Brake System Drum And Rotor

[chubyball]

I have a 100K miles on my car, I guess it time to replace new rotor. My question is do I really need to re-surface or machine the new rotors or new drum before install them with brand new brake shoe, anyone know?

[maxed_out]

What is the sympton you are trying to address...as far as the rotors I wouldnt think twice and take them to a shop. They will measure them and if in spec will true them up on their equipment. These things can warp and give you pulsation...so getting them machined is a good thing. I had 2 out and after machining no shaking on stopping.

In general shaking to a stop = warped rotors. Grinding noise can be pads and/or bearings or other stuff.

[sha4000]

I have a 100K miles on my car, I guess it time to replace new rotor. My question is do I really need to re-surface or machine the new rotors or new drum before install them with brand new brake shoe, anyone know?

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first off you have brake rotors in the front and back, no drum .are these the original rotors?if so i would recommend getting new rotors, they can be hadon ebay for cheaq. if you want to get tem shaved any brake shop can do this for you

[daffy]

Hi chubyball,

If you have no pulsations and the rotors look good, just replace the pads. As far as machining Lexus rotors, it doesn't last. I did this and in a short time after, I started getting pulsations, when stopping at higher speeds. So I had to replace the rotors and used the old pads and haven't had trouble since. I have a high mileage Ls400(265000 miles). Daffy

[Gumart1]

Daffy, when you say to keep the rotors if they "look good", what do you mean exactly? My rotors and pads are worn but within spec, and I plan to at least replace the pads before the sensors wear. I don't have any vibration from the rotor. They are within spec but probably 2/3 worn. If I put on a good pad set, is there a chance that the rotors will wear down and I'll have to then replace the rotors and my newer pads?

By the way, I purchased a digital caliper at my local hardware store for $17, greatest tool ever!

Hi chubyball,

    If you have no pulsations and the rotors look good, just replace the pads. As far as machining Lexus rotors, it doesn't last. I did this and in a short time after, I started getting pulsations, when stopping at higher speeds. So I had to replace the rotors and used the old pads and haven't had trouble since. I have a high mileage Ls400(265000 miles).  Daffy

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[SRK]

The only reason to machine brake rotors is to remove variations in thickness and runout, which are always felt as vibrations under braking. If you can stop quickly from high speed, and don't feel any vibrations (steering wheel shake in the front end, seat shaking for the rear axle), then just install new pads. Pads will bed into whatever surface, new, machined, or used, in a few miles.

Machining rotors to make them look nice is a waste of time and money, and also reduces the mass of the rotor which will cause them heat faster and warp more quickly. It is also possible to machine them incorrectly - if the machine is worn out or the machinist is not skilled - and end up with a rotor that has worse dimensions than when you brought it in.

If it ain't broke, don't fix it.

[prix]

I recently had new rotors and brakes put on, because I was told the rotors were 'under spec'. You should have your existing rotors measured if you have not done so. If they do need to be replaced, there ARE lots of cheap options on eBay (aftermarket), but on the idea that you get what you pay for, I went with OEM rotors, which you can find at discount parts places online. Or you can pay full price at a dealer for them if you are in a hurry. It is my understanding that there is a difference in quality between aftermarket and OEM rotors. New rotors will need to be sanded so they 'fit' with your brakes pads. I was told that if you do not do that, the rotors will develop 'hard spots' (I think this is what he said)...so yes, you need to have them lightly sanded to fit. You would not want to sand any more than is necessary though. Just until they make good solid (even) contact with the pads. Labor on brake installs doesn't cost that much...if you are not sure how to do this, I would have the work done by a pro! Replacing brake and rotors and labor will cost you a grand or so (using all OEM parts and having someone else do the install). Good luck.

so

I have a 100K miles on my car, I guess it time to replace new rotor. My question is do I really need to re-surface or machine the new rotors or new drum before install them with brand new brake shoe, anyone know?

