Soft/Weak braking after brake pad change?

[wildo]

I changed brake pads on all four corners this weekend. Went for a drive after and it seemed little weak, but I figured it was just the pads burning off a protective coating (which was just a theory, I don't really think pads ship with any coating on them...) and maybe just seating themselves.

Anyway, drove to work today, hit a decent straight-away, got to 65mph and slammed hard on the brakes. It barely threw me forward-- just came slowly to a stop! So yeah, something is wrong...

I thought that maybe I'd busted an ABS sensor, or broke one of the ABS wires running to the hub, but I've eliminated that theory by 2 methods: 1) the car is not pulling under heavy braking, and 2) I removed the ABS fuse (disabling the system) and I still have soft breaking.

I did not open the brake fluid system, and didn't have spongy brakes prior to the change, so I don't see any reason to bleed them. The reservoir is also full, and I really don't think there is air in the system.

Finally, I noticed that the brakes get REALLY hot under heavy braking. Hot enough to smell them in the car without even trying. I do experience some nose-dive, so I think that the fronts are at least partially working...

One last test that I did- I went about 10mph, and pulled the e-brake hard. It barely caused a change...

So I guess my two questions:

1. Is it possible that my fronts are working, but the backs just aren't? (Do the backs really supply that much effort?)
2. Can anyone think of anything else that it might be? Remember- the car is not pulling under braking- so it'd have to be a system-wide problem)

...the only thing I can think of at this point is that I need to readjust the rear calipers by tightening the hex bolt. I'd think that the e-brake should have more effect than it currently does...

 

[RWatters]

What pads did you use?

Some pads when brand new require a bit of a break in and can be VERY soft at first until they are fully broken in. I had that problem on an older Sentra I had. After a day or two of driving they felt great.

 

[major error]

Did you remember to clean off the rotors? They all ship with a protective oil film...

 

[wildo]

What pads did you use?

Some pads when brand new require a bit of a break in and can be VERY soft at first until they are fully broken in. I had that problem on an older Sentra I had. After a day or two of driving they felt great.

Just OEM ones from autoparts store. Nothing fancy.

Did you remember to clean off the rotors? They all ship with a protective oil film...

I didn't replace the rotors, they were in fine shape.

 

[TheMAN]

HAHAHAH there's your answer

you get what you pay for in brake pads... cheap vatozone pads will get you bad performance/killed... they are NOT OEM pads

OEM = original equipment manufacturer, that means STOCK... that means what you buy from the dealer or whoever originally made them

what you got are aftermarket stock replacements, which are CRAP 9/10 times

 

[wildo]

Cheap? sure... Crap? Perhaps a bit extreme. There shouldn't be anything wrong with replacing pads using ones purchased from an autoparts store. LOTS of people do this on a daily basis.

I agree- I'm not looking for aftermarket performance. But when I slam on the brakes, I expect them to actually stop me. And if I removed the ABS system- then I expect them to lock up. Neither of these things are happening...

 

[evilmonkeyMSP]

Auto parts store brakes = poo poo

 

[TheMAN]

Cheap? sure... Crap? Perhaps a bit extreme. There shouldn't be anything wrong with replacing pads using ones purchased from an autoparts store. LOTS of people do this on a daily basis.

I agree- I'm not looking for aftermarket performance. But when I slam on the brakes, I expect them to actually stop me. And if I removed the ABS system- then I expect them to lock up. Neither of these things are happening...

so if people jump off a bridge, it's ok for you too then right?

you're right there shouldn't be anything wrong, but what you're thinking is idealistic... reality is, most parts sold at parts store are garbage... they either don't fit right or work right

I have installed MANY aftermarket brake pads on MANY cars before, and I'm telling you that none of them ever had the same performance, feel, wear rate, dust rate, and noise rate as the OEM pads

I didn't think you want to have racing brakes either, but the fact remains that what you put on are crap and if you want your brakes to work right, you'll need to buy the ones from mazda or order in akebono pads (which is the OEM supplier for mazda) which are near impossible to find anywhere locally



bottom line is, just because the parts store sells them, doesn't mean its safe... there's very little government regulation in the US to persuade vendors/makers to supply parts that have equal performing characteristics as factory on the bare minimum (unless you "upgrade" to "premium" pads which are only slightly better than the cheapest s***)... europe has strict regulations regarding what parts can be legally sold thus ensuring safety of using those aftermarket parts

 

[major error]

I didn't replace the rotors, they were in fine shape.

