mflorant

Brake pedal/braking

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Hi all! (2009 T27 CVT 2.0)

My brakes are behaving a bit strange. When braking I feel that I need to push the pedal almost to the bottom to have some brake power. So when I push the pedal it is not really having brake power on the top only starts braking lower. When slowing the car discontinuously slows down. 

There is no air or leakage in the system, I have checked so far. Brake pads and discs are new.

I am clueless, any suggestions? 

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A few questions -

This is a problem that started when the disks and pads were replaced?

Were the rear pads replaced or just the front?  Was this a job you did yourself? 

How did you establish that there is no air in the system?

The extra brake pedal travel sounds like a brake pad or caliper has some 'spring' in it because it is not aligned properly to the disk after putting it back together, so the pressure on to the pad is not being evenly applied across its friction surface.  One or more of the pads is not properly seated, or less likely, the caliper is not seated properly on its mounting.

I have heard some people have suffered master cylinder rubber seal problems, after forcing back brake fluid to the master cylinder during pushing back of the brake caliper pistons.  Apparently, draining the excess fluid at the caliper bleed nipple, rather than pushing it back into the master cylinder, can prevent this risk.  I have never suffered this myself, though.

Hopefully, other posters will have some other ideas.

 

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When describing the brake pedal movement and feel, does the pedal need a lot of force or a lot of travel, or a combination of both?

You said the brake pads and discs were replaced recently. Did the problem start from then? Brakes need a little running in time. I just changed my front brake pads recently and the bed in after a while - they were fine a couple of days later. The pedal was firm but more force was needed. Now gentle press and the bite is back.

Hopefully the new discs faces were cleaned of any protective grease before installation!
Other things like checking that everything has been installed properly, the brake caliper clean and copper grease at certain points, the sliders have free movement.
Go over everything. 

 
 

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When I bought the car the discs and the pads have been changed. I only did the bleeding, when I have still felt braking is not like it was on my previous cars.

Checked the sliders, put brake grease on it.

The pedal needs a lot of force and a lot of travel.
 

My main problem is that there is no "bite" effect 😔

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When you bled the brakes, did you use a pressure bleeding system? Also the T27 supports ABS bleeding using Techstream or suitable diagnostic software. 
The 'bite' tells me that the vacuum pump, piping and servo may need checking, and flexible brake pipe could be damaged, or the brakes need to be bed in or discs not cleaned before installation, contaminating the the pads. Contamination can may result in glazed disc and pads, meaning less friction and no stopping power! Did you know who fitted your brakes? 

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No pressure system used for bleeding.

I have realized that when I am pushing twice the pedal I am having the "bite" effect.

Btw discs and pads were cleaned by myself. I also had a guess that this may cause the issue.

Does this give you some more clue?

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1 hour ago, mflorant said:

No pressure system used for bleeding.

I have realized that when I am pushing twice the pedal I am having the "bite" effect.

Btw discs and pads were cleaned by myself. I also had a guess that this may cause the issue.

Does this give you some more clue?

There is no leakage of Oil, the level doesn't change in the canister. 

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Hi! Maybe what i am going to say doesn't have to do with the problem but maybe could be.

 

If you keep the brake pedal depressed, do you gradually lose the braking power? For example, standing in a redlight or something. I'm asking this because my brother had a similar problem few years ago and was the pump that slowly was loosing pressure due to worn seals.

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4 hours ago, mflorant said:

 

I have realized that when I am pushing twice the pedal I am having the "bite" effect.

This suggests air in the system. Try vacuum bleeding..

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3 hours ago, doc_14 said:

Hi! Maybe what i am going to say doesn't have to do with the problem but maybe could be.

 

If you keep the brake pedal depressed, do you gradually lose the braking power? For example, standing in a redlight or something. I'm asking this because my brother had a similar problem few years ago and was the pump that slowly was loosing pressure due to worn seals.

Actually I haven't had such an experience with my pedals.

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I bought a vacuum bleeder, so I will try my best.

Will write my experiences.

Thanks for everything! 

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When pressure bleeding, you may need to go gentle, say 15-20 PSI, and go around to each wheel. After the first round of bleeding the pedal doesn't or improves slightly, raise the pressure to say 25 PSI or a little higher and do again. Two benefits are new clean brake fluid with air and contamination removed. 
The servo assistance check is done by pressing the pedal with the engine off. The pedal will sink and be firm. When the engine is on, the pedal will not sink as low, and the bite should be good with not much force. When you stamp on the pedal, the car should brake sharply, and if a wheel loses grip, the ABS kicks in.

I look for to ready your outcome. 👍   

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Dears,

I did the vacuum bleeding, the brake became slightly better.

The discontinuity is still on, but I can feel it less. Is somehow the CVT also affecting braking or not?

Or my new brake pads are sh@#$t.

Any further suggestions?

Ps.: I have checked all the hoses, no leakage or trickle

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We had front discs and pads replaced by a dealer on our old Corolla some years ago. It was absolutely fine for several weeks including a holiday in the Isle of Man which saw some pretty heavy brake action (70MPH roads and steep steep descents). All good. Came off the ferry and a couple of miles in and the pedal went nearly to the floor. Next application was OK, then same again. Lightly touching the pedal first and then applying the brakes saw them work each time.

The dealer looked at it the next day and apologised and said the problem was in fact residual air in the system and that the brakes could in some circumstances be extremely difficult to bleed correctly sometimes. That was seven years ago and its been trouble free since.  

    

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So back again.

Did bleeding with the vacuum thing again, not much happened...

I have serviced my brakes, meaning that I have removed everything at the front brakes, cleaned, greased where it is needed, discontinuisity is gone! I think the pads were locked, not well sliding.

I realized that I have to change the brake pads very soon and I also realized that I have two different brake pad brands on the left and right hand side...

Which brand do you recommend for pads? I was thinking about Bosch.

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