Drum brakes - do you disconnect the parking brake cable?

Are you *qualified* to judge?

Someone is way too anal to be a mechanic.

Best you toddle off and pay those inflated prices. THE OEM Toyota ones will be exactly the same friction rating as the ones you are replacing.

Um... you just proved my point. There's no spec for scoring and grooving in that PDF.

And in *anything* on a car, there is no such thing as 0 tolerance. It just doesn't exist. 0 may be 0.090 or it might be 0.001 but it's never going to be 0 on anything.

Specifically "free of scoring" is not a spec for how thick the scoring can be. (Yes, I know you *intimate* zero, but 0 inches is not the OEM spec, as I've seen OEM specs when I looked. They're hard to find, but they're nowhere near 0 inches).

I'm not chastising you for finding that PDF, as I know it's nearly impossible to find any manufacturer's spec for how thick a groove or scoring can be before it's rejected - but when you find the spec (as I have in the past), you'll be shocked how deep and wide the grooves can be and still be within manufacturers' specs.

Um... this proves point also, which is that there is no spec in there for scoring or grooving other than 0, which is a ridiculous number that isn't the manufacturer's spec.

Again, I'm not chastising you for finding out what I already knew to be the case, because I too looked and it's not easy to find a spec but when you find it, you'll be amazed how wide the grooves can be and still be within the manufacturers' specs.

Ch 8 Drum Brakes wasn't visible to me when I looked.

Again, this proves my point. Unless you actually believe 0 is the spec, but I already know, from my past searches years ago, that it's huge, so it's not even close to zero.

I see your words and I believe it says that but it's not a manufacturer's spec.

Now, I did look it up only for the rotors because the vehicle didn't have drum brakes, so, maybe drums are different - but that doesn't change the fact that none of these are Toyota specs.

Um. Again, it proves my point, saying only that "Minor pitting and scoring are acceptable as long as the grooves are not too deep and can be removed by resurfacing."

As in the other PDFs, that implies 0 but it's just not 0 IMHO. I may be wrong for drums, because what I looked up was the manufacturer's spec for scoring of rotors - but the scoring limit for rotors is *huge* so why would drums be different?

Maybe drums *are* zero (I'm not saying they're not); all I'm saying is that you and I both know that it's damn hard to find the *manufacturers* spec for the depth and width of a scoring that will fail a drum.

To be clear, I'm not trying to argue with you as you found exactly what I found, which is that it's damn hard to find the manufacturers' spec for the size of scoring where it's *easy* to find their spec for the diameter and other things.

That last article does say the following: "One way to tell if the surface finish is in the recommended range of 80 microinches or less"

Ok. That's 80 millionths of an inch, or 0.000080 inches, but that's the overall "roughness" factor and not scoring per se. And, notice it's not 0 simply because nothing in a vehicle is at 0 tolerance.

My main comment stands which is that, at least for rotors, scoring has to be huge to fail a rotor, according to the specs I don't have now but that I unearthed in the past from a vehicle manufacturer.

Whether rotor scoring is similar is unknown to me but it's a good question of what Toyota things is a scoring limit. But really this is theoretical since I'm keeping the drums as they're in fine shape with no "visible" scoring.

There are no asbestos brake linings available so everything else now is similar and adequate.

Clare Snyder posted for all of us...

I predicted this would happen...

Clare Snyder posted for all of us...

Hey Madman, have you checked the hoses yet? Don't bother with pix.

If simply responding truthfully, and providing referenced facts for my response is bothering you, I'll drop out now.

I do thank those who provided advice, and I comprehended *all* the advice, all of which was helpful.

Mostly to Clare Snyder, I appreciate his advice, born of experience, where he is correct that pretty much any shoe that is OEM quality will work unless they lie and, to Clare's point, the specs can lie too.

To Clare's point on the gouges, let's forget about that since the actual spec from the manufacturer is almost impossible to find, and all that Clare found essentially said zero (where to them, zero is 0.000080", which is pretty darn close to zero, I agree).

Besides, my drums are fine so the gouges are just an aside where I merely state that finding a manufacturer's spec on them for *rotors* is damn near impossible (but it can be done) and when I did that, I was shocked at how huge they were (for rotors!). I never found a spec for drums so I'll stick with Clare's "zero" for now - which is fine.

Regarding the cylinders, I saw the post of "how would you know", where that's a question that is actually insinuating more than it's asking - but the direct answer is so simple that everyone already knows it.

