John Galt Posted February 5, 2004 Report Share Posted February 5, 2004 Hello all, The front rotors on my 97 Seville seem to last about a week before I start to feel a flutter in them. I've replaced them and they warp. I have them turned and they warp. What do you suppose would cause this on such a frequent basis? They last about 6 months before the shaking gets so bad that I can't take it anymore and then I replace them. I've never had any issue like this before with past Eldo's or Devilles. Any thoughts? Thanks John ps: I've been away for a while - Al still around? (Bill?) Nice board Bruce. Link to comment Share on other sites More sharing options...
careldo Posted February 5, 2004 Report Share Posted February 5, 2004 try a different warp speed --- sorry couldn't resist LOL Link to comment Share on other sites More sharing options...
Scotty Posted February 5, 2004 Report Share Posted February 5, 2004 Usually this indicates that your rear brakes are not picking up there share of the stopping OR your rotors are TOO thin from being resurfaced, OR they are aftermarket and made in CHINA!!! Hopefully you do not ride your brakes, but its probably one of the above... Mike Link to comment Share on other sites More sharing options...
desolate1 Posted February 5, 2004 Report Share Posted February 5, 2004 may be a bad grade of rotors or cheap brake shoes. not that you are cheap but you know what i'm sayin Link to comment Share on other sites More sharing options...
Ranger Posted February 5, 2004 Report Share Posted February 5, 2004 I've heard that uneven lug nut torque can lead to this. I've since started torqueing my wheel lugs though I have to admit I have never had a problem not torqueing them. Al hasn't been here since I have (2 yrs). Bill is still hear. Link to comment Share on other sites More sharing options...
spr01sts Posted February 5, 2004 Report Share Posted February 5, 2004 There's a post on this site were someone installed drilled rotors on their car to prevent going through brakes so often. You may want to search the archive to see if you can find any info on drilled rotors. Drilled rotors may help reduce heat thus preventing warping. Just a thought. Link to comment Share on other sites More sharing options...
JasonA Posted February 5, 2004 Report Share Posted February 5, 2004 A week is way too soon for them to start warping, even cheap ones. It sounds like you have a mechanical problem, like uneven lug nut torque like Larry said, or a dragging caliper or something. Have you had it to a brake shop or a dealership for "professional" diagnosis? Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
JohnnyG Posted February 6, 2004 Report Share Posted February 6, 2004 I suppose I may as well add this to this board. That way it may go into the archive to be a searchable item. If this article fails to satisfy you, just do a search for "stoptech" and be amazed at all of the products available to upgrade your brake systems. http://www.stoptech.com/whitepapers/warped_rotors_myth.htm Never underestimate the amount of a persons greed. Link to comment Share on other sites More sharing options...
Bob D Posted February 6, 2004 Report Share Posted February 6, 2004 I suppose I may as well add this to this board. That way it may go into the archive to be a searchable item. If this article fails to satisfy you, just do a search for "stoptech" and be amazed at all of the products available to upgrade your brake systems.http://www.stoptech.com/whitepapers/warped_rotors_myth.htm Hey, good article!! Should be read by all car enthusiats. Thanks! '93 STS.. opened, dropped, wide...fast. Link to comment Share on other sites More sharing options...
ol'albert Posted February 6, 2004 Report Share Posted February 6, 2004 Sometimes a wheel imbalance will be exascerbated by braking. In my case it vibrated so badly while braking at highway speeds that it felt unsafe. It might be a good idea to start with a wheel balance check. Link to comment Share on other sites More sharing options...
tjtjwdad Posted February 6, 2004 Report Share Posted February 6, 2004 bbobynski Posted on Feb 5 2004, 07:36 PM Do you bed the brakes in as has been described many times in the past? I have in all my years never heard of this term. I hardly ever use my brakes hard but I will certainly try this out. Rotors on 4x4's get expensive! Jim White Link to comment Share on other sites More sharing options...
Marika Posted February 6, 2004 Report Share Posted February 6, 2004 Hello all, The front rotors on my 97 Seville seem to last about a week before I start to feel a flutter in them. I've replaced them and they warp. I have them turned and they warp. What do you suppose would cause this on such a frequent basis? They last about 6 months before the shaking gets so bad that I can't take it anymore and then I replace them. I've never had any issue like this before with past Eldo's or Devilles. Any thoughts? Thanks John ps: I've been away for a while - Al still around? (Bill?) Nice board Bruce. Do you bed the brakes in as has been described many times in the past? That is important to do to maximuze the braking capacity of the system. Bed the brakes? Can you please explain this expression? (is it legal to bed brakes?) If you really want to make people safe drivers again then simply remove all the safety features from cars. No more seat belts, ABS brakes, traction control, air bags or stability control. No more anything. You'll see how quickly people will slow down and once again learn to drive like "normal" humans. Link to comment Share on other sites More sharing options...
