[dhanushs]

Originally Posted by Rehaan

Nowhere has gou said that the pedal travel increased. He only mentioned "The brake paddle was getting fully pressed". There is a lot of uncertainty/vagueness

hmm.. Yes. I guess only his wife can confirm.

In any case, here's some common brake fail, problems and symptoms and the probable reasons.

Some food for thought for gou and his wife. .





Source: Clark's Garage Home Page

[gou]

Originally Posted by Rehaan

Please tell her to STOP the car completely and immediately when this happens. She might think driving slowly is safe enough, but its a huge danger for her and moreso pedestrians and bikers around her.




At this point it seemed like a fluid leak, but since fluid had not leaked at all, and the brakes came back to normal, this is not the case.

It could be one of the following :

- Pads lost their effectiveness (due to excessive heat, oil on them, etc)
- Booster stopped functioning (leak in booster, vacuum pipe, etc)
- Master cylinder failing somehow? (i dont know)
- Something stuck behind the brake pedal




Like other have said -- this part just doesn't compute?!?

Are you saying your wife managed to put the gear lever from "D" past N, R and into "P" while the car was moving (this seems unlikely)?

Or could she just not manage to move the car past D/N into R or P?

Assuming the car was at some point in "P" - it still continued to move??

Please get a clear picture from her.


Also - did she try and use the hand-brake / Emergency brake?


What you need to do before moving forward is try and figure out if :
A) It was a one-time human error (eg. overheating brakes, object behind pedal, etc)
OR
B) Some sort of intermittent mechanical failure that WILL happen again.


cya
R

I agree, need to clarify this part - when did she try to move to P. Probably she tried it when engine was on and might not have worked. You and others have created few queries which even I am not very sure. So will talk to my wife after evening and confirm.

Originally Posted by dhanushs

• Gou, if there is water or oil between the pads and disc, there would be reduced braking effectiveness, but still the pedal WOULD NOT go all the way in. If it had gone, then please rule out the possibility.
• Regarding the 2nd possibility, your wife should have recognized the pedal travel. The pedal travel when a floor mat comes in between and the when the pedal goes all the way in is very different.

The only possibility I see is Air in the System. As a 1st step, change the brake fluid and bleed the air in the system by a competent mechanic. After which, take the car out to an open area with no traffic and test the brakes hard (the ABS activating types), many times. If there is an Air leakage in the system, then atleast one time, the brakes will fail. If it does not fail, then you are good to go.

EDIT:



Hi Rehaan,

For all the problems you have mentioned, the brake pedal travel wont increase. I guess it will just get hard. Hence I suspect Air in the lines or master cylinder.

I shall check this out. I shall take it to Honda showroom and ask them to bleed air. Also, I am going to change the brake fluid anyways (in case it had caught moisture and is getting overheated).

Originally Posted by Rehaan

@dhanushs

Nowhere has gou said that the pedal travel increased. He only mentioned "The brake paddle was getting fully pressed". There is a lot of uncertainty/vagueness, which is why i've suggested he ask his wife a few more things.

But yes - air in the lines is another point i could have listed (along with overheating brake fuel, due to riding the brakes as pranavt mentioned).

cya
R

The pedal travel increased without any effect i.e., without providing braking power. In that case Rehaan, is getting the air bleeding done sufficient or should I check for Booster and Master cylinder also?

Originally Posted by sgiitk

As Rehaan has pointed out, you should NOT be able to move into P when the moving. In the new ATs it will not go into P unless the Stop pedal is firmly pressed. Let us assume that the pedal was firmly pressed, and the car was somehow shoved into P.

Then the car with stop with an almighty jerk, and there is very likely to be severe mechanical damage to the transmission.

Need to clarify this point with my wife as Rehaan pointed out.

Originally Posted by dhanushs

hmm.. Yes. I guess only his wife can confirm.

In any case, here's some common brake fail, problems and symptoms and the probable reasons.

Some food for thought for gou and his wife. .

Attachment 591276

Attachment 591277

Source: Clark's Garage Home Page

This is very informative dhanushs.


