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Brake pulsating/warping rotors

Discussion in '80-Series Tech' started by Imagery, Aug 31, 2003.

  1. Imagery

    Imagery

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    I have always had a problem with my brakes pulsating due to warped rotors on my '97 FZJ 80. I have had to replace the stock rotors with Toyota OEM two times. Then I finally put on DBA slotted and drilled rotors. They were smooth for a while but now after about 30K, they too are pulsating under braking. It really frustrates me and I feel like the brakes would not work like they are supposed to in an emergency situation. I don't think I can turn these new rotors because of the slots and holes, so I will eventually have to just replace them again. I am not sure what padds were put on the DBA's or if that would even make a difference. What should I do? Has anyone else had this problem.
     
  2. Gumby

    Gumby Supamod Staff Member s-Moderator

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    I have 115,000 miles on my stock rotors and they are not even a little bit warped. How do you drive to get them that hot?
     
  3. landtoy80

    landtoy80

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    Do all the rotors warp?
     
  4. Imagery

    Imagery

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    I don't brake hard ever unless it cannot be avoided. This issue is something that has always been on my mind so I an careful to not over use them. If I ever have to make a sudden stop at say an intersection, as soon as the vehicle stops, I open the calipers, let off the brake peddal in order to let them cool more evenly.

    I think that it is alyays the front rotors that are warping. I can detect it in the steering wheel. Sometimes, when it is really hot, and I am doing alot of city traffic stop and go driving, it seems to get worse. Then, as they tend to cool off again, they smooth out again but they are still pulsating. I don't know..... it has been 100 degres plus here in Southeast Texas lately almost every day it doesn't rain. Do you think that it is just causing my brakes to run to hot? Or perhaps thr rear brake load proportioning valve is not set correctly since the OME springs were installed. Right now, I have an ARB winch mount Bull Bar in front without winch at current, and the OME spring set up is 851 light front and 860 medium rear. Mabe the front brakes are doing most of the work and since the front of the truck tends to dive under braking, and the back rises, thus releasing the load on the rear brake proportioning valve, it is a situation of negative chain reaction. Does this make sense, or could it be something else? If so, then after I install the new OME springs and shocks - 850/863, I will need to have the rear brake line pressure checked and dajusted to within spec.
     
  5. landtank

    landtank SILVER Star

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    I had a warped rotor a while back and was sure it was the fronts. However after repairing my e-brake and replacing my rear rotors the pulsing was gone. The e-brake was stuck on slightly and the added heat from it warped the rotors. So the fronts are still the originals at 117k. If you have lifted the truck and not adjusted the proportioning valve to compensate for the lift then you are STRESSING the front pads quite a bit to compensate for the lack of rear braking which indeed would create more heat up front.
     
  6. cruiserdan

    cruiserdan SupportingVendor Emeritus Supporting Vendor Moderator

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    Rick is on to something..........

    The Gummer also has a valid point.

    I ran my first set of rotors til almost 100k before I went to 100 series pads. NO issues of ANY kind, ever.

    Something else is NOT right with your braking system. I can only guess what it may be: Mis-adjusted LSVP, hanging caliper (s), master cylinder, ABS actuator, crappy previous repairs, the list goes on. I'm not quite sure where to tell you to start but if you can find the gauges it might be a good idea to check the bias pressure front-to-rear per the FSM and then proceed from there.

    Dan.
     
  7. Photoman

    Photoman SILVER Star

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    As Dan mention with crappy previous repairs I know if there is any dirt etc. behind the new rotor when it is installed or if the bolts are not torqued and torqued in sequence the rotors can warp.
    Bill
     
  8. landtank

    landtank SILVER Star

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    One of the first things I guess would be for Imagery to let us know how his truck is setup. Any suspension changes or options that has changed from stock? Also by lifting a tire off the ground and having the t-case in neutral you should be able to rotate the tires to find the culprit rotor and is it always the same one or is it more than one?
     
  9. landtoy80

    landtoy80

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    I don't think its a issue with our big rotors but using a impact to tighten the lug nuts can warp rotors.
    One other thing that can affect braking is old brake fluid. Has your fluid been flushed? Maybe the front has been bled and not the rear. But with a lift and big tires and the valve not adjusted it would be the first place to check.
    THere are brake shops that can do a 4 wheel brake test, You might have to remove the front driveshaft to test. At the shop you can have them adjust the valve.
     
  10. sleeoffroad

    sleeoffroad Supporting Vendor

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    Has your front axle ever been serviced? Is your wheel bearings tight. Loose wheel bearings can also make you think you have warped rotors. In all cases were the warping checked by measurement or just your feeling?
     
