35+ers and brakes

[MrShoeBoy]

It is possible to have a warped set of rotors, as nothing is impossible. Lets take for example you coming off onto an exit ramp from the interstate and slowing down from 70mph. You are braking pretty hard for a fair distance and then the rotor which is very hot from the brakes being applied gets a large splash of water from a puddle. Hot metal can be warped if cooled too fast. I have seen it happen. My dads car is a prime example. Brakes where fine then one day coming off the interstate and having to brake hard and hitting a large puddle of water there was a pulse in the petal. It does take a lot to literally warp a rotor and most of the time what a driver feels is left over pad residue. I have seen and read the article listed above by Carroll Smith before. I have several of his books as well. He knows what he is talking about and I wont argue with what he is saying about pad deposits but the fact is hot metal can warp if cooled too quickly.

AARON

 

[GrayT]

What kind of tech response did you expect...Its the same damn thing. Adding metal to a rotor makes it untrue just as if it were warped. People use the term "warped" because it is easy to understand.

And I'm sorry if we don't run Carbon ceramic pads on our street vehicles, but we were discussing a Jeep, right? Not some exotic race car, or your Integra.


Its the same damn thing, If you want to feel special by calling it something else, thats fine, but don't expect everyone to bend over backwards to understand what you're saying.

Bottom Line....You say toe-may-toe, I say toe-ma-toe.

Not the "same damn thing" to me. From my end, dealing with race experience, both pit crew and driver side, I want to know what is exactly wrong with an automobile. From your POV, sitting in your seat and feeling a vibration in the pedal, yeah... sure, it's the "same damn thing" And that is DEFINITELY not why people call it warped rotors. Proof is in the responses of the people who quoted me.

I guess by trying to educate people in my FIRST post I was trying to have everyone bend over backwards, right? Call me stupid, laugh at me, and call bullshit on something I know is correct... you're god damn right I'm going to stick up for myself.

Yeah, we're talking about a Jeep. Are we also talking about brakes? Maybe I should find a Jeep owner that has written an article about this very thing so you can connect the dots.

All in all... I hope the thread starter has learned a few things and has drawn his/her own conclusion on how to correct his/her problem.

:angel:

 

[Ramsey]

 

[JEEPTUBE]

Edit, because this user is an idiot.

 

[Ramsey]

.......

Amen!








Edited, because this user is an idiot for quoting the previous idiot.

 

[Roxtar]

Weird how no one has any "technical response" to say now.

Perhaps because you're posting this in the middle of the night when some of us have real lives.

Say what you want. I've turned many rotors.
I've been in the metal working industry long enough to know if what I'm turning off is metal or a coating of residue.
I also know that a metal disk, subjected to rapid heating and cooling, will distort. Yes, even cast iron.
What I don't see is how you think brake pad residue can be turned into metal and joined to a cast iron disk to the point of basically making them one.
Welding to cast won't even give the kind of bond you're claiming is happening here.

Pad residue and cast iron are two completely different compositions. To claim they can create a bond that absolutely won't separate or flake apart (even while cutting on a lathe) is just silly.

It would be cool though. We could get rid of all the problems associated with cast iron welding by using rod made of brake pad residue.

 

[Rawbrown]

OK. Read the line right below my user ID... Class is in session...
The #1 cause of warped Rotors is improperly torqued lug nuts. The dumbass that uses an impact gun to tighten there lugs is the cause. There is no residue. Brake fade is cause by the gases created from the exesive heat. Thats why racers use slotted rotors.
I run 35" X-Terrains, Stock D44 drums in the rear. Up front I run The cheapest Rotors I run cheap $25 rotors and Ceramic pads. the downside to Ceramic pads is that they don't work well on cold rotors. but once they get some heat into them then work awsome. I used to deliver Pizza with 33"s on my jeep. I could consistiently make repeated hard stops from 60mph with no fade. but those rotors can get real hot.
I use a torque wrench every time I tighten my wheels and my brakes hold straight and true with no wobble. The one time I didn't use a torque wrench my rotors warped...
class dismissed.

