: Why are the rotors replaced also whenever the front brake pads are replaced?



jjohnkim
08-02-10, 09:23 AM
My dealer explained but I did not understand well. Can anybody explain plainly?

CadillacSTS42005
08-02-10, 10:34 AM
If the rotors are junk and too thin to cut then they need to be replaced to be within saftey (inspection) specs. Why replace worn brakes if the things they make contact with are complete crap too? I mean its only your brakes who need them right?
Nothing personal but if your upset about the cost of a proper and complete brake job then you best trade this car in asap.

caddyfat2
08-02-10, 11:36 AM
If the rotors are junk and too thin to cut then they need to be replaced to be within saftey (inspection) specs. Why replace worn brakes if the things they make contact with are complete crap too? I mean its only your brakes who need them right?
Nothing personal but if your upset about the cost of a proper and complete brake job then you best trade this car in asap.

First the rotors don't have to be changed unless they don't meet spec's any longer. Other than that the rotors are still functional. Two years ago the dealer told me I needed new brake pads all around. Well low and behold I changed the front but I am still riding on the rears and they haven't worn out yet. Don't take everything you hear on face value. Check them out yourself or get a second opinion. The dealer will tell you anything to make a buck.

CadillacSTS42005
08-02-10, 11:54 AM
I never stated they had to be changed for nothing, I stated if they are warped and too thin to be cut they must be replaced.

CBodyFan
08-02-10, 12:28 PM
Because the front brakes do most of the stopping the front rotors take most of the punishment. Living in NJ where stop and go driving is the norm I seem to go through front brake pads and rotors about twice as often as rear brakes. I know most will disagree with me but I miss drum brakes. So much more durable. If you know how to drive drums brakes work perfectly well. Of course the extra stopping power of discs is very valuable if you tail gate on a regular basis. :cop:

Midnight
08-02-10, 12:45 PM
Hmm, I didn't see where the OP said he was upset, he just wanted more info. And everyone knows that not all mechanics are trustworthy.

What did the dealer say that you didn't understand? There can be a lot of reasons for it... if your old brakes wore down so far that they gouged the rotors.. Rotors too thin or too warped to resurface, or maybe just "burned" right? Some people just replace them at the same time for peace of mind. Sometimes I wonder if a turned (thinner) rotor will warp easier than a new one. I think I will be replacing mine when it comes time to do the brakes, because they pulsate now. Nothing beats smooth brakes, and nothing's worse than wobbly ones.

On a side note, my last car had "captive" rotors... which, to remove you have to take out the pressed-in wheel bearings. It was a major undertaking. A horrible, design. So every time I pull the wheel off on the STS (not too often) and see the rotor kind of hanging there, loose, I smile. That's how it should be. Be glad you don't have captive rotors.

caddyfat2
08-02-10, 01:59 PM
First the rotors don't have to be changed unless they don't meet spec's any longer. Other than that the rotors are still functional.


I think that will wrap this up.

turnerbend
08-02-10, 02:17 PM
If the rotors are junk and too thin to cut then they need to be replaced to be within saftey (inspection) specs. Why replace worn brakes if the things they make contact with are complete crap too? I mean its only your brakes who need them right?
Nothing personal but if your upset about the cost of a proper and complete brake job then you best trade this car in asap.

You can more than likely replace brake pad 1 maybe 2 times befor you have to replace rotors. You can also turn rotors 1 or 2 times before they get below spec. The rotors that comes on the STS whould not be junk unless you change them for aftermarkets.

EChas3
08-07-10, 08:26 PM
Most shops recommend replacing rotors because even resurfaced ones are more likely to produce problems such as squealing. By the time the wear indicators begin to sound, rotors are usually worn beyond spec, anyway.

caddyfat2
08-09-10, 08:43 AM
Most shops recommend replacing rotors because even resurfaced ones are more likely to produce problems such as squealing. By the time the wear indicators begin to sound, rotors are usually worn beyond spec, anyway.
Sorry but I don't believe it.......
Maybe some shops would like to make extra money replacing the rotors unnessarily but the squeelers donot wear down rotors they only make noise to tell you that it's time to change your pads. If you check your squeelers you will see that they wear from squeeling not the rotor because the rotor is harder material.

