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should I feel my rotors pulsing more now after my mild lift??

Discussion in '1st Gen. Tacomas (1995-2004)' started by trevthefatty, May 9, 2010.

  1. May 9, 2010 at 7:07 PM
    #1
    trevthefatty

    trevthefatty [OP] Wheelin' the Great White North

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    Consecon, Ontario Canada
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    Toytec Coilovers, URD MAF calibrator, remote start, deck plate & grey wire etc.......lots of little mods....
    I'm trying to determine if this sound is my brakes pulsating (hopefully) or some problem with the suspension.....

    I have always had a problem with my rotors warping....the brake shop always said it probably happens because after I go through water the rear drums can't grab which overheats the rotors...... (which I have always tried to avoid, even with breather extensions...)

    Well that kinda made sense to me...although I always avoid water crossings......my truck is my baby....

    Anyways, after recently fixing my saggy rear end problem (2" lift) and raising my front coilovers about 1.5" to match the rear - I knew I'd have to make a custom little extension for the rear brake proportioning valve.....

    First, my rear brakes were locking up on the gravel just a bit....So i started adjusting it down (as if there was more of a load in the box).....weird thing is....that I get this kinda clunking sound from my front brakes now......

    sorry for the long description....i just think it's better to put EVERYTHING here for you experts out there-that which I am not.....

    So if I try it with the proportioning valve all the way down (full load in the box) the brakes feel fine.....even with nothing in the box

    So my only guess is that yes my rotors are warped - which I already knew....and that when I try to adjust my proportioning valve to engage the rear brakes more....for some reason the warped rotors feel more like a clunking instead of the pulsating I usually feel....lol...

    any thoughts???
    Thanks guys.....
     
  2. May 10, 2010 at 7:34 AM
    #2
    Whitfield

    Whitfield Well-Known Member

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    Bobbed Left front ~ Ok not really but I bought it crashed from the kids dad 4-CHEAP. Frame Swap and 04 Clip + 6" lift ~ Woo Hoo!!!
    1. Warped rotors should be irrelivant to lift though bigger tires will generate more brake heat.

    2. I don't belive the techs response for your warped rotors. They warp from heat yes / but I'm not buying his cause for the front brake over heat. The more common causes for excess heat / rotor warping are.

    A. Brake pad drag ~ Sliders / Calipers sticking and not returning to neutral position.

    B. Cheap rotors ~ Some China rotors are more prone to warp with
    heat cycling.

    C. Bigger tires generate more brake heat.

    D. Towing


    You said that your rear brakes locked up on gravel ~ Well Ya... Their is no weight on the rear.

    Pushing the proporting device down applies more rear brake causing them to lock faster on gravel... ???

    The thump you are getting is most likely drive shaft slip yoke travel / movement induced by brake applied axle wrap. Try lubing the drive shaft.


    My list if if were mine and I was looking on the cheap.
    1. Turn rotors / Install new pads (NOT $15 cheapies) TOyota / Name Brand
    EBC / Wagner / Bendix ~ are the names I'm familure with...
    2. Check calipers for uneven pad wear / piston return / and floating side
    to side freely
    3. Grease Drive shaft slip yoke
    4. Leave load sensiong proporting valve applying more rear brake unless it locks prematurely in the rain or causes other rear wheel locking issues (Gravel doesn't count)

    Some reduce brake heat with vented rotors but I'm a firm believer that a Bigger rotor and caliper has more mechanical leverage and can work more efficiently. I like the Ideia of the Tundra Rotor / Caliper swap. As I think this could be the answer for bigger tires / towing.
     