Rotors do not warp. Common misconception.

The "warped" feeling you feel is pad deposits after sitting on the brakes at a stop light after the pads have been heated to an extent that they leave residue.

The residue sits on the rotors and creates bumps on the rotor that simulates "warping"

When I used to track my Integra I would switch from street pads to race pads. I would get the "warped" effect on the street pads. As soon as I put in the race pads and went through a heat cycle there was magically no "warping"

Rotors do not warp.

 

[Rawbrown]

Taken from the very page you quoted... (taking deep breath)
"With one qualifier, presuming that the hub and wheel flange are flat and in good condition and that the wheel bolts or hat mounting hardware is in good condition, installed correctly and tightened uniformly and in the correct order to the recommended torque specification"
Thats why all discount tire shops now use a torque wrench on all vehicles, and thats why the mfg has a recomended torque spec for wheel lug nuts, and that is why ultimatly and mostly all rotors warp, and THATS WHY GUYS LIKE ME CAN MAINTAIN GOOD BRAKES IN OUR XJ'S WITHOUT MAJOR MODS TO OUR BRAKES. (Ace Ventura pulling his fists down while humping the air..."ugh, yeah.... CAN YOU FEEL IT!!!")

Not the "same damn thing" to me. From my end, dealing with race experience, both pit crew and driver side, I want to know what is exactly wrong with an automobile. From your POV, sitting in your seat and feeling a vibration in the pedal, yeah... sure, it's the "same damn thing" And that is DEFINITELY not why people call it warped rotors. Proof is in the responses of the people who quoted me.

I guess by trying to educate people in my FIRST post I was trying to have everyone bend over backwards, right? Call me stupid, laugh at me, and call bullshit on something I know is correct... you're god damn right I'm going to stick up for myself.

Yeah, we're talking about a Jeep. Are we also talking about brakes? Maybe I should find a Jeep owner that has written an article about this very thing so you can connect the dots.

All in all... I hope the thread starter has learned a few things and has drawn his/her own conclusion on how to correct his/her problem.

:angel:

 

[OT]

Great, another theory.

I still like the pad melting into the rotor theory best.
"Normal" pads (not ceramic) have metal in them, so it makes sense, to me, that some of those metal flakes in the pad can bond with the rotor, in pad sized patches on the rotor, causing high spots on it.
When the rotors are turned, you'd still be turning metal off of them, but it's mostly brake pad metal and not so much cast material, that's being taken off.

The water on hot metal causing rotors to warp seems likely, as well.

Much respect, Ryan, but the lug nut torque causing the rotors to warp seems about as far from a likely culprit as too much tire pressure would be.
Edit: Till I saw your second post. Still, it doesn't seem as likely.

Just using logic here, but that's how I see it.

 

[GrayT]

Never said it was the same thing as welding, but the same principle, yes. What I meant is that the two metals (brake pads and discs) get hot enough to where one of them will break down to the point where it can leave traces of itself on something. Hopefully the pads do this first and leave their mark on the disc.

I'm not trying to argue with anyone, especially now that people are actually treating me with some form of respect. I just find it really hard for me to believe that a race car can slam on it's brakes at 200mph, all the way down to 35mph and their rotors won't "warp" yet us Jeepers can have "warped" discs from 35mph to 5mph in in instant.

Also, some of you seem to be attacking my "rotors do not warp" statement in full barrage. I never thought of the water scenario, so I was proved wrong in that aspect. I don't, however, know how true-to-aim the lug nut scenario is. I've almost had my wheel come off due to impact gun torquing, and while my wheel whobbled on the studs, my braking was still fine. No variation what-so-ever. That's my own personal experience.

