Please school me on brakes

"nj959" (nj959) 08/13/2018 at 14:49 • Filed to: None

1

19

I put new rotors and pads on my Jeep this weekend, and while they work way better than the old ones, the pedal does feel a little... strange. The brakes engage very early in the pedal’s travel (way earlier t han they used to), but the pedal just feel s a little... soft maybe? The brakes bite just fine, but the pedal just feels really easy to press. I did bleed/flush the brake fluid, so could this be a symptom of air in the lines? Are there any tell tale signs of air in the lines beyond “pedal feels different”? I’ll probably end up blee ding them again just to be sure but I’d love to hear if anyone has any thoughts on the matter.

Michael > nj959 08/13/2018 at 15:01

1

Did you open the bleed screw as you compressed the pistons to keep all the dirty fluid from pushing back up through the lines and into the ABS pump?

nj959 > Michael 08/13/2018 at 15:08

0

I did not, however the fluid wasn’t that old so it wasn’t too dirty.

Spamfeller Loves Nazi Clicks > nj959 08/13/2018 at 15:15

0

ABS pump needs cycled. Stab brake pedal three times very quickly, listen for loud buzzing and feeling the brake pedal shove back at you.

itschrome > nj959 08/13/2018 at 15:19

0

No I’m no mechanic,hell I couldnt even play one on tv. But I have had this happen before when I’ ve done my brakes. I’m not sure what I did wrong regarding bleeding but all I did to fix it was to bleed and top it off some more.

merged-5876237249235911857-hrw8uc > nj959 08/13/2018 at 15:49

0

Might just need to bed in the new pads too. Some good hard stops from highway speeds to heat them up a bit and then a nice drive afterward to cool them off.

The cloverleaf interchanges work great for this. Never need to fully stop.

Also wouldn’t hurt to power bleed the brakes if you have access to a motive power bleeder.  

LOREM IPSUM > nj959 08/13/2018 at 15:50

0

Not a mechanic, but:

Engagement point sounds normal after new brakes, everything being essentially pushed back in an inch or so. Stands to reason anyway.

Wouldn’t expect any added squish if you didn’t open the bleed screws, because no air should have been able to get into the system under those circumstances. Pads might just not be fully bedded in yet, so incomplete friction surface mating is a possibility, or the p ad compound could be substantially different than you had before which can make a night an d day difference in brake feel.

I’d say take it in somewhere if you have doubts, but unless it’s a shop you know well and trust fully they’re probably going to give you some horseshit about needing a new master cylinder or something, because tweaking DIYers work makes them want to teach you a lesson.

Future next gen S2000 owner > nj959 08/13/2018 at 16:22

0

Do that. The fluid absorbs water. Get the dirty out. Brakes will feel much better. Most likely some air in the system. 

nj959 > Future next gen S2000 owner 08/13/2018 at 16:30

0

I did bleed them afterwards , I just didn’t open the bleeders when I was compressing the pistons.

nj959 > Spamfeller Loves Nazi Clicks 08/13/2018 at 16:30

0

I will try that.

nj959 > itschrome 08/13/2018 at 16:31

0

Yeah I’ll probably just end up bleeding them again.

dogisbadob > nj959 08/13/2018 at 17:30

1

speed bleeders are awesome

None of your business > nj959 08/13/2018 at 20:00

0

Im a little confused. You said that you bled the brakes, but later said you didn’t open the bleeders?

Hred my procedure.

1st make sure ur reservoir is full

2. Have helper with the car off, pump brakes 3x hold brakes, while holding the brakes open bleeder. Promptly close the bleeder and then helper releases foot off of brake.

Mke sure you go in the following pattern, I’ll explain why after.

Pssenger rear

Driver rear

Fromt passenger

And then front driver

Do this with the cap off!

Sometimes you get lucky and if the air bubble is close enough to the reservoir, it will burp it out when helper is pumping via the reservoir.

Aso doing it in the pattern as I highlighted, you’re routing the air forward out of the system.

If you still have air, go the route of gravity bleeding it. Do one caliper at a time and go in the pattern listed above.

