JL514

I changed my front brakes myself for the first time on Friday. I switched to Posi Quiets. Everything went smoothly and was really easy, but when I went to pump the breaks to get the piston back where it needed to be the pedal remained squishy -- never built pressure and got firm.

The car still brakes/stops there is just a ton more pedal play and I didn't think I could stop quickly if I needed to. I figured I must have gotten air in the brake lines somehow so I bled each line completely.

During bleeding, I never noticed any air bubbles coming out at all, just brake fluid. After bleeding all four lines I still had that squishy pedal.

I noticed that I hadnt put the shims & brackets back on the pads so I went to fix that before bleeding the front lines but they don't fit -- the new pads are shorter (on the dimension following the split in the pad) and the shims and brackets seem to be too "big".

Any ideas?

ack154

iTrader: (7)

If they are really squishy, you probably just need to bleed them further.

Did you also bed them in properly?

JL514

I have no clue how I would have gotten air in the lines, as these brakes are so easy to change and don't require disconnecting the brake line. I didn't see even a single bubble while bleeding.

As far as bedding them in -- I didn't because I didn't want to go to 60-80mph as I am not confident in my ability to stop as quickly as I should be able to. As far as I know the bedding process will make braking more effective and stronger but has no effect on how deep the pedal depresses.

Jan06xB

Make sure that the calipers are moving properly and are not bending to grab the rotor thus not seating on both sides like they should. If you bleed the caliper fluid back to the reservoir by pressing the piston into the caliper cylinder you force all the air back up and out of the lines. You should not need to bleed any fluid out of the calipers. If you pressed the master cylinder (pedal) too far down you may have damaged the master cylinder piston seals. Did you work on the rear pads too?

JL514

I didn't do any work on the rears, they were replaced a month or two ago for free (link) due to malfunction.

How should I check that the calipers are moving properly? Just watch their motion while the brake pedal is depressed?

Jan06xB

Yeah have someone press on the pedal while you watch and turn the wheel by hand while jacked up in the air. You want to check the inside and outside pad to make sure they are both touching evenly - rock the rotor back and forth and watch the pads move. Check for excessive play in the pad clearance between the inner and outer pads and rotors.

tkevin07

iTrader: (3)

just keep bleeding it

sciontc_mich

no damage to the master cylinder could occur if there is air in the brake lines. If the master cylinder wasn't disconnected then there's no reason to worry about it.

did you make sure that the bleeder screw is tight enough? Might be sucking air back into the caliper?

While bleeding the brakes did you make sure to keep the brake fluid was at the minimum level in the brake reservoir??

also. regardless of the rears being done already you should bleed the right rear, then the left rear, then the right front and finally the left front. rebleed the system in that order and see.

JL514

I didn't do any work on the rears but I did bleed them anyway. I bled all 4 lines in the correct order (passenger rear, DR, PF, DF)

I did not keep the brake fluid at the minimum level while bleeding -- didn't read that anywhere. I read that before and after each line you should be checking the level of the fluid and refilling as necessary. (Edit: I think you meant, did I make sure the fluid didn't fall below minimum -- the answer to that is yes)

When bleeding each line, the car has to be on.. right? Otherwise the brake pedal locks itself after ~2 presses.

Also, should the fact that I didn't put the brackets & shims on the new pads make a difference?

Jan06xB

First there was no need to bleed the lines and getting air into the ABS is a real pain in the butt. Second if you have missing hardware on the pads all bets are off if they are needed to operate properly. I would have to see what they look like to know for sure but if they came with the new pads you probably need them unless otherwise indicated with the instructions that should have come with them. Shimes usually insulate the cylinder from the heat that the pads generate and the brackets keep the pads floating in the caliper so they move freely. It looks like you have a single cylinder full floating caliper so make sure that the entire caliper slides on the pins i.e. press the piston side against the rotor by hand to retract the piston and the entire caliper should easily slide in and out on the support pins so that the inner and outer pad can hit the rotor. Then by hand pump up the brakes only using short pedal strokes and you should be able to do it with the engine off with a bit more pressure after the vacuum boost goes away. If you have a lot of rotor wear the faces of the rotor may not be parallel and that will cause some softness in the pedal as the new pads are not seating properly.

JL514

I bled the lines when the pedal was squishy -- I didn't plan to have to do that.

The new pads did not come with the brackets and shims (or instructions for that matter), they were on the stock pads. They didn't fit snugly on the new pads so I left them off.

This was something I noticed while replacing the pads. The caliper slides without a problem along the pins.

My rotors do not seem to be worn or warped.

I appreciate the input and guidance thus far. I am trying to give as much information as possible -- please do not take it as I'm trying to refute each of your points because that's definitely not my intent.