KHE Posted February 6, 2004 Report Share Posted February 6, 2004 Hello all, The front rotors on my 97 Seville seem to last about a week before I start to feel a flutter in them. I've replaced them and they warp. I have them turned and they warp. What do you suppose would cause this on such a frequent basis? They last about 6 months before the shaking gets so bad that I can't take it anymore and then I replace them. I've never had any issue like this before with past Eldo's or Devilles. Any thoughts? Thanks John ps: I've been away for a while - Al still around? (Bill?) Nice board Bruce. John, When you replace the rotors, do you follow make 10-12 medium stops from 45 MPH, let the rotors cool and then repeat 2 more times? This is called bedding in the brakes. If you're not bedding in the brakes, that could be why they seem rough. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
John Galt Posted February 6, 2004 Author Report Share Posted February 6, 2004 The issue is more of the "thumping" when I brake, not scraping or grinding like they have rust on them. Perhaps the lug nut torque is an issue, although I've never had that problem with any other car before. Maybe a caliper issue? I'm a married man, so I don't bed my brake pads... John Link to comment Share on other sites More sharing options...
Ranger Posted February 6, 2004 Report Share Posted February 6, 2004 The issue is more of the "thumping" when I brake, not scraping or grinding like they have rust on them. Perhaps the lug nut torque is an issue, although I've never had that problem with any other car before. Maybe a caliper issue?I'm a married man, so I don't bed my brake pads... John John, I had the exact same "thumping" noise in my right rear brake last summer. I found the rotor to be very badly pitted. Replaceed the pads & rotors. Problem solved. Take a look at your rotors. The problem may become very evident. Good Luck. Link to comment Share on other sites More sharing options...
Scotty Posted February 6, 2004 Report Share Posted February 6, 2004 I'm a married man, so I don't bed my brake pads...John John, bring them over I'll bed them for ya, no problem!! lol, Mike Link to comment Share on other sites More sharing options...
Marika Posted February 6, 2004 Report Share Posted February 6, 2004 I suppose I may as well add this to this board. That way it may go into the archive to be a searchable item. If this article fails to satisfy you, just do a search for "stoptech" and be amazed at all of the products available to upgrade your brake systems.http://www.stoptech.com/whitepapers/warped_rotors_myth.htm Good article!! If you really want to make people safe drivers again then simply remove all the safety features from cars. No more seat belts, ABS brakes, traction control, air bags or stability control. No more anything. You'll see how quickly people will slow down and once again learn to drive like "normal" humans. Link to comment Share on other sites More sharing options...
JohnnyG Posted February 7, 2004 Report Share Posted February 7, 2004 Thanks "John". I will not "shrug" off my responsibility to help you out as much as I can. At any rate, the bedding process can be guessed by some of the responses, treat 'em rough for the first few days and they'll be OK for the rest of your relationship. I've also never heard of this before reading this board, and have never personally engaged in such an abusive act. I also have quite well behaved brakes on my '99 so maybe it's one of those things that, though not always necessary, is a good thing to know. Never underestimate the amount of a persons greed. Link to comment Share on other sites More sharing options...
rjhat Posted February 7, 2004 Report Share Posted February 7, 2004 I believe jadcock is correct in saying that it could be a caliper issue. I've never changed the brakes on my caddy, so the best advice I can give is to take it to a GOOD brake shop and ask specificly for the calipers to be checked, along with the rest of the rear braking system. The frequency of your rotor replacement suggest constant pressure from the pads. I dont know if the rear brakes on caddys use adjusters for for the parking brakes on rear wheels, maybe someone here will know? If so, they should make sure they are operating to spec. Make sure your parking brake is adjusted to spec also. Link to comment Share on other sites More sharing options...
DocFey Posted February 7, 2004 Report Share Posted February 7, 2004 There can be up to 3 or more grades of brake pads for your car. The cheap ones are not even OEM rated for stopping distance! Mostly the rating is related to stopping distance but longer stops=more heat on your rotors. Many shops that give you "lifetime" brakes use the cheap ones so you'll be back more often and they can sell you extra, costly service with that friendly "free" set of brakes. This is another job that is easy to do yourself and so critical to your safety. Around here, NAPA or other automotive machine shops will turn rotors for $10-$15 each if you take them in. They will check the thickness and you will know what you're driving on instead of trusting some highschool dropout who is getting paid $7/hour to slap on some new pads. The guy turning the rotors can tell you if they have hard spots in them which will affect the stopping power and could give you some pulsing. If they need replaced, you can make the decision to go with the American made or foreign cheapies. The directions with the good pads will instruct you to "bed" or wear in the brakes with the 10 stops before you use them hard. The people at the shops rarely remember to tell you this! I have just always driven and braked hard so have done the work myself. That way I trust what I'm driving on. Went to Colorado last fall on new tires and fresh brakes so the STS was a joy to smoke through the canyons with! Link to comment Share on other sites More sharing options...