Putting pad quality aside, even if you didn't change the rotors, some prep is still required.

The pad works by initially putting a thin transfer layer on the rotor as part of the break-in...
When I changed my pads and rotors, the directions from the manufacturer (Hawk in this case) specifically stated to completely sand the braking surface if installing them on a used rotor.

Also, there is a break-in procedure. Instructions may vary, but usually follow the pattern of many hard-slows (not stops!) then leaving the car chocked to let everything cool off.

 

[TheMAN]

usually used rotor buffing/cross hatching isn't required if you didn't turn them.... I replaced pads before without touching the rotors too.... drove up and down the street and bed them just fine

 

[Maxx Mazda]

Sorry Edwin, that's a no-no. I'm sure they worked "just fine" for you, but you always need to (or should anyway) resurface the rotors in some capacity. Simply dropping on new pads won't cut it. Look at a brake rotor under a microscope and see all the little grooves and valleys. The new pad now has less surface area to work with, as it's not shaped to the rotor and will ride "on top" of the grooves.

You never change pads without resurfacing the rotors.

 

[TheMAN]

you can if the rotor isn't warped and majorly grooved

rotor turning isn't required despite what every shop out there does! they do it because they can make better money and reduce liability of rechecks!

but go to tech school and you'd learn something instead of saying I'm wrong

 

[slavrenz]

Auto parts store brakes = poo poo

Full ceramic "Adaptive One" brake pads from Napa (about $90) are definitely not poo poo. They dust about 1/2 as much as the OEM pads and give great performance out of the box.

 

[TheMAN]

they cost just as much as the OEM pads, might as well go OEM since it's guaranteed to fit and work SAFELY for our cars!

the OEM pads are semi-metallics... I prefer them over ceramics

 

[wildo]

This issue has been resolved.

There's a couple things you guys didn't catch- and I want to post them in case anyone else runs into this. One should check the vacuum line to the brake booster. One would also want to check to make sure they didn't "glaze" the pads by doing a very hard braking initially. You could check this by removing the pads and checking if the braking surface is dark and shiny.

On to my problem- Though I did pump the brakes after installing the pads, it seems that I didn't have fluid built up in the cylinders. If you were to think of the braking system as a hydraulic floor jack (where the handle is your brake pedal, and the jack point is your caliper piston) then you can see that to get the jack to a certain height, it might require n number of pumps. This is also true when changing your brakes. You compress the caliper piston entirely so that the new pads fit, but in doing so- you are pushing all of that fluid back into the master cylinder reservoir. Remember that the brake pedal only moves a finite amount of fluid. So in order to get the caliper pistons back into their working range, it's required that you pump the fluid back in... Until you get built up into the piston to the point where the resting point of the piston is just shy of the rotor (where the pad is just shy of the rotor actually) then you aren't going to have much braking power...

So pumping the brakes a number of times get me back into a working state. And imagine that- my Advanced Auto brake pads actually are capable of stopping the car.

 

[RWatters]

Of course they are. Hell I tracked a car on Duralast pads. They weren't the best but they were better than a set of worn-down stockers. They may not be OEM "awesome" but they'll get the job done. (rofl2)

Thanks for the quick writeup by the way. I just ordered some Pro-Quiets from Tri-Point and will be doing a brake job on my fianacee's Protege5 here in a week or so.

 

[slavrenz]

This issue has been resolved.