Make sure the reservoir is full with the cap off. Put clear hose on one end of the bleeder and the other end into an empty bottle. Simply open the bleeder and leave it open for about 30 seconds. While the bleeder is open do not touch the brakes!

Mke sure you’re keeping an eye on the reservoir and don’t let it get low, you don’t want to introduce more air. Keep an eye on the clear tubing. Most time you will see the air b ubble come out. Go one wheel onto the next. After you’re done turn on the car, pump the brakes until you get pressure and then keep your foot on the pedal for a minute pressed down.

these methods work the vast majority of the time. If not, you definitely have a ton of air more than likely in the abs and then will need to go the route of activating the module.

If you have the tech software you can do it via that method. If it’s a VAG vcds has the option to do this.

If you decide that you don't want to pay someone for the software like the dealer or mechanic, you can go the poor man's route.  Find a dirt road, bring it up to speed and slam on the brakes. Do this a few times.  Then go home and proceed to do the 1st bleed method I highlighted above. 

RacinBob > nj959 08/13/2018 at 20:21

0

Pull the wheels and make sure the disk pads are properly seated and loose in their slots. I once had one that was just stamped too large and wedged into the caliper. Instead of moving it was bending the back plate. A little time with my grinder and all was good.

Also corrosion on the caliper surfaces in the salty N orthland will also cause problems. Some manufacturers put a folded stainless steel surface for the pads to ride on. Nice idea but bad for up north as water/rust gets underneath the surface and pushes them up making the pads fit tight as hell. Again, if the pads are not free they will jam and give you the feeling you mention. If you have this problem, I personally have just pried off the surface and run without them. If you don’t go that route, then back to the grinder you go.  

I doubt it’s air as there should have been nothing that allowed air in during a pad change. If you want, crack all the fittings and let them gravity bleed into a rag. That’s all it takes.

nj959 > None of your business 08/13/2018 at 20:58

0

I did bleed the brakes, I just didn’t open the bleeders when compressing the brake pistons. Some people like to crack the bleeders when compressing the pistons to avoid pushing dirty fluid back into the ABS module and the master cylinder.

I bled the brakes again today and didn’t get any air at all. Really the only symptom I had was that the brake pedal was a little easier to press. I didn’t have any of the other symptoms of air in the lines (sinking pedal, long pedal travel, etc ). I think I was just a little paranoid about the pedal feeling slightly different. I think that the new brakes just weren’t fully broken in because there isn’t a great place to bed them near me (suburban nj ) so I had to do it in a parking lot. Also, the new pads are ceramic which I’ve heard feel a little different than oem pads. 

nj959 > LOREM IPSUM 08/13/2018 at 21:00

1

The new pads are ceramic, which is probably it, along with them not being fully broken in yet.

I bled them again today and didn’t get any air out. I’m pretty much ready to call it good.

LOREM IPSUM > nj959 08/13/2018 at 21:37

0

Sounds like you’re in good shape then. Hopefully the feel improves a bit, bit if not pads are easy and relatively inexpensive, worst case scenario.

What pads did you go with anyway, just out of curiosity?

nj959 > LOREM IPSUM 08/13/2018 at 21:42

1

I went with this kit since it included all the hardware and everything, plus it was a good price ($150 when I ordered it!). They seem like they’re of a reasonable quality, at least when compared to the rusty mess I had before.

LOREM IPSUM > nj959 08/13/2018 at 21:54

1

Should be all good. Afaik, Power Stop makes decent stuff.

ShockDoctor > nj959 08/15/2018 at 14:26

0

So one thing not many people realize is that brake pads are compressible . As a matter of fact everything is compressible . Now just looking at and feeling pads with your hands there is no way to perceive a difference in compressibility between different types of pads, but you will feel that in the pedal. There is a reason race pads are so expensive and there is a reason race pads are so tough on rotors. Not only is there friction higher, but they are much harder. Ask any brake pad manufacture, and they will tell you one way to measure and track manufacturing capability and part to part consistency with pads, is through compressibility testing. You’d be surprised the difference in compressibility between a high end expensive brake pad, and a cheap autozone pad. We are talking an order of magnitude difference. So everything else being the same, brake pads can have a huge impact on pedal feel beyond just bite and friction characteristics .