  3. May 10, 2010 at 8:47 AM
    #3
    trevthefatty

    trevthefatty [OP] Wheelin' the Great White North

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    Toytec Coilovers, URD MAF calibrator, remote start, deck plate & grey wire etc.......lots of little mods....
    awesome response Whitfield - thanks man! I'm gonna go through your list......just a little more info: I'm still running stock wheels and stock size tires (265 70 R16 Michelin LTX for now...:( great tire-just not big enough lol....)
    Also, I've had the driveshaft axle wrap problem before, so I keep her pretty lubed up, but that was my first guess too (btw: the Zuk coils in the rear completely got rid of the axle wrap clunking....)
    The sound is definitely coming from the front, and it's not a single clunk like when I came to a complete stop, it's a series of noises that goes with the speed of the wheels if you know what I mean (sorry for the poor description)
    Also this just occured to me, but I haven't done an alignment yet, mostly because the truck still drives straight, but could this have an effect on the front brakes? should I get it aligned anyways since my camber is probably off now even tho it's driving straight?? can you tell I'm no automotive expert lol.... Thanks again guys and gals :D....
     
  4. May 10, 2010 at 10:16 AM
    #4
    Whitfield

    Whitfield Well-Known Member

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    Central Virginia
    Vehicle:
    99 TRD X-cab on 35's / 96 X-cab on 33's
    Bobbed Left front ~ Ok not really but I bought it crashed from the kids dad 4-CHEAP. Frame Swap and 04 Clip + 6" lift ~ Woo Hoo!!!
    Alignment will have little to no effect on brake caliper / rotor.

    The noise you are hearing is most likely the calipers and pad spring shims dancing with the warped rotors with each wheel revolution as you come to a stop. With warped rotors the caliper / pads / rotors are all in a high speed boxing match each time you hit the brakes.

    Also possiable but not likely is if the front wheels were to dance any as you come to a stop the steering rack bushings might make noise in time / rythm with wheel speed. Any shaking in the steering wheel or just brake pedal pulse? (This is more common with one bad caliper / rotor).

    Have you tried to pull the e-brake while on a lonely straight desolate road and test the drums for out of round warping. Not often but every once in a while you will run across a rear drum out of round. You are not trying to lock the rear wheels ~ just easily activate the rear brakes / feel / then release.


    **** How long have those pads been on the front? Did you install them? Cheap pads or abused ~ hardened glazed pads due to over heating will require more pedal force to stop and can increase rotor temps.

    If you remove you calipers your self ~ the key is to make sure the sliders are cleaned to like new / lubed and free. This way the caliper can float with the rotor. On some occations this gets overlooked (Previous owner / Brake tech in a hurry / Newby tech / ect...).


    ***** Also more prevelant on Front Wheel Drive cars ~ Not torquing the lug nuts to spec evenly will cause warped rotors. Always torque your wheels ESPECIALLY aluminium wheels.
     
  5. May 10, 2010 at 10:36 AM
    #5
    Whitfield

    Whitfield Well-Known Member

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    99 TRD X-cab on 35's / 96 X-cab on 33's
    Bobbed Left front ~ Ok not really but I bought it crashed from the kids dad 4-CHEAP. Frame Swap and 04 Clip + 6" lift ~ Woo Hoo!!!
    Some warped rotor Tech I found on the Diesel Stop site from Jack
    Former Vehicle Test Manager - Friction Products.


    The full legnth post is worth reading if you get the chance...

    http://www.thedieselstop.com/forums/f27/warped-rotors-again-arrrrg-252661/


    Now that everybody is running around their truck with their hands in the air yelling “warped rotor”, warped rotor”[​IMG], lets think about this.

    A warped rotor is one where the rubbing surface is moving side to side looking down the length of the vehicle. Moving in parallel with the sliding of the caliper pins. The pins don’t magically lock in one place when the brakes are applied, so they allow the caliper to move in unison with our theoretical rotor runout or warp.

    But what happens if there is a thicker section of the rotor? When it rotates in between the pads, it will wedge the pads out, causing a higher hydraulic pressure in the caliper. Higher pressure means more braking for that 20° pie section of the rotor. If one wheel has a higher braking force, it will pull the vehicle to that one side until the thick area passes. That’s the pulsation and sometimes a steering nibble. With the wedging between the pads and higher pressure, you also can get push back in the brake pedal, depending on the design of the vacuum or hydroboost.

