New Rotor Warped Shuddering When Braking

[Kev1990]

1990 CB7 within the past six months I had the right passenger rotor replaced months later I feel light shuddering when braking like its starting to warp and the car pulls to the right. Just about a month agp I had the left one replaced with a high quality rotor it seems to be doing just fine but the inner tie rod boot is torn I've made posts about it but this is definitely the pop in the wheel when turning left. My question for this what type of grease is used to lube the inner tie rod and rack-pinion? I'm going to be putting a new boot on it and re-lubing it before so. Any help is greatly appreciated thank you in advance.

['93CB7Ex]

most rotors need to be turned out of the box...

as for the tie rod, just replace it.

[H311RA151N]

most rotors need to be turned out of the box...

as for the tie rod, just replace it.

Do you care to elaborate on this? I have never heard this bit of information nor experienced anything of the like.

['93CB7Ex]

i worked at kauffman tire for a couple months.

every single car they did brakes on with new rotors, they would turn out of the box. BUT they only got parts from napa and we were talking today about it at the shop, and lots of people have had issues with rotors warping. i guess it just depends on how it was stored on the shelf.

i put brand new front rotors on a f150, oem motorcraft, today and it had 0 problems. but ive got brand new autozone rotors, and they were shaking in less than 1 day.

[H311RA151N]

i worked at kauffman tire for a couple months.

every single car they did brakes on with new rotors, they would turn out of the box. BUT they only got parts from napa and we were talking today about it at the shop, and lots of people have had issues with rotors warping. i guess it just depends on how it was stored on the shelf.

i put brand new front rotors on a f150, oem motorcraft, today and it had 0 problems. but ive got brand new autozone rotors, and they were shaking in less than 1 day.

That would be a pain in the neck. I guess I have been lucky enough not to have any problems. I know for a fact that Oreilly's stacks almost everything on pallets sky high.

I like Brembo factory replacement rotors and Wagner thermoquiet pads for my Accord. Which I have now and really like. Everything else gets Duralast pads and rotors. I think I got a set of Brakebest rotors from Oreilly's years ago and they warped rather quickly. 6 months IIRC. I thought they were too bad to even attempt to turn though...

[Kev1990]

So what do you think I should suggest doing then? Do you think my mechanic would replace under the one year labor/parts warranty? Or would it be better to get them turned or resurfaced?

[illinois_erik]

So what do you think I should suggest doing then? Do you think my mechanic would replace under the one year labor/parts warranty? Or would it be better to get them turned or resurfaced?

theyll probably replace it versus turning it, since its a captive rotor most places cant do it unless they possess an on car lathe..as for turning new rotors ok, must've been one of those quirks that a shop thinks is beneficial when it doesn't do anything, or they just liked milking dumb customers wallets.

if youre warping rotors on a regular, Id look into rebuilding or replacing your caliper, even taking the slide pins outs and thoroughly clean the slide pin bores and slide pins and using the proper synthetic brake grease during reassembly. do *not* use antiseize to lube the pins. when i rebuild mine, I take a drill bit the size of the bores and use it like a scooper, you wouldnt believe all the shit that gets packed in there, if the pins have pitting on them replace them, and the little bellows that are there. Also if you can source it,there are caliper pressure gages and although I havent seen any numbers on what type of pressure numbers youre supposed to get, its a good diagnostic tool to see if there are any variances between calipers, and also if there is static pressure after releasing the brake pedal, which would be indicative of a sticking caliper.

The inside tie rod is a hassle, luckily i haven't had the pleasure of having to replace one yet.

[Kev1990]

Right now its shuddering under light braking 35 MPH and up. Is this something you think should be covered under warranty? How would I prove it so they don't try jerking me around. It does shudder it's just starting to though not nearly as bad as the left one was that I got replaced. It has all new calipers and hardware. A bad MC was causing them to seize up but ever since I changed the MC no problems.

[illinois_erik]

Right now its shuddering under light braking 35 MPH and up. Is this something you think should be covered under warranty? How would I prove it so they don't try jerking me around. It does shudder it's just starting to though not nearly as bad as the left one was that I got replaced.

the place i worked at, word was enough, unfortunately enough time has probably lapsed where they wont have to claim responsibility for a free redo, the rotor should still have warranty left, so youd be stuck with labor, and with captive rotors could amount to a few hours @ $80 or so. Id first call them and play dumb, like yeah you just did work and i have shuddering and see what they say, they might redo it for a cheaper price since they were the last ones to touch it, and shops rely heavily on word of mouth for business.

Pretty much the reason I do ALL my own work. Im very particular with the way I work on stuff and dont have problems lol. If I do I can onl blame myself or an inferior product, with the latter usually being the case.

[Kev1990]

Erik this shops warranty covers the labor+parts for a full year. So you think word would be enough? I've never had a problem at this shop before so.

[illinois_erik]

Erik this shops warranty covers the labor+parts for a full year. So you think word would be enough? I've never had a problem at this shop before so.

well yeah, shits fucked they were the last to touch it, "fix it. and get it right this time around"

[johnl]

most rotors need to be turned out of the box...

Never come across that, though I haven't changed a large number of rotors. Every rotor I have changed has been fine, including the cheap Chinese Prelude front rotors on the Accord (no problems with them for the last 20,000km or so, still look nearly new and work well).

[illinois_erik]

Never come across that, though I haven't changed a large number of rotors. Every rotor I have changed has been fine, including the cheap Chinese Prelude front rotors on the Accord (no problems with them for the last 20,000km or so, still look nearly new and work well).

lol even the premium rotors from parts store are from china. everything is from china nowadays.