Thanks guys for your inputs,
Gourav.

[Sprucegoose]

I had the same problem with my car quite some time ago.
Inspite of getting my Master Cylinder replaced the problem persisted.

I got the car worked on.
No Work was done on the brakes, but they worked fine post that.

Things that were done.
1> Brake Fluid was changed & it was bled. All air bubbles were removed.
2> I had my suspension changed, so the Brakes were removed and re fitted.

I suggest you do these 2.
It should solve your problem.
Also change the Master Cylinder, since it's not too pricey.

[pranavt]

Honestly, if you are going around changing parts, go and change the brake lines first. They will make a bigger difference than a master cylinder. Years of use makes the brake lines soft.

[oxyzen]

Originally Posted by gou

The brake paddle was getting fully pressed without any effective braking at all.

The most important question is when the pedal was fully pressed was the force needed to press it less than usual?
If yes
- There is Air in system
- Master cylinder gone bad.
Pumping the brake pedal may help in such situation. (temporary solution)

If the force needed is more
- there may be a problem with brake booster or vacuum hose.


EDIT

Originally Posted by gou

The pedal travel increased

Then I guess you need a bleeding.

[chinkara]

I too think it is likely an air issue -- as Dhanush says. I had exactly the same problem some 2 months back (although in a MT Wagon R), and bleeding seemed to solve the problem.

Check if:
1. The pedal sunk fully in the well
2. The pedal became soft and easily "pumpable" -- rather like a cycle / football pump
3. Hand brake did not hold

Best thing to do in such is a situation is to gradually stop the car using Engine braking; and call mobile help ASAP.

[Sprucegoose]

Originally Posted by chinkara

3. Hand brake did not hold

AFIAK The Hand brake is usually Mechanical, not Hydraulic like the foot brakes.

[gou]

Originally Posted by Rehaan

What you need to do before moving forward is try and figure out if :
A) It was a one-time human error (eg. overheating brakes, object behind pedal, etc)
OR
B) Some sort of intermittent mechanical failure that WILL happen again.

R

I believe its some sort of mechanical failure and might happen again. Thats why I want to make sure it does not happen.

Originally Posted by dhanushs

The only possibility I see is Air in the System. As a 1st step, change the brake fluid and bleed the air in the system by a competent mechanic.

For all the problems you have mentioned, the brake pedal travel wont increase. I guess it will just get hard. Hence I suspect Air in the lines or master cylinder.

Originally Posted by sgiitk

As Rehaan has pointed out, you should NOT be able to move into P when the moving. In the new ATs it will not go into P unless the Stop pedal is firmly pressed. Let us assume that the pedal was firmly pressed, and the car was somehow shoved into P.

Then the car with stop with an almighty jerk, and there is very likely to be severe mechanical damage to the transmission.

Certain clarifications:
My wife tried to put gear selector in "P" mode while driving, and it went there but provided very little braking (or not braking). I believe it should not allow to go there when the vehicle is moving. Is this an anomaly?

After this she tried hand brake and offered little help but by then the auto came to help it to complete stop .

Originally Posted by Sprucegoose

I had the same problem with my car quite some time ago.
Inspite of getting my Master Cylinder replaced the problem persisted.

I got the car worked on.
No Work was done on the brakes, but they worked fine post that.

Things that were done.
1> Brake Fluid was changed & it was bled. All air bubbles were removed.
2> I had my suspension changed, so the Brakes were removed and re fitted.

I suggest you do these 2.
It should solve your problem.
Also change the Master Cylinder, since it's not too pricey.

Originally Posted by oxyzen

Then I guess you need a bleeding.

Originally Posted by chinkara

I too think it is likely an air issue -- as Dhanush says. I had exactly the same problem some 2 months back (although in a MT Wagon R), and bleeding seemed to solve the problem.

Check if:
1. The pedal sunk fully in the well
2. The pedal became soft and easily "pumpable" -- rather like a cycle / football pump
3. Hand brake did not hold

Best thing to do in such is a situation is to gradually stop the car using Engine braking; and call mobile help ASAP.