  11. Imagery

    Imagery

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    Well, I don't think the axles have been serviced but it is coming up in the next week or so beacuse I am looking at doing a 100K service schedule at the dealership. I know the service manager and he is good about carrying out any special requests I may have. I will have them check the front and rear axles and to inspect the condition of those bearings as well. In all previous rotor service, they were measured and turned once. I had two sets of OEM and noe I am on the DBA's slotted/drilled. My break/tire shop told me that they probably would not be able to turn the DBA's because of the slots and holes, but that it is possible to be dont with the right machine. I should not have to be doing this all of the time though. I will have the LPV checked and measured and perhaps have the brake system flushed and replace fluid.

    It really does make a difference from when the brakes are really hot and when they are cool like at night. Unless something that I just thought of could be happening somehow... it feels like someone has taken oil or fluid and put it on one area of the rotors. Imagine that and it feels like the fronts grab and then let go, grab and let go. Today I pressure washed the under cariage and really spent some time on the brakes since I got off in the mud last night. Now the brakes feel smooth with very little of the slip/grab sensation. I just can't emagine that they could change their physical shape that much with varying temp. That would not make sense especially with these high performance rotors. Maby they aren't warped now but it is somethin else going on. I'll get it checked and corrected and be sure to let everyone know what is found to be the cause.
     
  12. IdahoDoug

    IdahoDoug

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    If you have lifted your truck and not adjusted the LSPV, then you are definitely putting more heat than you should into the front brakes. If you have larger tires, you're adding even more heat and it's headed right for those front rotors. Toss in poorly maintained brakes (no regular flushes, wheel bearings loose) and you may have dragging pads that keep the fronts semi hot all the time so that when you use them you cycle them to their max just in regular driving. Toss in someone overtorqueing your lug nuts and thinning the rotors for you regularly by turning them and you're gonna be buying new rotors every 18 months.

    IdahoDoug
     
  13. landtank

    landtank SILVER Star

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    What you're describing is glazing of the rotors. I've had this a couple of times. Not sure what I got into but took some 400 grit wet/dry sandpaper and brake clean and went around the rotor to get it off. I could actually see that something was there on the surface and sanded it off.
     
  14. nakman

    nakman addict. Supporting Vendor

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    Imagery, I have the exact braking symptom that you describe, and have followed your post with much interest. With a very light peddle, it's like it grabs, lets go, grabs, lets go... I'm running my second set of stock rotors, had them replaced about 12K ago but they felt warped again almost instantly. I took them to get turned about 4 weeks ago, when I had them off to repack the front end, and they felt better for about a day and now they feel just like they were before. I'm thinking it must be something else, wheel bearings are torqued properly, not loose. The pads do drag on the rotors all the time, but afaik that's normal?

    My lspv is intentionally adjusted so more braking is done in the rear, to combat this issue. I try to not use the brakes, leave lots of space in front, downshift down hills... literally baby the truck so I only use the brakes when necessary. You say you got 30K on the DBA's? For me that's 3 years, so maybe I'll just drop the $200.. who besides MAF sells them?

    Next on my list is getting an indicator so I can measure the runout on the disks, while still installed, and see if they actually are warped. Anyone know how much RO is considered too much?
     
  15. Imagery

    Imagery

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    It sure does sound like we have the same symptoms. I am going to take what I have learned here on this topic and troubleshoot the problem until I get to the source rather than treating the symptoms. I should not have to be constantly turning and replacing rotors. But like I said earlier, after yesterdays cleaning, it is barely noticeable currently. Perhaps it is this glazing Landtank suggested and it could be that the bearings are loose enough to cause slack, allowing the pads to drag and over heat the rotors. Yes it does get worse when I have done some highway driving and then get to town where I have to stop and go more often in traffic.

    Speaking on this subject, I am reminded of something that has always been an issue ever since I had my first toyota SR5 4WD truck in 1987. The front brake pads rattling. I can still hear them on my second LC and if I just lightly touch the peddle to apply tension, they stop. It is really only noticeable when I am driving at slower speeds on dirt roads with the windows down, especially on cortaroy surface. It just always sounded like something was loose and would fall off at any time but the brake shop said that it was only a retaining spring that was not tight and that it was just supposed to be that way. I When running with my buddies in the truck with me, they usually comment about it and say something is rattline under the truck and sounds like we borke something. I have just gotten used to it and if I get tired of hearing it, I just roll up the windows. Is this normal or should I get in there and check it out myself and based on my findings, if unable to fix it myself, then I will know what to tell the machanic what I want done to make the repair or adjustment. Who knows, they may have always been using non OEM peplacement pads which work ok but don't fit like they should. ???
     
  16. landtoy80

    landtoy80

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    My 87xcabsr54x4pickup (my first new pu) made the same click from the brakes,so does the 94 80