So I'm going to put on some new rotors. My current pads are only 1/3 worn. The old rotors have some grooves on them. Do I have to put on new pads?
New Rotors Going On... Do I have to put on new pads too?
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The short answer is that it is okay to do. When I took my E150 in for a safety check it had one worn rotor so I went ahead and replaced it. Well, when I got the wheel off I found a groove the width and depth of a dime in my rotor. The mechanic didn't mention this and I didn't have new pads so I tossed the rotor on and had the safety check completed. The mechanic said it was okay to use old pads because they won't wear a rotor in an unusual way. Bear in mind that it takes time for your pads to wear flat...I've sanded them flat before but if you turn them into wedges that ain't too good.
The shorter answer is to change them anyway.
Cheers, Steve
The shorter answer is to change them anyway.
Cheers, Steve
Definately. You do want the brakes to work to their full efficiency I presume. Can't do this if the pads are not fully contacting the rotor as the pads will have grooves in them as well.
Check the manufacturers bed-in procedure. It can make quite a difference to how they work if done properly from the start.
Check the manufacturers bed-in procedure. It can make quite a difference to how they work if done properly from the start.
I would replace them, brakes is not an item where you want to cut costs. Rotors affect the pad wear and if the rotors are bad, they made have uneven wear and if you reuse them, could cause more rotor problems.
Replace the pads. I replaced the rotors once, leaving 6 month old pads in, and the pads would not bed properly. Ended up ruining the rotors. Thankfully, I had an understanding parts-guy...
New rotors would be like turned rotors. When you have rotors turned because they are warped or have hard spots, you usually don't change pads. On the ether hand, turning rotors seldom seems to be a lasting fix.
Still, even better pads aren't that expensive and you have done 2/3 of the work of replacing pads.
Still, even better pads aren't that expensive and you have done 2/3 of the work of replacing pads.
Generally you should replace the pads when you turn or replace the rotors. No need to have a misshapen pad starting the rotor wearing funny.
2nd good reason is that brake work is dirty nasty work so the longer you are able to go until you have to muck with the brakes again, the better.
2nd good reason is that brake work is dirty nasty work so the longer you are able to go until you have to muck with the brakes again, the better.
This is opposite of what I"ve read about race cars and race pad compounds. If I recall, you want to bed new rotors with old pads, and new pads with old rotors. Of course, I'm sure the differences between racing an street application make this so.
This type of thing is EXACTLY why someone coined the expression "Don't save a penny now to spend a dollar later." Pads are cheap, considering the big picture. Don't ruin your new rotors by using them with old pads, especially ones used on grooved rotors.
the old race car maxim is
"new discs-old pads, new pads-old discs"
It has to do with the binder resins boiling out of the new pads contaminating the porous, green disc rotor, which will have oils, etc boiling out of it. Cast iron needs a certain amount of time to 'cure' and stabilise when first used.
Yes, I know a new car has green rotors and new pads, but it doesn't mean it is the optimal situation.
Do a search, it has been discussed to death on here before, along with some excellent outside links.
"new discs-old pads, new pads-old discs"
It has to do with the binder resins boiling out of the new pads contaminating the porous, green disc rotor, which will have oils, etc boiling out of it. Cast iron needs a certain amount of time to 'cure' and stabilise when first used.
Yes, I know a new car has green rotors and new pads, but it doesn't mean it is the optimal situation.
Do a search, it has been discussed to death on here before, along with some excellent outside links.
JHZR2
Staff member
do it all. not worth it to skrimp on brakes.
JMH
JMH
In anything other than an emergency-type of situation, IMHO you should put new pads on there with new rotors. For the same reasons stated above.
Like theguru says above, make sure you bed them for optimal performance. (Old pads will not bed properly due to wear patterns on the old pads from the old discs)
Like theguru says above, make sure you bed them for optimal performance. (Old pads will not bed properly due to wear patterns on the old pads from the old discs)
I just replaced the rotors on my Cavalier seeing they were warped.
Still had 1/2 the brake pads left so I just swapped on the new rotors and kept on going.
If there is an 1/8 of an inch or less, replace them, if not, I would wait until they wear out so you can get your moneys worth out of them.
