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Discussion Starter #1
The truck is a 2008 F-450 pickup that I have owned since new, now with 60,000 miles. 5,000 miles ago I replaced the brake pads on both axles due to the material separating from the backing plate on one side of the rear axle. Have not had any issues until recently. The brakes are now what I can best describe as grabbing. Not pulling to either side, just grabbing. Quite severe at low speed. I removed the wheels and calipers, inspected the rotors. No signs of overheating or cracking. I used my portable grinder with sanding pads to go over both surfaces of all four rotors to remove any high spots, rust. The truck does sit covered in the driveway for extended periods of time. While the rotors look good, I reassembled the brakes, drove the truck and the problem persists. Before I spend $119 per rotor to replace, I am looking for a second opinion of the possible cause. The suspension looks good, no loose ball joints, tie rod ends. Tires are good, only 10k miles. You may be asking why I just do not have the rotors resurfaced, the reason is not many shops have the capability to turn these larger rotors. Any suggestions are much appreciated.
 

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Try asking around. There are some places that can turn those rotors.
 

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Once you sanded the rotors, did you bed-in the brakes again?

I am not saying thats your problem. I just wonder if anyone does this anymore. I still do.
 

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Possibly your calipers are not retracting. One of the two could be working correctly and the other hanging up.
 

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Slide pins greased?
Fluid changed?
Fluid level OK?
Any fluid leaking down by brake pedal and firewall?

What brand pads?
 

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Try asking around. There are some places that can turn those rotors.
Ford doesn't recommend turning rotors. Jack (FMTRVT) says that if they overheat and get hard spots, they can't be successfully turned out. They might be OK for a while, but the pulsation will come back. I'd say the same would be true for sanding rotors, which would be less precise than turning them on a brake lathe or even on the truck.
$119 each for rotors doesn't sound all that bad, but I'd check all the stuff that ArcticDriver mentioned.
Brake hoses might also be worth changing out. If they're deteriorated it can affect brake performance.
 

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Good suggestion, but be careful with the RockAuto listing. They list some rotors for Single Rear Wheel. I'm betting that an SRW F450 is a rare animal.
Yes, rare, but not completely extinct, although I'm guessing that they don't take a different rotor, but what do I know? :saythat::hat::alfdance::domotwak::eek:fftopic::banana::grouphug:

https://www.thedieselstop.com/forums/f15/dumb-question-f450-srw-9902/
https://www.buckstopinc.com/single-wheel-conversion/
Rickson Wheel Manufacturing
 

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Discussion Starter #10
I installed new rotors this morning. Duralast brand, Torqued the rotors on the hubs, and checked for runout. They are good. Checked the calipers, everything works. Put the truck back together and the issue is still there. I am starting to wonder if I am having an issue with hydro boost, low pressure from the power steering pump. What is odd is that the grabbing, pulsating is happening all the way down to zero mph. Does not feel like warped rotors at all. No side to side shake in the steering wheel at all.
 

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So you did grease the caliper pins and checked fluid lrvel and hydroboost for leaks?
 

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Discussion Starter #12
Did all that. Since I haven't since new, I am going to pick up a couple gallons of Mercon V and flush out the old fluid.
 

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I would get some brake fluid and flush that system out as well.
Could be that your calipers are hanging up.
You might shoot a PM to FMTRVT and ask him to take a look at your thread. He's spent years on brake systems.
 

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Did all that. Since I haven't since new, I am going to pick up a couple gallons of Mercon V and flush out the old fluid.
If you're flushing the Power Steering system, I would use Mobil 1 ATF. The synthetic should perform better. It's a bit more expensive, but you only need about 3 quarts.

Is the pump making noise?
 

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Discussion Starter #15
No, no unusual noises. I used my vacuum pumped to draw down the power steering reservoir but I cannot get to the bottom. There is something blocking access inside the tank. Odd design only allowing me to remove maybe half a quart of fluid. Access to remove the return line to the reservoir means pulling the battery tray with the degas bottle attached. Not sure how get to the bottom of the tank. Another person suggested to disable the ABS system and take the truck for a drive. If the issue disappears, he says a speed sensor is going back. Good possibility since I have checked or replaced everything else. Thank you for your time and help
 

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Discussion Starter #16
Removed fuses 6 & 9 from the fuse panel under the hood. Both for the ABS system. Did trigger an ABS light but the problem remains. Back to the drawing board.
 

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If you are trying to replace the fluid then the Mobil-1 works best. I tried Valvoline Synthetic ATF in the red jug and it made noise so flushed & re-filled with M1 and no more pump noise.

You can raise the front wheels on jackstands and remove the return line at the reservoir. There is a DIY available with a photo.

Clip that hose to a container and the old fluid will be pushed out by force as you SLOWLY turn the wheels left and right. Slowly or it creates air bubbles. Ofcourse, keeping an eye on the reservoir and filling with fresh ATF to keep it from running dry.
 
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