    An extremely high rotor lateral runout will cause some pedal pulsation and vibration, but it has to really excessive and at high speed to generate the G-forces that overcome the speed that a caliper can change direction.

    So what can cause the rotor to have thick and thin sections? Actually rotor lateral runout; warp if you will. But warp suggests that the rotor was distorted by heat, and that’s not what is happening here. You can stress distort a rotor if don’t tighten the wheels down in a progressive and even manner, just like you will distort a motor’s head or intake manifold. You can have a rotor that is poorly machined so when it’s installed it has high runout. With the slip-on rotors, you can have a hub mounting flange that has a high runout will then be magnified by the rotors surface. You can have rust and dirt between the hub and rotor. And you can have loose bearings (hub) that allow the rotor to flop around. Usually this flows a tire imbalance sidewall to sidewall (static balance is OK but dynamic balance is not) so it occurs at the same point of the rotor..

    And it doesn’t take much thickness variation. A driver can feel 0.0008” thickness difference. The service spec for an installed rotor is 0.0015” runout, while the production line spec was 0.0010”. So theoretical even under the best case the highest runout point could contact a pad and wear down that 0.0010” high spot on the outside rotor rubbing surface while the inside surface is untouched and develop pulsation.

    So the rotor needs to be true mounted up to a good hub, the caliper pins need to move freely, and the caliper O-Rings need to be pliable to pull back the pistons to provide proper running clearance. And the steelbacks need to be free in the brackets to slide away from the rotor when the rotor knocks them back. Some runout is good.

    A huge problem in the brake service industry is the “rotors warped after they have been turned” situation. There is all this speculation that the rotor “heat warped” now that it’s thinner. Well they are designed around the thinnest specification, and then added on for wear and service turning. The problem is hard regions that form in the rotor.

    With a used rotor you can’t see this with the rust and friction material transfer layer. You often can hear a difference in the work the lathe is doing when trying to cut the rotor. The lathe bit cannot cut into the harness as it can with the softer, normal iron of the rest of the surface. If you’re very good and the rotor has a very smooth finish (like it’s supposed to at 50 micro inch, but rarely does from an autoparts store or garage), you can see the shinier surface of a hard region. You can also feel it if you have the rotor turning on a lathe and use sandpaper to relieve the rougher turn grooves.

    You can’t use that rotor because for one the hard region is most likely thicker since the lathe tool could not cut as deep, and if it did come close to parallelism, the hard region will not wear down as fast as the softer areas and you end up with thick areas again in 5 to 10 thousand miles. It’s not that the rotor warped, it’s that it has an inherent hardness problem. So turning a problem rotor is not a fix, it’s just setting back the clock for the issue to reappear.

    And you can buy a rotor with all the slots, holes, cryo, etc treatments you want to. It will not solve this issue. Time and time again we hear the accolades of I bought this rotor and ‘a more aggressive, rotor wearing pad’ and my pulsation went away. It’s not the rotor; it’s the more abrasive pad formula, as long as the rotor is mounted with a low runout. But you can have a repeating problem if there is an issue with the hub or bearings even with a new rotor.
    __________________
    Jack
    Former Vehicle Test Manager - Friction Products


    03 F350SC 4x4 6.0 Auto 5/30/03
     
  6. May 10, 2010 at 11:24 AM
    #6
    trevthefatty

    trevthefatty [OP] Wheelin' the Great White North

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    Toytec Coilovers, URD MAF calibrator, remote start, deck plate & grey wire etc.......lots of little mods....
    wow you are my hero Whitfield.....that is GREAT info-I greatly appreciate your time.....i'll get back to you tonight after I go through everything you gave me; in order to give you a proper reply...thanks again man.....
     