There's a couple things you guys didn't catch- and I want to post them in case anyone else runs into this. One should check the vacuum line to the brake booster. One would also want to check to make sure they didn't "glaze" the pads by doing a very hard braking initially. You could check this by removing the pads and checking if the braking surface is dark and shiny.

On to my problem- Though I did pump the brakes after installing the pads, it seems that I didn't have fluid built up in the cylinders. If you were to think of the braking system as a hydraulic floor jack (where the handle is your brake pedal, and the jack point is your caliper piston) then you can see that to get the jack to a certain height, it might require n number of pumps. This is also true when changing your brakes. You compress the caliper piston entirely so that the new pads fit, but in doing so- you are pushing all of that fluid back into the master cylinder reservoir. Remember that the brake pedal only moves a finite amount of fluid. So in order to get the caliper pistons back into their working range, it's required that you pump the fluid back in... Until you get built up into the piston to the point where the resting point of the piston is just shy of the rotor (where the pad is just shy of the rotor actually) then you aren't going to have much braking power...

So pumping the brakes a number of times get me back into a working state. And imagine that- my Advanced Auto brake pads actually are capable of stopping the car.

Sorry man, I don't quite buy that - I think you were just having more of an issue with your pads taking time to bed. There is no way that several days of driving and braking wouldn't have fully seated your caliper pistons against the brake pads.

I'm glad your issue is resolved, but there are people on this forum (not me! ) who have had decades worth of experiencing working on cars, and if pumping the brake pedal was even remotely a viable solution, it would've been mentioned.

 

[slavrenz]

they cost just as much as the OEM pads, might as well go OEM since it's guaranteed to fit and work SAFELY for our cars!

the OEM pads are semi-metallics... I prefer them over ceramics

Potatoe/Potato They each have their pros and cons.

 

[wildo]

Sorry man, I don't quite buy that - I think you were just having more of an issue with your pads taking time to bed. There is no way that several days of driving and braking wouldn't have fully seated your caliper pistons against the brake pads.

I'm glad your issue is resolved, but there are people on this forum (not me! ) who have had decades worth of experiencing working on cars, and if pumping the brake pedal was even remotely a viable solution, it would've been mentioned.

Instead the solution was to return the "crap" autoparts store brake pads that couldn't possibly have worked...

 

[TheMAN]

This issue has been resolved.

There's a couple things you guys didn't catch- and I want to post them in case anyone else runs into this. One should check the vacuum line to the brake booster. One would also want to check to make sure they didn't "glaze" the pads by doing a very hard braking initially. You could check this by removing the pads and checking if the braking surface is dark and shiny.

On to my problem- Though I did pump the brakes after installing the pads, it seems that I didn't have fluid built up in the cylinders. If you were to think of the braking system as a hydraulic floor jack (where the handle is your brake pedal, and the jack point is your caliper piston) then you can see that to get the jack to a certain height, it might require n number of pumps. This is also true when changing your brakes. You compress the caliper piston entirely so that the new pads fit, but in doing so- you are pushing all of that fluid back into the master cylinder reservoir. Remember that the brake pedal only moves a finite amount of fluid. So in order to get the caliper pistons back into their working range, it's required that you pump the fluid back in... Until you get built up into the piston to the point where the resting point of the piston is just shy of the rotor (where the pad is just shy of the rotor actually) then you aren't going to have much braking power...

So pumping the brakes a number of times get me back into a working state. And imagine that- my Advanced Auto brake pads actually are capable of stopping the car.

your brakes isn't a hydraulic floor jack

when you push the brake piston back in, there is still fluid inside the piston... how the hell can air go in? you pump the pedal after installing the pads the first time ONLY because there is a massive gap between the brake caliper piston and the brake pad... there is no contact on it... pumping it makes it adjust to the new pads, thus removing this gap! it ONLY takes 1 pump to do this unless something is horrendously wrong with your brake system!


you have much to learn about brakes