PDOUBLEOP

Okay, the brakes on my truck gradually start to thump when I hit my brakes. I figured my rotors are warped so when my front pads started to get thin I replaced the pads and had my rotors turned. I also realized that it had only been less than a year since I replaced the pads the last time. Maybe the back brakes need adjusted?? I checked them and they were a little loose so I adjusted them out. Took it for a test drive and the thump was still there. So then I says to myself...self, it must be the rear drums that are warped! I took them in and got them turned. It still thumps as bad as ever! What the Hell!??? Is it likely the machinist didn't turn enough??? The rotors/drums were completely faced. How could they be completely faced if they were still warped?

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shakran

ok first off, don't have rotors turned. That shaves metal off of them, and thinner metal warps faster than thicker metal. In other words, every time you have 'em turned, you're shortening the time between now and the next service to the brakes. Rotors are cheap, and the labor is less extensive to just replace them (unless they have crappy on-car turning machines, they gotta take the rotors off anyway if you have 'em turned)

The back brakes do maybe 20-30% of the braking - often they do less. So the front pads are gonna wear a LOT faster than the rears.

My best guess would be the turning didn't smooth them out enough.

lt1s10

Normally they do check and see if the rotors are warped before turning them. If a machine shop turned them then it's worth asking about. If a parts store turned them then they may or may not check or be able to check if they are warped. I've known of parts stores that just put them on the lathe and hope for the best when turning drums and rotors.

The thump is a audible noise or something that you feel in the pedal? Hows the wear on the pads and shoes? Does one side look more worn then the other side (left/right side of the car) not inner and outer pads or front and back shoes. It could be the caliper/wheel cylinder not maintaining pressure. Leak in the system somewhere causing pressure loss. Or caliper/wheel cylinder is extended out to max and the pad/shoe is rattling. Could be other things besides the rotor and drums. That's why I hate chasing brake and suspension noises.

PDOUBLEOP

The wear was fairly even per side. The rotors had not been turned prior to this time. A higher quality parts store/machine shop did the work. They may have let a less experienced employee run the lathe at the time.

Shakran, I agree with you to a certain extent but when I do the labor it costs me $10 to have each rotor turned versus buying new which, if I bought the absolute cheapest, would be over $30 each. I would not have rotors turned more than once or twice depending on the amount of material removed each time though.

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cyrnel

From your posts here I'm still not sure if you've identified a warped brake surface. That'd be my first goal, starting up front. Did you try holding a stationary object next to the spinning rotor before removing them?

Get before and after readings when you have them turned.

Almost any rotor/drum can handle at least one turning, assuming it hasn't been damaged by bad shoes/pads or excessive warping. You'll lose mass, so the next warping can happen earlier, but vs. buying new every time it makes economic sense for the average daily driver. I'm more picky for tow rigs or vehicles that see lots of hard braking.

Use a torque wrench on those lug nuts, especially for the rotors. Beware shops using impact guns to tighten. Uneven lug torque or even wheel surface contamination can cause rotor damage, or sometimes just feel like something warped.

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PDOUBLEOP

Thanks for all the help. I'll probably pull the wheels off and try to check for warpage and clean the wheel/rotor surfaces. Also, is there some trick to adjusting the rear shoes??? There isn't an adjustment slot like there was on older cars with drums. I just adjusted it out til I could barely get the drum back on.

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black94lt1

If all your components are working correctly, your shoes should self-adjust, usualy by the parking brake, and maybe backing up etc. but usually you just have to get them close and the self adjuster will do the rest.

catback

What kind of car is this? I've come across the same on my car, I'm just glad I never had a problem getting the drum off cuse sometimes you have to back off the adjuster to release the shoes from the drum to get it off and without a slot or hole for adjusting there just isn't a way to get to it.

PDOUBLEOP

It's a '93 chevy truck.

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Craven Morehead

Amen to that. Also make sure you follow the correct pattern when tightening the lugs. Usually a star pattern, not the next one to the one you just tightened.

PDOUBLEOP

I tried stopping the truck with only the parking brake and it became obvious that the problem is in the back. I'll take the hubs back and see if they're still warped.

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