Brake pedal going to floor

Forum for wheels, tyres, suspension, chassis, brakes
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Johnny333
Posts: 1
Joined: Mon Nov 12, 2018 12:47 pm
Qashqai Model: Mk.1 Qashqai - J10 (2006–2013)

Post by Johnny333 »

Hi All

Just joined the Forum.

Tried searching for similar previous topics first on this forum without any luck, hence this post.

I have a 2010 Qashqai +2, 1.5dCi which has done over 115k miles with full Nissan service history.
Tended to do things like brake disks and pads myself to keep costs down having worked on cars most of my life. Swapped out the front pads at the weekend.
Took cap off brake fluid reservoir and left it on loose then after taking my old pads out I pushed the pistons back using a g-clamp. Went back fine. In hindsight I maybe should start letting fluid out the callipers via the brake nipple in future as oppose to pushing back up towards the master cylinder but that’s how I have always done it without any problems.
Put new disks in, sucked excess fluid out the reservoir to max level then pumped brake a few times.
Found straight away that the brake pedal is strong/stiff when engine is off but as soon as I switch the engine on the brake pedal can be slowly pushed right down close to the floor. The brakes work but there is a slight high frequency vibration through the brake pedal.
The disks were lipped but I didn’t feel it was large enough to warrant replacing.
Can lipped disks cause this problem and maybe need time to bed in.?
Reason I mention that I may start opening the Cali per bleed nipples for future pad changes is that I have been reading that the mater cylinder seals can be damaged pushing the fluid back up towards the MC, although I’ve never had a problem in 30yrs if doing so.
Problem is that it could be air in the lines however I have done a 4 wheel bleed without any change.
Going to clamp the flex hoses to the fron calipers and see if that affects the pedal (eg if there is air in the piston cylinders).
Not sure whether to try bleeding the MC brake line fittings? or change the discs and see if that helps. Can get very expensive considering I was just originally changing the pads..

Cheers
John

Deleted User 3871

Post by Deleted User 3871 »

John,

I cant answer your question exactly, but I can say that I have changed 2 full sets of brake pads on x2 mini's and always replaced the rotors. Its a little more but they usually wear enough as to warrant it. So, my advise is always to replace rotors.

If your foot goes to the floor make sure you have the correct pads. Some cars (Mini Coupe) were manufactured in the same year with different front callipers. With the mini the pads looked identical but had a big rivet under the point where the calliper pressed. This made the caliper flex a lot and caused very poor braking. "Check the pads are correct".
Johnny333 wrote: Mon Nov 12, 2018 1:12 pm Hi All

Just joined the Forum.

Tried searching for similar previous topics first on this forum without any luck, hence this post.

I have a 2010 Qashqai +2, 1.5dCi which has done over 115k miles with full Nissan service history.
Tended to do things like brake disks and pads myself to keep costs down having worked on cars most of my life. Swapped out the front pads at the weekend.
Took cap off brake fluid reservoir and left it on loose then after taking my old pads out I pushed the pistons back using a g-clamp. Went back fine. In hindsight I maybe should start letting fluid out the callipers via the brake nipple in future as oppose to pushing back up towards the master cylinder but that’s how I have always done it without any problems.
Put new disks in, sucked excess fluid out the reservoir to max level then pumped brake a few times.
Found straight away that the brake pedal is strong/stiff when engine is off but as soon as I switch the engine on the brake pedal can be slowly pushed right down close to the floor. The brakes work but there is a slight high frequency vibration through the brake pedal.
The disks were lipped but I didn’t feel it was large enough to warrant replacing.
Can lipped disks cause this problem and maybe need time to bed in.?
Reason I mention that I may start opening the Cali per bleed nipples for future pad changes is that I have been reading that the mater cylinder seals can be damaged pushing the fluid back up towards the MC, although I’ve never had a problem in 30yrs if doing so.
Problem is that it could be air in the lines however I have done a 4 wheel bleed without any change.
Going to clamp the flex hoses to the fron calipers and see if that affects the pedal (eg if there is air in the piston cylinders).
Not sure whether to try bleeding the MC brake line fittings? or change the discs and see if that helps. Can get very expensive considering I was just originally changing the pads..

Cheers
John
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