes like the electronic ABS. Under hard braking one can feel the vibrations on the brake pedel as well as the vehicle. It was effictive and better than not having one at all. Details are given in the Owner's manual of the Tata Sierra.
I am not sure about Tatamobile and the Sumo having this feature. But logic says they also should have the Mechanical ABS system as they all share the same chassis and mechanics.
Can any one confirm?.

nitrous · 3rd October 2009, 15:19

Quote:

Originally Posted by sudharma

I am not sure about Tatamobile and the Sumo having this feature. But logic says they also should have the Mechanical ABS system as they all share the same chassis and mechanics.

In my 12 years/200,000 kms of the Sumo ownership, I haven't seen anything of this sort. And I stopped counting the number of times I've locked the tyres while braking. Kind of trained me into loading an "ABS" into my brain.

sukrit7 · 3rd October 2009, 18:02

I'm sorry for disappearing, health prevented me from replying.
Firstly a few answers, I run my car on 32psi, stock tyres as on emotion pack.
Did the test as you guys had recommended, took her upto 120 and slammed the brakes while twisting the steering just a bit, the car did respond to steering input, tyres screeched a bit but I didn't feel the brakes juddering.
Seems everything's fine though, either there's something wrong somewhere or the fusion judders way to madly.
Thanku everyone!

DerAlte · 4th October 2009, 19:13

Quote:

Originally Posted by sukrit7

... Did the test as you guys had recommended, took her upto 120 and slammed the brakes while twisting the steering just a bit, the car did respond to steering input, tyres screeched a bit but I didn't feel the brakes juddering. ...

Who recommended that? Why would you 'twist the steering a little bit'? That's a sure fire formula to flip the car at that speed, if the wheels lock.

When braking hard, whether with ABS or without, DON'T try to steer the car unless you want to avoid crashing into something. Even then, steer it when the speed is below 30. At 120, it is safer to quickly steer and correct to avoid collision and then brake, rather than brake and steer.

To test ABS, one DOESN'T have to go to 120kmph - 20-30kmph on gravel or wet road is good enough. Braking at 120 anyhow doesn't lock wheels - the car's momentum is enough at that speed to overcome brake friction. Most screeching locked wheels occur at 20-60kmph on dry tarmac.

sukrit7 · 5th October 2009, 01:36

It sounds very dangerous na, I guess what you're saying is correct but I did it with extreme caution even though I know it was wrong. I braked, let the speed come down and slightly, just slightly on the broadest of roads tried this.
Sorry though, guess it was wrong.

yogeshnaik · 7th January 2010, 15:29

Sukrit,
During hard braking the ABS control unit sends signals to the actuator/piston of the discs, applies pulsating brakes approximately at 10 - 15 times per second. That is why you are feeling a pulsating effect on the brake pedal. But to be on the safer side, get it checked at the Authorised Service centre rather than checking the effect on different model cars. Better you try out testing in another Punto or on a test drive vehicle to find this happens or not.

ssbiitm · 8th January 2010, 23:57

Thought I would share this ABS experience with you. I was taking a driving holiday through Karnataka last week in my i10 Asta 1.2 Kappa. We were going along a relatively less used road SH 50 from Jog Falls to Bhatkal on the west coast. The road is quite poorly topped and narrow (just wider than a bus), winding its way (horizontally and vertically!) through the Sharavati reserve forest over the western ghats. There is a not-too-wide gravel shoulder to the road and fairly tall hedges and bushes at each side, which implied that every turn was like a blind corner. I was keeping my speed to about 50-60 kmph at most, pushing the car speed up ever so slightly (because I wanted to get to Bhatkal before dark and dusk was beginning to fall). As we came down a slope which wound to the right, I saw a bus coming up directly at us at the moment of the turn (having been completely unsighted). As I am quite clear that ascending traffic always gets priority on hilly roads, my immediate (and involuntary) reaction was to climb onto the shoulder and slam on the brakes hard. Instantly I heard the "drrrrrrrrrrrttt" sound that seemed to come from under the car and the car held ABSOLUTELY steady. My first reaction was that the sound was because of stones/large gravel pieces hitting the underside of the car! There was not even the slightest lateral movement or shudder on the steering wheel and no pulsating feedback from the brake pedal. Neither were there any screeching or squealing sounds. My previous car, a Santro, that I drove for the past 10 years till about 6 months back when I upgraded to the i10, would have definitely skidded a little accompanied by the usual brake squeal. In the short moment when all this happened I was expecting a similar thing (skid and squeal) from the i10. Nothing of the sort happened here. Full marks to the i10 and hyundai.

I must say that I am very impressed at this inadvertent and impromptu test of the ABS and handling of the i10. Although I do not think there was any real danger here (as the speeds were low) and perhaps the only thing to be wounded or dented would have been my ego, I would strongly advice all to have ABS in their cars. This is really a great safety feature. It would definitely be the best to have ABS and drive as if there wasnt one. That way the control would be total and risks minimal!

Cheers,
Ssbiitm

SamtheLeo · 10th January 2010, 00:06

I own a Grande Punto & most of the time only when you are travelling at very very low speeds & tend to brake hard then you hear a "drrtttt" sound & thats all. No squealing, neither judder. All goes with out any issues.

infinitesadness · 10th January 2010, 01:39

I've faced a couple occasions where I had to brake suddenly from 60-70 kmph in my MJD, but did not experience any 'pulsating' or vibration. The car smoothly slowed down (in spite of me slamming my foot on the pedal), allowing me to finally swerve and avoid the vehicle ahead of me.
I haven't driven any vehicle without ABS, but then again, based on theory, this is how I would expect it to behave.

