Dino Saga 071202 _ Hot Left Caliper

Dino Saga 071202 _ Hot Left Caliper

Seems I did some damage to the left rear caliper a couple of weeks ago. Had pads stick in and things got really hot. Cooled all down, made a quick check and drove carefully for two days before I could get the brake hose changed. Guys changed the hose and said nothing about other problems. Drove for a week and pulled the wheel. Found brake fluid on the outside of the disk. Oh Oh. Cleaned things off and got my wife to pump the brakes. Outside piston was leaking slowly. Damn. Well I had rebuilt calipers before. Must have cooked everything that touched the piston. Went into the house and called GT Car Parts. They had the kit, could ship today (Wednesday), regular UPS. Refilled fluid reservoir, put wheel back on and drove slowly. Got kit Friday afternoon. Good service, now for the fun.

Saturday I pulled wheel and took some pictures. Leak hadn’t gotten any better. Bit the bullet. Pulled metal brake line that goes from hose to caliper. Line wanted to drip so found a short piece of vinyl sleeving that would go into the tube. Pushed a finishing nail a little way into the vinyl. Pushed vinyl into caliper end of metal tube until firmly sealed. Tightened metal tube into brake hose so it was out of the way. No more leaking. Pulled both caliper mounting screws and made sure I had both shim washers that center caliper. Retracted outside piston, Pulled pads, caliper came off easily as emergency cable fell away.

Boy what a mess now that I could see what had happened. Pads had gotten hot, heated piston, completely fried dust shields and undoubtedly done horrible things to the seals. Same thing had probably been happening for years and I never noticed it. Can’t understand why it didn’t leak immediately. Maybe the changing of the brake line and the subsequent bleeding and cycling had knocked everything loose. At any rate, I had a good afternoon cleaning job.

Mineral spirits and a soft stainless brush did pretty well. Didn’t look like anything but rubber had been hurt. Pistons came right out with the retracting screws going backwards. Seal rings came out with a scribe. Inner surface of rings had been fried. No way they could seal at low pressures.

Let everything soak for the night. Will clean up and replace the rubber today. If weather stays nice. Saturday was sunny but air temps were in the 60s. That’s cold for working outside but as long as you can stay in the sun it is OK. Got down to the 40s last night and still waiting for sun to get air temps up. One of the problems with a car port in the winter. Even a Santa Barbara winter. So far, so good. Mid 50s and rising fast. Converted New Yorker. Been here 53 years and only go back under duress.

Will have more photos and news next week. Should be rolling again this afternoon.

John
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Thanks for the feedback. I cleaned all up, replaced rubber and all is right with the world. I think the old hose is the problem, not the parking brake. Pistons can't retract if oil can't get out. I double checked the inner piston retraction after parking brake test and all looked good. Will get into more detail in next week's Saga.
John

 

Scott,
No sign of pitting. I used a stainless wire brush and mineral spirits to clean up and piston OD still had perfect ground finish. The piston never rubs against the caliper body which is quite a bit larger in diameter. Piston just rides on square O-Ring. It is dry here so that even with cracked dust seals there is little chance of water getting in and causing corrosion. Also, I drive the car every day and the heat drives out any moisture that sneaks in overnight. Good luck on your rebuild.
John

 

Thanks to you and all others. Car is doing fine. No new pictures since all is working well and no oil leaking. Nothing to take picures of! Winter will be over in a few weeks and we will travel some more. Will find something to write about.
John