Hello, all. Great forum here. I've been lurking for awhile, studying. Anyway, I'm a farm boy, heavy equipment operator, worked as a mechanic in college. I know my way around trucks, and wrenches. A few months ago my '03 F350 6.0 started acting like the rotors were warped, front end hopping/shaking on braking. I let it go till funds became available, threw on a new set of Napa pads and rotors (good stuff, not the cheapies). The hopping actually got worse. I had my tires balanced, truck aligned, no help. But the tires were way out of whack, 7-8 ounces each. So, good excuse to buy new tires. And rims. Now I'm rolling on 285/75/16 Cooper STT's wrapped around Moto Metal 951's. Hopping (rotor shake) still there. I've only put 1500 miles on the rotors, so I talked the dudes at Napa into replacing them. Another new set of rotors, it got a little better, but not gone. The guys at Napa won't warranty another set of rotors till I get bearings/suspension checked out. The suspension is stock, replaced the lock outs, repacked the bearings at 65K. Truck has 81K now.

Funny thing is, I've heard two separate stories of Ford truck owners going through 3-4 sets of brand new rotors from the same store, before finding a true set. One of our mechanics at work actually had a brand new set turned because he was so frustrated, problem solved.

Anybody have any experience with something like this, does it sound like the rotors or the truck? BTW, one of the Napa guys suggested that I bleed my brakes, could be an air pocket

 

2x4 or 4X4?

 

Did you go all the way around with rotors? Does it hop as soon as you change or does it start after a while driving? I went the PowerSlots and haven't had a hop yet.

 

I had a similar problem with mine and it was the front bearings. It only happened when braking also so i was for sure it was rotors but........... mine is a 2x4 thats why I ask

 

I would check the run out on the rotors.

Then turn if needed.

( I'm not much on napa parts FWIW )

 

Ive seen loads of rotors and drums, warped as you question. The problem seems to stem from storing and or shipping the units on there side in stock rooms and transfers. Seen them standing on side behind the counters. Almost every time I replace either I have them run up on a lathe. I have had counter guys look at me like I was nuts about it only to find that the darn things have a warp to them. Some times not bad, and its true that some is somewhat beneficial to piston retraction, but wheel bearing clearance is usually sufficient for that.
All this is not to say you don't have some other gremlin, but run out is worth avoiding. Even freshly ground units have a slight off-center grind sometimes depending on the lathe and the cleanliness of the operation. ? Did you replace all the mounting hard where as well, slide bolts, anti rattle clips, and such? all should be replaced at any rate. I found disc brake lubricant to be a strange, but necessary item in all brake jobs after finding it, as well. A bind in your caliper could cause oscillation and result in uneven breaking of the pads and rotors. A loose ball joint could amplify any such maladies as well. Good hunting

 

Sorry to pipe back in so soon but i noticed the air pocket theory. Hm, the pocket being in one piston bore of the caliper might mean uneven application of pressure, sure, but this, in modern single inlet multi piston caliper units would just possibly cause( in my opinion ) spongy brake application on that or booth sides(a slight pull). Probably not it. Another cause tho that Ive heard of for the malady of jumping, is that the supplied finish on some new rotors is just to fine. It doesn't lend its self to proper break in of the two surfaces ( pads and rotor ) causing uneven pad to rotor friction. Softer composition semi-metallic lined pads tend to be alittle more capable to cut a flush surface rather than, say ,a long life hard lining designed to last in fleet type replacements. At any rate I'm just presenting food for thought. Hope it helps.

 

If it turns out to be rotors, I recommend Power Slot. Mine were extremely warped. Turned them and they warped almost immediately. I went w/Power Slot 6 months ago and and have had no more brake issues!! The work great on the brake-killing mountian passes here in SoCal.

 

Gotta run, but, it's a 4x4

 

Thanks for the replies, definitely food for thought. Answer questions, yes, I changed all hardware, all lubed the sliding parts and pad backs. No, I didn't do the rears. And yes, it does it as soon as I start driving. The last set of rotors were actually hopping before I got out of the shop driveway.
I've been thinking about just returning the Napa rotors, getting my money back. I've also thought about taking the rotors off of my work truck, total PITA, but it's the exact same truck, and I know those rotors are true. Then putting them back on the work truck and telling Napa where to put their rotors. On the other hand, it could be some weird bearing malady that only presents itself on braking. No growl on hard turns, no higway hum, just severe front end hop on braking.

 

Rear rotors could be the culprit. They will warp just like the front.

 

Well, I had a hunch, actually from doing my homework here. I put a new set of Rancho RS5000 shocks on her tonight, and, lo and behold, the problem got WAY better. The old shocks were trashed, I found out after I took them off. I couldn't tell, none of the usual symptoms of failed shocks were there, but what a difference! Apparently, the old shocks were amplifying the slight rotor hop the truck has. New rear rotors tomorrow.

 

I hope the rear rotors will fix your problem. And I don't know where my manners were, but Welcome to the site and let us know if that fixes it.