Rotor and brakes question

KL

klahanie

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Joined
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SW BC
Looks like I missed this during my annual spring brake R and R

miJXdUU.jpg


Rear wheel, first cm of inner rotor surface is damaged (is below smooth surface plane, prob rusted and broke off). Pad doesn't look too bad, about 40-50% worn. Rear rotors are orig IIRC (7+yrs, 120K miles)

With my previous "ensure the brakes are 100%" pronouncement in mind what would be the best practice here: replace rotor, new pads, both for both rear wheels ?

Thanks for any help.

~David
 
Given the pads don't rub/stop against the disc on that area you were probably ok but, I'd replace the pads and the rotors. If you are that far into it, they aren't that expensive.
 
ditto. Any idea what caused the damage? Nothing embedded in the pad? The alternative is turning the rotors and getting new pads. Usually almost the same cost as new rotors. Remember to lube the caliper pins!
 
Yeah, figured on replacement. Guess I was hoping to have been done with brakes this year...

Vic, dunno. Maybe a rock in there + 8 yrs of rust ? I'll take a better look when it is off (fully expect it to be a bear, LOL)

Are you guys saying replace both rear rotors and pads as a match or just the damaged side ?

Thanks
 
BOTH sides... never just one! I'm cringing at the thought of one tire locking up, or the ABS kicking in on one side and preventing braking altogether!
 
Replace all the braking system parts. Does not appear to be enough material remaining on the rotors to even consider having them turned. Plus the rotors appear to be deformed, so best to replace them.

Slotted rotors are cool in both appearance and cooling. Pun intended. Yet, slotted rotors are more appropriate when you're trying to reduce weight or enhance the cooling aspect of the rotor due to heavy braking like racing. Not really necessary on trucks carrying campers. Further, slotted rotors will not last nearly as long as solid rotors.

While not a necessity, rotors should be turned (when they are in good condition) every time you install new brake pads. Not doing so, greatly reduces the life span of new pads. Pads and rotors should be mated to respective surfaces. Be sure to adhere to manufacturer break-in for new pads. Getting them too hot during break-in hardens the compounds and reduces braking effectiveness. Especially for ceramic or organic brake pads.

While you're at it, replace the parking brake cable spring and lube the cable (if possible) with dry graphite. Looks like that spring is on its last bit of service life.

From the looks of the corrosion, you must live in or drive on salted roads quite a bit in winter. If so, I would start thinking about having the axle bearing and seals inspected, if not replaced. You don't want to be out in the boonies and have a axle bearing fail.

I'm big on preventive maintenance. I'd much rather perform such in my garage then reactive maintenance trail side.
 
I disagree, I never, ever turn rotors. Doing so reduces their life and worse, reduces their mass and dimension. That lost mass and dimension is important to their proper function.

If slotted, turning them will result in chatter from the interrupted cut, and the turn-er won't be happy about what turning them does to his/her cutting insert.

If new pads w/o new rotors I use a body shop long board w/ 60-80 grit to rough up the faces of the rotor. You just need to break up the surface of the previous pad's Transfer Layer, no need to scour them within an inch of their life. A broken-up and slightly rough surface will allow the new pad to transfer its own layer to the rotor.
 
Really appreciate the prompt replies and advice offered. Would prob have let it go if was off season but now feel better about complete replace both sides. Waiting on parts now ..
 
I agree with not turning rotors, especially on a Tacoma where thinner rotors are vulnerable to warpage -don’t know about other trucks. If you replace the solid rotor with a slotted one and quality pads you will immediately see why I recommend that. The braking improves right away, not because of heat dissipation (that is done by the fins between rotor faces) but more because the slots clean water and dust and I regularly deal with one or the other. I have not experienced the rotor wearing more because of the slots but that is possible. My pads do tend to wear fairly fast because I buy ones that are a little softer but they also brake better and I am all about the best braking I can get taking the weight down those mountain passes and steep BLM roads here in the West. With all of the rain here, deep puddles and small stream crossings the slots also recover faster from getting wet. I would never use the drilled and slotted rotors for a number of reasons but the slotted ones make a lot of sense when you carry the weight of truck and camper.
 
^ Thanks, I do take it all under consideration.

I hear what you're saying tho I've been sticking with oem or Motorcraft's retail version for this vehicle. It has been working out ok for me and pricing from my dealer is decent (like Rockauto w/o the freight). Also truck is oddball (C&C, srw) so I'm sometimes a little wary about fitment...

Curious now about surface wear, will micro the old and new for giggles.

cheers,
 
It Tacoma rotors are that thin, perhaps one has to expect to replace them at more frequent intervals than full size or HD trucks.