[johnl]

Right now its shuddering under light braking 35 MPH and up.

'Warping' is really a build up of pad material on the rotor faces, more correctly called 'rotor thickness variation' (I'm told by experts). Because of localised pad material build up on part of the rotor face, the thickness of the rotor effectively increases slightly at that point. Because of the thickness variation, as the rotor passes trough the pads, with every rotation there is a point at which the pads grip the rotor somewhat harder, so braking force varies during each rotation.

The pad deposit exists over the entire surface of the rotor (which is normal), and is so thin as to be transparent (invisible). However, if the rotor becomes hotter at some localised area then more pad material tends be deposited at that point on the rotor, but it's still impossible to see (but can be measured with a dial indicator or micrometer). Because the rotor is now effectively thicker at this point the calliper grips the rotor harder at this point, and the rotor then gets even hotter at this point (sometimes seen as an area of dark discolouration), and more pad material tends to get deposited both at the original 'hot spot' and on the opposing rotor face adjacent to the original hot spot. The problem now gets worse and worse as more and more pad material is locally deposited on both sides of the rotor and the thickness variation increases.

The problem might initially be caused by a rotor that has an uneven wall thickness in the faces (or a casting dag partially obstructing air flow through a vane?), so it tends to get hotter at some point on the face than at other places. Over heating the rotors is not unlikely to make the problem more severe, which might be why a rotor may work OK for quite some time, then develop a problem after some hard braking. It might also be why a seized calliper can appear to cause the problem (causing an overheated brake), though isn't likely to be the root cause.

A rotor that develops thickness variation may work acceptably after machining, but may just as easily develop the problem again, since the root cause probably still exists. I know of a taxi that had 'warped' front rotors re-machined a few times, but it always re-developed the problem, until the rotors were replaced.

[illinois_erik]

Brake rotors don’t warp unless overheated. It’s very common to misdiagnose brake problems and attribute them to a warped brake rotor. Warping is caused by excessive heating of the brake rotor and the resulting distortion of the cast iron.

The main symptom of warped rotors is a pulsation felt in the pedal when brakes are applied. If the vibration is felt in the steering wheel or in the dash of the vehicle, it’s more likely a completely different problem: brake judder. A simple run-out measurement will confirm the diagnosis.

The only way to confirm a rotor is warped is to measure run-out with a dial indicator gauge. Most shops are equipped with this measuring tool and can check the bare rotor run-outs on the vehicle. If your installer says a rotor is warped, be sure to ask them for the run-out numbers on the rotor as well as the run-out numbers on the hub under the rotor. The new rotor should also be checked for excessive run-out using a dial indicator gauge once it is mounted and before the caliper and pads are installed. If a rotor has excessive run-out of over .004" (.10mm) it should be replaced.

All brake rotor manufacturers will require run-out numbers when processing a warranty claim.

Brake rotors are checked at the factory for machining flaws and excessive run-out before they are packaged and shipped. It is rare for a new rotor to have excessive run-out right out of the box.

Installing new brake pads with used, unturned, or worn rotors can also cause warping due to the uneven overheating. Most used rotors will have irregular, grooved wear patterns on the surfaces. Mating this with the flat surface, a new brake pad will generate heat and friction only on the raised areas of the brake rotor causing those sections to heat faster than the recessed areas not touching the pads. Any brake pad transfer film from the previous set of pads can also affect the new pad’s ability to bed-in properly. The residue on the rotor can quickly lead to hot spots on the surface that can result in noise, vibration, dust, and warping problems.

Sticking calipers or other components can also lead to overheating rotors and excessive wear of the brake pads.

Excessive run-out of the hub could indicate worn wheel bearings that need to be replaced or debris trapped between the rotor and the hub surface. Both of these can cause excessive run-out and pulsations in the brake pedal. Once the hub and bearings are checked, the new rotor should also be checked for excessive run-out using a dial indicator gauge. This should be done before the caliper and pads are installed. If a rotor has excessive run-out of over .004" (.10mm) it should be replaced.

Overheating brake pads beyond their designed temperature range releases large amounts of gas and uneven, sticky deposits of melted binders/fillers that coat the rotor surface. Every time the brake system heats up, those uneven deposits will grip the pad more aggressively than the areas without the deposits. The brake pad will slip over the non-coated areas because it can’t grip as well on those bare areas. These heavy concentrations of compound material are called hot spots because they cause uneven overheating on the rotor surface. This can actually alter the molecular structure of the cast iron rotors forming hard spots. Severe overheating forms a compound within the cast iron structure called cementite which is harder and more abrasive than the surrounding iron. It’s also not as effective as a heat sink as the surrounding cast iron. The compound cannot wear down these hard spots and the result is more heat building up in those areas and a thumping you can feel whenever you apply the brakes. Continued use of the rotors will expand these areas of cementite and uneven heat distribution. Eventually this will distort and warp the rotor. Once cementite forms in the rotor, it cannot be removed. The rotor needs to be replaced.

New brake pads need a smooth, clean surface to lay down an even transfer film. Residue from the previous pad compound on the surface or an uneven transfer film from overheating the new pads will cause the pads to grip-slip-grip-slip as they pass over the rotor surface under pressure. The resulting vibrations and noise telegraph and amplify as they pass through the suspension and steering components of the vehicle. This vibration and noise is known as brake judder or brake shimmy. This is often misdiagnosed as a warped rotor. If caught early enough, this can be fixed by cleaning the rotor surfaces with 200 grit garnet paper followed by spray brake cleaner to remove any compound buildup on the rotors. Then the pads should be re-bedded following the manufacturer’s instructions. Normally this will eliminate the judder and noise issues.