EChas3
08-09-10, 10:58 PM
I was not referencing the wear indicator squeelers. Resurfaced rotors just aren't the same as new. Even the best machine shops can't (or won't) turn an old rotor as good as new. Even disregarding industry standard wear limits, warps & imperfections, a fair part of the time a resurfaced will make more noise or have a rough feel. New pads seat best with new rotors. No good shop wants a customer back with the same complaint.

It's different if you're DIY or pinching pennies. You can pay now or pay later.

Want the best?

Joe Pagano
08-10-10, 04:43 AM
Here is my $.02...............
As stated, the front brakes do almost all the action of stopping the vehicle. Rotors are tricky items, and new pads love new rotors. So, here is how I have cared for my previous 2 Mercedes Benz and 3 Cadillac's (2 current, STS4 N* & CTS4 Lux). When I first take possession of the car I have the wear sensors removed from the pads. Then I drive until I get that first indication of grinding, you will get enough safe mileage at that point. Now, I go to the auto parts store and purchase new Chinese rotors and quality OEM spec pads. Now, because I dont have the equipment, or the desire, to do the install I have my local service station take care of it. And, of course, the wear sensors are removed again.
Reasoning - wear sensors will start annoying you WAY before brakes are needed, and since I do rotors anyway, I get the most bang for my buck by extending my brake life. Of course, once in a blue moon, if you keep the vehicle long enough, you will do the same with the rear set.
As far as I am concerned this is the only way to go, no need to throw good pads in the garbage just because of an annoying little tab of metal, since your not looking to save the rotor anyway, too many issues with new pads on old rotors.
But hey, that's just me.................................. Joe P

Greg00coupe
08-10-10, 01:28 PM
Joe's aftermarket parts and local mechanic approach is not that bad. I'd keep the wear indicators however. If they begin to squeek it is simple to bend them back. Take it as a prewarning. Frankly if you don't go to the dealer parts are not that expensive.

I usually watch my pads, check them every 6 months or so and when they get low I just change them out and don't turn the rotors because they are usually smooth.

The local Honda dealer (I know this in Cadillac) told me Honda does not require them to turn rotors if the rotors are true and not too thin. I found that odd but started doing it and it's worked for me.

There is only two reasons to change rotors...they are too thin and or warped.

caddyfat2
08-10-10, 04:27 PM
There is only two reasons to change rotors...they are too thin and or warped.

Amen, so don't waste your money!!!!!

next2pool
08-11-10, 02:16 AM
Amen, so don't waste your money!!!!!

Rotor replacement is another great example of great American marketing ingenuity--a total waste of money unless they truely have run out or thickness variation. Most times pulsation (if you have it) Is due to resin build up not warping.

fps_dean
08-15-10, 01:48 PM
Nothing personal but if your upset about the cost of a proper and complete brake job then you best trade this car in asap.
Actually, most newer cars need rotors everytime they need brakes too, so trading the car in won't do much. If you think STS brakes and rotors go fast, try a Honda Accord where you can expect new brakes and rotors every 5-10k! I got 25k on my fronts, and most of my driving is on a 45-55mph road with tons of red lights so I have no complaints there.

If you don't like replacing rotors (or pads for that matter) get a 1981 Buick Century. That was my first car, I got in '99 with 30,200 original miles, original brakes and original rotors still on it. I replaced my fronts at 85k and the original rotors were still good. They just don't make rotors and pads like that anymore though... I eventually did replace my back pads too, but the rotors were still in great shape.

doowap57
08-15-10, 06:53 PM
THERE IS A 3rd REASON !
To upgrade from, flat, OEM, rotors, to slotted and drilled rotors.
Which by the way "ARE" an option at Cadillac !
Have Fun !:wavehi::wavehi:

After I got my Cad, I went on a long trip,to Fl., and during rush hour,
they faded on me. So I put on drilled and slotted to possibly eliminate
that problem.That "IS" what they are for....