Its an AT, best that can be done is put the gear selector in "2" mode insted of D4.

As I mentioned earlier, she brake travel increased and was it was travelling all the way down. So accordingly to suggestions by people here, I guess there is air in the system. So the solution is:

1. Bleed the air in the system
2. Change the brake fluid

Is this sufficient? There were other suggestions also which might be useful:

• Change master cylinder
• Get the brakes removed and refitted.

Should I go for these also? Anything else that should be done?

What puzzles me is that brakes have been functioning properly after that one incident. Car has already run around 80+ kms after that without any problem.

[Sprucegoose]

And as Pranavt mentioned, Change the Brake Lines as well.

Ask your wife if she felt the car was slightly sluggish, could be that one of the Brakes was in permanent contact with the rotor.
Overheating brakes also have these symptoms.

Your brakes stop the car by converting the Rotational movement of the Rotors to Heat.
After a certain point when the brakes when the brakes are too hot, 2 things happen.
1> If your Brake fluid boils, all the dissolved air will start bubbling out. [Causing sponginess in the brake pedal]
2> The Rotors overheat, additional rotational motion cannot be converted to heat. [Everything will seem fine, but braking power will be very bad.]

[dhanushs]

Originally Posted by gou

What puzzles me is that brakes have been functioning properly after that one incident. Car has already run around 80+ kms after that without any problem.

When there is air in the lines, you never know when you loose braking. Now, PLEASE DONT go driving around, without atleast a check up.

Originally Posted by gou

1. Bleed the air in the system
2. Change the brake fluid

• Change master cylinder
• Get the brakes removed and refitted.

Should I go for these also? Anything else that should be done?

There is no need to change the master cylinder, just check for any leaks, if yes, replace.

Originally Posted by Sprucegoose

And as Pranavt mentioned, Change the Brake Lines as well.

lol man!!.. I dont think pranav was serious about that comment. Well, if the problem is not solved by doing the above, then one might go changing the lines. In any case, for sedate speeds, I don't think its necessary, as the reason mentioned is them getting soft. May be, he can clarify.

[gou]

Originally Posted by Sprucegoose

And as Pranavt mentioned, Change the Brake Lines as well.

Ask your wife if she felt the car was slightly sluggish, could be that one of the Brakes was in permanent contact with the rotor.
Overheating brakes also have these symptoms.

No the car was not sluggish. Just the brakes travel increased to a point it traveled fully and with it it lost its effectiveness as well.

Originally Posted by Sprucegoose

Your brakes stop the car by converting the Rotational movement of the Rotors to Heat.
After a certain point when the brakes when the brakes are too hot, 2 things happen.
1> If your Brake fluid boils, all the dissolved air will start bubbling out. [Causing sponginess in the brake pedal]
2> The Rotors overheat, additional rotational motion cannot be converted to heat. [Everything will seem fine, but braking power will be very bad.]

Though overheat might cause issues, I don't think heat has caused this issue, because I have checked with braking more than what she would have done that time.

Originally Posted by dhanushs

When there is air in the lines, you never know when you loose braking. Now, PLEASE DONT go driving around, without atleast a check up.

There is no need to change the master cylinder, just check for any leaks, if yes, replace.

Thats true, thats why decided to first check it. Sitting in Magnum Honda service center right now. Says he will 2 hrs to fully check. Will anyways do the air bleeding and replace brake fluid.

if after checkup SA mentions about any other leak will do the needful. Otherwise it will be only air bleeding and fluid change. What do you guys say?

Originally Posted by dhanushs

lol man!!.. I dont think pranav was serious about that comment. Well, if the problem is not solved by doing the above, then one might go changing the lines. In any case, for sedate speeds, I don't think its necessary, as the reason mentioned is them getting soft. May be, he can clarify.

The problem here is that I did not experience any problem with braking after that. Other thing is we might go out, this being the long weekend, so there will be some highway driving.

[Sprucegoose]

Originally Posted by gou

The problem here is that I did not experience any problem with braking after that. Other thing is we might go out, this being the long weekend, so there will be some highway driving.

