Issues: Post brake pad replacement

[mupmanyu]

Hi:

I replaced my brake pads with Axiss Heavy Duty pads. The work was done by yours truly.

I had the initial spongy pedal, but besides that, I seem to feel a two stage braking action, especially when I brake to a stop at slow speeds. The first stage brakes smoothly, and then there is a second abrupt braking action that makes it jerky.

What could this be? Could it be that I pushed back the pistons too much? Or, do I need to torque the caliper bolts to spec (I wasn't too particular about that)?

Any ideas?

 

[cdodkin]

I get this effect with the original brakes on my LR3 from new - so it may be a 'feature', or I may have an issue on my brakes as well.

I've just adapted to it.

Anyone else noticed this?

 

[MonLand]

What did you do to the pads before installing them?
What did you do right after installing the new pads?

We have a used 06 LR3 and did not experience what you guys have described so far. (and pads will need to be replaced in the next 2-3 months, so... who knows).

 

[mupmanyu]

Before install:

i) Applied CRC brake quiet on the metallic housing (behind the pad), for 10 minutes.

ii) Then, applied a coating of CRC brake grease on the metallic housing.

After install:

i) Pumped the pedal a few times to get the piston adjusted to the new pads

ii) Drover to 40 mph, and then floored the brakes to come to a stop. Did this 3-4 times.

That's it...

 

[jwest]

sounds like the abs sort of

 

[MonLand]

Before install:

i) Applied CRC brake quiet on the metallic housing (behind the pad), for 10 minutes.

ii) Then, applied a coating of CRC brake grease on the metallic housing.

After install:

i) Pumped the pedal a few times to get the piston adjusted to the new pads

ii) Drover to 40 mph, and then floored the brakes to come to a stop. Did this 3-4 times.

That's it...

Brand new brake pads are typically flat. Unless you replace the disks, those are (slightly?) worn and the brake pad will dig in creating a recessed area. Now, You'd think that recessed area would be a perfect brake-pad-wide groove, it's not, it's a progressive slope. Which means that if you stick a brand new pad on top of it, the pad will only touch on those two sides and not in the center.

Typically, you have two ways to "fix" this, either you take a file and you create a to "break-in" your pads before you install them so you artificially help the pads take care of the slope or you drive your truck with the new pads and lightly keep your foot on the brakes for a mile(?) or so to force the pad to wear around that progressive wear slope/groove edge.

From what I was told by my father (not sure where he got that, never tried to confirm that information neither, in those days, we did not have the Internet, you just trusted what is passed from generation to generation! ;-) ), you should not "Drover to 40 mph, and then floored the brakes to come to a stop. Did this 3-4 times.", "breaking in" the pad should be progressive, not aggressive.

If the pads are "heavy duty" (read: do not wear too fast) and are not properly "broken in", then this would explain both the "not that great braking" you experienced and the current "2 stage braking" since the pad might have to slide into the groove before it hits the flat surface and really work/brake the wheel.

 

[mbrummal]

This site has some good info on brakes.
http://www.stoptech.com/tech_info/tech_white_papers.shtml

this specifically relates to breaking in the pads
http://www.stoptech.com/tech_info/wp_bedintheory.shtml

this may shed some light on brakes.

 

[scot]

After driving enough race vehicles, I would agree with monland's assumption. The bedding surfaces are not quite matched, so you get uneven pressure. Considering that these are street use brakes, they will eventually mate themselves and you will be fine. No worries.

Try this, turn off the truck and pump a few times. Does it become rock solid? If there is any "squish" in there, you might have dislodged some air bubbles. This is NOT effective when the vehicle is turned on as the brake booster will mess with it and make it feel spongy at all times. (its supposed to)

If you have bubbles, the only answer is to bleed the brakes. Thats a bit longer of a discussion but still pretty easy. Honestly I suggest to everyone that flushing and bleeding brakes should be done once a year or two on all vehicles.