Leaking caliper piston

[pasvorto1]

I am looking for some confirmation on my thoughts.

Last month I was having a "dragging" noise from my '78 whenever I would leave from a stop. After A few seconds it would go away. I took it to a local shop. I was told that the right rear caliper was leaking. The mechanic showed me the mushy pads (after he chaged the caliper). Well, $280 later and the noise went away. Yesterday it was back! Not having the budget for a shop right now, I took the left rear caliper off (assuming the RR was good since it was replaced). One of the pistons is leaking, though not really bad, IMHO. I can get a new caliper at MPE for $90+.

Does that sound like that could be the problem? The noise sounds like it's coming from the LR portion of the car. I can't think of anything else that would make that noise.

I bought the car a couple months ago. It had sat for quite a while. Maybe the piston seals had become brittle. I am assuming that, when brake pressure was applied, the RR was in the worst shape, so it did all the leaking. It is now fixed and the LR is now the weak point, so it has succumb to the pressure. Does that make sense? Could it be that the LR wasn't leaking before because the RR let enough pressure out to not affect the LR.

 

[Tom Bryant]

You're on the right track. If you are going to let your car set for a period of time it is a good idea to occasionally push the brake pedal a few times to keep things lubed and flexible. With your brake system divided into a seperate front and rear system you should replace both rears or both fronts together even if only one is leaking. As you said, with the right caliper now holding it is putting more stress on the left, which was probably on the verge of leaking anyway.

Replace the left caliper and use the same pads that were put on the right side and you should be ok. From now on keep a close watch on the fronts too. They may be close to leaking. I replaced the fronts on our '81 3 years ago when the left just started seeping and the rears have not yet given any problem.

Tom

 

[Blue82]

I had to rebuild all four of my calipers shortly after I bought my car. You should consider rebuilding them yourself. It isn't hard and the kit is inexpensive. Also, the mags sell clips that you can put over the pistons when you are changing the brake pads. Slip them over the piston, open the bleeder valve with a piece of clear hose over the valve and it is a snap to push the pistons back and swap out the pads without removing the caliper.

Open the bleeder anytime you are pushing the the pistons back into the caliper or you will blow out the seals. I blew them out twice before I finally wised up.

Good Luck.

 

[pasvorto1]

Good things to know. I tried rebuilding a Master Cylinder on am MG Midget once. Met with limited sucess. My tool supply is about as long as my mechanical skills.

 

[pasvorto1]

Is it easy (possible?) to hold the pistons in without the tool? I am getting a new caliper after work and would like to get it installed, and not wait a week for the clip.

 

[mkapp7879]

Shouldn't be a problem. Put the pads into the caliper on the bench, spread them apart and stick the appropriate sized socket between the pads. When you slip the caliper over the rotor the socket will pop out. If you don't have a socket that fits, you can just hold them apart by hand till you get it over the rotor. New caliper, won't have to worry about blowing a seal with the fluid pressure cause it will be dry til you bleed it.
Mike

 

[69_Dream]

My car had been sitting for years when I bought it, only ONE leaking caliper. So I changed it. 2nd one started leaking. So I replaced THAT one. Another starting leaking :cry Said "Screw this" and replaced the remaining 2.

Lesson here: Let a car sit there for too long, seals and gaskets dry up and then ANY additional pressure will cause problems, or at least allow them to resurface. Try one, if that causes any others to start leaking, replace the remaining 3... actually, looking back if I would have replaced all 4 at once I would have saved 50 bucks or so on the package.

 

[The73vetteman]

Is it easy (possible?) to hold the pistons in without the tool? I am getting a new caliper after work and would like to get it installed, and not wait a week for the clip.

I actually found it easier without the tool. I got the O ring calipers from VBP and fitted the pads exactly the way they said to, that is, on the bench, before fitting the caliper to the car.

