[RainMan]

Hi Community

When in idle i can depress my brake pedal completely and with an estimated force of 20 kg (44 lbs) fully down to the floor.

It is a mess, because i have changed all brake cylinders and master cylinder and bleeded and bleeded up to 10 times with about 5 litres of DOT3.

All linea are tight, all hoses okay and no loss of fluid.

This problem sucks ... If the car has to be examined by German TÜV (inspection, MOT) they will refuse the anual licence plate.

My first question: Do all nitros drop the pedal by lite ( not enhanced) foot pressure in engine idle mode?

Please help - feedback of your nitros brake pedal resistance is essential for me. Do all drop?

If engine is off, the pedal is sticky and cannot be depressed. Some issue if the engine was on and the brake servo is on suction pressure after some minutes, the pedal has not full resistance on the first down, but becomes hard on the second pumping.

Okay, honestly speaking there is a minimum amount of air inside. The first Inch on the pedal is soft .. but then it stiffens rapidly.

But nothing explains the soft pedal in idle. I know there is an engine driven pump which generates the suction. Is there any suction regulation which does not work and supplies full suction? I dont know ...

Greets by the home of nitro madness ..

 

[Jan]

Brake booster has no saying in brake pedal travel. Engine off you just don't have enough strenght to press the pedal all the way. I think the "problem" is associated with ABS pump and it's internal pressure sensor- the system is just protecting itself from unnecessary overpressure. My car does the same thing, but during the TÜV everything is ok. I have seen brand new BMW's do the same.

 

[RainMan]

Good morning Jan,

Thank ,you for lifting my understanding to an extended next level.

Jeep JK owners report the sams issue. But in germsn jeep forum the administration has closed the thread without leaving enough time for the users to find out whether it is a bug or a feature.

Your hint pointing to the ABS block behind the master cylinder is very helpful for my further investigation. The Jeep JK owners report this issue to be present in cars from 2006 until 2010, afterwards they changed something to make the pedal drop effect vanish.

I will be back if i find more about this issue. Next week i will upgrade to Stahlbus bleeder screws, because it pisses me off lying under the car and the genuine bleeder screw sucks bypassing air when the pedal is on its backward travel.

Anyway, this car is a buch of enginering mistakes and layout errors. The common engineering of american and german engineers did not work as expected and suceed to make a homogenous unit of this car.

 

[Jan]

Just tested brand new rental car (Toyota Corolla 10000miles)- first press goes to the floor, second one doesn't.

 

[RainMan]

Hmmm, is this behaviour caused by Toyota or by poor Service of the rental company?

I will try to remove the poor rest of minor bubbles from my nitro by excessive bleeding. Time by Time.

No wonder, the front bonnet is more open than the driver door.

 

[Jan]

I'm pretty sure it hasn't had any service st 10,000 milles.

Have you done this?

 

[RainMan]

Hi Jan, i commit to have forgotten to have this routine / tool. I did traditional old school pressure bleeding but i assume the ABS to block proper and easy flow.

Yesterday I ordered new 3 litres of DOT3 and i swear, i will continue bleeding with AlfaOBD.

I am always very happy to read your advices, because i feel very good supported .Thanks a lot, your help is a brick in the wall of happyness.

 

[Jan]

I have never used alfaobd for bleeding. I allways use vacuum bleeding and in the end pressure bleeding with brake pedal. Also, you don't need dot3, dot4 is fine(better) and more common in Europe.

 

[RainMan]

I researched because my smart requires DOT4 SL6 and by incident i used the Container with fluid for the smart for the nitro.

Right now it is a mix of 2 litres DOT3 and 1 litre of DOT4 in the front calipers of the nitro.

I will go back to a full load of DOT3 because DOT3 has more viscosity (thicker) and might better avoid my.brake fast pedal dropdown.

AlfaOBD bleeding is fun and easy. The ABS works like going mad and forwards air to the caliper.

Only pressure bleeding adds an strange effect: After unclamping the pressure line from the master cylinder and doing a first press on the brake pedal the pedal drops without any resistance. Only aproxximately 10 times of pumping brings back a hard feedback and resistance of the pedal.

To.some extend this car is some new kind of John Carpenters Christine and has it's own odds.

I hope she won't finally kill me and refuse braking.

 

[Jan]

I think we do different type of pressure bleeding. My method is two man job. All nipples closed, engine off- one person pumps the pedal a few times and then holds it down. Then release one nipple- pedal drops to the floor. Now close the nipple, before releasing the pedal- repeat it twice and you're done with one caliper.

 

[RainMan]

You are right, Jan. We are different. I had 1.5 bar pressure in the reservoir. The manual says to do this way but i will turn to your method.