That's why... if there was an intermittent mechanical problem where by excess heat was being generated and getting transferred to the Brake Fluid, that would cause your problem.

Lets say hypothetically if one of the calipers is not retracting properly, and is in contact, but not under pressure, with the Rotor, Heat will be generated. Your brakes will not get a chance to cool down. This heat will get transmitted to the brake fluid, which will start boiling.

The wet boiling point of Brake Fluid is significantly less than it's dry boiling point, so if there is some water dissolved in the brake fluid, it will come to a boil at a lower temperature, this will negate the hydraulic effect of the system as a gas is very easily compressed when compared to a liquid.

I'd say there is some intermittent mechanical problem that is leading the Brake Fluid to heat up.

When i had this problem on my car, which magically disappeared after i changed the suspension, i figured that it was probably something loose in the brakes. I had changed the master Cylinder & the Brake fluid after the first instance, but the issue resurfaced.

That too it never happened when i was driving, happened when a friend was driving. In his defence, the brakes failed while he was driving the car on 2 separate instances [Before and after changing the master cylinder & the Brake fluid], but he's never had a problem in the other 15000* odd times he has driven my car. [That is before i ever had a problem of brakes failing, after i thought i got it fixed and then finally when it did disappear for good. And it's not yet reared it's ugly head again.]

* I'm exaggerating to add to the dramatic effect

[dhawcash]

Hi,
Would like to share my braking experiences, which might help rule out some possibilities.

1. Did some spirited driving in some ghat sections in my esteem, and noticed brake fade. stopped the car and was delighted {yes, that was my actual reaction} to see smoke pouring out of both front calipers. The pedal did not get spongy and the only reason for brake fade was overheating. The brake fluid did not boil under this extremity, and i think you should rule this possibility out. Brake fluids are designed not to boil, and their reluctance to boiling can be judged by their DOT rating. Google for more details.

2. The stopping power of the handbrake: the mechanical ones have just enough dosh in them to keep the car from rolling, and are very ineffective at stopping the car. even if you pull it very firmly, it will lock the rear wheels and the car will continue to move forward, as most of the braking is done by the front wheels (which the handbrake does not cover). These are so weak, that cops tow away cars merrily with their handbrakes engaged!

3. Had a similar problem with the brakes of a buggy i made. the brakes were moody, worked like a dream one day- fell to the floor occasionally, and after a few pumps on the pedal, returned to normal. The master cylinder had no leaks. the brake lines were new. Calipers had been overhauled. Tried bleeding the brakes, but to no avail ( wasted almost 2 litres of brake fluid while bleeding). Eventually replaced the master cylinder, and Viola! problemo solved!

4. Oil/ water on rotor would cause brake fade, but pedal would in no case go mushy. Not the problem in your case i think.

5. Also get the flexible brake hoses ( which connect the calipers to the metal brake line) for softening or bubbling. unlikely to be a problem, but just to be sure.
What i'm trying to say is, that mechanical units may seem to work fine- but might develop little gremlins which show up only occasionally : which may be life threatening.

In your case, as the problem cannot be pinpointed, I'd suggest you replace your vehicle's master cylinder, bleed the lines, and also get the brake liners at all four wheels checked to ensure a trouble free reliable, and safe braking system.

[dhawcash]

Also, Modern cars have a tandem master cylinder. which means that front and rear brake circuits are separate for safety reasons. Even if a leak was present, or the brake fluid boiled, the probability of this happening to all four wheels simultaneously is 0.01 in a million. So even if you car has a problem with a brake line or something, the master cylinder should still not go to the floor, and still provide braking to the circuit without a leak/problem. Basically even if the system has a leak, some braking prowess would still be left.

[chinkara]

In my case, although bleeding was required, after the initial incident I drove something like 120 km without problem before I could get the bleeding done, and there was no problem.

Basically the mechanic explained that since I was using the brakes sparingly after that incident, the air was dissolved in the fluid rather than pockets of it in the linings and thus things worked ok.

Check this for a more detailed understanding.