Jan06xB

Yeah no problem I just want to make sure what you have done so far. You did bleed the brakes properly by keeping the reservior above minimum (perfect!) but the more critical adjustment is making sure you close off the bleeder nipple before you let up on the brake pedal so you don't draw air back into the caliper cylinder. Usually I only open the nipple a little so that it takes a lot of pedal pressure to force the fluid out. If the fluid came out fairly clear then your fluid should be ok. There is a small amount of flexing on the caliper that can make it feel soft but more likely if you feel more softness in the pedal after the brake job then the pads are flexing or there is air in the lines. Assuming you have NO air in the lines then the next thing would be to hold onto the caliper and rotor with your hand as someone else pumps the pedal and see if you can feel some flexing in the caliper. It only takes a small amount of flexing on the caliper to make the brake pedal travel a lot. If you can see the piston on the caliper moving a lot that is also a good way to tell what may be going on since you would see the pads flexing a little if they are not seated properly. The other thing to do is to take a magic marker and write over the rotor then rotate it and see how the pads are touching the rotor. If you find that only part of the magic marker is rubbed off then you know that the pads are not making proper contact. DO it to the inner and outer surfaces of the rotors. You could also have a damaged brake hose so check the rubber hoses for cracking.
How were the old pads - even wear or angled pad surface wear?
The only other thing that is fairly easy to do is to pop the caliper off the rotor and carefully and slowly pump the caliper piston out a lot further - no so much that the piston pops out of the cylinder or so much that the reservoir gets too low and pumps more air into the lines. THEN press the caliper piston back into the cylinder to flush any air back up into the reservoir - you may have to do it a few times to each wheel to back flush the air. Make sure the caliper hose is straight up to let the air out of the cylinder.

JL514

The pads were the original that came on the car, car has 30k miles. Pads were evenly worn although the split in the pad to show depth was uneven -- looked like brake dust got into the crevice in some areas and compacted. Not sure if this is normal as this is my first time changing brakes.

I actually got a self-bleeding kit because I wasn't sure if I'd have someone to help when I wanted to bleed the lines and my schedule was a bit crazy this past week. The kit was a small bottle and hose with a small tip at one end that fit into the screw. Bleeding with the kit went as follows:

• Unscrew the bleeding screw until fluid begins to drip out (~1 turn)
• Insert tip into screw opening
• Pump brakes using full strokes ~3 times.
• Repeat until no bubbles are seen leaving the lines.
• Tighten bleeding screw and remove hose.

The tube didn't allow backflow and I didn't see any air bubbles at all. The fluid that came out was very close in appearance to the new fluid I added, maybe slightly more amber.

I will try the trick re: pumping the cylinder far out and pushing it back in. What is the best way to push the cylinder back in? By hand? C-Clamp?

Jan06xB

You can sometimes get air back into the caliper through the bleeder threads but not likely. The problem with the full stroke on the master cylinder . . . and I have seen this happen several times . . . is you are moving the master cylinder seal much further than it usually travels and it sometimes damages the seal and causes the master cylinder to fail afterwards. It can also trigger a brake line failure in the braking system where the brake system thinks there is a brake line leak and goes into a failure mode where it may operate all four brake cylinders off of part of the master cylinder pressure in dual braking systems.
Yeah I usually pry the piston back into the cylinder with a flat tire iron or a block of wood so I don't chew up the metal surfaces. You want to press it in quickly so you flush the brake fluid back through the lines fast to blow out any air bubbles trapped in the lines. If the piston moves easily you can do it with both of your hands or a piece of wood and channel lock pliers . . . don't pry against the rotors.

JL514

If I had damaged the master cylinder it was when I put the new brakes on but before I bled the lines as I had this squishy feeling prior to bleeding. If that were the case, how can I confirm it and what do I do about it?

Jan06xB

NOPE you didn't damage the master cylinder just changing the brakes - it sounds like something is not quite right with the new pads that is giving you that soft feeling. That's why I said to have your hand on the caliper while someone steps on the brake . . . something is flexing in your brake system and I don't think it is air in the lines. If the pads are not seated properly then they bend and give that soft feeling. DO the magic marker on the rotor trick and see what the contact patch looks like. If you jack up the front end so that the car is very secure and you can run the motor with the tranny in gear you can spin the front wheels and work the brakes a little and seat the pads in - just don't run them for too long or you could overheat the rotors without air cooling them from lack of motion. Actually you don't even have to jack up the front end since you have mag wheels you can reach right through the spokes and mark it up then just roll the car a little and check them. Even checking the outside rotor surface could show you a problem if there is one there.

Jan06xB

Hey if all else fails then put the original pads back in and see if the brakes are hard then.

JL514

When I bought new brakes I ordered Axxis Deluxe Pluses. When they arrived I had received Posi Quiets. I wrote the place asking why I received brakes I didn't order and I received this response:

I opted to take a 10% refund and thought that was pretty good customer service. Then I had this whole thing happen. Turns out I was sent p/n 105.08220 which are front pads for prius, xB and xA (among others, 00 celica, 00-02 MR2 etc). NOT A TC! The tC part number is 105.08170. So not only did they send me the wrong brand, but they sent me the wrong part as well.

The pad fit well on the front side of the rotor, but on the back side, it was just a TAD bit too large at the corner causing it to get caught on the caliper frame. The pad has semi-deep wear marks from the piston trying to get it through the caliper, and the pad must have been flexing and partially making contact. When I put the inside pads on I wasn't underneath, I did it by feel. Since it was my first time I didn't know any better.

Old pads are back on and the car is braking/stoping as it should and the pedal only has ~5" of play instead of a foot. What an experience -- thanks everyone for your help!

sciontc_mich

^^ after reading all this, yes you did everything correctly! I was commenting about the min level of the brake fluid, which of course you didn't go below when bleeding, so everything you did was correct!

what is with this place sending you xa, xb parts? lol. completely different. I'm glad you didn't drive long on that incorrect setup! Whew! I'd definitely get your money back from that place, or are they replacing the incorrect part?

JL514

Just remembered I should update this thread. I sent a slightly sarcastic email to the effect that im down $50 and in the same place i was weeks ago (needing brakes) except I was the proud owner of prius brake pads. Received this response:

The correct pads arrived but i have been having one hell of a work week... and it snowed in NY yesterday. SNOWED. Hopefully I'll get a nice, warm day to get these new pads on. Thanks again everyone