EChas3
08-15-10, 10:40 PM
They look nice but have little advantage under street conditions.

next2pool
08-17-10, 03:45 PM
""After I got my Cad, I went on a long trip,to Fl., and during rush hour,
they faded on me. So I put on drilled and slotted to possibly eliminate
that problem.That "IS" what they are for.... ""

Another thing can happen that sometimes feels like fade. As the brake fluid gets older it will absorb humidity. When the brakes get hot, that water will boil and drastically reduce stopping power since the fluid then becomes compressible. That's one reason you will see recommendations to flush the fluid every so often. I'm not saying that's what is going on but it does happen.

EChas3
08-17-10, 11:16 PM
^^^ A lot of car guys advocate upgrading classic cars' brake systems to newer (or synthetic) fluids because traditional DOT 3 is so hygroscopic (attracts water) and removes paint.

Periodic brake fluid flush & fill isn't pure BS. It can help reduce corrosion of brake system parts in humid environments. People do worse things to their cars.

z06bigbird
08-18-10, 12:20 AM
Rosin Buildup??? Splain some more about this. First time I have heard about this, Lucy.

I will not accuse you of stealing the thread, as I have already stolen it.

EChas3
08-18-10, 12:31 AM
Rosin Buildup???? I musta missed a post!

Loose Lucy is my delight! (No offense intended.)

next2pool
08-18-10, 12:40 PM
Rosin Buildup??? Splain some more about this. First time I have heard about this, Lucy.

I will not accuse you of stealing the thread, as I have already stolen it.

Many times dirt, road oils, and resins within the pads will deposit on the rotors and cause pulsation even if the rotors aren't warped. This is most common if you do a lot of city driving and don't get any significant hard stops. You can remove this either by making several hard stops (don't lock them) from about 80mph in succession or remove the wheels and clean the rotors with an abrasive pad on the end of a drill.

DauroT
08-23-10, 12:50 PM
How much they end up costing you..Im thinking of buying a Cadillac and would like to know some costs associated.

02603sec
05-20-11, 06:12 PM
i havent changed a rotors on a car since early 80's my bro in law sold me a 2 year old Riveria with pulsating brakes. MY GF is hard on brakes. I can get 75k out of a set of fronts... if the rotors are smooth, and not warped, you're good. Beware; you can warp a rotor with a sticky caliper.

EChas3
05-20-11, 09:38 PM
The reason most shops recommend rotors is to make money. Even quality shops often do so to prevent return visits. Customers hate brake squeal and new pads love new rotors.

Many owners also wait too long to replace pads. Most drivers won't notice until the damage is already done. It really isn't hard to warp a rotor. If you do it yourself, they aren't really that expensive, either.

turnne
05-20-11, 10:11 PM
The German manufacturers DO NOT recommend turning rotors
I have never seen a BMW or Mercedes dealer that would not it...that being said you can buy aftermarket rotors( for those cars) for not too much $$
And based on the way the brakes on those feel...I would say they are on to something
ie...no fading and much shorter stopping distances
The 2005+ plus STS has much better brakes than the older model...but still not to the levels of the germans

turnerbend
05-20-11, 11:52 PM
If the rotors are junk and too thin to cut then they need to be replaced to be within saftey (inspection) specs. Why replace worn brakes if the things they make contact with are complete crap too? I mean its only your brakes who need them right?
Nothing personal but if your upset about the cost of a proper and complete brake job then you best trade this car in asap.
What dealer do you work for? Most rotors are good for 2 maybe 3 sets of pads. You might have to have them turned because the are out of round. Pads wear, rotor don't unless you wear the pads down to the metal.

