brake question

[79elcamino]

a little over a year ago i changed everything on my 06 sentra, pads,shoes,drums,discs,master cylinder and bleed the brakes and everything was good, and now i feel the pedal is not as hard as it should be, it all started when i dont know how but the new master cylinder started leaking from where is connected to one of the brake lines so i had a new one put on cause it was still under warranty and had everything bleed and the pedal still wasnt the same, then like 2-3 weeks later one of the calipers started leaking from the bleeder screw so i had both calipers changed cause they were under warranty and bleed the 2 front lines and the pedal still isnt the same, the pedal does not travel all the way to floor but i feel it travels more then it should. when i put my foot under the pedal the distance between my foot and pedal is not a lot i remember when i first did the brakes there was more room between my foot and pedal, also sometimes the pedal is inconsistent, sometimes it travels a little bit more,i thought maybe it was the pads and shoes but when i had the calipers changed i had my mechanic take them off so i can see them and they look like i just bought them there looks like there is 95% of the pads and shoes left. i have no more leaks the pads have no uneven wear and are still brand new, i guess im not hard on my brakes, my mechanic is started to get annoyed at me cause i keep saying theres something wrong but he is like theres nothing wrong its all in your head the pedal is fine and the car stops fine. i dont know what else to do should i bleed the brakes again or could it be something else?

[dtuna42]

Re: brake question

Might be a silly question... but I'll start simple- with all the bleeding, have you check the fluid level in the reservoir? If it's low, that can cause your symptoms. Next, maybe bleed all 4 lines, with reservoir cap off, and then top off the reservoir. After that, I'd say check that calipers and pistons are clean and moving freely (just spray liberally with brake cleaner). Finally, assuming no air in lines, pads/shoes are good, master cylinder is good (and slave cylinder if equipped- but I can't imagine an '06 having one of these..), fluid is filled, and calipers and pistons are moving freely, the last thing I can think of that may bring back a tight pedal, is to change the brake lines. Especially if they're rubber. They can stretch out and loosen up with age (although yours isn't that old - so maybe one is defective?), and if they are stretching when you step on the pedal, it will feel like a soft pedal. In this case, new brake lines - especially if the aftermarket offers braided steel brake lines for your car- might help get the tightness back in the pedal. Good luck, and let me know if any of this helps...

[79elcamino]

Re: brake question

thanks, yeah the reservoir is full, ill try bleeding the brakes one more time, the only thing i didnt change was the brake lines and yes they are rubber, visually they look fine on the outside

[Detroit CC]

Re: brake question

Are you using the correct grade of brake fluid for your vehicle?
Yes, there are different grades, depending on the rubbers used in the piping and the calipers.

Do you have access to a comparator vehicle, try the, back to back to see ofnthey perform the same.
Are you comparing your car to another in the household? Are they the same type of vehicle?

I'd start with the basics:
Is there any evidence of fluid leak on your drive, garage floor, inside the wheel rims? Has paint flakes off any axle beams or calipers? Has your fluid level dropped? If no, then I'd pretty much rule out a leak.
As asked in a previous response, have you inspected the rubber pipes between the calipers and the metal body tubing?
Do they look perished?
A possible way to eliminate which part of the brake system is giving your nightmares.
Take four brake line clamps and clamp each rubber hose (at the same time), DO NOT DRIVE THE VEHICLE, YOU HAVE NO BRAKES. Now, when sat inside the vehicle, pump the brake pedal a few times, it should go hard. Whislt keeping your foot on the pedal, start the engine, did the pedal drop a little? If yes, then you have vacuum bing pulled on the servo, this is a good thing.
Now, with the engine still running, pump the pedal a few more times until goes hard, leave the pedal pressed, does the pressure remain the same or does the pedal start to soften and head towards the floor?
If heading towards the floor, you know the leak is well before you get to any of the clamps on the flex pipes.
If it remains the same, then the issue is after one of the clamps.

With the clamps still in place, have someone pump the brake pedal.
Looking at each flex pipe, can you see any bulging? I'd also use a torch (flashlight).
If no, then onto the next step.

Remove one of the clamps, again pump the pedal, does it feel good or is tailing off again.
Check all around the caliper and pipe work on the corner that you removed the clamp.
Remove another clamp and follow the same process (by now, you should have two clamps on the vehicle and two clamps off.
Keep following the process.
If you find nothing and your mechanic has said that brake pads are making full contact with the brake discs (rotors), then all is good.

[Detroit CC]

Re: brake question

Hope that info helps, but it is by no means a full inspection of your vehicle. It is only advice and I am sure your mechanic has already offered his/her view and ways of investigation.

[79elcamino]

Re: brake question

thanks i will be trying that on friday when im off