New Rotors + Old Pads = Bad Idea?

[HopefulSHO]

So I bled the **** out of the SHO's brakes today..made a BIG differnece too - I should have done this long ago. However the pulsating feeling of warped brake rotor(s) is only making itself more apparant after my "testing" of my new brake fluid. Soo...

The pads on all corners are still pretty beefy. Throwing them out for new ones really feels like a waste..
I read that someone took some sandpaper and *lightly* sanded off the faces of his used pads before putting them on with new rotors.. Does this sound okay to everyone? It dosent sound like it will mess anything up, and provide a new surface for the rotors...

Or should I ditch the idea and just pony up for new pads?

TIA,

Jeremy

 

[Dave Kegel]

No. Just throw new rotors on there. Or, get yours cut. Pep Boys cut's rotors for $6/each by me.

Dave Kegel

 

[Grifter]

Like Dave said, putting on the old pads should be fine as long as they are in good condition. I've done many brake jobs at my work and you always check the pads and rotors, if the pads have enough life left there's no reason to buy new ones.

 

[Shoaz]

What they said...

Getting the rotors turned is inexpensive and will eliminate any "warp" problems. Old pads are fine, and sanding them is okay if they're not flat.

 

[sdpatt]

I have used "old" pads with new and resurfaced rotors. I will add a note of caution though. Even with new pads and new rotors, there is still a break-in time required to allow all of the pad to contact all of the rotor and to embed the pad material into the rotor surface. This last part is especially important with carbon metallic pads. You should note the swept area on the rotor and not use the brakes hard until the pads are contacting the full surface of the swept area of the rotor.

 

[SHOZ123]

I agree with Scott.

I "rotated" my pads to try and get even wear. They did not make good and full contact for many miles. I ended up cooking them because of the smaller contact area.

I would just get new pads if there is any variation in thickness on the individual pad or between a pair of pads.

 

[Camarok]

ok really, for as cheep as these parts are just get all new stuff.... i believe that the rotors are 20 bucks a pop... which is CHEEP for rotors, and pads can be as cheep as 16 bucks, go new, plus turning warped rotors is only a temp fix, they will go warpy again over time, they have already heated and changed physically..

So when you turn the rotors, it will cut into the high point, making them less thick there to be "even" with the rest of the low points, thus making them more susepable to being heated faster, then again warping... just get new ones for the price.

my $.02

 

[Shoaz]

ok really, for as cheep as these parts are just get all new stuff.... i believe that the rotors are 20 bucks a pop... which is CHEEP for rotors, and pads can be as cheep as 16 bucks, go new, plus turning warped rotors is only a temp fix, they will go warpy again over time, they have already heated and changed physically..

So when you turn the rotors, it will cut into the high point, making them less thick there to be "even" with the rest of the low points, thus making them more susepable to being heated faster, then again warping... just get new ones for the price.

FWIW, I've never seen a documented case where a "warped" rotor was really twisted or out of true like you're describing. What people describe as "warped" is really an uneven surface loading of the pad material which results in an uneven coefficient of friction as the rotor turns. This will feel like a vibration, but it is only due to the difference in Cf as the rotor turns.

Overheating the brakes can lead to pad "imprinting", which is a very common source of the uneven surface loading. Parking or sitting still with the brakes applied while hot will do this.

Having the rotors turned just exposes fresh iron and removes the unevenly loaded surface of the rotor. The turned rotor, if turned competently, will still be true and even and ready to be evenly surface loaded or "seasoned" (look that up on SHOtimes, you can help yourself out a lot by "seasoning" your rotors and bedding your pads after a brake job).

I'd be much happier having a good set of rotors turned for $6 a pop than buying cheap-o poorly annealed rotors for $20.

 

[SHOZ123]

And the major reason that pads deposit material is they were not properly bedded in or heat cycled. Could also be cheap pads.

 

[shojuan]

I'd be much happier having a good set of rotors turned for $6 a pop than buying cheap-o poorly annealed rotors for $20.

Good rotors can be ruined by going through a bad heat cycle and turning them won't fix them if that happens. They'll be no better than those poorly annealed rotors for $20 and perhaps worse. Good rotors are good because of: high quality alloy, consistant iron crystal structure, and quality machining. A bad heat cycle affects the first two and I'd have a hard time believing that your $6 turning is going to match the original machining that your good set of rotors came with. I'd expect that $6 turning to be more on par with what you would expect from the brand new cheap-o rotors or worse.

 

[RonPorter]

I also go with Dave: get them turned for $5-10 each, and be done with it.

In fact, I'll be taking my 2nd set of (AZ Aimco ) rotors in to be cleaned up tomorrow, and will install a used set of 50% Porterfield R4S pads, as the current R4S pads are about dead from Thunderhill, and I found a chunk of pad on the garage floor the other day.

FWIW, I have been using AZ Aimco rotors on three SHOs now, and all have done track events, dragstrips, and my street driving. I will never spend large $$ on rotors,as these rotors, at $36 each for the '96 size, have served me very well, and all have been turned at least once (I always get them turned before changing pads).