How many pad slaps from a set of rotors?

[01rangerxl]

I'm just curious to know how many sets of pads BITOGers have been able to run on one pair of brake rotors without turning them.

My truck has EBC rotors that were installed about 57K miles ago with Motorcraft pads. The MC pads were pretty thin about 27K miles later, so I pad slapped some Wagner ThermoQuiets on. Those have been excellent with about 30K miles on them, still zero complaints, but it's getting to the mileage where this truck typically needs pads.

I never turned the EBC rotors because that's why I had them in the first place...my parents had a brake job done at about 30K miles when they owned the truck, and the dealer turned the rotors. The rotors were trashed by 70K miles, and I think it was because they were thinner. After a little bit of towing the OE rotors that had been turned were done. The EBC rotors have done more towing, but have never been turned and still seem to be totally fine. The truck stops very straight with no pulsing in the pedal.

So I'm thinking pad slap again when the pads are due and see how it goes. Turning didn't seem to benefit the OE rotors any, and the EBC rotors have performed flawlessly after one pad slap with TQ pads. Super quiet and good pedal feel.

 

[Kuato]

On both of our Jeeps (see sig) we have original rotors. Both are on their second set of pads, no vibration and neither have been turned.

It might help that most of our driving is highway.

 

[The Critic]

Have you used a micrometer to measure the thickness of the rotors in at least several different spots?

Have you checked the lateral runout?

Those are the only ways to accurately judge whether the rotors are suitable for continued use.

 

[01rangerxl]

Lateral runout is not an issue...stops very straight with NO wobble. Not worried about that.

I just want to know how many miles of mixed driving/sets of pads rotor "meat" can possibly withstand assuming no issues with warping, runout, etc. No, I haven't measured the rotors, but visually inspecting them they aren't worn enough to need replacement this time.

I haven't heard of that many cases of people using rotors for more than maybe two or three sets of pads if they keep a vehicle long enough to do that. I am curious to know if people have gotten long life out of rotors in situations where pad life was just average (not all highway miles).

 

[The Critic]

Measuring the rotor thickness with a micrometer will tell you how much material is remaining.

 

[01rangerxl]

Obviously, but all I want to know is if it's possible to use one set of rotors over several sets of pads assuming the rotors are not warped or otherwise damaged. If I need new rotors I'll get them, I want to know what's possible/what others have been able to get from their vehicles.

 

[wirelessF]

I did a pad slap on the rears of my 02 Silverado. Did not go well after that. After a hard dead stop it left a pad imprint on the rotor and it had the effect of warped rotors. I might get it cut so the pads have a fresh surface to break in.

 

[berninicaco3]

I worked at a volvo dealership for a year.
Our policy was one pad slap, then pads + rotors. We never turned volvo rotors. Depends on how deeply dished the rotor is: AND of course if there is deep scoring or any warping at all, or scaled rust, or hot spots.

Enough of the above, and I suggest re-turning the rotor (to spec of course, if there's enough meat left: not going to advise cutting to thinner than suggested, or you're more likely to warp the rotor).

Also did a pad slap on a friend's ford ranger that did have some light grooves from hardened spots going on. It was fine; the pads just wore down to match the rotor in not too much time at all.

Other shops have a policy of always resurfacing the rotors with new pads, no matter what. It's a customer satisfaction thing, so no one can complain that it squeals because of hard spots you didn't cut out on the lathe. On my own cars if not yet dished, I just slap pads on. More an aesthetic than performance issue sometimes.


By the way! A lot could depend on the materials in question! Soft materials that abrade off can often do better braking. Volvo's rotors lasted usually 60,000 miles, maybe 80, for 2 sets of pads. Maybe a harder iron will last longer. Maybe softer -likely better performing- pads will burn up faster, and you'll get 4 sets of pads to a rotor (you'll likely have to resurface at least once in that case though). Starting to get into variables that are beyond my experience to speculate.

Too many possibilities. Just measure, and check with each set of pads, and replace what you gotta replace when you gotta replace it no matter what mileage you think you "should" have gotten out of a part.

Don't end up like this guy

http://www.youtube.com/watch?v=rwMM6hC9xQM

 

[SteveSRT8]

Originally Posted By: The Critic
Measuring the rotor thickness with a micrometer will tell you how much material is remaining.


I can't understand all the conjecture when a simple measurement of the thickness will quickly tell you the answer to the question "can I use these again"?

Almost every rotor has the minimum thickness right on it. If not it's always specified by the mfgr.

