Brakes – Rotors, and Pads, and bleeding, Oh My!

[Kaz]

Been doing brakes a long time. Yet, it seems that with aftermarket products there are so many choices that they challenge what you think you know about brakes. I have an 02 Jeep Grand Cherokee WJ with Akenobo front calipers. I’m experiencing that embarrassing and annoying brake squeal that is often reported.I serviced these brakes a year ago (almost exactly 12 months).

I have two questions in my mind and so I thought I would get the folks here to weigh in before I go spending money on the wrong parts.

1. How concerned should I be with the front pad friction material – for a daily driver (city/highway) are today’s ceramic pads adequate to reduce squealing and still prevent excessive heat fade or phenolic piston wear in the caliper? I started just thinking of switching out the semi-metallic pads on the front with ceramic, but the more I read, the more unclear it becomes. Then I started reading about the proper rotor material and design – finned, not finned.. Chrysler ships the vehicle with “damped cast iron” rotors. That got me to thinking about matching friction material with the rotor. My head is spinning. Any thoughts about this?

On Bleeding… The best method I have ever found is the buddy bleeding system – that said, I’ve only connected tubing to the bleeder bolt a couple of times (with a buddy and without, per Eric’s videos) and have… well, crappy experience. Typically, when servicing brakes with the buddy system, They hold the brake down and you open the bleeder bolt until no more air comes out. Simple.

With the tubing attached to the bleeder bolt, whether it’s a buddy system or with a vacuum based bleeding kit, or with Eric’s home made bleeding setup, I ALWAYS see air in the tubing – apparently from the bleeder bolt threads. I’ve carefully tried to wiggle, loosen only 1/4 turn, put grease on the threads… and I still always get that fine stream of bubbles.

2. Is there some trick to use tubing that prevents air from the threads seeping in that I may have missed? It’s like I never know when the brakes are bled using these systems. It’s kind of making me nuts.

Ignorance WAS bliss… now, it’s kind of a PITA

Topic

[Brian]

I understand the importance of bleeding, but maybe a flush would be even better.
For bleeding, I only crack open the bleeder valve about 1/8 turn max. A friend will push long and hard three times on the pedal, the hold it while I open the valve then close it again quickly. About ten to 15 rounds of that gets out the air.
Now, the squeal can be caused due to not enough hydraulic pressure in the lines. I say that because water mixed with brake fluid causes less than adequate pressure. Is the brake fluid clear or very nearly clear? Then it’s likely good. If it looks like strong coffee or tea, then it has a lot of atmospheric moisture mixed in and is rusting the hard lines from the inside out. Time to do a total fluid flush. Buy 1 new quart of brake fluid and start with the right rear, then left rear, then right front then left front wheel sequence. Like a big letter Z. Hook up the clear tubing leading to an empty two liter pop bottle, open that right rear valve, and have a buddy do long slow pedal pumps until the master cylinder is very nearly empty. Then refill with new fluid and keep pumping until the stuff coming out looks very nearly transparent again. Do that at each corner in the Z pattern and you should notice a significant increase in pedal effectiveness.
I’ve seen people replace rotors, pads, even calipers then wonder why it still makes noise or takes forever to stop, but after a simple and cheap to do fluid flush they work fantastic. Look up the word hygroscopic. Brake fluid is strongly hygroscopic. That is why I flush all my brake fluid out ever 2-3 years.

[Andrew Phillips]

I’ve noticed that ceramic pads are noisier and tend to squeal much more than semi-metallic pads. For most daily drivers I do not see the practicality of ceramic pads since they are: more expensive, more prone to noise, and give a stiffer/harder pedal feel. Some people say the ceramic pads last longer. They may, but in my experience, they are changed out sooner due to noise and other problems rather than wear, so that argument is moot. I would go with semi-metallic pads personally. As for drilled/slotted rotors, again, that’s a luxury that a daily driver may not need. I would just go for the stock rotors. The only brake upgrades that I have ever really endorsed for a daily driver are changing out phenolic caliper pistons for steel pistons where applicable. In most cases that will eliminate fade and piston seizing issues. Aside from that, any other “upgrades” are more for bragging rights, “bling” factor, or placebo effect. Any performance gains by most of those are usually too small to be worth the price unless you go all out for the upper end brands and “racing” components which are just plain unnecessary for a daily driver. Just my 2 cents.