turnerbend
05-20-11, 11:59 PM
Most shops recommend replacing rotors because even resurfaced ones are more likely to produce problems such as squealing. By the time the wear indicators begin to sound, rotors are usually worn beyond spec, anyway.
Wear idicator has nothing to do with rotor wear, the indicator is a warning that the pads are below spec.

turnerbend
05-21-11, 12:04 AM
I was not referencing the wear indicator squeelers. Resurfaced rotors just aren't the same as new. Even the best machine shops can't (or won't) turn an old rotor as good as new. Even disregarding industry standard wear limits, warps & imperfections, a fair part of the time a resurfaced will make more noise or have a rough feel. New pads seat best with new rotors. No good shop wants a customer back with the same complaint.

It's different if you're DIY or pinching pennies. You can pay now or pay later.

Want the best?
I have had to get new rotors turned before they was useable.

mckellyb
05-21-11, 04:34 AM
I have had to get new rotors turned before they was useable.

Wait, they were warped out of the box?!

Those would have gone back to the supplier!

STS guy
05-24-11, 04:25 PM
IMHO dealers try to rack up a certain number of dollars on each unit they take in for repairs. At the dealership I use it appears that the magic number is $300.00. Seems like no matter what you take it in for they will find at least $300 for "needed" repairs. That's my opinion and I'm sticking with it.

STS guy

caddyfat2
05-24-11, 05:37 PM
Usually when I put new rotors on I will scuff them up ( not turn them) so they will have a better grab.

Platinum06
07-07-11, 06:24 PM
Replace the rotors with the pads...They were $70 each at my local auto parts store. I think the dealers even replace the calipers up here in the Chicago area. I do them myself and really dont see the need for calipers.
Everything new and there is no problems.

mckellyb
07-07-11, 08:05 PM
Calipers?!

Really?

That's flat-out criminal.

Oh, wait...Chicago. Never mind...business as usual.

/sarcasm

M.A.C
07-08-11, 02:56 AM
I replaced the original rear rotors and installed new brakes last week and will replace original front rotors and install new brakes this weekend. However, I will not replace them or have them resurfaced when I replace the brakes in the future. I will just replace brakes as needed. I will not waste time and money resurfacing. I will simply replacing them if there is uneven braking, vibration or they are otherwise excessively damaged by scoring.

Lifer
07-10-11, 09:57 AM
IMHO dealers try to rack up a certain number of dollars on each unit they take in for repairs. At the dealership I use it appears that the magic number is $300.00. Seems like no matter what you take it in for they will find at least $300 for "needed" repairs. That's my opinion and I'm sticking with it.

STS guy

I swear that that the Cadillac dealers in the Ft Worth-Dallas area target $1,000 per visit. That's what it costs me if its not warranty.

z06bigbird
07-11-11, 03:38 PM
This thread seems to be analyzing all of the problems of the world.

Re: the replacement of calipers--In the snow belt, after after about 4 or 5 years of use (plus perhaps 50,000 miles or so), some calipers will corrode and begin to stick. This is especially true on the passenger side of the car because the wheel hits all of the water, snow, ice, and salt on the curbside of the road.

EChas3
07-11-11, 09:11 PM
Re: the replacement of calipers--In the snow belt, after after about 4 or 5 years of use (plus perhaps 50,000 miles or so), some calipers will corrode and begin to stick. This is especially true on the passenger side of the car because the wheel hits all of the water, snow, ice, and salt on the curbside of the road.

After driving nearly 40 years in the snowbelt, I have to agree that there is some truth to this, especially when a car isn't garage-kept. Corroded calipers stick, wear pads & rotors, hurt mileage & ruin performance; both stopping & going..

Platinum06
07-12-11, 01:00 PM
Wait, they were warped out of the box?!

Those would have gone back to the supplier!

I think he means they had paint on them...I just threw them on as is and ran with it. They work fine.