29 replies to this topic

[moveinon]

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.

[klahanie]

^ 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,

[Advmoto18]

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.

[ntsqd]

I've posted this link many times, but rotors rarely warp. What does happen is that they get an uneven transfer layer that feels like the rotor is warped.

 

Recommended reading:

http://www.stoptech....and-other-myths

Edited by ntsqd, 18 April 2018 - 12:45 PM.

[Advmoto18]

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.

Edited by Advmoto18, 18 April 2018 - 03:16 PM.

[klahanie]

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.

 

 

But the inside surface was kinda ugly.

 

 

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,

[smlobx]

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.

[fuzzymarindave]

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!

[Optimistic Paranoid]

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.

[klahanie]

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.

Re compress piston, hold it with clamp and again depress brake pedal 2 strokes. The piston that previously did not extend now does so.

FWIW, fluid line enters the caliper between the two pistons. Assembled.

 

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

Edited by klahanie, 10 April 2019 - 09:31 PM.