Incidentally, I started with just a leak from the front right caliper so, to save money, just replaced the front calipers (and the rotors, and the bearings - another story!). Within a week a leak had developed at the right rear, so I ended up replacing them too. What I'm saying is that I think you're right. As soon as you fix one leak the next weakest point will be stressed.

John

 

[pasvorto1]

You guys (and gals) are super. I did decide to order the clip anyway. I butchered the brake line with vice grips, so figured 'What the Hell?" as long as I have to wait for a brakeline, I might as well... I also bought a brakeline wrench

Thanks for all your suggestions and comments.

 

[ARW]

I have been doing mine one corner at a time due to brake hoses. They go bad internally and act like a one way valve. The brakes remain slightly applied, get hot, ruin everything including rotors, pads, seals, and even wheel paint. Very expensive lesson(s). I'll never rebuild calipers again without replacing the #%#% hoses. They looked just fine---on the outside.

 

[GTR1999]

Cars sitting for long periods absorb moisture in the DOT3 fluid,turning it to an acid base muddy brown mess. DOT5 doesn't have this problem but you can't just swap it in there without cleaning out the system.

In your case the car has been sitting a while and the fluid is bad. Unfortunately your garage wacked you big time to change a caliper and pad set. You can get SS lined calipers with the factory lip seals for $65 each from Muskegon Brake in MI. Buy a car set and get free pads if they still run that offer. A complete car overhaul system runs about $300. You have to check the entire system to have a safe stopping car. The rubber hoses should be replaced if they are several years old, add in copper washers for the front calipers, check the rotor runout and thickness> runout shouldbe under .005" with .000-.003 preferred. Check the M/C for leaking too. Rolled flare nuts may leak if you don't get them fully seated. Bleed the entire system once you have it back together. The best tool for this is the Motive pressure bleeder,cost about $60. You can use the 2 man method too. Be careful not to spill fluid on the paint- it will eat into it very fast. asK questions if you're new to these cars or else if will cost you a lot of $$$ from the garage. Good luck

 

[pasvorto]

I'm always amazed by the people who buy a cool car and let it sit for years. I am sure they assume 'low mileage = big $$ from the buyer'. However, I am finding 'low mileage = big$$ to the garage'. Time to put on my mechanics hat again. I put it somewhere when I left my 20s. Now where was that....

 

[GTR1999]

You're correct, a low mileage car can be costly to get road worthly again if it's been left sitting unprepared. I always like to start a car up every couple of weeks and run it for a good 30 minutes to get out the moisture out of the oil and to work the brakes. Bleeding the brakes every season wouldn't hurt either. Check the differential for oi leaks at the seal points too.

 

[pasvorto]

Well, the brakeline came in from Mid America on Friday. Only took 5 days using UPS ground. So, I was pleasantly surprised. When I went to install it, I got a bit confused. When it is in place, it runs between the emergency brake stuff and the shaft. I looked at the old brakeline and it ran 'over' the shaft, nowhere near the emergency brake stuff. Hmmm. I checked, and double checked. Yep, they sent the right part, according to their catalog. I checked the other rear caliper (which I had a 'professional' replace). It was routed the same as this new one. So, evidently, at one time the wrong brakelines had been put on it.

Anyway, I got everything put on. Bled the brakes and went for a test ride. The test ride is no 'easy' project for me. I have a steep driveway which abuts a steep street. A test drive for brakes can be an exciting adventure. Don't ask me how I know.

I got her rolling and tested the brakes lightly. Worked nicely. A little more speed. A little more brakes. Looking good. Went into town for a test ride in traffic and promptly had a mini van pull out of a gas station, right in front of me, the driver not even looking in my direction. The brakes worked flawlessly! Harder than morning wood in a frat house.

It is very nice to not hear the brakes sticking everytime I pull away from a stop. Given my luck, the front calipers will fail now. But, if they do, I know I can fix them.

Next saturday, it is off to the dragstrip to see what a bone stock 78 will do.

 

[69_Dream]

Harder than morning wood in a frat house.

Now, THAT's funny