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[prix]

Hmmm...SRK...I just read your post (after posting the advice I was given on a recent pad/rotor install. What you are saying directly conflicts with what I was told). At the time of my brake/rotor install, I told them I did not want them to machine the rotors (thinking that this would just reduce the life of the part), and I was advised by the mechanic that they really needed to do a light machining to get a good fit. Now I wonder...I might have his work checked out to see whether he did a good job. He seemed v. competent (this was a while back), but it still would not hurt to have someone review his work. I'll ask around..what you say makes sense though.

SRK,Nov 13 2005, 01:44 PM]

The only reason to machine brake rotors is to remove variations in thickness and runout, which are always felt as vibrations under braking. If you can stop quickly from high speed, and don't feel any vibrations (steering wheel shake in the front end, seat shaking for the rear axle), then just install new pads. Pads will bed into whatever surface, new, machined, or used, in a few miles.

Machining rotors to make them look nice is a waste of time and money, and also reduces the mass of the rotor which will cause them heat faster and warp more quickly. It is also possible to machine them incorrectly - if the machine is worn out or the machinist is not skilled - and end up with a rotor that has worse dimensions than when you brought it in.

If it ain't broke, don't fix it.

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[lenore]

I would not machine new rotors, they tell you to do that, but it removes mass. I just replace the rotors and all pads on MY RX300 and they work great. Got all parts from tirerack.com Brembo rotors and ceramic discs. $250 for everything including shipping. (two rotors and two sets of pads for front and rear. My orginal rotors went 118k miles

[SKperformance]

If you have to machine a rotor before installing a new one then you

1. are not buying OEM

2. what kind of crap doesn't even have enough quality to make the rotors straight

oh yah never waste your time maching a rotor if it is pulsing just get a new one from a name you know like Toyota brembo or other big names.

[SRK]

SKperformance is right. If you are advised to machine a new rotor, it isn't worth buying. And buying a rotor because it is cheap, well you get what you pay for.

I have done hundreds of brake jobs, on cars of all sorts. I stand by what I say Prix, and that is that if the rotors you have now have no symptoms of warp or vibration, put new pads on them and be done with it. I did this with both my cars tow months ago. Two years ago I put new rotors on the LS and re-used the existing pads. No problem.

Of all the new rotors I have ever installed, from Jaguar to Mercedes, GM to Volvo, whatever, I have never seen rotors of the quality of Lexus. Sealed in a plastic bag, and not machined to size, but GROUND to final size and surface. Works of art, AND they cost less than Raybestos aftermarket rotors. So what did I do? Buy the Lexus part. Perfect. Thirty minutes later I had perfect front brakes. The exisiting pads bedded in in about five miles. Left for a 3000 km trip three days later. Those pads wore out in two years, put in a set of LEXUS pads, and after five miles the brakes were perfectly bedded in again.

The idea that some groink "mechanic" would put a new Lexus supplied rotor in his worn out little brake lathe and bugger it up to "make it fit" is insane.

So you have a choice - believe me or believe some guy who wants to up-sell you a machine charge you don't need, or over machine the rotors and then claim you need new ones. He'll probably tell you some deal about "safety" and that the "law" says......Ignore him. Pads only if you have no vibration. If you have vibration, buy Lexus rotors, not some offshore made "Charging Rhino" brand piece of third world crap.

I would be far more concerned about the condition of the sliders on the calipers, and the piston retraction on the calipers causing problems at that mileage, than the rotors. Did he happen to mention that, or did he leave that more important stuff out of his little "pep" talk to take your money?

[chubyball]

Here is the history of my front brake system. At 45K miles, I replace brake pads without machine the rotors, and the first few thousand miles (1k-2k) the front end wables due to new pads and old rotor were not perfectly same surface, what I mean is the new brakepads has even surface but not rotors. Then at 95K miles, I replace front brakepads again without machine the rotors, it also had same symtom like as first time replacement. But now, the car is at 105K miles It start make a weird noise at low speed braking, it sound like there is something rubbing between the pad and the rotor.

I check the rotor and see the edge of the brake may have rubbing on the rotor where which does not shine. If you look carefull at your old rotors you can see rust at outer and inner of rotor are un-even with the surface of the brake pads applied on.

