Have to turn brake rotors every time?

[ExtremeSi]

Noobie question:
Do you always have to have your brake rotors turned or replaced when you change your brake pads?
Case in point, car's brake pads are squeeling, but brake pedal is still firm and solid with no vibration. Can I just change the pads and call it a day?

[cobber112879]

If your rotor surfaces are smooth you can most definetly leave them alone. As lont as they are not warped or out of round. If you have a solid, non pulsing braking pedal, you're o.k

[Thaco]

generally you turn your rotors every other brake change. or if there is obvious gouges/burning/wear.

[GTS Jeff]

Originally posted by cobber112879
If your rotor surfaces are smooth you can most definetly leave them alone. As lont as they are not warped or out of round. If you have a solid, non pulsing braking pedal, you're o.k

Nope. The point of turning rotors is to machine off the old brake pad material that's bedded into the rotors. Your new pads won't work at their 100% if they have to interface with old and different pad material.

[Skyline_Addict]

if your new brakepads are not OEM-spec (if they are thicker) you will have squeeling when you press on the brake lightly. happens sometimes with my lude. has extra thick pads and only squeels when braking very lightly at very low speeds (pretty much coming to dead stop). i'm told it's an issue with all prelude as their brake calipers have alot to do with this.

[ryder_23]

^
doesnt really have to do with turning the rotors. And i havnt had a problem with mine at all...

As for turning them...I believe its a good idea everytime you change your pads, for the exact reason jeff said.

[Skyline_Addict]

Originally posted by ryder_23
^
doesnt really have to do with turning the rotors. And i havnt had a problem with mine at all...

As for turning them...I believe its a good idea everytime you change your pads, for the exact reason jeff said.

probably because you're using OEM brake pads to replace.
most people don't, and this is from whom i hear about this "problem".

[cobber112879]

Originally posted by GTS Jeff
Nope. The point of turning rotors is to machine off the old brake pad material that's bedded into the rotors. Your new pads won't work at their 100% if they have to interface with old and different pad material.

The point of machining rotors is to give yourself a smooth uniform braking surface for your pads to apply against. If your rotor surface isn't ridged or rusted or warped you are doing yourself a disservice by machining them for a couple reasons.
1. The surface left by a brake lathe is not as smooth as the surface left by the old brake pad IF the old brake pad had worn down properly. I have looked at disected rotors of normal wear and machined ones at college with multiple instructors.
2. The brake pad material is much softer than a rotor material. Brake material wont imbedd itself in the rotors. Rotors can deterioate over time leaving the surface material weak and rusty, but this is fairly obvious on visual inspection.If this is not the case, leave the rotor alone.
3. Turning a rotor removes metal from the rotor. This makes the rotor less of a heat sink thus making the rotor less effective and more prone to warping.
If you want or need to machine your rotors, by all means, go ahead, the brake shops love to see you at the counter. Just letting you know that it isnt necessary unless you have a braking or surface problem.

[GTS Jeff]

Originally posted by cobber112879


The point of machining rotors is to give yourself a smooth uniform braking surface for your pads to apply against. If your rotor surface isn't ridged or rusted or warped you are doing yourself a disservice by machining them for a couple reasons.
1. The surface left by a brake lathe is not as smooth as the surface left by the old brake pad IF the old brake pad had worn down properly. I have looked at disected rotors of normal wear and machined ones at college with multiple instructors.
2. The brake pad material is much softer than a rotor material. Brake material wont imbedd itself in the rotors. Rotors can deterioate over time leaving the surface material weak and rusty, but this is fairly obvious on visual inspection.If this is not the case, leave the rotor alone.
3. Turning a rotor removes metal from the rotor. This makes the rotor less of a heat sink thus making the rotor less effective and more prone to warping.
If you want or need to machine your rotors, by all means, go ahead, the brake shops love to see you at the counter. Just letting you know that it isnt necessary unless you have a braking or surface problem.

