Bedding in new brakes

So, I've heard everything from the "do 10 high speed panic stops and let them cool" to "just be easy on them" to "just drive it" on how to bed in brakes.

I've never really had an issue with new pads/rotors until now.

Bought a 1996 C1500 with a warped left disc. After looking at the paper thin pads, decided to go ahead and get new pads and rotors. (180K+ miles). Cleaned off the rotors with brake cleaner (but didn't scrub them, maybe I should have) and lightly scuffed the pads before installation.

Brakes felt fine until driving to work, yesterday. Going down a pretty steep hill they did fade quite a bit and stunk like crazy. Luckily, I was almost at work so they cooled off. Drive home seemed fine, but no major downhills. They faded again on me this morning.

Not sure what to do from here: 1) Do the high speed stops and really cook them (I'm afraid they would fade after two stops) 2) Do nothing and just let them bed in with normal driving 3) Chalk it up to cheapie pads (it's a beater truck, I didn't think it warranted EBC pads) and pay for better ones 4) Take it all apart and scrub the snot out of the rotors

Ideas?

-Rob

the goal of bedding the pads is to evenly distribute some brake pad compound on the face of the rotors.

Fresh fluid would likely help a little with the fade, but it is a heavy truck and there is a lot of mass to slow down and that generates heat. You could try shifting down a gear and letting the engine help a little with the braking down the hill.

To help get more cool air through the brake rotors, calipers and pads you may want to remove/trim any shielding behind the rotor. Change the wheels to one with a more open face or more clearance around the rotor/caliper (larger diameter wheels basically). Or even go so far as to fashion some brake ducting into the center of the rotor, but that would be a last resort for a beater truck.

It's odd, because I never noticed any fade with the old pads (although a lot of shimmy). I kinda figured it was just a big truck with weak brakes, but given that I'll be towing a small trailer with it, I hoped they would work better than this.

I'm sure I could rig up some cooling ducts pretty easily. It's a beater afterall, function before fashion!!!

-Rob

Every pad manufacturer has different recommendations based on pad compound, etc. See this article at TireRack.com for a good example. That being said, I've used the Zeckhausen Racing instructions in the past even with stock pads on my 328i and had good results. Sounds to me like the pads are either (a) really cheap or (b) really in need of having all the excess "stuff" from the manufacturing process cooked out of them some more. I'd try the Zeckhousen method to cook 'em good myself.

Scott

So, what about changing break pads at the track? I know enough people do it, and don't seem to have much opportunity to bed the pads.

I'm wondering because I have a track day coming up in a couple weeks. My brake pads are at a level where I'm not sure whether or not they'll be able to last a full track day. I ordered new pads, and figure I can replace them at the track if necessary.

Of course, I'm also switching from Hawk HPS to Hawk HP+. Does switching compounds necessitate the procedure? Might I be better off switching to the HP+ before the event, and then swapping the HPS back on afterwards, and using those up?

There are a bunch of good brake articles here: http://www.stoptech.com/tech_info/tech_white_papers.shtml

Hope that helps.

I switched from HPS to HP plus on my ZX2 and bedded them in per Hawk instructions. Works great. I'll be putting the HPS pads back in for winter driving. A major cause of brake fade is old fluid that has a lot of moisture in it.

Salanis wrote: So, what about changing break pads at the track? ... Does switching compounds necessitate the procedure? Might I be better off switching to the HP+ before the event, and then swapping the HPS back on afterwards, and using those up?

Depending on who you ask, switching compounds may or may not require bedding in if there's already brake material on the rotors. I fall in the camp that bedding in is necessary when switching compounds, although I will usually switch rotors if I'm switching compounds.

If I were you, I'd switch to the HP+ before the event (in your garage) just for convenience. It's always easier to do it at home than at the track, and the HP+ is perfectly streetable (although sometimes noisy).

When you get back home, switch back to the HPS and use them up. You might as well get your money's worth out of them.

Full disclosure: I run HP+ full time on my street/track Focus SVT, although I've thought about getting a set of HPS pads for the street because of the noise and dust from the HP+.

I have found that new pads, no matter how you bed them in, will fade the first few times you use them.

I have experienced this on 10,000mi old brake pads, when the previous owner drove like a sissy.

I bed in customer brakes by firm 40-20mph braking events followed by a casual run back up to 40, until noticable fade or brake odor. Then a drive back to the shop without touching them at all.

On personal cars, after doing that and then driving normally for about 100-200mi, I do some pretty heavy stops from 70-80mph until the brakes fade heavily, followed by a good cooldown. After that they're good to go. I find that regular abuse keeps them "tuned up", and any time someone else drives my cars, they marvel at how well the brakes work/feel. They're like muscles, you gotta use them for them to work.

I never buy anything but the cheapo green-box NAPA pads, either.

Are the pads the same as what you pulled off? They might just be crappy pads...

I've always had luck using the (IIRC) Hawk bed-in procedure: 35-40 mph down to around 15mph 3-4 times with about 15-20 seconds in between runs and then from 55-60mph down to 35-40 3-4 times, again around 15-20 seconds between runs. I'll leave the car in one gear and use my left foot for braking and right for acceleration to minimize time between runs. Try to stay off the brakes with the exception of the actual application of the bed-in. Firm braking is required.