The whole 105K miles, I have not replaced the rear drum brake yet. It does not seem wear out as quick as front brake. But I am thinking about to replace front rotors & brakepads, also rear drum and pads.

What do you guys think?

[sha4000]

you use the rear brakes less, something like 70/30 and its not a drum inthe classical sense

[SKperformance]

If you warp rotors very shortly after installing them(less than 5000miles)

It is because you did not lube the sliders

or

have a sticking caliper/piston

or

bought a really cheap material for the rotors

or the #1 reason you need to learn how to drive better and are heating them up by not being fluid in your application of the brakes.

Case in point , i have never had to replace any of my rotors on my cars one i got rid of the original ones the cars came with.

No vibrations no warping and no pitting.

All of them have about 20 000 km on them .

Many others i know and have done their brakes , i have had to change them 2-3 times in the same time frame and driving environment.

Case in point ,look at the surface of your rotors

are they shiny and smooth

slightly rough

pitted with lines

pitted with lines and some rust spots?

The rougher your rotors look the more pressure you are applying to them causing them to wear more . So unless you are driving a obstacle course you are braking with too much force without leaving enough space or looking far enough down the road to anticipate the change in momentum.

Change that way you drive and save money in gas and part replacement.

[prix]

SRK, good advice no doubt, but it's after the fact. The new brakes and rotosrs were put on at a couple of months ago. I knew I needed new brakes and new rotors, because the last time the pads were changed (a few years ago), I was told the rotors were very thin. So it was no surprise to me when I was told this year the rotors were now under spec. I went with new OEM rotos and OEM pads. There was no extra charge for machining the rotors (if in fact that was done...I am going to look into this), so I don't that was any motivation for advising me that this needed to be done. He did look at the calipers and said they were in good condition. I can have a mechanic who will be looking at the car shortly give me some diagnosis on how well the brake job was done. If he screwed up some "work of art" OEM rotors by machining them unnecessarily, I will seriously pursue them for damages. Needless to say, I have no plans to return to that shop.

SKperformance is right.  If you are advised to machine a new rotor, it isn't worth buying.  And buying a rotor because it is cheap, well you get what you pay for.

I have done hundreds of brake jobs, on cars of all sorts.  I stand by what I say Prix, and that is that if the rotors you have now have no symptoms of warp or vibration, put new pads on them and be done with it.  I did this with both my cars tow months ago.  Two years ago I put new rotors on the LS and re-used the existing pads.  No problem.

Of all the new rotors I have ever installed, from Jaguar to Mercedes,  GM to Volvo, whatever,  I have never seen rotors of the quality of Lexus.  Sealed in a plastic bag, and not machined to size, but GROUND to final size and surface.  Works of art, AND they cost less than Raybestos aftermarket rotors.  So what did I do?  Buy the Lexus part.  Perfect.  Thirty minutes later I had perfect front brakes.  The exisiting pads bedded in in about five miles.  Left for a 3000 km trip three days later.  Those pads wore out in two years, put in a set of LEXUS pads, and after five miles the brakes were perfectly bedded in again. 

The idea that some groink "mechanic" would put a new Lexus supplied rotor in his worn out little brake lathe and bugger it up to "make it fit" is insane. 

So you have a choice - believe me or believe some guy who wants to up-sell you a machine charge you don't need, or over machine the rotors and then claim you  need new ones.  He'll probably tell you some deal about "safety" and that the "law" says......Ignore him.  Pads only if you have no vibration.  If you have vibration, buy Lexus rotors, not some offshore made "Charging Rhino" brand piece of third world crap.

I would be far more concerned about the condition of the sliders on the calipers, and the piston retraction on the calipers causing problems at that mileage, than the rotors.  Did he happen to mention that, or did he leave that more important stuff out of his little "pep" talk to take your money?

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[SRK]

Sounds like you are on the right track in asking about the machining. There is no way a Lexus rotor needs to be machined before installation, and probably they didn't do that. It was also a good choice to go with OEM parts. Good luck with it.