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To turn or not to turn...that is the question...brake rotors.

was thatguy

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So my Tahoe is in the driveway on jack stands. Replaced rear window regulator, rear hatch struts are done and replacements will be here today or tomorrow, front brakes are apart and I have the pads and everything is cleaned up and ready for assembly EXCEPT rotors. They have little wear, but I can’t get them turned until tomorrow. New ones are a mile away at 2 different parts stores at $45 apiece.
I can save $50 by waiting, or I can replace and get it done today.
What’s the consensus these days? Just replace em?
 

wsuwrhr

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Are they warped or why do you want to turn them?
 

dribble

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If they meet manufacturers specs of for thickness, thickness variation and lateral runout, leave them alone. I have a replaced a few rotors on my own vehicles in the last 25 years due to the brakes going metal to metal. I have not machined one of my rotors in that time.
 

was thatguy

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They caliper OK, but had abnormal pad wear on drivers side, and the drivers side had a low speed squeal that got louder with brake pedal.
It wasn’t into the warning tab at all, but showed sort of crooked wear on the outer pad.
Given all that I’m not going to just pad them.
I plan on selling this thing (‘02) in the next year so having spares really isn’t a priority.
Maybe if I fuck around on RDP all day my decision will be made for me!

Thing is that in the past rotors were expensive. You didn’t replace them unless they were hammered. Now it seems that they aren’t much more to replace as machine.
 

wsuwrhr

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Might be the caliper/mount that is causing the goofy wear.

They caliper OK, but had abnormal pad wear on drivers side, and the drivers side had a low speed squeal that got louder with brake pedal.
It wasn’t into the warning tab at all, but showed sort of crooked wear on the outer pad.
Given all that I’m not going to just pad them.
I plan on selling this thing (‘02) in the next year so having spares really isn’t a priority.
Maybe if I fuck around on RDP all day my decision will be made for me!

Thing is that in the past rotors were expensive. You didn’t replace them unless they were hammered. Now it seems that they aren’t much more to replace as machine.
 

wsuwrhr

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Try to find components made in the US is why.

Thing is that in the past rotors were expensive. You didn’t replace them unless they were hammered. Now it seems that they aren’t much more to replace as machine.
 

was thatguy

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Might be the caliper/mount that is causing the goofy wear.

Yeah, it took my ingersol half inch impact with the torx socket, heat, and a lot of WD 40 to get the slider bolts out on that side. The sliders themselves were free and working, but holy hell those bolts were tight!

Anyway, its supposed to freaking rain again tomorrow so fuck it, I’m headed to the parts store.
 

lbhsbz

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If you had no pulsation previously, the rotors are still above minimum thickness, and there is no excessive grooving (which would likely put them below minimum after machining) then there is no reason to do anything to the rotors. It is tough to find anywhere that knows how to machine rotors properly such that they end up with less runout than they had before.

If you had any tapered pad wear, I’d recommend replacing that caliper or rebuilding it with new pistons. The sideloading of phenolic pistons due to tapered pad wear can cause material to displace, causing the piston to look like a piece of corrugated pipe to a minor extent, which can result in poor retraction after you shove it back into the caliper.
 

CLdrinker

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Turn them. Or buy new. If you leave them you will be up on jack stands again in a few weeks doing right the second time.
 

wallnutz

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Last time I did brakes on my little beater Sonoma, I replaced rotors, calipers and pads for $125. Totally worth it.
Actually I need to edit, I bought the more expensive pads so I was into it for $150 total.
 

CobraDave

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For me I try not to throw money in the trash. If I can turn them, I do. If it’s a Daily driver and you need it fixed now, I get it. That does sound pretty cheap for rotors.


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Maestro

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Clean all surfaces, turn rotors if no blueing or cracks. Lube slide pins and contact points on pads, don't paint lube, a little goes along ways.
Now don't go out and buy the $30 value pad and complain 10k later that they did not last. Buy quality get quality.
 

JDub24

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Funny you bring this up. Must be national brake job day today. Just did a four corners on the wife’s Durango. Pads had 75% life left but front rotors were warped. Threw them all in the trash and went will all new. The shits been sitting in boxes in my garage for almost two months. I find that with limited time it’s easier to spend the extra $100.00 and be done with it.

Plus as @lbhsbz stated... good luck finding a machine shop that knows how to turn down a rotor.
 

TripleB

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Have Midas do the brakes and get the life time warranty
 

was thatguy

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FWIW I have a guy that is spot on turning rotors. He fixed the rotors on Debs 2 year old Camry when it developed a bad pulsation with almost zero pad wear.
Getting them turned first thing in the am.
 

Justfishing

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Abnormal pad wear is from either a stuck caliper piston or sticking calipers.

Calipers float on thier brackets. Rust and debris can cause them to stick. There are little metal anti rattle clips that can be the problem. Replace those and clean and lube slide surfaces.