If I'm changing pads on MY car I always use different rotors, that way I don't have to rebed them everytime I change pads and I don't have to worry about dust from different compound pads potentially f'ng up my wheels, etc. YMMV

billy3esq wrote: Depending on who you ask, switching compounds may or may not require bedding in if there's already brake material on the rotors. I fall in the camp that bedding in is necessary when switching compounds, although I will usually switch rotors if I'm switching compounds. If I were you, I'd switch to the HP+ before the event (in your garage) just for convenience. It's always easier to do it at home than at the track, and the HP+ is perfectly streetable (although sometimes noisy). When you get back home, switch back to the HPS and use them up. You might as well get your money's worth out of them.

Thanks.

This is on the Miata, which is my track/street car, and not my DD. I have not had any problems with fade or anything on the HPs pads that are on there now. I spent good money on those pads, and really don't want to throw them out prematurely.

I don't really want to swap rotors right now. Mine are in good shape still.

I think that once I use up the last of the HPS pads, I'll probably just stick with HP+ on this car.

I use the Hawk method. Not only does it bed in faster, but I never seem to get pulsation from high spots on the rotor any more. I say cook em, then let them cool down....and don't use the e-brake when you get back from cooking them or sit on the brake pedal at stoplights.

The Mag had an article on this some time back. You have to put Magic Dust on the new rotors and cook the chemicals out of the new pads.

When I did the brakes on the LS400, a big, heavy, fast car, I put new "premium" pads (Brakebest or something like that) all the way around and new rotors on the front. Initial stopping was seriously lacking. I beded them in by taking it up to 20, slowing to almost stopped as fast as I could, then 40, then 60, then 80, then 100 once or twice. By then, they were getting plenty warm. I drove around a few miles to let them cool off and it has been stopping perfectly since.

I had a problem with newly-installed Raybestos rotors about seven years ago. I called the Raybestos engineer I knew at the time, and he asked if I really cleaned the rotors. I told him I used Brakleen liberally. He told me to use Dawn and hot water. Brake problem fixed.

This was before the Chinese Rotor Invasion (somewhat caused by the company I worked for), and Raybestos USA-made rotors came with an anti-rust goop and plastic-bagged. I don't see rotors like this any more-most are Chinese, and pretty dry (somehow rust-free, though).

on that truck, you might want to look into replacing the brake hose on that side as well. the C1500 hoses have a tendency to collapse inside near where there is a bracket built onto it that can tend to "kink" or bend the hose when the bracket is bolted in its proper spot.

what happens is the hose is pinched off but when you push the pedal, fluid moves past the kink, but then can't go back up the line when you let off. the result is a dragging caliper and warped rotor. probably wouldn't hurt to replace the caliper as well since you can get rebuilt ones for all of 12 bucks and new for around 30.

Salanis wrote: I don't really want to swap rotors right now. Mine are in good shape still.

Swapping the rotors for track use has nothing to do with how good the rotors still are. There are several benefits to running dedicated rotors/pads for the track. Ease of use is one, there's no more bedding in different pads each time you change. Bed in a street set on street rotors and a race set on race rotors.

I always bleed the snot out of my brakes when I change pads. One thing to not do when replacing brakes is to force the pistons back into the caliper without opening the bleed screw. It can push trash back into the anti-lock part of the system (if you have that).

Just re-read the OP. I noticed you had one warped rotor. May be a sticking brake and i would have thrown a kit at that b*tch.

Lots of great suggestions.

I haven't had a chance to do the cook procedure. Hopefully, I can do it on the way to the track tonight.

Thought about rebuilding the calipers, but I didn't have the time at that point. Not sure why it warped as I've only had the truck a couple of weeks. Maybe it was sticking.

Thanks for the info about the pinched hose. I honestly haven't had a chance to just start going through every nook and cranny of the truck, just fixing little things as they have come up.

-Rob

when i worked at AZ, the guys with chevy trucks that knew what they were doing would almost always buy a set of pads, rotor, caliper, and a brake hose for the side that went south. the ford trucks of similar vintage have the same issue.

to hell with rebuilding the caliper, you can buy one already rebuilt for probably 12 bucks with $8 core.

Also, those trucks are notorious for the back brakes not self adjusting. Check that and make sure you're not stopping on the fronts alone.

which you do by driving in reverse as fast as possible and skidding to a stop, repeatedly.

Learned that one here. Works like a champ.

The reason the rear brakes don't adjust is usually because the self adjuster is rusted solid. Happens to everything, not just GM.

The horrible low pedal is due to the ABS, if it is equipped with RWAL. A small handful of brake line unions will solve that problem quickly.

The pedal isn't low, just the pads fading.

I knew GM truck brakes weren't the best, but didn't realize some of the issues pointed out here. Thanks for the info!

Next free weekend I have, I'll plan on a full brake go through with rear shoes (if needed), checking the lines, maybe rebuild the calipers and bleed and refill the system.

What's RWAL? It'll probably be a "duh" moment when you say it, but I just can't think of it right now.

-Rob

Rear wheel anti lock.

I've always followed the Hawk HP+ and HPS break in procedures.

4 medium stops from about 45mph 4 hard stops from 25mph

then let them cool overnight without the ebrake on. I usually chocked the tires/wheels with a board so my car doesn't roll out of my garage :)