hello all:


i don't know if this came about because of the driving conditions that i put my car under -- 88 miles/day, highway inside city driving (means lots o' traffic), occasional hard braking to avoid punting 62mph suv lane-changing into (my) left lane. I started this routine at the beginning of the year, so maybe 4000 miles of this stuff.

I have noticed that my brakes are beginnning to pulsate, as if one (or more) of the rotors is warped.... is this supposed to happen by 27.5k miles? this wouldnt be covered under warranty, would it?

so what should i do now... do i get all four rotors turned? and do i have to replace the pads when i turn the rotors?

let's talk upgrades... any one with suggestions of what to get? i dont want a $1000 brake kit (too expensive), but given this opportunity, i would like to upgrade to something better.... new rotors (cross-drilled, slotted, etc.) and performance brake pads?

thanks for any info/suggestions..

dfwmax

 

If they were damage, I would up grade them to cross drill. I replaced mines with…well cant remember it's made by Power (their some thing behind the word power) cant remember. But I love them have Axxis pad front and back run me $72.42. So far no brake fade, stop like a B**ch! The rotors where a little over $400.00

 

I have 100k on my original brakes/rotors and the rotors are just starting to ever so slightly get warped. The pads are about 60% worn. These damn things may outlast the rest of my car!

 

Rotors may become warped for a variety of reasons, including...
- lug nuts unevenly torqued by a careless technician
- cold water splashed on hot rotors
- defective materials

The first and easiest thing to do is loosen all the lug nuts are retighten them evenly. A torque wrench is the ideal tool but you can tighten them with reasonable uniformity by "feel".

The dealer may choose to resurface or replace warped rotors as a no-charge warranty repair. This is a judgement call for the dealer. If he thinks it was a factory defect he might agree. If he thinks the defect was the result of abusive driving or an ignorant tire-shop jocky, he might refuse. It won't hurt to ask.

There's no need to replace the pads when you replace the rotors. However, it is good practice to replace both front rotors and/or both rear rotors. A new rotor won't have the same friction characteristics as a used one. If you put a new rotor on one of the front wheels you might get a "pull" when braking because one front brake would be more effective than the other.

 

well, i did get new tires put on in the back, and i had all four tires balanced; this was done at discount tire. and i can verify that the tech used a torque wrench to torque all the lug nuts, except for the "locking" nut. he said they wouldnt torque those because -- (1) it was possible for them to break the key, (2) they have had too many complaints about people not being able to loosen the keyed nut. but anyway, i think the tech did a good job tightening the nuts evenly..

i've heard about the 'cold water on hot rotor', and i understand how this could warp the rotor. i know about not washing the car when the rotors are hot, but what do you do when you are driving in the rain? could you damage the rotor because you hit the brakes hard while driving in the rain? and then you hit a puddle and got the rotor wet? we have had a lot of rain this year in dallas.

given that the damage is already done..... i have questions about doing the repairs... does the rotor come loose after you remove the caliper? so then all you have to do is take the caliper (two bolts, right?) off and put new/resurfaced rotors on? is it the same for the rear calipers? i've never seen how the rear calipers are connected.

i've done this once before on my old maxima, but i had help and i cant remember all the details..

dfwmax

 

I bought my car with 32k miles and when I took it to the dealer, they told me all four rotors were warped and that the last owner must have been driving it like the batmobile. The price they quoted me was too high, so I shoped around. I looked into getting cross drilled and/or slotted rotors while keeping the stock calipers, but one of the sales people told me that it doesnt make much of a difference is stopping distances and it reduces the life of the rotors.
I ended up just going to pep boys and paying $45 per rotors instead of the $130 per that Nissan was charging. The Nissan mechanic said that pep boy rotors were the same as the factory ones.

 

I don't have a good answer for this. Here are some ideas.

1) The rotor is most vulnerable to thermal shock warping when it is really hot. If there are rain puddles on the road avoid driving in a manner which requires hard brake usage. Moderate braking won't make the rotors dangerously hot.

