Rusty spots on brakes

[flagmanruss]

I just can't drive my CTD daily. (signature 2001.5 w/ 4 wheel discs) It seems I get brake chatter every time it sits. The garage... claims rust forms under the pads where they sit against the disc. He claims he gets lots of work from folks who let vehicles sit... claims they all do it! Physically, I can not pull the brakes myself to check... but I'm damn tempted to replace the discs with something that won't rust. Stainless steel (some won't rust) or ceramic.I'm sure somebody here knows more about this than I do.Russ

[Mopar1973Man]

Well becareful of the what brake pad material you use. If the pad material is harder than the rotor material you eat the rotors quickier. It might provide better braking power and such but could wear the rotors faster. Like my Mom's 96 with Drum rear tend to stick and grab for the first mile or so. Once the truck has gotten to highway speed the rust is gone. So it might be a matter of dragging the brakes for the first little distance like pulling out of the shed to the driveway scrape the rust off the rotors.

[flagmanruss]

The thump - thump is very noticeable & never goes away... I've tried dragging the brakes for a mile down the road to clean the discs for each use. It only happens when the brakes are applied. The brakes have needed to be turned every time it goes in but the problem recurrs within a week or so. It definately reduces stopping power. I do not trust the shop anymore & will not be going back there. (They charge as much as a dealer... but can not think out of the box.) I only have their word for the rust spots. I wonder about a disc warping. I've been surfing looking at disc brake info. I found two possibilities. 1) a caliper sticking (maybe just one one side) heating the disc, causing warpage2) improper torquing of lugs causing a disc to warp.If I could get the discs off myself, I own a lathe...

[Mopar1973Man]

How about debris on the piston causing them to bind up...Let me gather up my notes and I'll explain how to fix it...

[flagmanruss]

I'm still doing research, reading everything possible on disc brakes. This began after the discs were turned the first time. One point I've uncovered is that discs can have stresses... which cause them to warp. You true them on a lathe & the first time they heat at all, they warp again. You turn them again & the same thing happens. The fix is new discs. I wonder if it's the same singe disc doing this again & again? Discs aren't cheap but repeated repairs aren't doing it. I'm reminded of a story of an engine. It was a 289 Ford blocked Interceptor marine engine. I tuned it up & it ran like a top. The customer took the boat out & it came back out of time, popping & farting. I reset it all & the same thing happened. I thought the customer or one of his buddies had messed with it so I marked the distributor & the next time found they had not.I told him there was something wrong internal in the engine... I pulled it out & put it in his truck. He returned the next weekend with his marine gear on a fresh block. The customer left on vacation... the rebuilder called, irate! What's he trying to do? Stick me with a dead block? It seems the block went through all the machine steps before they discovered cracks down below the cam journals... allowing the V angles to change at whim. The customer happily paid the core charge when he returned... and I spent the next 3 years replacing the steel freeze plugs with correct brass when the seawater cooled engine ate them out. The ones behind the front motor mounts really s*cked... laying over the engine upside down with your head in the bilge! Back to brakes. I think the shop was not paying attention that the same job kept coming back. Maybe it's not RUST but warping. I gotta find someone I can trust.Russ

[Dave3500]

Cool story Russ, I bet you've got a million of 'em!Try changing the fluid to get the 2% accumulation of water/condensation out per year so the rust on the pistion calipers doesn't come back so fast.Dave

[flagmanruss]

Most boats don't have brakes! I was a marine mechanic for 17 years.

[flagmanruss]

I know I'm heading for another brake overhaul... the emergency brake cables anchor point is AWOL... rusted away! I'm reading everything I can find on disc brakes. One source, insists that the brake hub & discs must be cleaned so the discs will seat correctly against the hub. They state rust & dirt as being able to make the disc... even a perfect disc... off-true as mounted. Maybe you are thinking no way... but my truck has rust problem underneath. I wonder if this detail was missed by my former mechanics... I'm willing to be open minded... it will take fairly little to check this once it's appart.Thanks for letting me ramble.Russ

[Mopar1973Man]

How about a binding piston in the caliper dragging the pads???How about rusted slide pins??How about debris in the bottom of the piston cylinder causing a binding problem???