Many times if there is no runout or other issues you simply put in new pads, lube the moving parts (if any) and reassemble. We typically do this on service trucks at least once between rotor replacements, and these vans weigh just short of 10k pounds.

 

[Falken]

I think I know what you want to attempt.

If you are able to sand the rotors with course sand paper extremely well and the wear area is relatively flat to the naked eye....

I don't think it would be a problem to run a second set of pads off the original discs if they aren't all rusted out in the cooling fins.

But, it could pull or vibrate, or make annoying sounds. And your stopping power may be very mild for a long time until they re-bed fully.

In my opinion, don't measure anything or bother. Call for prices on new rotors in the quality level that you want and get new rotors with the pads. You guys pay almost nothing for basic auto parts it's envious.

 

[01rangerxl]

Originally Posted By: SteveSRT8
Originally Posted By: The Critic
Measuring the rotor thickness with a micrometer will tell you how much material is remaining.


I can't understand all the conjecture when a simple measurement of the thickness will quickly tell you the answer to the question "can I use these again"?


I'm not looking for someone to tell me when to replace my rotors, I am looking for experiences where people got good life out of rotors with just pad replacements and no cutting. Just curious to know if it's even possible and if maybe rotors will last longer if never turned. Like I said, if I need new rotors I'll get them.

I've never run multiple sets of pads on one pair of unturned rotors before; I have always just replaced them. This is the first set of rotors I have done a pad slap on and it seemed to work fine, actually better than turning rotors did. I only use semi-metallic pads, figuring they might not be as rough on rotors as ceramic "lifetime warranty" pads.

 

[SteveSRT8]

^^^Bravo, good for you. Even when my car was tracked heavily when new I could get two sets of pads to one rotor set. And that is with HARD racing type pads with a big heavy car going really fast.

On my fleet trucks I have made 3 sets, but the norm is two for us.

Turning them is only good if done correctly. Many a rotor is actually ruined by a dolt operating the lathe!

 

[KrisZ]

It all depends on what type of pads you're using. Generally speaking organic pads or pads that are soft are not hard on rotors therefore rotors can be reused without resurfacing.
I've done that with my old Chevy Corsica and rotors held up OK.

If you want to use more aggressive pads, then most likely the rotor will not be in good shape for reusing or sometimes even resurfacing.

 

[Kestas]

Same here. My experience has been all over the place with regard to rotor/pad life. Measuring is the only way to go. Even a ruler helps against the side of the rotor.

 

[mechtech2]

Every rotor is an individual scenario.
All that counts is the one I am dealing with at the moment.

What good is knowing someone got 20k, and someone got 100K?
Answer: None.

I must add that 'slapping on pads' will ensure less performance and life.

 

[01rangerxl]

Originally Posted By: mechtech2

I must add that 'slapping on pads' will ensure less performance and life.


How do you know? That's why I want to hear examples. I'm thinking not turning the rotors and sticking to softer pad materials that are replaced more often might get the best life out of brake rotors.

 

[Danh]

The short answer is you should be able to get at least 2 sets of pads per rotor.

Rotors should be replaced if there's vibration when stopping or if the rotor is worn to less than the specified minimum thickness.

Of course, new rotors look nice and it isn't that expensive or time-consuming to replace them too...

 

[mechtech2]

Originally Posted By: 01rangerxl
Originally Posted By: mechtech2

I must add that 'slapping on pads' will ensure less performance and life.


How do you know? That's why I want to hear examples. I'm thinking not turning the rotors and sticking to softer pad materials that are replaced more often might get the best life out of brake rotors.


How? Decades of experience.

 

[Kuato]

Originally Posted By: 01rangerxl
... all I want to know is if it's possible to use one set of rotors over several sets of pads assuming the rotors are not warped or otherwise damaged. ...


Short answer: YES


The only time you will have to replace your rotors is if they are warped so badly that they cannot be turned (on a machine lathe to remove material to make them smooth again) or if they have been turned so many times that they are no longer thick enough to use safely.

 

[01rangerxl]

Originally Posted By: mechtech2
Originally Posted By: 01rangerxl
Originally Posted By: mechtech2

I must add that 'slapping on pads' will ensure less performance and life.


How do you know? That's why I want to hear examples. I'm thinking not turning the rotors and sticking to softer pad materials that are replaced more often might get the best life out of brake rotors.


How? Decades of experience.


Sure, but that doesn't really tell me anything about why replacing pads only and not turning would ensure reduced performance and life from brake rotors.