Tomahawked Posted March 27, 2009 Share Posted March 27, 2009 I have a right side caliper sticking after driving thru too much stop and go traffic today. I could either swap for a rebuilt caliper $17, replace with just a new plastic piston $15, remove old piston and machine the 0.005" off OD it has swollen over the last 20 years of use, or just machine a new one out of stainless steel. All are easy enough to do. I hate just replacing with rebuilts, especially if something simple to repair. The rebuilt caliper will not have a new piston. It would be just cleaned, painted, and rubber parts renewed. Replacement piston fixes problem and should be good for many more years, but cost is nearly the same for a rebuilt. For the 30 minutes it would take to drive and pick up another caliper, I could have the old piston taken out, machined and replaced. Machining a new one out of SS stock is te most time consuming, but a permenant reapir good for the next 50 years. What would you do? Link to comment Share on other sites More sharing options...
Automan2164 Posted March 27, 2009 Share Posted March 27, 2009 To be honest, I would just go and get the rebuilt. They have been gone through, and as long as you buy from a reputable place, will be just as good as new. Plus if you want, you could rebuild the one if you don't turn it in(core?) and have it as a spare. Rob L. Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 27, 2009 Share Posted March 27, 2009 Replace it with a rebuilt. Less time, same $$, and you get a warranty. No brainer.............. Link to comment Share on other sites More sharing options...
SomeNew Name Posted March 28, 2009 Share Posted March 28, 2009 I haven't been out working on my comanche in a long time.. nor have I seen it in a while.... but collapsed flex line? Link to comment Share on other sites More sharing options...
Tomahawked Posted March 31, 2009 Author Share Posted March 31, 2009 I took all of the above suggestions under consideration. But since I always think outside the box, decided on this fix. Removed the wheel and there was the usual black dust and burnt smell. I had just machined the rotors and replaced the pads. So was expecting there to be some problem with calipers sticking eventually, and common to plastic pistons with high milage. Just didnt expect the trouble to be almost immediate. I removed the caliper and noticed how badly the pads glazed over. Whats really ridiculous is there is only 35 miles on them. Removed caliper and tried pushing piston back in. Just curious how tight it felt. Not good. So I used the air hose with blower and popped out said piston. It measured about 0.004" larger(thickness of a fat hair for reference) in size than should be. In the lathe it went and shaved down to the right size. Polished it with some 600 grit and was done. Wiped the inside of caliper out and slid piston back in using existing seal and square cut oring. It went back in much easier than before. I would normally replace rubber parts, especially for a new dust seal. The oring is not normally subject to wear or swelling unless fluid has been contaminated. But nobody locally had them in stock. I also heard a clunk when applying pedal after changing pads originally. I noticed the usual worn gouged area where inside pad rides on caliper mount. It was stepped more than I cared for, so grabbed the MIG welder, ran a bead over, and built up where the step was. Ground it down smooth. The welded surface was extremely hard. Actually much harder than spindle itself. Maybe a good thing. The file wouldnt touch it. But now there is no ridge for pad to bind up on and piston is not sticking. So tire spins freely when pedal is released. I guess that makes me a happy camper. But not so fast. After doing the extreme test run, I noticed the left side is starting to act up the same. So tomorrow, I will do a pete and repeat on it and should be good to go. I know I should have done both at same time, but a big storm was fastly approaching. Now you are wondering why I would go to this much trouble. Just slap another caliper on and get on with my life. Well that is one way to approach it. BUT, I would not have educated myself at all. Just spend some money and learn nothing. When I repair something I really want to learn more than I need to get by on. Not only did I repair the problem. But did so in the same time would have taken if I drove down to the store and purchased a replacement part. So for the same amount of time spent, I did the repairs for nothing out of pocket. AND got a complete understanding or what was wrong and what it took to fix. If I had done all of this and didnt correct problem, it would have been irritating. But I would have eliminated the more obvious reason and looked further into what more serious issues there might be still lurking. Link to comment Share on other sites More sharing options...
jaekl Posted March 31, 2009 Share Posted March 31, 2009 Isn't it great to be handy? The beauty of being an owner mechanic. You repaired only what was worn, used less resources, honed your skills, and had a constructive past time. It would never work as a pro doing it to a customer car. Sometimes with this approach it's a fine line between a real repair and a haywire patch but this look thorough. The only questionable area is what cause the piston to increase in size and will the rate accelerate so the next time will be in 15 years. It's good to hear there are still people who approach a problem this way rather than always throwing parts at it. It's a personal choice of course. Link to comment Share on other sites More sharing options...
Eagle Posted March 31, 2009 Share Posted March 31, 2009 You should still consider replacing the flex hoses. The insides deteriorate over time and they begin to act like check valves -- they allow fluid to flow into the caliper, but not back out. Link to comment Share on other sites More sharing options...
Tomahawked Posted April 1, 2009 Author Share Posted April 1, 2009 You should still consider replacing the flex hoses. The insides deteriorate over time and they begin to act like check valves -- they allow fluid to flow into the caliper, but not back out. With this line of thought, I might as well replace every wearing part on the truck. Lines were fine. Not even cracked on outers. When lines do go bad, its usually from someone pinching them shut in the past when doing repairs, or letting the weight of caliper hang down by only the line. The inner layer ususally has to be broken for the line to get clogged. If it deterorates, the fluid would be very dirty, contaminated and hold some residual pressure immediately after driving. Trying to rotate the wheel showed a lot of drag but no pressure when opening bleed screw. So now you know an easy test to help diagnose brake problems. Link to comment Share on other sites More sharing options...
Tomahawked Posted April 1, 2009 Author Share Posted April 1, 2009 The only questionable area is what cause the piston to increase in size and will the rate accelerate so the next time will be in 15 years. The reason for piston to swell up is due to heat pressure, and brake fluid. Not necessarily in that order. Chrysler was one of the first to change over to phenolic pistons. And the first to have major problems shortly after. Link to comment Share on other sites More sharing options...
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