I have been having trouble with pulsing while breaking.
the kind you get from warped rotors. this is my second
set of rotors in 2 years and it is driving me nuts.

I'm carefull not to over touque the lug nuts

what else could be causing it?

Is there a brand of rotor that is better than others?

daajr

94 f150 supercab 4.9, 4x2, e40d, 3.55s, 31x10.5s

 

Need to torque lug nuts evenly - I usually go around at 50 ft # after the initial snugging, then 75 , then 100 ft# twice. Any time anyone uses an air wrench improperly they can warp drums and rotors (drums are not as bad); ie, wrenching one nut all the way up without bringing up the rest evenly. Another cause is heavy braking heating up the rotors and then hitting a mud puddle, water resulting in uneven cooling of the rotor. I do my own rotating and ususally request that tire places hand torque the lugnuts when I get tires. Guess I'm paranoid. Good luck.

 

Improper lug nut torque is a common cause, but cheap parts are even more common. The quality of the rotors and pads makes a big difference.

 

I am having the same problem. The problem with my 94 F150 2w is on the passenger side. I have installed new rotors, new shocks, new bearings, alignment, and a new caliper. I put new rotors, bearings, etc just before getting new tires, also had the alignment at same time. So I figure no problems, wrong. After a month or two, the right rotor warped and the tire starting beating out in flat spots. I took the truck to a front end shop here that has an excellent reputation, they pulled both rotors, turned rotors, repacked bearings. This was about Oct 20 or so. Now the rotor is warped, tire getting flat spots, and sometimes when braking, the whole front end does a shimmey, like the cartoon trucks do (:>).

I am thinking about replacing the coil springs, and if it continues, replacing the axle pivot bearings. I have about run out of ideas. Any ideas or help anyone????
Lauvone

 

Springs won't help.

You say you replaced one caliper and not the other? Bad idea. You have to replace calipers in pairs. Not necessarily related to your problem, though.

There is nothing inherently wrong with the twin I-beam suspension that would cause that behavior, so you obviously have something going on that can be fixed, but it can be anything in the front end. You might have worn bushings someplace, bent parts like a sway bar or I-beam, or the truck might have cheap parts on it. If you buy brake parts from someplace like Autozone, you can expect to have problems.

 

When you change rotors there's somthing you must be very, very careful about. The mating surfaces where the disk meets the axle must be clean. If a tiny pebble gets trapped in between there it doesn't matter what parts you buy or how many times you have them turned. They're not aligned straight and you end up with pulsating brakes and warped rotors. Take a wire brush and clean the mating surfaces thoroughly before installing the rotor.

 

Can you explain what you mean by where the disk meets the axle? I've never heard that advice before, and I'm curious what you mean.

 

I don't mean the axle literally. What I mean is whatever steel surface the disk mates up to. When you put the disk back on it will meet metal to metal with something and that is what I'm calling the axle. It could be a flat surface and it could even include all the lug bolts.

I haven't done brakes in a while so I'm digging into my memory. I think that on both my old Volvo and my Taurus, the rotors don't get bolted by themselves on but are held on by 1) being in between the pads, and 2) are pressed tight when the lug nuts are tightened. I had this problem with my Volvo for years and replaced rotors and turned rotors and replaced calipers and the works. The pulsating also caused ball joints to fail and I could never get the pulsating to go away for good.

Anyway, when I replaced the pads on my Taurus last summer, I was reading my shop manual and it went out of its way to make the point to make sure that all metal to metal mating surfaces are clean. It is where I got the advice that even a tiny little pebble will throw brake parts out of alignment. Think about it. The reason the tires start wobbling is because something in the tires/brake system is out of alignment. The parts are all cast or machined to be straight so that that all you have to do is mount them and there should be no wobble. The parts don't start out mis-aligned but they get there somehow. This isn't my advice but something I gathered from my shop manual. Its also something that had never crossed my mind.

 

Just thought I'd throw my two cents in - I had a 1967 Jeepster Commando
and it had serious shimmy problems. If your truck shimmies under braking it's your rotors, but if it's shaking violently, or if braking seems to set off some sort of reaction, it may be your suspension. In my Jeep it was the "king pin" suspension that was loose - nightmare. I would check everything. Tie rod ends etc. are pretty cheap.


1994 reg.cab,long box,I6,E4OD,limited slip,Victoria B.C.

 

All of the above then pray!!! Beg! Plead! Bribe! Brown nose!! Whatever it takes!

I have had a few Ford products that had POORLY engineered brake rotors. A 68 Montego and 98 & 99 Sable. Still have the 99 Sable and NO AMOUNT of mechanic trickery will eliminate the warped brake rotors!! It is a Ford engineering nightmare you will have to live with until you say goodbye to it. Ford will never admit to their poorly engineered brake system nor come out with a better design brake rotor to replace what you have. I have certainly tried all of the above and all has failed. Driving like an old fart certainly didn't help. I could replace them on the 99 Sable every 3,000 miles and it still wouldn't help. Sorry guys, car has new halfshafts also. Like I said, been there done that....nothing helps! Pray!!

 

A couple of bits of advice I didn't see above. Replace brake hoses every 8 yrs or so, use brake lube to lube all sliding surfaces, nad replace those triangular sliders/pins every time. If you're still having problems you might try the pricey stuff. The premium brands that come to mind are Bendix and Raybestos.

 

Tried the pricy stuff also!!! I have a set of Raybestos on the 99 Sable now and they react the worse. Tried lubing parts! I haven't tried replacing brake lines although it's a 99 model. Maybe when it needs new brakes I'll just trade it in! Or oil change? Or windshield wipers replaced? DOH!!

It most assuredly is an engineering flaw you will have to live with. UNLESS! Unless you go with a complete aftermarket system and those can get kind of pricy.

Haven't found an aftermarket brake system for my 99 Sable. SHO owners have complained about the same thing also, although their brakes are a little bigger.

 

Have you checked your hubs for runout? If the hubs (where the brake disc bolts attaches) are not turning true, the rotors won't turn true either.

 

What about having the rotors turned? When you're having trouble nailing down a problem like this, it may be unwise to ASSUME that the rotors were machined true from the factory. Clean everything and use brake grease where appropriate (all metal to metal contact points, except pads-to-rotors) is also very good advice...

Jason

 

The way rotors come nowadays, there isn't any material left on them once you turn them. That also increases the chances of the rotor heating up and warping when you take that material off. The rotors are thinner and the metal heats up faster and cannot dissapate heat throughout the metal evenly.