[Kaz]

@peshewa:

Ya know, I think you hit the nail on the head. As I said, I’ve been doing brakes a long time, and it didn’t occur to me that old saturated brake fluid could be the cause of longer pedal travel (which I never mentioned) as well as not enough pressure being applied to the pads. I’ll be changing out the fluid this evening and will report back on the progress.

@cap269:

Your logic is exactly the same as mine. I was fine with the current hardware except for the squeaking during a stop. Somewhere I thought I read that ceramics were quieter – that may not be the case, but that’s what I was willing to try until peshewa above weighed in. My brake fluid looks like coffee. That said, as a harder material, I was also concerned that it would cause unnecessary rotor wear, so I’m glad to hear your opinion on it. OEM pads are semi-metallic, and I prefer to use that.

I may have not written clearly enough about the “finned” rotors. I didn’t mean slotted – I mean the type of rotor that has fins between the inboard and outboard surface.I bought these Duralast rotors from Autozone since they had the anti-rust coating on the hat, but they are not finned, rather, they are solid.

Solid, non-finned

Finned Rotor:

Finally, caliper pistons for daily drivers seems to be like a religion – some are in the metal camp, some are in the phenolic camp. I’m in the latter. Today’s phenolic material are better than when the problems first started getting reported, but that doesn’t mean they never seize. That said, the manufacturer used phenolic pistons because they don’t transfer the heat as metallic ones do. Which is better? (shrug) Seems as though it’s a matter of opinion, and in those cases, I default to using what the manufacturer specified. It’s about tradeoff’s really.

[Ingvar]

1. Do NOT use ceramic pads. That’s main cause of squeal or rub.
2. Look at your rotors? Are they glazed? As in – looking like a mirror? Glass shiny? If yes, that’s 2nd component to your squeal.
If I am right on both cases, all you need to do is to take rotors off, take high speed grinder with rough sand paper on it to it, and take glaze off in circular motion. It’s actually much easier to do on the back side as hub hump is not getting in your way. But you should see nice criss cross from sand paper. Same principle as honing cylinder walls.
Then install decent price semi mets. IMMEDIATELY do bed in procedure. If you can’t “get around the corner” to do it, creep to proper street barely touching brakes, as you do not want to build up any pad material on rptprs at this point. Then RIP it. Get them bedded in and be happy.

[Kaz]

Well, I flushed the brake system, it was like coffee. Nice fresh, new fluid. That’s done and I feel moderately better. Still have squealing though. Even though I thought for a moment that flushing might improve either the squealing or pedal travel, it didn’t. Thanks for the suggestion peshewa.

So this means, I have to take a Saturday, and do a full service on the brakes, with replacement semi-metallic as ukrkoz suggests. Yes, I will try to remove any glazing on the rotors with some sandpaper and a battery operated drill. It may not be high enough speed, but it’s what I have. So I’ll do that, re-lube pins, and install new pads. I’ll bleed it thoroughly, as I’ve been lazy in the past.

Which brings me to an important point – so…. why are we bleeding the brakes when we replace pads? Did we introduce air somehow into the system? How? I crimp off the brake line, open the bleeder, squeeze the caliper piston, close the bleeder. Where did air get into the system? I mean, I do it as a matter of course, but this one’s been bugging me.

So now to address ukrkoz‘s suggestion of “break in”. This, my friend, seems to be a controversial issue. Below are three different (and there are many more, I assure you) web sites that all recommend different break in procedures.

http://www.autoanything.com/brakes/how-to-bed-in-brake-pads
http://ebcbrakes.com/articles/how-to-bed-in-your-new-brakes-for-streeturban-driving-2/
http://www.tirerack.com/brakes/tech/techpage.jsp?techid=85

So who’s right? 300-500 miles for complete break in with no hard stops? Or 30-40 MPH and rapid quick stops? It seems as though, this too, is a religion.

Where or where is the science in all of this? Is it all anecdotal? Do you just say, “this is what I’ve been doing for years and it’s always worked”?? Why are there different recommendations? Who’s right?

And outside of “air in the system” (cuz there ain’t), what should I be looking at to reduce pedal travel? Booster? Some line that should be tightened?

Btw, there was no commentary on finned v. non-finned rotors.