2) Check your brakes to make sure you don't have a sticking caliper. A brake which drags gets hot and is vulnerable to warping.

3) This is a tip I'm passing along without being confident of its accuracy. Subject it to your own BS detector...

When the rotors are really hot and you come to a stop, don't rest your foot on the brake pedal. If you do that, heat transfers out of the rotor through the pads. That contributes to warping.

 

that last one kinda makes sense, but how do you keep your car from rolling without having at least light pressure of the brake? at least you would want to have the back lights be on while you are at a stop.

i'm probably going to have the original rotors resurfaced. but for my info and future plans, do you have any comments about slotted/cross-drilled rotors? i.e. which one do you think is better, do they last longer, etc?

thanks for your inputs and suggestions.

dfwmax

 

There's a little more to it than removing the caliper, but replacing rotors is something the home mechanic can do. Here are instructions for the front wheels. The rears are similar, but for the handbrake cable, and that shouldn't be a problem.

Loosen all lug nuts one full turn. Jack the corner of the car. You won't be crawling under the car so a jackstand won't be required. Remove the wheel.

The brake caliper is fastened to the torque member with 2 bolts. Remove the lower of the two and swing the caliper up as far as it will go. Remove the brake pads.

The torque member is fastened to the steering knuckle with 2 bolts. Remove both bolts. Don't let that caliper dangle; use a piece of stiff wire to hang it from one of the strut spring coils.

Remove the rotor. No bolts, it just pulls off.

Note: Don't replace all four rotors unless there is a clear need to do so. You can measure rotor runout with a dial indicator gauge. You can measure thickness variation with a micrometer.

If you don't have those precision measuring instruments you can still make an informed judgement. Drive 15 mph on a smooth level road. Pull up on the handbrake handle, holding the release button all the while. This applies the rear brakes only. If you feel no pulsation in the handbrake handle, the rear rotors are probably okay. If the rears seem bad, replace them first. Then road test the vehicle and proceed to replace the front rotors only if necessary.

 

A 5-speed will sit still if the road is level. If you have an automatic, shift to Neutral or Park. You don't have to drive this way all the time. This tip is useful when you've been braking hard and know the rotors are hot.

 

I,ve heard that hard braking can cause rotors to warp prematurely. Any truth to this? If so maybe it,s being done more than he thinks. I,ve had a warped rotor before and maybe I caused it also. TYIA

 

i'll admit that i have had to do more hard braking now that i drive so far to get to work (it used to be 1 mi down the street), so it probably was caused by me. i'm not trying to put blame on anyone, just wanted to know why/how it happens.

thanks for the info on doing the repairs. i'll try the handbrake test and see where the warped rotor is.


thanks for the info.

tommy

 

There seems to be no clear consensus about the cause of rotor warping. This makes me think several things can cause it.

- Thermal shock (especially cold water splashed on hot rotors)
- Non-uniform torque on wheel lug nuts (distorting the wheel, the rotor, and possibly the hub)
- Rotor materials (metallurgy defects)

Pulsation in the brake pedal is often attributed to warped rotors. I think this is a mistake, but a forgiveable one. Gentle warping won't cause pulsation because the caliper can slide to accomodate a small degree of lateral runout. Thickness variation is the major cause of pulsation. The pedal didn't pulsate when the car was new, so what changed? As the brake pads wore, so did the rotors. This is especially true with hard composition brake pads. If the rotor had hard spots, those spots wore less and the soft areas wore more. Ultimately the thickness variation was enough for the driver to notice pulsation in the pedal.

Some owners observe that resurfacing warped rotors provides only a short-term improvement, and the pulsation comes back as bad as ever. They are right, and the reason is that resurfacing restored the rotor surfaces to be flat and parallel, but did nothing to change the metallurgy of the material. The hard spots are still there and the results are predictable.