Heh thats just wrong then. Here's a good read for you. There are tons of other great articles in the tech section too.

http://www.stoptech.com/whitepapers/...otors_myth.htm

I personally don't bother with machining rotors...waste of time when new rotors only cost $20...

[ExtremeSi]

Thanks for all the info guys. There's a lot of interesting info on that site Jeff.
It's my friends car, so I'll present him with the information and he'll decide what he wants to do.

[Supa Dexta]

One question I have is how the article ends:

If the brake fluid is topped up the first warning of warn out pads will be the screech of steel backing plate against iron disc. This will be both annoying and expensive.

He makes it sound like you've done something wrong at this point, does he only mean you should have replaced the pads before the warning screech? (Is that the "Expensive" part, the pads replacement? Or now instead of replacing just the pads, you'll have to do the rotors too? if so, whats the point of having the screech show up that late? if you could have an earlier warning and possibly gotten out of rotor replacement... Only thing that stuck out to me, other than that very interesting...

[ryder_23]

Originally posted by Skyline_Addict


probably because you're using OEM brake pads to replace.
most people don't, and this is from whom i hear about this "problem".

I have far from oem pads and rotors

[GTS Jeff]

Originally posted by Supa Dexta
One question I have is how the article ends:

If the brake fluid is topped up the first warning of warn out pads will be the screech of steel backing plate against iron disc. This will be both annoying and expensive.

He makes it sound like you've done something wrong at this point, does he only mean you should have replaced the pads before the warning screech? (Is that the "Expensive" part, the pads replacement? Or now instead of replacing just the pads, you'll have to do the rotors too? if so, whats the point of having the screech show up that late? if you could have an earlier warning and possibly gotten out of rotor replacement... Only thing that stuck out to me, other than that very interesting...

Hawk pads don't come with the wear indicator tabs like OEM pads do. If you want the OEM wear indicator, you might be able to transfer it from the old brake pads.

[dcoultis]

if the rotor was fine before i don't see no reason to have it turned..... that article prooved nothing jeff.

[CokerRat]

Stoptech's white papers are an excellent resource and they don't recommend any "preventative" turning of rotors when you change pads. Many track nuts swap street pads to track-only pads specifically for an event, with no ill effects provided they bed them in properly when the switch. There is no need to turn rotors unless you are experiencing problems.

I'd like to know where you can get good quality rotors for $20 a corner for a high-performance car. I looked recently at Powerslots ($230 / pair), Brembo blanks ($350 / pair) and Stoptech's 2-piece Aerorotors ($600 / pair, though that is cheaper if you're only replacing the outer piece).

[GTS Jeff]

Originally posted by CokerRat
Stoptech's white papers are an excellent resource and they don't recommend any "preventative" turning of rotors when you change pads. Many track nuts swap street pads to track-only pads specifically for an event, with no ill effects provided they bed them in properly when the switch. There is no need to turn rotors unless you are experiencing problems.

I'd like to know where you can get good quality rotors for $20 a corner for a high-performance car. I looked recently at Powerslots ($230 / pair), Brembo blanks ($350 / pair) and Stoptech's 2-piece Aerorotors ($600 / pair, though that is cheaper if you're only replacing the outer piece).

I find it hard to believe that you are saying that if you've read through Stoptech's tech articles. The point of turning rotors is to remove the old pad material that was bedded into the rotors. When you swap in a different set of pads, you need a fresh surface of metal for the new pad material to properly bed into.

Take a read through this if you have some spare time:

http://www.stoptech.com/whitepapers/bedintheory.htm
http://www.stoptech.com/whitepapers/bedinfaq.htm

And actually, here's a great quote addressing your misconceptions:

FAQ #4: What precautions must be taken when switching from street pads to track pads?