[keydl]

This fits one of the instructions on a pad set. Make 3 hard stops from 60 to 5 mph to break in and set the pads. Cooks the flex agent at the surface to leave a pad with less to transfer to the rotor. Drive 15-20 min without setting with the brakes applied (light).If the warped feel goes away - the cause is the pads. It will come back after a hard stop at a light, and you will know for sure. Lightly dragging the brakes will eat the rust in a 1/4 mile on most, same thing holding hot pads on the rotor will transfer material so cool them before a full standing stop.Not all pads work this way but the last 3 sets from different places have and 2 had the same instructions in the box.Several ways to 'do' the brake fluid, mine - suck the MC contents when changing the oil. Partial change same as the transmission. There is no drain plug on the converter so you change the gallon in the pan. Do it every 1k miles or 6 wks until the MC contents are clear after 6 wks. Unless the calipers are inverted and the fluid blown clear or the calipers replaced/rebuilt it is still a partial change.Changing the contents of the MC when discolored is another way to do partial changes, check monthly and change when color shows.It is nearly free when compared to parts and labor.keydl

[flagmanruss]

keydl & all,Thanks for the rely but I'm confused. The brakes already have a serious thunk - thunk - thunk almong with greatly reduced stopping power. Are you saying I should cook the brakes now that they already have the problem? Can it be seen when they are dissassembled? What would I look for? I was thinking that if a disc was warped, the marks in the rust should show when disassembled. I was never told to "set" the brakes in any of the previous repairs. If I knew what to buy, I'd rather have my buddy fix it than trust a shop again.Russ

[cummins2k]

Just thinking outside the box here. But a malfunction of the hydroboost unit will cause a characteristic thunk in the braking system also. It will also cause a decrease in braking power. Often times this is caused by a malfunction of the spool valve in the hydroboost unit and flushing the power steering system well can resolve the problem. If that doesn't work a replacement unit runs about $200-$250 depending on where you buy it. However this is a shot in the dark because it could very well be something else in the braking system.

[flagmanruss]

I can't tie the truck up until after this weekend... then I need to get all the wheels off & inspect the discs & pads. Clearly something has been missed, since it keeps recurring as fast as it is put back in service. If all four corners check out, then I'll get back to you guys & we can go from there. Sincerely, Thankyou all for the ideas.Russ

[flagmanruss]

CTD is in on the lift now... Front brakes were perfect. The inside of the Left Rear disc had numerous slightly dark spots on the otherwise bright disc. I don't know if I would have spotted it under field conditions. Brake mechanic & I did show & tell in the service bay. Pads are perfect, sliders clean & free. He does not see anything wrong with caliper... though I don't see how there can not be. We've just replaced that disc... I'm nervious that the caliper "has to" be contributing to it. The rusted out part on the E brake is the link between L & R rear cables. He has one off a junker, so that's an easy fix. Hope to have my baby home soon. Russ

[flagmanruss]

I've got the truck back. The NEW disc on the Left Rear has fixed the thunk, thunk, thunk. Now, I will try to drive it more often & keep the brakes from getting so rusty. I still should have kept the disc & tried to mic it to understand just what was going on. Anyway, I'm happy to have my baby back in the yard. Russ

[Mopar1973Man]

Most liekly like a hot spot on a flywheel.It would be interesting to mic it and see what was occuring. Also I wonder if the rotor had formed harden spots in it (work hardened)? :confused:

[flagmanruss]

I no longer trust the work of the first shop... no way to tell what was or was not done. This brake man showed me, thought it was unusual to have numerous marks on the inside of the disc. He usually sees them on the outside. It would not take much of a warp to cause problems. I just hope it stays fixed.Russ