Brake Caliper Core Charges
 

I have a big problem but it might no be that big of a deal. Well having a very tight budget to work worth i think that i have a problem. Both front brake calipers have one half of them seized. my question is will this still be an acceptable core or will say autozone or some other places refuse it. I tryed autozone and they wanted $140 per caliper (ATE) i really dont have that money right now and if there do accept the core then i can get them for like $85. I really dont want to go in there and ask them the question before i order them because then they might say something. So I have one side of both of my front calipers sized are these acceptable cores or im i screwed.
81' 300d

Seized pistons is probably the primary reason for caliper replacement. That should not be a problem with regard to the core charge.

If you want to save money, consider a seal kit. You will need to remove the pistons to check for scoring/pitting. If the pistons are just "gunked up," new seals and boots will probably be all you need.

I would expect them to accept the seized calipers because they are going to rebuild them anyway. If you want to make sure, just call up and ask them without giving your name.

You return with your old calipers in the box.


"Well, Mr. Boom, we've carefully examined your calipers........removed the pistons.........and, unfortunately Mr. Boom, the cylinder bores are scored to a level of .003" and it will be impossible to recondition these cylinder bores. Accordingly, Mr. Boom, we will be unable to accept these calipers as a returned core for rebuild".

.........now.........we're talking about the chimps at AutoZoo.........do you honestly think the aforementioned statement is even a remote possibility?

I would recommend against getting a seal kit. If a piston is seized, it is very likely to be pitted or scored and won't be usable.

The rebuilders expect to put new parts in the caliper as well as the labor for the work. As Tango says, they also expect some seized pistons. I would wonder how many pistons they expect to be usable. More than zero?

I've done three of them.........the pistons are chromed.........very unlikely to pit or score unless water entered the cylinder over a lengthy period of time.

The accumulate rust deposits on the surface from the cast iron cylinder, but these are easily polished away with fine emery paper.

Just throw the old calipers in the box and return them. The moron behind the counter will just make sure a caliper is in the box, and give you your money back.


You could probably throw calipers in the box from any car, they don't know what MB calipers look like.

I don't know about your Autozoo, but I can't stand mine because everyone behind the counter is dumb as a stump.

The problem occurs when the dust seal fails, and water does get to the piston. It will sit in there for a long time before it evaporates, damaging the piston.

I've seen the damage before on calipers that weren't seized. I've never seen a seized caliper come apart with a usable piston in my life.

Just return them, the boys here could careless what's in the box. Hell, I could stuff a brick in there... they don't check.

Would you return a perfectly good PS pump as a core? Of course not, core items need to be reman/reconditioned/re-whatever to be used again.

You're thinking WAY too much into this.

I have seen plenty that have cleaned up nicely and given good service with new boots and seals. And Boom might be able to make one good caliper out of the two bad ones, so he only has to buy one new one.

Of course, it is entirely possible that the pistons are scored and the bores are pitted. But it only takes a few minutes to find out. Rejecting the reseal option "sight unseen" is nonsense, especially when money is tight.

One of the three that I did had one piston frozen so badly that compressed shop air wouldn't budge it. I needed the hydraulic system of the vehicle to move it out of the bore.

No damage to the piston........cleaned up fine and was reused.

i tried to get the pistons out and i just can get them out. I planned on rebuilding them but if i cant get the piston out then I'm suck buying new ones.

Get yourself a bicycle pump, and hook it up to the bleeder screw (you'll have to hold your thumb over where the line feeds in), and start pumping. They should pop out fairly easily. MAKE SURE you do not throw away the boxes to your new caliper. If you do, they won't return your core. Ask me how I know...:mad:

Oh that's nothing, I had a buffoon at AutoZone once tell me that they were unable to accept my used oil as it was, get this, CONTAMINATED! :eek: Well Ace, obviously so as that's why it is no longer in my vehicle!

The one by my house is cool about oil. I bring it in, and they just say, "Take it through those doors and just dump it in the recepticle." I could be dumping toxic waste in there, and they wouldn't know. Of course, that's the only reason I ever set foot into the place; WAY too many bad experiences in that place, like having some 16 y/o kid arguing with me over the equipment on my car because their computer is showing the wrong parts...

A core, be it a caliper or any other is expected to be bad!!! Thats why you are replacing it.... So, returning it should not be an issue:).

As to rebuilding it, although I have not done one, I was told by an indy who had rebuilt a few that they do not last as long. I am not arguing this with anyone in the forum. Jsut sharing what i was told.

I've only replaced one and that was on my 85D recently with a good, used one. The old, bad one is sitting in my garage and may atempt to rebuild it this winter. At which time I will be picking the brainiacs in the forum:).

He might be right. The condition of the groove for the seal is never all that great on an existing unit. The rebuilds usually attend to this area via media blasting.

He also might not want to expend the time............if he spends one hour on each caliper...........he might as well have bought proper rebuilds.

The only time a core charge will be refused is if you hand the guy a caliper that is not repairable by visual inspection, meaning if the thing is cracked in half, or one of the ears with a bolt hole is broken off, etc. Other than that, the previous sentiments noted are correct - you are replacing it because it is broken.

The rebuild guys will turn down/grind/polish the pistons and rechrome and final size them, along with the cylinder bores. For a proper rebuild these tolerances are beyond what anyone is going to do without special tooling. They recover most of the returned cores as very few have real damage that won't be addressed by the rebuilding procedure.

I have used a "C" clamp to break a piston free in the past. Just be careful you don't punch through the caliper wall (that will make your core charge non-refundable). And, rebuilding works if there is no damage to the area that contacts the rubbing seal, the square cross section rubber ring that goes in the bore groove on the piston. If there is, well, the fix doesn't last long,

Good luck, Jim

I also suspect that the improper use of petroleum-based solvents is a factor in the premature failure of field overhauls.

The question is always the amount of the "damage". None of those grooves are pristine after 20 years. There's always a bit of corrosion and surface contamination. Sometimes you can clean it up somewhat..........sometimes you can't. But, none of them are as good as a rebuild. The do manage to get that area quite clean. I'd be curious to know the required surface finish for long term durability of the seal.