Rawbrown: Change your brakes, and do not beed them. Tell me if tightening your lugs nuts keeps away "warpage." :sunshine: Brake fade is not caused by the gases on the brake pads. It is caused when the boiling point of the brake fluid is exceeded and boils. It forms air pockets and when you apply pressure to the brakes, the air compresses creating a sponge feeling in the pedal. Actually... you are half right on the lug nut scenario. This is how I see it though. If you tighten all of them to spec, all but 2, then the rotor will be somewhat lopsided to the caliper/pads. Regardless of full pad contact, the pad will still hit the disc evenly (as per pad to disc contact, not full pad contact) and take away some of the pad and disc metals. Doing so for prolonged periods of time with wheels not properly torqued, will mold the disc in a slanted fashion. It will be slanted because of not being torqued correctly and eventually forming to the pads contact because of the torque specs. When you do decide to actually torque everything down the way it should be, the pads will NOT move, but the disc WILL move. This will create vibration in the pedal... and that is when a lathe is needed. I would not call that warping, which most people see as the disc getting too hot and not being able to disappate the heat quick enough. It has nothing to do with the types of pads, or discs you use... if you slant the disc it will happen to any disc, regardless of cross-drilling or slotted, or both.

 

[cracker]

I stop fine on 37s with 3/4 ton 44 brakes on front, explorer brakes on the rear, ZJ prop valve, and dual diaphram booster.

 

[KarlVP]

Your stock brakes will do fine. Just make sure you pay more attention to them.

And brakes do get hot. That's what they are there for. Friction makes you stop.

 

[cracker]

I have a 99 XJ with 35s and I've been having quite a bit of trouble with the stock brakes (to be expected).

Your stock brakes will do fine. Just make sure you pay more attention to them.

:dunno:

 

[Ramsey]

Try staring at them and having a nice talk with them before you drive.

 

[RWKHausSupply]

I stop fine with stock 1990 front D30 brakes, WJ booster and master, no prop valve, and stock rear explorer disk (8.8 rear).

I can lock up the tires (all 4) at about 30 (never tried faster as with 35's and very soft sus. it felt knawly at 30 as it was), I dont ever feel unsafe or lacking brake power on the trail or street.

 

[Roxtar]

Never said it was the same thing as welding, but the same principle, yes. What I meant is that the two metals (brake pads and discs) get hot enough to where one of them will break down to the point where it can leave traces of itself on something.

Leave traces? Sure.
Leave the high spots that you turn down? No.
The first couple cuts are interupted cuts, IOW, they are only cutting off the high spots.
It would be very obvious whether this material being cut off was metal or brake pad residue.
The welding comment was included due to this:
If you had a dissimilar material bonding itself to the cast iron surface, as in your residue idea, it would undoubtedly flake off at some point during the machining, ie turning, process.
Even when welding to cast iron and machining afterward, you have to be careful to avoid this flaking. There is simply no way the scenario you discribe could avoid it.

 

[Rawbrown]

ok, I'll try this again. from the Powerslot website.
"Excessive heat can cause resins in your brake pad to vaporize or "outgas." As the brake pad wears, the used friction material turns into a fine dust. This boundary layer of heat, gas and dust builds up between the pad and rotor surfaces and inhibits performance"
And so far I've turned up several websites stating the same thing.
going through water is more of a myth. here is Southern California we don't have much water to go through yet lots of folks have warped brake rotors.
stopping with your foot on the brakes after a long hard stop... I busted that myth in my honda years back. when after a new set of rotors, the car induced a vibration when braking from 80mph. the vibration started right in the middle of a hard stop after new rotors were installed and the nuts were not properly torqued.
the same damn principles apply to a cylinder head. if not properly torqued down in the correct sequence, you can warp the cylinder head and blow the head gasket. Same reason whey gear installers properly torque the ring gear bolts and bearing caps. Same reason why tranny builders assy a tranny and torque every bolt to a proper sequence.
c'mon, this was autoshop 101 from your first year in high school.
Fluid fad is a posibility but usually way after pad fade.
And back a second on the water on the rotors... how many times have people driven through water or better yet, driven in deep water only to have there exhaust gasket start leaking from a warped flange? But where the bolt fell out is where the leak is...
consider the fact that I have been on the same front brakes for the past 5 years! same ceramic pads, same rotors. every time I pull the front wheels I use the torque wrench to tighten them down to 90 lbft. There is no pulsing in my brakes and my jeep makes hard repetative stops time and time again. Next time you put new rotors on, I dare you to use a torque wrench. Sorry, No POBI from me only 17 years of learning.

