Drilled/Slotted Rotors on a Truck?
- Thread starter AdmiralYoda
- Start date
Thanks all....this was essentially my somewhat dated opinion on slotted/drilled rotors but I wanted to run it by others, so thanks! To answer a couple comments:
- Off the shelf Cryo treated rotors don't exist yet for this truck, and sending good new ones out for treatment might be a bit costly.
- No big brake kits yet for these trucks that aren't custom and $$$$$.
- I'm 99% sure it is a warped rotor or rotors, but I could be wrong. My tires are brand new and had a great balance. No vibrations at any speed, vibration only happens when braking. Steering wheel shakes back and forth a little, you can feel a slight brake pulsation and the characteristic rur-rur-rur sound while on the brakes.
- I don't drive aggressively, pretty conservatively in fact. But in MA it is common to go from full speed to a full stop many times over a typical commute. 95% highway so when you come to a stop...your stopped.
Anybody who's ever done (or seen) friction welding will understand how this happens.
Try bedding them to clean up the deposits. Ball joint wear can also cause that vibration under braking.
@CarlB I'd be very surprised if my ball joints were toast at 50k, this truck has had an easy life except for the stop-and-go. I just had a vehicle inspection and that is one of the main things they check for and had an alignment done with the new tires as well. Everything was within spec.
I'll try re-bedding them. A bunch of 60-10mph stops and a long period of driving without brakes to let them cool down. Just need to find a safe place to do it!
I'll try re-bedding them. A bunch of 60-10mph stops and a long period of driving without brakes to let them cool down. Just need to find a safe place to do it!
4WD
$50 site donor 2025
You can use lower speeds, just build up some heat. Also don't overdo it and boil brake fluid. You should be able to feel if the aggressive braking is cleaning them up and the vibration should improve.
Just remember they don't warp. But they can have uneven wear and/or deposits.
4WD
$50 site donor 2025
Carbon Ceramic doesn't apply here. He has iron discs.
A $6k brake job on a 911 is the same cost ratio as the dealer doing a $1k brake job on my mid-sized truck.....
How do the drilled rotors in your 911 handle mud, snow, salt and dirt/gravel? Any brake fade while towing?
How do the drilled rotors in your 911 handle mud, snow, salt and dirt/gravel? Any brake fade while towing?
Classic example of brake judder from uneven pad deposits and assumption that rotors are warped. If your driving style is more conservative, it may be contributing to the deposit situation. Heavy vehicle, stop and go traffic, heated pads will eventually leave an uneven layer of pad material on the rotor. Best thing to do is bed the brakes properly from the start so as to get an even layer of friction material transferred to the rotor. This will create an adherent friction interface versus a strictly abrasive one which produces better braking performance overall. It also helps prevents those uneven deposits. You may have to have the rotors "skimmed" to remove the deposits. Trying to re-bed on top of deposits already there may produce more deposits and high points that lead to a conversion of the iron into cementite around those high point areas. At that point, the rotors are toast as cementite while cause the iron to gain/shed heat unevenly and start the unending cycle of more uneven deposition of pad material. Stoptech had an excellent white paper that explained this phenomenon very clearly.
Lovely brakes. However they aren't drilled. The holes are cast when the rotors are molded.
Edit: The IRON Porsche rotors have the holes cast in them, the CC ones ARE drilled. Mea Culpa.
Last edited:
No way are those 18" rotors. 20" wheels yes but rotors are not.
Typo? ............... 13", 14" ?
Last edited:
edyvw
$50 site donor 2025
Those are NOT 18” rotors.
And the reason they are $3k is bcs. they are ceramic.
And the reason they are $3k is bcs. they are ceramic.
Your rotors most probably aren't "warped". Either you suffer from pad
deposits (only IF you happen to stop with VERY HOT brakes) or due to
installation deficiencies. The latter is much more common.
Time for a change. I'll explain later.
Probably not the issue and it supports my supposition: (sadly popular)
installation deficiencies . . . .
No, drilled rotors won't run cooler or remove heat quicker. Nothing like
that - nada, zero. Just marketing BS.
Drilled and slotted rotors are for looks or if you love humming noises.
Actually you're still on the wrong track. Cast iron hardly warps.
Your dealer. Most garages tend to miss cleaning thoroughly the hubs before
installing new rotors and ultimately, measure run-out with a gauge. This flaw
inevitably leads to some run-out of your new rotors. Your calipers may move
and compensate to some point as long the rotors are fairly newish. BUT, with
some time your pads WILL wear your rotors at one single point on one side
and on the other side at the opposite end. This inevitablly leads to increasing
thickness variation (DTV), finally resulting in shudder. YOUR issue apparently.
Add to that not abiding by torque values, not maintain calipers, residues of
grease on the rotors, not to mention the aforementioned pad deposits . . .
You guess what helps. A real good diligent mechanic.
.
Last edited:
I actually get to respond to a thread where I get to be an 'exshpert'
YAY!
I worked in brake pad and rotor manufacturing, for a pretty well respected company.
Your past buying habits are pretty much optimal. I shan't go into reasons why, but much smarter people who had worked at said manufacturer for much longer than I had gave me the cliffs notes and told me to "just buy our standard stuff, that fancy stuff is only for the race organizations that we are the official supplier to, and obviously, Porsche. We don't even make that stuff for your truck"
I'll give 'em a plug by saying this - PFC Carbon Metallic pads are fantastic pads.
Pull the rotors off and go see what O'Reillys has to say. Only reason I will go to the big O' is to get rotors turned. They still do it (or at least they do here) and last time I did it, they didn't charge 75% of what a new rotor would cost (like many other places charge)
Also - what the guy above me said....
YAY!
I worked in brake pad and rotor manufacturing, for a pretty well respected company.
Your past buying habits are pretty much optimal. I shan't go into reasons why, but much smarter people who had worked at said manufacturer for much longer than I had gave me the cliffs notes and told me to "just buy our standard stuff, that fancy stuff is only for the race organizations that we are the official supplier to, and obviously, Porsche. We don't even make that stuff for your truck"
I'll give 'em a plug by saying this - PFC Carbon Metallic pads are fantastic pads.
Pull the rotors off and go see what O'Reillys has to say. Only reason I will go to the big O' is to get rotors turned. They still do it (or at least they do here) and last time I did it, they didn't charge 75% of what a new rotor would cost (like many other places charge)
Also - what the guy above me said....
