When I brake my car kind of "pulsates" or bounces until I come to a complete stop. I'm guessing my rotors are warped or something b/c my pads still have good life left on them. I was plannin on getting some Powerslot Rotors/Hawk Pads in the very near future to correct it but I just wanted to see if my guess was right...

Its either rotors or drums, if it only does it when brakng.

To test going about 20mph put your foot ON the brake pedal but DONT depress it, instead use your e-brake, not like slam the thing but you know do it with some force. Do you feel a pulsation, if yes your drums are out of round, if no your rotors are warped.

Did you know a .003 causes a pulsation, thats three sheets of paper causes a viberation.

Good luck




- 2004 Cavalier - 124k, owned since new

yea all you need to do is go have your rotors turned at your local brake shop

Try moderate braking at 60 miles an hour and see if you still have the problem. If so, replace your rotors. Five pair of rotors and counting for my Z24. They warp easily.

You don't have to just throw your rotors away and buy new ones once theyre warped they can be machined down its called turning them your local brake shop can do it unless theyre worn past minimum thickness then you will need new ones
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Andrew, I've braked pretty hard going about 60+ and it has it very bad. If I REALLY kind of bear down on the brake or push it just right it doesn't do it but 80% of the time it vibrates pretty bad. I already had the rotors turned some months ago when I got my pads... It was fine for a while but just recently it's started doing this. I'm really guessing it's the rotors though....

I have to replace the rotors on my Z24 every six months because the warp resulting in a pulsating brake pedal when the brakes are applied. I recently acquired a torque wrench so I am hoping to reduce this problem because most garages don't torque wheel lugs which is a contributing factor to rotors warping prematurely.

Andrew Gillan wrote:I have to replace the rotors on my Z24 every six months because the warp resulting in a pulsating brake pedal when the brakes are applied. I recently acquired a torque wrench so I am hoping to reduce this problem because most garages don't torque wheel lugs which is a contributing factor to rotors warping prematurely.

I'd love to hear where you got that idea from. Yes torquing your wheels is a great idea but it will have no effect on your rotors warping.

As to the original question do as others say, get your rotors machined and keep them until they're at minimum thickness. If you have already had them turned then they probably will be at min. thickness when you try it again. Powerslot rotors are a good chocie I think, I'm probably getting them in the near future also.

Well Justin, I happen to believe that torquing wheels leads to rotors warping prematurely. I also believe that the sky is blue, but only on clear days of course.
In my opinion machining rotors is a poor choice. When one can purchase new rotors for under $20 each why bother machining them?

A slight typo in the previous posting - it should read:
Well Justin, I happen to believe that by not torquing wheels/lugs correctly, the rotors will warp prematurely. I also believe that the sky is blue, but only on clear days of course.
In my opinion machining rotors is a poor choice. When one can purchase new rotors for under $20 each why bother machining them?

Not sure if you are being hypothetical but with all the probs I've had with warping I sure wouldn't buy rotors that cost less than $20.00.

Mine were pulsing quite noticeably every 3 months after being machined and replaced. I bought a set of cross-drilled rotors and changed to ceramic pads and that extended the period to approx. 8 months with no pulsing. The rotors were bought on ebay for about $50.00 for the pair and the pads I got at Lordco. Recently I took the rotors to Canadian Tire to have them turned but was told they can't machine cross-drilled rotors- they have to be taken to a machine shop due to the holes. They quoted me a price of $40 each for Monroe brand so i took the chance and just replaced them. This only happened last week so I don't know what the outcome will be as far as their useful "service life".

I also don't see how torque affects the rotor wear unless you were to say torque one nut really hard and leave the rest loose as a severe exaggeration.

I'm not saying you're wrong Andrew or trying to discredit you- I'm just saying that I can't see how that would really make a difference.

Anyway, just my 2 cents.

$40 for 2 rotors for six months usage or $50 gets you eight months usage. It all balances out in the long run. Unfortunately I'm on rotor pair #5 and I have had my car for 32 months now. Fortunately I have been torquing sticking the wheels with this latest set of rotors installed and I have no pulsating petal and I am into month four.
Something to think about - if you had a head gasket job done on your car and the mechanic didn't torque the head bolts, do you think it would matter?

I bought my torque wrench on sale at Princess Auto for about $28 (taxes included).

I am going to replace the rotors and pads on my 2002 sunfire this weekend, myself, for the first time. I have a torque wrench, as I have heard that improperly tightening the lugs will contribute to rotors warping.

I wondered if anyone knows the proper specs to torque the wheels back to? I have heard 100lbs, but I wanted to get a consensus.

Also, if anyone has any recommendations of what brand and type of parts to buy that would be great too. I am looking at wearever golds at Murray's or Raybestos PG Plus. Not trying to be a performance modder, just trying to maintain my car. Any thoughts? Links to threads that spell that out already?

Thanks, undivine

don't waste your time with cheap $20.00 rotors.

Get some powerslots, or some baers (eradispeed, or oem style).

I religiously "warped"(actually its more of an uneven wear problem) my old rotors to death. Upgraded to powerslots and havn't had an issue since.

There more expensive initially but they'll last A LOT longer.


-Chris

Yes, 100 ft lbs is the spec for most GM products. You should owners manual should confirm this. Not sure if the spec differs should you have specialty wheels. Perhaps someone else may have some insight into this.