If you are changing pad compounds, such switching from street pads to track pads, you need to remove all of the material on the rotor and replace it with a fresh transfer layer of material from the new pads. To be honest, rotors do not like to have different compounds used on them, and virtually all rotor and pad manufacturers recommend that you do not swap pad compounds on the same rotors

[CokerRat]

Originally posted by GTS Jeff
I find it hard to believe that you are saying that if you've read through Stoptech's tech articles. The point of turning rotors is to remove the old pad material that was bedded into the rotors. When you swap in a different set of pads, you need a fresh surface of metal for the new pad material to properly bed into.

Jeff my boy, believe it, I have read those pages many times and even linked to them in discussions here. I'm afraid you are missing something. Go back and re-read the link you provided earlier, it really does a good job to explain adherrent friction as a braking mechanism, why uneven deposits lead to "shudder", and why it is a vicious cycle once it happens. Even machining the rotor may not neccessarily fix the problem, because if you are overheating the rotor in localized areas -- that's not just a surface problem. As you wear the rotor metal away, the cementite inclusions remain and cause further hot spots. if you drive on the street at low brake temperatures, the braking mechanism is abrasion and you will wear away the transfer layer. You don't need to machine the rotor to get it off. But don't take my word for it, see the Stoptech quote below.

Originally posted by GTS Jeff
And actually, here's a great quote addressing your misconceptions:

Holy Hannah... did you even read the next sentence in that FAQ!? Talk about a selective memory.... I'll copy it here for you!

The reality is, however, that most customers don't have two complete sets of rotors, so here are our recommendation for managing compounds between track and street use. Note that diligent bedding-in is the key.

When switching from street pads to track pads, one needs to make sure that as much of the street compound is removed from the rotor as possible before aggressive track use. The risk here is that any street pad material remaining on the rotor will be suspect to deterioration from overheating. This can ultimately cause severe vibrations due to uneven pad deposits (a smearing of the street pad material on the rotor face).

A common method for removing street pad material is to install the track pad prior to driving to the event. Because most track pads operate in an abrasive mode during regular street operation, driving them to the track will wear off any existing brake pad material en route. You will know when the street pad material is gone by the squealing noises coming from your brakes after a short while…

[CokerRat]

Just to recap for the original post, yes, you can throw on the new pads and go, as long as these are street (eg. OEM) pads in a typical street car. If you plan to do seriously hard driving and these are not OEM pads, then you should follow the proper bed-in procedure before ya work 'em real hard.

[GTS Jeff]

Originally posted by CokerRat

Jeff my boy, believe it, I have read those pages many times and even linked to them in discussions here. I'm afraid you are missing something. Go back and re-read the link you provided earlier, it really does a good job to explain adherrent friction as a braking mechanism, why uneven deposits lead to "shudder", and why it is a vicious cycle once it happens. Even machining the rotor may not neccessarily fix the problem, because if you are overheating the rotor in localized areas -- that's not just a surface problem. As you wear the rotor metal away, the cementite inclusions remain and cause further hot spots. if you drive on the street at low brake temperatures, the braking mechanism is abrasion and you will wear away the transfer layer. You don't need to machine the rotor to get it off. But don't take my word for it, see the Stoptech quote below.


Holy Hannah... did you even read the next sentence in that FAQ!? Talk about a selective memory.... I'll copy it here for you!

Your quote doesn't apply to ExtremeSi's question. He's not looking to swap in track pads, he's just wondering about getting a new set of pads, likely for the street. For that, it makes perfect sense to get a new set of jobber rotors since they're cheap and it'll ensure proper bedding-in of the new pads.

[djayz]

you wont notice a difference if you change your rotors unless you have something wrong with your current ones. If right now you have no problems braking and are just running out of padding then switch out the pads and dont worry about the rotors...they make them to last long enough as long as you arent braking hard at high speeds(which can cause warping)

i had an 89 prelude with the same rotors from the day it was made and i had brake pads which were close to the metal when i bought it...i replaced the pads and it was fine.