  7. May 15, 2010 at 6:49 PM
    #7
    trevthefatty

    trevthefatty [OP] Wheelin' the Great White North

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    Hey I took my rotors in to get them resurfaced - one was out for sure, cleaned up and lubed my slider pins too. My pads were installed by a brake shop last year and look to have lots of life left, and look to be wearing evenly to me.
    So that helped a lot, my brakes no longer pulse. Even so, there is still this knocking sound if I apply the brakes pretty hard, even tho they're so smooth now......So I'm thinking my brakes are fine and it could be something else:confused: (happy I did the brakes tho, obviously)
    I still have a bunch of stuff to try that you suggested - I did try the parking brake to test the rear drums, didn't seem to cause any problems....(altho I think I have to adjust the e-brake cause it wasn't grabbing very hard at all...)
    Also, yeah my steering rack bushings are in pretty bad shape-I have the bushing kit with the main clamp bushing installed, just can't get the bolt for the smaller vertical bushings.....
    It is this knocking sound that is proportional to the wheel speed, but it only seems to happen when the trucks centre of gravity is shifting.....like if I brake hard the brakes are nice and smooth now with my newly refinished rotors, unless the truck kinda shifts forwards or from side to side too much......then you hear the clunking.......could it even be a CV or ball joint from when I raised the front?
    So today I noticed that my front shock bushings are both kinda cracked from being twisted when I was adjusting them. :mad: -So I'm thinking I'll change my steering rack and shock bushings and see if that helps - thanks again so far for the help Whitfield - much better brakes now!! I just have to figure out my next little problem lol.....
     
  8. May 15, 2010 at 6:56 PM
    #8
    tacobo670

    tacobo670 if you have to ask, u can't afford it

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    if the rotors were warped, u'd be able to feel shaking in the steering wheel while braking. i would not have adjusted the prop valve as it will prematurely wear the rear brakes (tricking the vehicle to apply them when there is no need for it)
     
  9. May 15, 2010 at 6:59 PM
    #9
    Whitfield

    Whitfield Well-Known Member

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    99 TRD X-cab on 35's / 96 X-cab on 33's
    Bobbed Left front ~ Ok not really but I bought it crashed from the kids dad 4-CHEAP. Frame Swap and 04 Clip + 6" lift ~ Woo Hoo!!!
    Cool... glad that helped. Just keep in mind that the hardness of the rotors may have changed in spots and that may cause the defect to come back (as posted in the attached article from my post above)...

    Rear ~ Parking brake and pedal travel are proportional to rear brake shoe wear and adjustment.

    Rack bushings should help. Also check sway bar bushings.
    Ball joint /cv would be prone to make noise elsewhere before here (braking).
     
  10. May 15, 2010 at 7:09 PM
    #10
    Whitfield

    Whitfield Well-Known Member

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    99 TRD X-cab on 35's / 96 X-cab on 33's
    Bobbed Left front ~ Ok not really but I bought it crashed from the kids dad 4-CHEAP. Frame Swap and 04 Clip + 6" lift ~ Woo Hoo!!!

    While deviating from stock settiong is best left to those with experience ~ Brakes are your #1 safety concern. I think dialing in a little more rear brake on these little trucks with bigger tires is a safe bet.

    Prematurely wear the rear brakes???

    No need for it???

    If he is running over sized tires then the factory rear brake proportioning may no longer be relevant. Front brakes were overheated as obvious by the warped rotors. Adjust the proportioning and add more rear brake to even out the brake work load and reduce heat up front. The rear drums can deal with the additional heat and wear better then the front ~ not by design as much as they usualy are subject to less of the breaking duty. Give them some more work to help even things out.
     
  11. May 15, 2010 at 8:42 PM
    #11
    trevthefatty

    trevthefatty [OP] Wheelin' the Great White North

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    04 V6 TRD
    Toytec Coilovers, URD MAF calibrator, remote start, deck plate & grey wire etc.......lots of little mods....
    cool man thanks again for the input - I'll let ya know how things go once I get some of these new bushings on. Yeah I read that post about how the rotor can develop soft or hard spots so the "warp" will come back....thanks again man-great info
     
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