Never said it was the same thing as welding, but the same principle, yes. What I meant is that the two metals (brake pads and discs) get hot enough to where one of them will break down to the point where it can leave traces of itself on something. Hopefully the pads do this first and leave their mark on the disc.

I'm not trying to argue with anyone, especially now that people are actually treating me with some form of respect. I just find it really hard for me to believe that a race car can slam on it's brakes at 200mph, all the way down to 35mph and their rotors won't "warp" yet us Jeepers can have "warped" discs from 35mph to 5mph in in instant.

Also, some of you seem to be attacking my "rotors do not warp" statement in full barrage. I never thought of the water scenario, so I was proved wrong in that aspect. I don't, however, know how true-to-aim the lug nut scenario is. I've almost had my wheel come off due to impact gun torquing, and while my wheel whobbled on the studs, my braking was still fine. No variation what-so-ever. That's my own personal experience.

Rawbrown: Change your brakes, and do not beed them. Tell me if tightening your lugs nuts keeps away "warpage." :sunshine: Brake fade is not caused by the gases on the brake pads. It is caused when the boiling point of the brake fluid is exceeded and boils. It forms air pockets and when you apply pressure to the brakes, the air compresses creating a sponge feeling in the pedal. Actually... you are half right on the lug nut scenario. This is how I see it though. If you tighten all of them to spec, all but 2, then the rotor will be somewhat lopsided to the caliper/pads. Regardless of full pad contact, the pad will still hit the disc evenly (as per pad to disc contact, not full pad contact) and take away some of the pad and disc metals. Doing so for prolonged periods of time with wheels not properly torqued, will mold the disc in a slanted fashion. It will be slanted because of not being torqued correctly and eventually forming to the pads contact because of the torque specs. When you do decide to actually torque everything down the way it should be, the pads will NOT move, but the disc WILL move. This will create vibration in the pedal... and that is when a lathe is needed. I would not call that warping, which most people see as the disc getting too hot and not being able to disappate the heat quick enough. It has nothing to do with the types of pads, or discs you use... if you slant the disc it will happen to any disc, regardless of cross-drilling or slotted, or both.

 

[gregmondro]

:dunno:

gonna try my hand at the rear disc conversion one of these days. In the mean time i'm gonna try and adjust the rear drums. I also found some powerstop slotted rotors on the net for just a little over $100 for the pair, I might try my luck with those if I feel the urge to spend the money



thanks for the GREAT thread guys.

 

[Broke]

I like all the feed back :rock:

I did a axle swap D44 and Ford 8.8 4 wheel disc. is nice. You can swap the rear axle out for cheep, which it might be cheeper than getting the conversion for the 8.25 or the D35. I personally love the set up i have 12-13" rotors in the front and 10-11" in the rear.

Good luck

 

[fordtech]

Im not here to argue, nor do I have all the proof like what has been put up here. I have heard 2 reasons for brake pulsation over the years in a dealer enviroment...1. warped rotors, as in runout of the braking surface, which also includes hot spots caused by excessive heat (blueing) 2. improper lug nut torque (Im talking all tight but different torques, not some tight others loose) Which I dont really believe in, but most auto manufactures seem to.

The transfer thing makes sense, and I have seen the outline of a pad on a hot rotor after a vehicle has been stoped hard and sat stationary for a bit. I just have a hard time with enough material transfering and 'blending' with the rotor. Of course, whats glazing on the rotor caused by?

Ive turned alot of rotors, and dont recall any being thicker than the replacement part, unless a micrometer cant pick it up......so that goes against transfer.

Interesting information though, I never really have done much indepth reading on this subject.