The Pistons in the calipers can bind keeping pressure on the pads.

Disc brakes don't have return springs like drum brakes. So they must float freely and the pistion retract.

Have you ever flushed the brake fluid? Brake fluid is hydroscopic and absorbs water. This can lead to rotting from the inside. You can get pitting in the metal that the seals ride on. It can lead to a bad caliper, master cylinder etc. After putting in new pads I only give small pumps to the pedal to limit the travel of the piston in the master cylinder.
 

was thatguy

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Abnormal pad wear is from either a stuck caliper piston or sticking calipers.

Calipers float on thier brackets. Rust and debris can cause them to stick. There are little metal anti rattle clips that can be the problem. Replace those and clean and lube slide surfaces.

The Pistons in the calipers can bind keeping pressure on the pads.

Disc brakes don't have return springs like drum brakes. So they must float freely and the pistion retract.

Have you ever flushed the brake fluid? Brake fluid is hydroscopic and absorbs water. This can lead to rotting from the inside. You can get pitting in the metal that the seals ride on. It can lead to a bad caliper, master cylinder etc. After putting in new pads I only give small pumps to the pedal to limit the travel of the piston in the master cylinder.

Yes I changed all the clips and lubed everything.
The pistons look good and were easily and smoothly pushed in with a used pad and c-clamp. Everything was free moving.
It almost looks like the last time someone was in there the rotors were replaced but not by the same person or at the same time.
I say that because the slider bolts were completely different torque from one side to the other.
The driver side was almost impossible to get them loose. Took my ingersol half inch impact with the air jacked up to break them loose. Torque on them should be 80 pounds according to several sites I looked up, the bracket bolts to the knuckle are 130 and they were easier to get loose. Looks like about a 1/2” fine thread?
Going after the rears as well tomorrow because I can feel through the wheels that the rear rotors definitely are far more worn than the fronts.
It’s got 150K on it so it’s likely the rears have been neglected. (I’ve had it 2 years or so)

I’ve done a lot of brake jobs in the past and know all the tricks such as baby steps on the pedal to seat the pads etc.

Just seems like these days replacing rotors is more common than turning them like we always used to do.
 

was thatguy

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Found my squeak...

Rears are hammered.

9942CA27-3E04-4B89-B7FA-D5B894BEC2CD.jpeg
 

Outdrive1

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Replace them and have the other turned for spares.

This is exactly what I did. Now I have a spare set. I can do front brakes on my F150 in an hour.


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stoker2001

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be careful buying new rotors,seems they are all china made these days..i would stick with OEM,even those are china too..
 

ka0tyk

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i always keep an eye out for rockauto's discount section whenever i buy a car and load up on consumables when they're on sale. sometimes you can get name brand rotors and pads for cheap and free shipping.

if you dont know... go to rock auto, click your manufacturer, then year, then model... before click your engine size theres a yellow "rss" button. Click that. A page pops up and on the right hand side theres a "love a bargain" section and click the blue "html" button. Patrol this page weekly and grab wipers, brakes, belts, etc when they're on clearance pricing.
 

was thatguy

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Got Bosch rotors and Wagner pads.
Not cheap.
Got Napa parking brake bands.
Lunch at outback then home to assemble it all.
 

Flying_Lavey

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Tell you what, I can get a good look at a T-bone by sticking my head up a bull's ass but I'd rather take the butcher's word for it. Go buy some Callihans.
Haha! Love that movie!

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SBMech

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Always replace pads and rotors. Since around mid 90's shit is only good for 1 run of pads, sure you can machine them to close to min spec, but you will just be pissed off when you have to do it all over again because they warp easily at near or at min spec.

Don't skimp on brakes. Ever.

This is not 60's and 70's shit where you can machine them 2x before they get close to min spec. Unsprung wheel weight is how they achieve CAFE requirements. Everything is disposable.

Do it right the first time, just replace pads AND rotors, and lube/inspect the pad carriers and slides. Any grooves in the carriers warrant replacement. Make sure you use a quality brake lube, and hit all the metal to metal surfaces.

Be aware that late models have gone back to glued pads again, you need to assemble them correctly or you will have noise issues.
 

lbhsbz

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because they warp easily at near or at min spec.

Do I really have to go through all this shit again?

The min-thickness spec has nothing to do with heat and rotors don't warp. The min thick spec exists because if the rotor gets much thinner and the pads wear out, they'll fire clean out of caliper between the bracket and the rotor and/or the pistons will come out past the seals and you'll have catastrophic instant brake failure.

Rotors "warp" after machining because someone machined more runout into them than they had in the first place...but they don't realize they fucked up because they never measure runout after the rotor goes back on the hub and make sure they meet or beat the spec published in service information...which they also don't read when doing a "simple" brake job.
 
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