I truly appreciate everyone chiming in. Right now I’m working on what is the science, and what is anecdotal. I admit, I was poor for a couple of years and bought cheap parts that would keep the car running. Things have changed and the squealing of the brake pads is driving me nuts. I should be able to solve this. Eric’s video’s and commentary say “buy good stuff”. But whose? I’ve seen front brake pads for $80. Is that the deal? Is it always how much they cost?

[Andrew Phillips]

[quote=”SilkyTP” post=144377]Btw, there was no commentary on finned v. non-finned rotors. [/quote]
No commentary needed. You’re discussing solid vs. ventilated rotors, and the reason some are vented and some are not is for heat management. The vanes between the rotor faces can be straight or curved, some debate could be had over which is better. Ventilated rotors, or vented, whichever term you desire, are used to prevent rotor warp in vehicles expecting heavy duty service. Small cars and light trucks that do not see severe duty will probably not need them.

Much of what you decry lacking of science comes from anecdotal evidence and best practices employed by independent and dealer service shops through methods development over decades of practice. The same thing happens in physician’s offices. Although medical doctors go to school and learn about the body, most of their diagnostic practice is first learned from older experienced doctors and then refined as they go along and as they adopt industry-wide conventional best practices. You’ll see that same thing occur in most service industries. FWIW, in almost 40 yrs of servicing vehicles, I have never ‘bedded’ brakes.

Crimping the line and using care when opening the bleeder should prevent the need for bleeding, as you are correct that no air was introduced. However, sometimes !@#$ happens, so a follow-up air bleeding isn’t a bad idea, even if it’s not needed.

[Kaz]

Thanks Cap, I appreciate the reply. The vented rotors issue is now clear in my mind, so I’m grateful.

I’m also SO grateful that someone validation the logic about bleeding – that isn’t to say that I take it as support of not bleeding, but at least my thoughts about it aren’t wonky. So thanks for that.

So next, I have to try and de-glaze the rotors, and find some quality brake pads.In consideration of “best practices”, do you have any recommendations for mid-range semi-metallic pad manufacturers?

[Andrew Phillips]

Best practices are more for procedural or method based application, and do not consider brands or manufacturers. Having installed every kind of brake lining product from high-end brand to big-box store shelf brand, I can honestly tell you that while there are definitely differences, those differences are not monumental. The cheaper brands use lower quality friction material mixes that may tend to wear faster, or aren’t as carefully molded or shaped. The lower end linings can have backing plates that aren’t shaped exactly like the OEM pads and can have fitment difficulties. They also tend to have lower quality hardware such as pins and springs. I’ve had great success in the past with Napa brake parts when not using OEM. On my own vehicles, for my Toyota and Hyundai the OEM pads are right around the same price as parts store pads, so I use the OEM. I have always used Napa brake linings on my Jeep. Recently, I have also been warming up to Centric brake products. Other brands that I find favorable (and this is my opinion only and not an endorsement) are Wagner/Federal-Mogul, Brembo, and Akebono. In most cases, though, I will probably stick with Napa and OEM.

[Kaz]

Great answer! Thank you. I too have been reading about centric lately. You know for my Jeep, you can get a 4-wheel set of rotors and pads for around $120.

There’s a Napa within walking distance of my house. I know what to do now.

Thanks a ton. I will report back on the squealing after the job is done. Problem is, it’s going to be a couple of Saturday’s from now.

I truly appreciate the candid discussion.

[Kaz]

So just a follow up. I bought some NAPA semi-met pads, I know the guy there and he said they have good luck with this particular series of pads as it relates to squealing, and they were about $40. I replaced the pads, and the squealing has ceased. So “YAY” for quality pads.

I had flushed the brake fluid to try and solve a braking distance problem – it didn’t solve it, but the fluid looked like coffee so it needed to be replaced. But while installing the new pads, I discovered that one of the caliper slide pins had seized in the caliper mounting bracket. I had a pipe wrench and a cheater bar trying to work it loose – I gave up on that and bought a new mounting bracket, slide pins, and boots. Now, I can stop on a dime.

I just thought I’d post the progress and close this one out.

Thanks to all who chimed in (and those who read with some level of interest).

Peace.

[Andrew Phillips]

Awesome, glad you got it all fixed up 🙂

[Author]

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