But, I've turned (resurfaced) solid rotors at every other pad installation on Ford Super Duties for over 40 years. While turning does remove material and ultimately reduce life span of the rotor, the enhanced braking quality of a turned rotor due to debris and warp removal can not be discounted. All rotors warp, thinner ones more so. Warp is just a fact and by-product of the disc brake system.

Leaving warp and debris on the rotor will greatly reduce the life span of new pads.

I use a coarse grit ceramic sandpaper on the rotors between resurfacing events. While this removes most of the embedded debris; it does not reduce or eliminate warp.

YMMV based on your chosen technique.
 
I'm familiar with that link and article.

Warp is a common, catch-all term used by many, especially in the racing community. It is a very common term thrown around in NASCAR garages here in NC. And when the term is thrown around, folks know you're referring to the braking surface and not the entire rotor.

I never said the entire brake rotor warps because of heat, because they do not. Warp is a term that can also describe a braking surface out-of-plane due to uneven wear. And this is the phenomenon I'm most concerned about when replacing brake pads and/or resurfacing braking surfaces of the rotor.

I turn (resurface) rotors every other pad installation to return the braking surfaces of a rotor in to a single plane.

Recall how your old vinyl LPs use to warp, due to heat? Again, while the brake rotor do not warp due to heat, the braking surface of a rotor does take on the appearance of a warped LP due to uneven wear. Hence, many folks use the term warp, but, without understanding what is really happening and more importantly, why.

And my apologies for not offering a more thorough explanation of what I meant by "warp" in my previous posts that may have led to some confusion.
 
Follow up.

Well, I guess I've been kidding myself about my brake maintenance. I thought the outside surface wasn't too bad, being 8 1/2 years old 'n all.

fxzeHyI.jpg


But the inside surface was kinda ugly.

xNnuJGB.jpg


Attribute it to rust. Prob not helped by any dust and maybe bits of rock that might have been trapped by the rotor shield. Was going to mic the old vs new thickness but, um, hello, my micrometer is only up to 25mm and these puppies are min 32.4mm thickness new. Not like my Escort, LOL. Near as I can figure the old were worn down ~0.7mm, say ~0.027". That's for 80K miles.

Naturally the inside of the hub/drum was full of rust and dust which prob wasn't helping the function of the parking brake. So I guess going forward I'll pull the rear rotors as part of the annual service.

I can see from looking at the new rotor surface where a sandpaper treatment would help re freshen an old one. Not gonna lie, if I had the means and skill to turn them I'd prob try but but getting someone else to do that would be another story. I should check if the dealer does ...

Anyhoo, thanks again for all the help and comments.

Cheers,
 
I'm sure the amount of wear allowed on the rotors varies by manufacturers but I was always told if the wear exceeded 2 mm the rotors should be replaced. Basically, if you can feel a "lip" on the outside edge of the rotor it's time to replace it.
 
Rotor replacement rather than turning seems to be the norm these days. I had the shop do my F250 front brakes and went straight to new rotors without any consideration of turning. However on my 2005 Jaguar I recently slapped in new pads on the Brembo brakes and I used my angle grinder to remove the ridge on the existing rotors. Works great even at triple digit speeds!
 
I used to turn brake drums and rotors on an Aamco machine when I worked in an auto parts store back in the seventies and eighties. We had a measuring gadget with a dial indicator, and Aamco published a spec book which listed minimum thickness. We never cut below that.

As for drilled and/or slotted rotors, I've read that they are not a good idea for off-pavement vehicles because small pebbles can get trapped in them, ruining the pads when you brake. Possibly that's more the drilled than the slotted, but I'd stay away from them both. Leave them to the Speed Racer wanabees.
 
Hi folks,
Old thread, new question. Doing my annual brake check/ r and r.
On the rear dual calipers - 9.5 yo, ~ 90k miles - boots look ok, no leaking. As a way "testing" them I compress with a C clamp, then depress the brake pedal 2 full strokes to asses movement. One piston extends, the other doesn't appear to move.
first.jpg
Re compress piston, hold it with clamp and again depress brake pedal 2 strokes. The piston that previously did not extend now does so.second.jpg
FWIW, fluid line enters the caliper between the two pistons. Assembled.third.jpg

Am thinking this prob the result of one piston being a bit more "sticky" than the other, is not unusual and is likely not an issue under actual braking conditions - brake system has hydro boost. Pads show even wear. BUT, I want everything 100% and you folks were very helpful to me before.

So... is this normal, anything to address ?

Thanks, David
 
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