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Can Drilled and Slotted Rotors be Turned

Big T

Big T

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Put a set of Power Stop drilled and slotted rotors on the front of my wife's 4Runner and they are already warped after 25K miles. Had to replace the OEM rotors due to warping at 75K. Turning those lasted 10K miles and the warp returned. I'll try one turning on these if they'll do it, then look for others if it returns.
 
Can't confirm, but I've been told that's a problem with drilled/slotted rotors.

Sent from my SM-G892A using Tapatalk
 
Yes they can be turned, only slow speed by wide body carbide. Hard to find places that do it. Warping is from overheating. You need to get different pads, slow the travel speed before the hard braking, or something.
Maybe look into the regenerative braking system if nothing else.
More braking power like bigger multi piston calipers is not going to do it. Your caliper power is obviously enough to ruin rotors.

If the AC Delco rotors lasted longer, consider going back to them.
Also maybe cryogenic treatment of the new rotors, then thermal coat the non friction part of the rotor to shed the heat.
 
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Is she riding the brakes going down hill then stopping hard and sitting? Maybe rears are not helping enough drums out of adjustment? Or need better pads in rear? Or do you think she is just hard on brakes in stop and go? Are traffic knots that bad there?

I am pretty easy on my truck I know it won't stop quicker than much of anything so I give a little more space. Its a manual so get some compression braking too but our minivan I am kinda hard on. I think minivans should come with numbers on the side just like NASCAR. Sometimes in a pack of soccer moms it feels just like a race with and drafting and all.
 
Improper torque can cause warpage too. Especially the 'slip on' rotors. Being drilled, they can plug up and holes will rust shut. Rust is powerful and can displace any metal. Not to mention saw off your pads in record time.

Sticking calipers and collapsed hoses will give you fits as well.
 
Will L. said:
Yes they can be turned, only slow speed by wide body carbide. Hard to find places that do it. Warping is from overheating. You need to get different pads, slow the travel speed before the hard braking, or something.
Maybe look into the regenerative braking system if nothing else.
More braking power like bigger multi piston calipers is not going to do it. Your caliper power is obviously enough to ruin rotors.

If the AC Delco rotors lasted longer, consider going back to them.
Also maybe cryogenic treatment of the new rotors, then thermal coat the non friction part of the rotor to shed the heat.
Click to expand...

This is on a 2014 Toyota 4Runner. They have never had the Raybestos Slotted, but they're going to get them. Pads are Raybestos Advanced Technology semi metallic.

I replaced the OEM Rotors and pads at 75K miles. Pads could have gone another 10K miles. That is inline with what other 4Runnwr owners report. They do have dual piston calipers and the stopping power puts our GMT 400 trucks to shame.

We do many trips up and down from Big Bear Lake. I've observed and she's not riding the brakes downhill. She does downshift the auto transmission. There are still moments of heavy braking,but then you're continuing downhill unbraked.
 
3500GMC said:
Improper torque can cause warpage too. Especially the 'slip on' rotors. Being drilled, they can plug up and holes will rust shut. Rust is powerful and can displace any metal. Not to mention saw off your pads in record time.

Sticking calipers and collapsed hoses will give you fits as well.
Click to expand...

No rust, SoCal car. Holes are not plugged. Slip on Rotors. I torque the wheels on.
 
schiker said:
Is she riding the brakes going down hill then stopping hard and sitting? Maybe rears are not helping enough drums out of adjustment? Or need better pads in rear? Or do you think she is just hard on brakes in stop and go? Are traffic knots that bad there?

I am pretty easy on my truck I know it won't stop quicker than much of anything so I give a little more space. Its a manual so get some compression braking too but our minivan I am kinda hard on. I think minivans should come with numbers on the side just like NASCAR. Sometimes in a pack of soccer moms it feels just like a race with and drafting and all.
Click to expand...
schiker said:
Is she riding the brakes going down hill then stopping hard and sitting? Maybe rears are not helping enough drums out of adjustment? Or need better pads in rear? Or do you think she is just hard on brakes in stop and go? Are traffic knots that bad there?

I am pretty easy on my truck I know it won't stop quicker than much of anything so I give a little more space. Its a manual so get some compression braking too but our minivan I am kinda hard on. I think minivans should come with numbers on the side just like NASCAR. Sometimes in a pack of soccer moms it feels just like a race with and drafting and all.
Click to expand...

She's retired. About the only aggressive pet of her driving is refusing to get stuck behind a Prius in the fast lane.
 
You could have sticking calipers or slider pins as mentioned, but i would think you would feel it. Especially in the yota. It's a light handling rig that tires makes a big change in the feel. Dragging brakes or loss of rear brakes is something I think you would say something feels abnormal. Go for a high speed drive then slow with only the transmission, using the parking brake to stop, then temperature gun the rotors to see if any heat is there. That will show any drag.

Back with the gmt400 fleet we found the longest lasting rotors were the factory. Putting over 100,000 miles a year on many of the trucks guaranteed many were drivin hard. We tried every brand rotor that was available back then. Including slotted, drilled, both. The best results we had was having the factory rotors drilled, well, water jetted anyways. But it didn't help enough to be worth doing. We just had to accept that being under rougher than average conditions meant a set of rotors (pads also) didnt last as many miles for the application.

Toyota is on point with quailty parts. It wouldn't surprise me if no brand does better than the factory for it. I wont question her driving skills she is a smart gal, nice too. But in over 200,000 miles on the suburban we had back when we met at your place, that mountain is the only time I ever heated up the transmission. It is easy to see wearing the brakes a bit faster than average. Especially when half the country is flat and people drive slow compared to what we are used to.