EssYouWe · 10th January 2010, 01:51

My Scorpio's pedal reverberates noticeably when the ABS gets engaged.

Slight squealing is normal.

Please DO NOT try it at speeds above 50 kmph! And definitely no steering play while you are at it!

Some systems do manage to mask it well, although not completely.

@Sukrit : Try it on gravel at speeds like 30. Remember to stand on the pedal.

PS: The mechanical ABS thingy was neat!

3rd October 2009, 18:02	#38
sukrit7 BHPian Join Date: Feb 2007 Location: delhi Posts: 722 Thanked: 185 Times	I'm sorry for disappearing, health prevented me from replying. Firstly a few answers, I run my car on 32psi, stock tyres as on emotion pack. Did the test as you guys had recommended, took her upto 120 and slammed the brakes while twisting the steering just a bit, the car did respond to steering input, tyres screeched a bit but I didn't feel the brakes juddering. Seems everything's fine though, either there's something wrong somewhere or the fusion judders way to madly. Thanku everyone!
	() Thanks

5th October 2009, 01:36	#40
sukrit7 BHPian Join Date: Feb 2007 Location: delhi Posts: 722 Thanked: 185 Times	It sounds very dangerous na, I guess what you're saying is correct but I did it with extreme caution even though I know it was wrong. I braked, let the speed come down and slightly, just slightly on the broadest of roads tried this. Sorry though, guess it was wrong.
	() Thanks

7th January 2010, 15:29	#41
yogeshnaik BHPian Join Date: Dec 2009 Location: Bangalore Posts: 347 Thanked: 216 Times	Sukrit, During hard braking the ABS control unit sends signals to the actuator/piston of the discs, applies pulsating brakes approximately at 10 - 15 times per second. That is why you are feeling a pulsating effect on the brake pedal. But to be on the safer side, get it checked at the Authorised Service centre rather than checking the effect on different model cars. Better you try out testing in another Punto or on a test drive vehicle to find this happens or not.
	() Thanks

8th January 2010, 23:57	#42
ssbiitm BHPian Join Date: Dec 2009 Location: Chennai Posts: 28 Thanked: 5 Times	ABS experience in the i10 Thought I would share this ABS experience with you. I was taking a driving holiday through Karnataka last week in my i10 Asta 1.2 Kappa. We were going along a relatively less used road SH 50 from Jog Falls to Bhatkal on the west coast. The road is quite poorly topped and narrow (just wider than a bus), winding its way (horizontally and vertically!) through the Sharavati reserve forest over the western ghats. There is a not-too-wide gravel shoulder to the road and fairly tall hedges and bushes at each side, which implied that every turn was like a blind corner. I was keeping my speed to about 50-60 kmph at most, pushing the car speed up ever so slightly (because I wanted to get to Bhatkal before dark and dusk was beginning to fall). As we came down a slope which wound to the right, I saw a bus coming up directly at us at the moment of the turn (having been completely unsighted). As I am quite clear that ascending traffic always gets priority on hilly roads, my immediate (and involuntary) reaction was to climb onto the shoulder and slam on the brakes hard. Instantly I heard the "drrrrrrrrrrrttt" sound that seemed to come from under the car and the car held ABSOLUTELY steady. My first reaction was that the sound was because of stones/large gravel pieces hitting the underside of the car! There was not even the slightest lateral movement or shudder on the steering wheel and no pulsating feedback from the brake pedal. Neither were there any screeching or squealing sounds. My previous car, a Santro, that I drove for the past 10 years till about 6 months back when I upgraded to the i10, would have definitely skidded a little accompanied by the usual brake squeal. In the short moment when all this happened I was expecting a similar thing (skid and squeal) from the i10. Nothing of the sort happened here. Full marks to the i10 and hyundai. I must say that I am very impressed at this inadvertent and impromptu test of the ABS and handling of the i10. Although I do not think there was any real danger here (as the speeds were low) and perhaps the only thing to be wounded or dented would have been my ego, I would strongly advice all to have ABS in their cars. This is really a great safety feature. It would definitely be the best to have ABS and drive as if there wasnt one. That way the control would be total and risks minimal! Cheers, Ssbiitm
	() Thanks

10th January 2010, 00:06	#43
SamtheLeo BHPian Join Date: Apr 2009 Location: Melbourne Posts: 451 Thanked: 26 Times	I own a Grande Punto & most of the time only when you are travelling at very very low speeds & tend to brake hard then you hear a "drrtttt" sound & thats all. No squealing, neither judder. All goes with out any issues.
	() Thanks

10th January 2010, 01:39	#44
infinitesadness Newbie Join Date: Sep 2009 Location: Mumbai Posts: 11 Thanked: 3 Times	I've faced a couple occasions where I had to brake suddenly from 60-70 kmph in my MJD, but did not experience any 'pulsating' or vibration. The car smoothly slowed down (in spite of me slamming my foot on the pedal), allowing me to finally swerve and avoid the vehicle ahead of me. I haven't driven any vehicle without ABS, but then again, based on theory, this is how I would expect it to behave.
	() Thanks

10th January 2010, 01:51	#45
EssYouWe Senior - BHPian Join Date: May 2009 Location: Lucknow Posts: 1,391 Thanked: 18 Times	My Scorpio's pedal reverberates noticeably when the ABS gets engaged. Slight squealing is normal. Please DO NOT try it at speeds above 50 kmph! And definitely no steering play while you are at it! Some systems do manage to mask it well, although not completely. @Sukrit : Try it on gravel at speeds like 30. Remember to stand on the pedal. PS: The mechanical ABS thingy was neat!
	() Thanks