1. Visual inspection
2. Mechanical inspection
3. Measurements

That's how you know *anything* needs to be repaired, so the question is moot, as you can't do #3 or even much of #2 or #1 without taking it apart and if you take it apart, you may as well rebuild it, which is likely what I'll do.

Regarding the procedure, I think I have it down now, where all I need to do is do it, so there won't be much (if anything) to report back until I buy the pads, the repair kit, and do the job.

Thanks for all your advice and help, and please do realize that my only differences with Clare are that he trusts certain things more than I do and I trust certain things more than he does - but I understand and agree with all his points.

I will chide anyone who puts "E" pads or shoes on a vehicle, and I always have, since E is the friction coefficient of steel on steel (that's a fact).

Nothing wrong with E pads if E is the OEM pad, but if the Oem pad is F, G, or H, (most likely F though as G and H are less common), then putting an E on is below the manufacturer's spec.

The nearest Toyota is 50 miles round trip, so I am on the phone with dealer after dealer trying to get just one of them to open up a box to tell me what is printed on the shoes. I'll report back what they tell me if I can convince one of them to open a box and look.

Thanks! If I don't report back - it will be because I have no new information for you. Thanks!

Hi Tekkie, Thanks for your advice. Please see my detailed response to your other post.

As for hoses, I'm not trying to overhaul the vehicle - so I haven't checked anything.

In fact, I wasn't even looking for brake issues, because the owner didn't report any brake issues. I was simply rotating her tires for her, and since I had the wheels off, I popped the pins out of the rotor to look at the pads in front and I pulled the shoe off to look at the shoes in the rear.

So, my main goal is just to refresh the pads and shoes, but it's sound advice when I do the job on a weekend to check her hoses and cable for fraying.

So what I'll do, as per your helpful advice, is buy the pads and probably the rebuild kit, and then when I do the job, I'll inspect from the front to the rear all the cables and hoses.

I'll also order a liter of DOT4 fluid (even though it only specifies DOT3), and I'll borrow her kid and replenish her entire brake fluid until it is all new too.

Thanks for the advice.

Remember, none of us differ except that I seem to be caring more about friction for friction materials while others care more about it being the OEM spec - both of which aren't necessarily different.

However, if the OEM spec is E, I will likely refuse to put them on the vehicle as I have never put anything less than F on any vehicle.

I called Rock Auto but they don't do any customer support over the phone. I called three Toyota dealers, all of whom refused to provide the information printed on the pad.

One said "come down and look" but they're 50 miles round trip, so I'll try at the computer first and let you know as the friction coefficient is the most important job of friction materials.

I found a clue to the J866a OEM friction coefficient on Amazon.

I looked at the zoomable photos on Amazon, where out of about a score of choices for the specific vehicle entered, 3 of the photos had the J866a numbers visible which are legally mandated to be printed in every shoe.

All were SAE J866a FF friction ratings. E = 0.25-0.35 F = 0.35-0.45

Because if there is scoring that cannot be polished out by hand the drum MUST be refinished or replaced. There is no spec because there is no tolerance for scoring or grooving. If you can feelit - it fails. Period - end of discussion.

no - the spec you talk of is how deep the scoring can be and still be correctable, not acceptable - you can machine uot deep scoring as long as you don't excede the machining limit, which is generally about 30 thou less than the discard limit - but on the heavy drums of a 4-runner or land cruiser, is equal to the discard limit.

Give me proof

Give me proof.

. Because there IS no spec.

It IS different. There is NO spec for drums. There IS a spec for rotors, but even there, the spec is for "in service" rotors - not for pad replacement.

meansd you don't have to throw them away if they can be resurfaced within spec. It does NOT mean they can be returned to service asis with new friction material>

Because drums are not rotors and you are reading the rotor spec weong.

Because, as I said, there IS NO SPEC other than if it cannot be polished out, it should be resurfaced, and you cannot reserface beyond the machining limit, which is GENERALLY less than the in-service wear limit

And seldom is a tolerance plus or minus 50% - so that leaves you, at the outside, with 120 mict=roinches with a "50%/-0 TOLERANCE.

With rotors directly exposed to road grit, stones, ets it is obvious they WILL suffer some scoring in use, wheras drums, being enclosed should not. WHAT is going to cause scoring in drums?????

And the spec for rotors is for in-service failure - NOT for tolerance for replacing friction material.