kenricrose Posted February 8, 2004 Report Share Posted February 8, 2004 It is not only important that the lug nuts are evenly torqued in a criss-cross pattern and in stages, but that they are not over torqued. One of the things many people do is just crank on the lug nuts or run them in until the impact wrench stops on high setting. This is because no one wants the wheels to fall off. Shops will do this because the don't want the liability if a wheel falls off. All of this is particuarly true with alloy wheels. The correct thing to do is to torque to exactly the right torque. In stages, and in a criss-cross pattern. THEN, check the torque again a couple times again after some thermal cycling of the wheels (due to brake use). Dealers and shop owners know that most people won't do this and that most won't bring it back to have it done. So many will just torque the heck out of them. In many cases this will cause an abnormal stress distibution which will cause warping. The best way to turn rotors that have already warped is to turn them while they are properly torqued down with a dummy hub/wheel plate. Of course this is not often done. Another thing I have noticed is poor quality of over seas (westward) rotors. They do tend to wear and/or warp faster. Must be poorer quality metal and/or manufactuing proccess that lead to an uneven grain structure. This uneven grain structure will cause uneven deflection and warping after thermal cycling. Another thing I have noticed is that once a rotor (even a good one) has truly warped, it is very likely that it will warp again after being turned. I'm not sure why this is. It could be because the rotors aren't turned while the uneven compression loads due to lug not torquing aren't applied. Or, it could be because if the the rotor warped due to uneven grain structure, just turning the rotor will not correct the grain structure. Of course everything mentioned in the earlier posts about surface finish and bedding the brakes is also true. Try to verify that the rotors are truly warped. Once again though the only correct way to really know is the measure the rotor while the wheel, or a dummy wheel hub is torqued exactly as it is when the car is driven. If, for whatever reason, you do end up with an uneven surface finish, there will be an uneven brake apply as the rotor rotates through through the brake pads. This will cause uneven heat in the rotor. And once again you end up with warping. Even though the warping is temporary due to the heat of braking, the uneven wear resulting will not be. It all boils down to thermal cycling of the rotor and the reaction over time to uneven stress conditions. This reaction over time is called creep. In order for a rotor that wasn't warped initally to warp, there must be creep in the grain structure of the metal. Once this creep has occured, it is very hard to ever salvage the rotor. Even if you turn it perfectly. The now uneven grain structure may still cause uneven braking/heat and lead to further creep and warping. Use top quality brake parts, OEM if possible or at least USA or Canadian made. Remember that if the rotors have already truly warped, even though they be premium, you may not ever be able to avoid warping again. Not that you shouldn't try at least once before you scrap them. Evenly torque the lug nuts, in stages. Check the torque at least twice after the wheels have thermally cycled (heated AND cooled). Bed the brakes as described in earlier posts. Avoid hard stops until the bedding proceedure has been completed and the wheels have been thermally cycled a few times. In general, the hotter the rotors get the more likey that you will get warping. And once they warp even a little, the more likely that uneven wear will cause a cascade that will result in permanet warping. So, try to keep in mind your brake temperatrue and avoid unnecessary frequent high performance braking. If this is what you like to do, consider high-performance rotors. With all precautions being equal, an experienced shop owner will still notice a pattern of "all cars not being equal". That is that some will keep coming back for brake pulsations and other will never come back. Keep in mind that the only truly diffferent thing in these situations is the driver, and of course their driving habits. Try to avoid letting the rotors rust (not always possible of course). If they do rust. go through a gentle bedding process to try to clean them up evenly. Pray. Good Luck, Kenric Link to comment Share on other sites More sharing options...
adallak Posted February 8, 2004 Report Share Posted February 8, 2004 a frozen caliper might be another reason. check for uneven wear of brake pads The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
95SLS Posted February 8, 2004 Report Share Posted February 8, 2004 My problem was the rust from sitting a lot as I do 3 day trips away from the car. It was real obvious when I had it done. You could see a rust - shine - rust - shine surface of the disc, that caused a thump thump like it was warped but it clearly was not warped. Proably could have been turned but the brake shop said it you turn them they will be so thin they will warp and they just put new on. It worked, Since then, I stand on the brakes every so often to keep them clean. MC Link to comment Share on other sites More sharing options...
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