Andrew Gillan wrote:Yes, 100 ft lbs is the spec for most GM products. You should owners manual should confirm this. Not sure if the spec differs should you have specialty wheels. Perhaps someone else may have some insight into this.

correct 100 ft lbs. Warpage is not going to happen if you overtorque the bolts. The worse case scenario would be stripping the threads, or cross threding because they tightened them without threading them on by hand.


-Chris

I am hoping to just pick some parts up here in town, we have Autozone, Murray's, Advanced, NAPA, CarQuest, among others. I dont see any of these parts (powerslots, eradispeed) in their websites, any other recommendations from the basic lines out there (Raybestos, Duralaast, Wearever, etc....etc...etc...)

HAIL TO THE PRINCESS!!

i love that place, bought my wrench for less than $30 on sale. everytime the catologue shows up in the mail i get all giddey!

anyways...

http://www.automedia.com/Replacement/Rotors/ccr20050201rr/1

Tighten Right wrote:

Another cause of warped rotors is improper wheel nut torque. Over-tightening of wheel nuts can cause undue stress and warping of brake rotors. The best solution is to use a torque wrench. This is an especially important consideration with aluminum or performance alloy wheels. Proper torque values are also crucial when refastening slider pins, caliper mounts and associated brake hardware. A service manual is the best place to find the correct information on brake and rotor replacement procedures. When working on your brakes remember that "good enough" simply isn't. Taking the time to do it right is the best and safest route to take.

basically, when you dont torque the wheels, the amount of force holding on lug down versus the other lugs can varry. with automotive fastners (like my wording?) precision and repeatability is very important. torque sticks( on the end of the impact wrench) are crap. get a hand torque wrench.

if more force is placed on one lug nut versus the others, YOU CAN cause some distortion in the rotor as one part of the rotor is having more force placed on it than the others due to the mounting flange of the rim contacting the rotor.

basically, andrew nailed it on the head. why wouldnt you torque them? why would GM take the time to calculate what stress of force the lug nut and stud combined are needed to hold the bloody wheel on if it didnt mean anything??




Injection is nice but id rather be BLOWN!

I have noticed this proper distribution of force myself. After adjusting the rear brake shoes on my car I always put the wheel and 2 lugs on, give the wheel a spin to make sure I didn't overadjust my brakes and I always get a different result when 2 lugs are on as compared to all five on and properly torqued. The difference is day and night. Similarly in your explanation previously, you have made it clear how the amount of force equally distributed across the brake rotor is important and we both know this can only be achieved through proper torquing methods.
Thanks Whitegoose

I still don't understand where torquing the wheels comes into play. I understand that torque sticks and such are not as accurate as torque wrenches but unless the guy putting them on hammers on them for a good amount of time, actual difference in torque will not be that different. As for that causing the rotors to warp, no it will cause thickness variation. Different then warping. Oh and for buying new rotors when you can have them machined, new rotors you say =$20, machining at your local shop =$8-10, which is $10 you will save each time you need to get rid of the pulsating pedal. Plus the rotors you currently would have are now used to how the parts of your vehicle work with each other, therefore having a nicer fit then putting on new ones all the time which requires a good amount of sanding, etc to get a perfectly good mounting surface. Also I'm not just some joe blow off the streets and I do have actual knowledge about this kind of stuff if you think I'm just full of $#@+.

In my opinion, once a rotor is machined down it is thinner and more likely to warp. Also for the time and cost to driving to a machine shop and waiting for rotors to be turned I would rather pay the extra $8- $10 per rotor for the added peace of mind knowing that I have nice new/thick rotors on my vehicle.
I am not a joe blow off the streets either. I have been working on and around vehicles for close to 15 years now. Perhaps you cannot visualize what was discussed earlier. I cannot help you with that. My intent on this message board is to provide helpful advice to anyone I can. Perhaps we agree to disagree. Cheers.

whitegoose wrote:if more force is placed on one lug nut versus the others, YOU CAN cause some distortion in the rotor as one part of the rotor is having more force placed on it than the others due to the mounting flange of the rim contacting the rotor.

basically, andrew nailed it on the head. why wouldnt you torque them? why would GM take the time to calculate what stress of force the lug nut and stud combined are needed to hold the bloody wheel on if it didnt mean anything??

The only problem with the argument is that the point or force is distrubuted. The rim takes the point of force load, the load to the rotor is distributed over a much larger area because the mating surfaces are flat.

torque specs are to keep the lugs from coming loose.

If your applying enough force to warp your rotors while tightening the lugs, your applying more than enough torque to strip the threads.

Secondly our rotors are not completely flat. There's a significant amount of structure between the actual mating surface of our rotors and the location at which they make contact with the brake pads, 2 hard planar changes.

The knowledge that "it can cause warpage" is more of an age old wives tail than actual truth.


-Chris

I have almost 57K on the original brakes on my Z24. Its about time to change pads as they are getting a bit thin, but the rotors will see another 50K before I change them, unless I decide to get some better ones. Rotors will last a long time unless abused. (Track days, Extreme Driving, etc...)
When you get a little pedel pulsation, pull the front wheels off and hose down the brakes with some brake cleaner. It gets rid of pulsation every time for me. And it lasts for a few months. Rotors don't warp from driving, by the way. There was a nice write up on this topic that was posted a while back, done by the good folks at brembo. What you are feeling is minute amounts of your brake pads sticking to the rotor after they get hot. If not cleaned off it builds up over time. Thats what causes pulsation. If the brake cleaner doesn't work, get new rotors, they are easy to change and don't cost very much. There is one way to warp a rotor, its called overtightening the lugs. Torque wrenches are a good mechanics friend.