Still had 1/2 the brake pads left so I just swapped on the new rotors and kept on going.
If there is an 1/8 of an inch or less, replace them, if not, I would wait until they wear out so you can get your moneys worth out of them.
This is the type of thing to do when they are shooting at you.
Get new pads.
Get new pads.
What he said ^^^. Plus use them only if they are square (the same pad depth all the way around). Get some sandpaper & lay it flat on some level concrete with the sand pointing up. Put the pad on the sandpaper facing down. Sand each pad this way turning in circles until all the grooves are out of it. Groovy brake pads may be cool but aren't good for new rotors.
What's the issue on grooving or a small set of them. From what I see, it actually INCREASES surface contact area over a perfectly flat pad. The heat generated is the same grooved or not since heat or energy is what is generated from conversion of the kinematic energy to heat during a stop. So a grooved pad/rotor combination will lead to lower peak temperatures on rotors and pads.
So why the fuss on grooves?
So why the fuss on grooves?
This sounds like the 3000 mile oil changer "Its cheap insurance" crowd.
High quality pads are not that cheap anyway. A set of quality pads for my car cost almost as much as a set of rotors.
Read the tdi-rick post again. If you replace both at the same time, expect a 300 mile bed-in where you have less than optimum braking. What happens if you have that emergency where you need maximum braking during that first 300 miles?
High quality pads are not that cheap anyway. A set of quality pads for my car cost almost as much as a set of rotors.
Read the tdi-rick post again. If you replace both at the same time, expect a 300 mile bed-in where you have less than optimum braking. What happens if you have that emergency where you need maximum braking during that first 300 miles?
Ok, I'll agree. If your pads are not too worn, if you sand them flat and square, and if you don't mind going back in a bit sooner than you would have, go ahead and use the old pads.
Personally, if I've replaced the rotors, I'm going to replace the pads. It takes a few more minutes, that is, if the old pads did not already fall out, and, for most cars, is not that much more money. My Perfomance Friction CMs were $85 for a set of 4, vs the $350 for the 4 rotors. 'Course, I could have went with a $200 set of rotors, which would have put the costs closer, but then, I could have went with $34, but still good, pad set too.
With my fresh rotors and pads(same type of pad as before) on the Impala, I did not feel any loss of effectiveness vs the old rotors and pads, which were not down to the squealers yet, after the initial bedding. On the contrary, the brakes felt a lot better. I replaced the rotors because they were causing pulsation and were showing some fine "spiderweb" cracking. Althought the pads were not down to the squealers, I don't think anyone would have debated reusing them. They were probably at the 1/3rd left mark.
I know it's pretty gradual, but they don't feel any more effective now, after about 300 miles, than they did after the initial bedding. I'm pretty sure I could have engaged the ABS at will, at any time after they were bedded.
The other times I've done a full brake job, including new parts all around, I've experienced the same thing. Bed them in, and I can lock 'em up/engage ABS at anytime. Could the racing pads be different because they are a different compound from street pads?
Personally, if I've replaced the rotors, I'm going to replace the pads. It takes a few more minutes, that is, if the old pads did not already fall out, and, for most cars, is not that much more money. My Perfomance Friction CMs were $85 for a set of 4, vs the $350 for the 4 rotors. 'Course, I could have went with a $200 set of rotors, which would have put the costs closer, but then, I could have went with $34, but still good, pad set too.
With my fresh rotors and pads(same type of pad as before) on the Impala, I did not feel any loss of effectiveness vs the old rotors and pads, which were not down to the squealers yet, after the initial bedding. On the contrary, the brakes felt a lot better. I replaced the rotors because they were causing pulsation and were showing some fine "spiderweb" cracking. Althought the pads were not down to the squealers, I don't think anyone would have debated reusing them. They were probably at the 1/3rd left mark.
I know it's pretty gradual, but they don't feel any more effective now, after about 300 miles, than they did after the initial bedding. I'm pretty sure I could have engaged the ABS at will, at any time after they were bedded.
The other times I've done a full brake job, including new parts all around, I've experienced the same thing. Bed them in, and I can lock 'em up/engage ABS at anytime. Could the racing pads be different because they are a different compound from street pads?
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