front brakes seem weak after new pads

3033 Views 15 Replies 8 Participants Last post by radamm, Jul 20, 2011

mcola

Discussion Starter · Jul 19, 2011

I just put new front pads on my 87 Quad because they were squeaking and low (about 15% left). Now brakes seem weak.

I should mention - I took drive side pads out and compressed the piston to find the replacement pads were wrong. Put the original pads back in and pump the brakes to seat the pads. Took car for ride and car was pulling to passenger side (side I never touched). Next day put new pads in and now car doesn't pull but brakes seem weak.

Don't see leaks anywhere. I think the car didn't like having the piston fully compressed and then brakes pumped to force the piston back out that much when I put the original pads back in.

Plan on purging all the existing brake fluid because its really dark, and wonder if doing this and bleeding them all will give me better feeling brakes. Also manual says to bleed front and back simultaneously on one side and then go to the other. Whats up with this? Normally you do one at a time working from furthest to closest.

Thanks.

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JoeCab

· #2 · Jul 19, 2011

Does it feel like you have a spongy pedal (air in the lines) or a good, hard pedal but the car isn't stopping well?

Bleeding brakes is always a good idea, you should do it at least every other year.

But if the pedal has good feel but the car doesn't stop well, my bet is you need to properly bed in the new pads.

bianchi2

· #3 · Jul 19, 2011

1 you replace both front's or rears at the sametime, not just one side... 2 bed your brakes in 4-5 stops, 60% pressure from 50 mph to 10 mph , will bed them in.. at this point, not trying to be rude.. i really do not think you should be working on your brakes,, if you mess up a tune up, it won't kill you, you mess up the brakes, it will kill you..as for bleading the brakes right rear first, left rear, right front, left front, repete 1 time, but at this point, perhaps you should have someone else take it over,, at best you might be out 100-200$, at worse badly damaged alfa spider, and poss. DEATH ..

mcola

Discussion Starter · #4 · Jul 19, 2011

Not sure I'd say they feel spongey but the pedal seems a little low and not very assuring feeling. I plan on replacing the fluid anyways, but can't see how I might have gotten air in the system. What should I do to "bed" the brake pads. Somebody told me that when I pumped the piston out that much, I could have set off an internal valve in the master and the master needs to be bleed?

mcola

Discussion Starter · #5 · Jul 19, 2011

Bianchi1 I appreciate your concern. I had every intention of doing both sides of brakes at that time, but after trying to do the first side I noticed I was given the wrong pads. So I threw the original pads back in until I got the correct ones which was the next day. I put them in because I wanted to take the car around the block to get a feel for front shocks that I put in at that time. I certainly didn't go joy riding. Anyone that would purposely do one side of brakes (not sure why) needs to have his head examined.

Andrew

· #6 · Jul 19, 2011

It does take awhile for new pads to bed, especially if you don't surface your disks.
Andrew

bianchi2

· #7 · Jul 19, 2011

just making shure that you wer'nt going to get hurt.. i have seen folks taking apart the calipers to put new brake pads in..darwin award time. or new folks for jerrey springer, ever notice the closer you get to wal-mart the worse driver get?

Saar

· #8 · Jul 19, 2011

Andrew said:
It does take awhile for new pads to bed, especially if you don't surface your disks.
Andrew

+1.
You may have to sand your disks, or give it a little while.
Saar.

alfaparticle

· #9 · Jul 19, 2011

If the disks are worn and have a ridge, then the new pads may be riding on the edge of the ridge. If that is the case you should get the disks resurfaced or replace them (or you could shave the edge of the pads that are riding on the ridge.

mcola

Discussion Starter · #10 · Jul 19, 2011

Thanks for all the advice. I plan on replacing the brake fluid and bleeding the system in the next couple days (the car isn't a daily driver), and if that doesn't work, maybe I'll give it a couple more rides to break them in. Otherwise, I might go back in and see if cleaning the disc helps. Starting to wonder if this problem is just in my head, and because I changed the pads was expected much better brake performance and when it wasn't, I started thinking it was worse, and its really about the same (mind over matter). Thanks again.

mcola

Discussion Starter · #11 · Jul 19, 2011

Regarding my question about the bleeding procedure... as I mentioned the manual says to do front and back on one side simultaneously and then do the other side front and back simultaneously. I've never heard of this. One of you guys replied the process that I'm familiar with (furthest to closest - pass rear, driver rear, pass front, driver front). Any idea why the manual says what it does and if anyone has followed the traditional method and run into any troubles. Its certainly easier to do the traditional method - one at a time. Thanks.

Andrew

· #12 · Jul 19, 2011

So you can get full piston travel each time. If you do just front or rear, you're opening only one circuit in the dual master cylinder (pistons one behind the other). In the long run, it hasn't made much difference for me whichever way. Especially with a power bleeder, no pumping is necessary; hook up the bottle, pressurize it, open one bleeder at a time. Saves wear and tear on the MC and the person pressing it.
Andrew

radamm

· #13 · Jul 19, 2011

The advantage of doing one side at a time is you are not likely to trip the pressure differential switch.

mcola

Discussion Starter · #14 · Jul 20, 2011

Radamm or somebody else, can you explain the "pressure differential switch".

I replaced all the brake fluid and bleed all the brakes (furthest to closest calipers) and the pedal feels a touch better. But I've also driven the car a bit more and broken in the pads more. I think it was just a matter of needing to brake in the pads, and I should've scuffed up the rotors.

86spider

· #15 · Jul 20, 2011

Check out this for the Brake Pressure Differential Valve/Switch

http://www.alfabb.com/bb/forums/alf...ta-sedan-other-bloody-brakeline-problems.html

radamm

· #16 · Jul 20, 2011

I think you have gotten to the crux of the problem by allowing the pads to break in. I usually turn the rotors to achieve a fresh surface which aids in the bedding process. If you use the method Bianchi1 suggests, make sure to let the brakes cool a little between applications. "Normal" driving usually works great for the break-in period.

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