If rotors are scored, you don't get full friction surface engagement, and the "high spots" overheat as they wear in - then when wornin the surface area increases by the annular surface of the groove, and the friction co-efficient of the pads to rough rotors is different than the co-efficient oif friction with proiperly machined rotors (and glazed rotors are different again)

For someone so fixated on friction ratings, you are certainly missing the point on damaged rotors and drums, which have SIGNIFICANT effects on the friction effects of the brakes.

I'm going to step right out and say it - you are an IDIOT if you cannot grasp the significance of what has been said, bothabout friction materials and rotor/drum condition.

Your drums did look OK in the pictures. Now just buy the OEM SPEC linings and get it done!!!! - and before you install the drums on the new shoes DEGLAZE THEM WITH 80 GRIT ABRASIVE PAPER tocondition the surface to properly break in the new friction material.

Some garden vegetables concentrate trace elements to a possibly significant degree. That said, the guy who calls a restaurant asking for today's spectrograph analysis of the salad gets a click to dial tone. And rightfully so.

Mad Roger posted for all of us...

Hmmm, all this have a 589 part number, what conclusion can one draw?

Wow. That's a great point. You are perceptive since I didn't even notice that. There is a PDF that the US government puts out every few years that must contain a lookup for *every* brake shoe or pad ever sold in the USA for passenger vehicles.

I'll see if I can find it on the net because it allows us to cross reference a full number (like the Centric CEN11005890-110AA1436-FF-14-N16) to the actual manufacturer (which might not be Centric who themselves may not even make shoes as it may be a re-brander just like Axxis and PBR are exactly the same pads).

The PowerStop number doesn't look like the full number, so I'll skip that.

But the Bosch number looks like a full number at FB0589-80S?-584-FF-N14-0709.

Here's an older listing from 2011 titled: AMECA Compliance List of Automotive Safety Devices: Friction Material Edge Codes(TM), May 2011 It's 176 pages so I'll go through it to see if I can find out more information about the Toyota OEM friction ratings, but I'm pretty sure that it's getting to be a safer bet that they're FF rated shoes.

I haven't been able to find a *newer* friction-codes document yet though.

You bring up a good point which is the "discard limit", where I never delved into whether the number given is the number that you start with or the number that you expect to end with.

I always assumed it's the start limit (but it might not be).

For example, these rotors say 297mm maximum diameter.

Even if a drum passed all other tests...

- If the drum measured 297.1mm in diameter, it would be discarded.

- But what if the drums measured 296.9mm in diameter?

I'll have to dig that up separately as it's on a car I don't even own anymore so I have to dig up the spec for the rotor grooves.

But even if I have trouble finding it, may whole point is that it's almost impossible to find a MANUFACTURER's SPEC for groove thickness failure.

(I understand your point that it's assumed it's zero.)

That may very well be the case, so let's table this until I can dig up the spec I found on an older vehicle.

I'm not sure what you mean by "in service" rotors. Is that just an inspection of the rotors without a pad replacement?

Both may be true.

Good observation!

Another good observation.

Yet another good observation.

Thanks for that advice. I am honing in on the friction rating for OEM being FF, but that's not definitive yet.

That's interesting. Thanks for the advice. I never deglazed a rotor before. I do the standard multiple-60-to-10mph stop that everyone does to bed them.

Thanks for the advice! You pointed out things, as did Tekkie, that I hadn't thought of. Much appreciated.

o thios is not your own vehicle and you are doing brake work on it?

Ihope to hell you have good insurance!!!!!!!!

Call your insurance company and tell them what you are doing. It is ILLEGAL in most provinces and states - and financially VERY dangerous foran unqualified person to do safety related repairs on a third party's vehicle.

Then you are CRAZY as MOST vehicles come with ee, or at best EF brakes standard equipment.

Pay up your insurance first - this is a third pary vehicle - you need a commercial garage policy to cover your liability - and as a non qualified mechanic, good luck getting insurance. If something goes wrong aznd someone is killed, or worse yet maimed for life, wheather the brakes actually CAUSED the accident or not, you will be fighting an expensive lawsuite - even if you win, it will cost you BIG TIME. -

ANd yet even police cruisers come from the factory with EE pads - according to the information you provided.

Don't know about you, but those sure don't look like "disc brake shoes" to me!!!!

And they couldwell be "stock photos" too - not necessarily what youare buying. You are putting a lot of "trust" in Amazon.