As for the drilled/slotted ones you have now, contact the supplier or mfr. about replacement. Maybe a partial reimbursement if they won't pony it all.

Remember anytime you install new rotors, pads, or both to burnish them. It makes a difference. And I onow not applicable to you, but for others learning from this in the future: drilled and slotted rotors are a huge no-no for muddy or sandy applications. The air holes and pockets just turn into sand paper and wear out pads in no time, often scoring the rotors. I have seen a person try mud bogging for the first time ruin it all in half an hour.

Anyways, pull the rotors off and show some pics. Mic them or at least strait edge with sunshine behind (no not the eclipse on monday). Could be the trapped heat scenario. When after some descent heat build up you come to a stoplight and sit there with foot on the pedal. It lets the rest of the rotor cool quicker than where the brake pad is in contact. Freeway exits are bad for this, your mountain cant be any better. This could be why the faster cooling drilled rotors warp quicker than normal ones.
 
Will L. said:
You could have sticking calipers or slider pins as mentioned, but i would think you would feel it. Especially in the yota. It's a light handling rig that tires makes a big change in the feel. Dragging brakes or loss of rear brakes is something I think you would say something feels abnormal. Go for a high speed drive then slow with only the transmission, using the parking brake to stop, then temperature gun the rotors to see if any heat is there. That will show any drag.

Back with the gmt400 fleet we found the longest lasting rotors were the factory. Putting over 100,000 miles a year on many of the trucks guaranteed many were drivin hard. We tried every brand rotor that was available back then. Including slotted, drilled, both. The best results we had was having the factory rotors drilled, well, water jetted anyways. But it didn't help enough to be worth doing. We just had to accept that being under rougher than average conditions meant a set of rotors (pads also) didnt last as many miles for the application.

Toyota is on point with quailty parts. It wouldn't surprise me if no brand does better than the factory for it. I wont question her driving skills she is a smart gal, nice too. But in over 200,000 miles on the suburban we had back when we met at your place, that mountain is the only time I ever heated up the transmission. It is easy to see wearing the brakes a bit faster than average. Especially when half the country is flat and people drive slow compared to what we are used to.

As for the drilled/slotted ones you have now, contact the supplier or mfr. about replacement. Maybe a partial reimbursement if they won't pony it all.

Remember anytime you install new rotors, pads, or both to burnish them. It makes a difference. And I onow not applicable to you, but for others learning from this in the future: drilled and slotted rotors are a huge no-no for muddy or sandy applications. The air holes and pockets just turn into sand paper and wear out pads in no time, often scoring the rotors. I have seen a person try mud bogging for the first time ruin it all in half an hour.

Anyways, pull the rotors off and show some pics. Mic them or at least strait edge with sunshine behind (no not the eclipse on monday). Could be the trapped heat scenario. When after some descent heat build up you come to a stoplight and sit there with foot on the pedal. It lets the rest of the rotor cool quicker than where the brake pad is in contact. Freeway exits are bad for this, your mountain cant be any better. This could be why the faster cooling drilled rotors warp quicker than normal ones.
Click to expand...

You have personal experience with that mountain run to and from Big Bear. I've coached her on rolling in her stops so as to not concentrate the heat in one spot.

I doubt the manufacture will cover anything. Their warranty is 12 months 3,000 miles. We're probably over 12 mos and at 26,000 miles. Truck has 102K miles on it. She's having fun in retirement.

I just checked Rockauto and they do not have the Raybestos Advanced Technology in slotted, only OEM surface. They're around $70+ per. Not a big deal. Just continued disappointment in performance. The PowerStop drilled and slotted have worked great on the Honda Accord and the Mercedes SLK 280.
 
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I am not a fan of buying any part at a dealership pricing. I buy from rockauto every chance I get.
Unless you are 100% you are getting the exact same, go buy the rotors at a dealer imo.
 
Will L. said:
I am not a fan of buying any part at a dealership pricing. I buy from rockauto every chance I get.
Unless you are 100% you are getting the exact same, go buy the rotors at a dealer imo.
Click to expand...

When I checked most of the performance rotors were using G3000 grade iron, which is what the OEM rotors are made of.
 
Throw the rotors away and buy new ones. Turning is a waste of time. Will is correct they are difficult to fine a place to turn them. Rotors really need to be ground anyway.

I would put a magnetic measuring tool on the rotor and look for runout. Spin the rotor in place on the vehicle. Then the same with new ones. Something else may be bent, bad bearings, etc. At the minimum you know things went on true.

mic.jpg

Due to cracking around the holes I recommend slotted rotors only. I don't turn them so it really doesn't matter for overall life to me. I don't turn rotors anymore due to the chemical change cast iron goes through : you just can't turn the expanded hard spot out and the brakes will pulse in 3000 miles. You can see the discoloration from this. I would look for it and then you can see if the rotors just warped or had hot spots despite creeping on the brakes after a hard stop.

I got longer pad life from drilled and or slotted rotors on the 1/2 ton overheated and undersized brake systems. 1995 Yukon went from 12k per pad change to 17K in CA traffic.

They make the argument that the rotor mass is reduced, but, they cool down faster and let the out gassing dissipate better. Drying off wet brakes is a night and day difference.

Even though I give out and follow the advice of creeping after a hard stop I still manage to kill rotors now and then - just not as often.
 
Put the new rotors on this AM. Some pics of the old ones.
 

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See the difference in color before and after the slot? Then again before and after the holes?

This is the build up of pad material to rotor. This amplifies the concentration of heat and the problem is cyclic.

I'll see if I can find something to better describe it
 
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