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I respect your input, Dave, and a lot of what you mention makes some sense.
I only would note that you have not held or used OUR rebuilt calipers. So, as such, you are commenting on a rebuild service that you have never actually seen or used.
Is that True?
Carl, I'm commenting on the pictures *you* posted above. Are those not pictures of calipers that are rebuilt by your rebuilder? Or are you writing that my observations about what's pictured are in error?
I can certainly understand that you may disagree with my assessment of a possible failure mode when original (or new) guide plates are coated. My 'fear' of this failure may simply be the result of an improbable clustering of problems with the guide plates that have skewed my assessment of overall risk probability.
For folks that have, or will have, calipers with coated guide plates, they simply need to make sure that the pad edge has 1-2mm clearance along the guide plates throughout the pad travel toward the brake disc. This, along with a visual check of the plates, is an important 'test' regardless of how the calipers are refinished (or not refinished.)
As to whether or not I've held calipers rebuilt by the same service... maybe. Maybe not. I have a set here - as in 6 feet from my desk - right now. In the case of the set I have, I specified unconditional replacement of the guide plates because the originals had started to warp. The rep grumbled and complained and whined about it like a little girl and charged extra. But that was all fine by me. Overall I'm not impressed with the ones *I* have here. The ones you picture above look better - especially the area around the pistons - with the exception of the guide plates.
Personally, I don't like connecting pipe to be coated either. But that, unlike the guide plates, is not a functional complaint. It's an 'originality' and aesthetic preference and would just add cost to the rebuild for something that's non-functional.
We seem to agree that paint build up on the guide plates can hamper the movement of the pads. That is why our rebuilder uses a chemical dye, the polycoat, instead of paint. It penetrates the metal and colorizes it without the buildup that is common with paint. As to warped or worn guide plates... again yes, we agree with you. If the guide plates are warped or worn they should be replaced and we do that as well when necessary, as I posted above.
All of the additional parts, pistons plates and bolts are available, just like the ones you supplied for that other project, but it adds a considerable cost with no need or benefit. If the customer insists on having these parts replaced, buy them and send them in with the calipers and I will install the parts at no additional cost, and I keep the old parts.
I think the only place where we diverged was at your statement that all piston plates and hardware should be replaced automatically, and we do that on a as-needed basis. However, should a customer request the guide plates and hardware be replaced regardless of their current condition, we can do that. It adds to the cost, but no problem.
Thank you for your input. I am sure you brought guide plate warp and wear to the mind of many who did not know about that issue.
John, Dwayne's Garage has some nice documentation for rebuilding the rear calipers on an '84. I would imagine most of the steps are the same if you wanted to try and tackle it yourself. Does not look difficult, just time consuming.
Dwayne did have his front calipers media blasted, but I would concur with Carl that media blasting could screw up the cylinder if not careful. I'd be more inclined to just thoroughly use a parts washer and brake cleaner. Other than that, it looks pretty straight forward.
Dwayne did have his front calipers media blasted, but I would concur with Carl that media blasting could screw up the cylinder if not careful. I'd be more inclined to just thoroughly use a parts washer and brake cleaner. Other than that, it looks pretty straight forward.
I know bead blasting and sand blasting are specifically verboten.
What I do not know is whether some other media, like baking soda blasting or walnut shell media, could remove the paint without harm to the bores.
Maybe someone who knows could answer that for us.
I think the only place where we diverged was at your statement that all piston plates and hardware should be replaced automatically,
Yeah, well... we’ll need to diverge further because I made no such statement. The only thing I wrote consistent with your above claim is that I think the guide plates should be removed before coating and left bare metal. I stand by that. When you paint a wall do you paint over furniture that’s against the wall or do you move the furniture and paint behind it?
I *did* ask a question - my first post in this thread - about the extent to which “refurbished” brake calipers are refurbished so as to allow you to set expectations for the OP.
The point is that my calipers are cosmetically in such good shape, I don't really want them recoated. My idea was to just have them rebuilt.
Dave, thanks for the comment about the parts the additional parts that can be checked in a rebuild. If the button bolts can be replaced, I am wondering, if 300° does not mean you need to have the calipers recoated anyway. I was aware about the guides but just assumed they would be replaced.
It looks to me like there are two choices for my personal needs:
1.) Rebuild as per Dwayne's instructions (thanks Chris!), not necessarily sufficient, if the guides are warped, but certainly a doable task, and keep the original coating.
2.) Find somebody, who really replaces the guides, button bolts and seals and "while they are in there" just being forced to accept a recoat, if the guides look warped.
In any case, I think this thread is useful to others looking for this service. So, I meant that the post should be relatively general post about the topic. If I wanted a recoated caliper, I can see how Carl's service could be attractive.
If the button bolts can be replaced, I am wondering, if 300° does not mean you need to have the calipers recoated anyway. I was aware about the guides but just assumed they would be replaced.
Each ‘repair kit’ for the guides comes with a new guide and a new button-head bolt.
As for the heating... consider what brakes do. They turn kinetic energy into radiated heat. Calipers regularly see these temperatures. This is why we like brake fluid that doesn’t boil below 400 degrees.
In any case, I have replaced the plates several times and the factory coating isn’t fazed by the treatment.
Note that 300 degrees is I think a maximum release temperature for the bolts. It’s likely closer to 250.
Couple of years ago I replaced every seal, dust cover and guide plate on every calliper (new button screw and bleeders too), repainted and put on fresh decals (paint before the seal work and after removing old guide plates). New flexible-hoses all round too. All the original pistons looked like new. Car had about 75K miles on it at that point.
It’s still rewarding each time I look at them, but much more so is the lovely pedal feel every brake application. Good brake rebuild is the 928 gift that keeps on giving!
"The area behind that pad plates is coated at the manufacturer. It corrodes behind the plates and can be painted if he wants that done. That does not mean the plates need to be replaced though, but I can be if the owner wishes. If he wants the plates removed, cleaned, caliper painted behind the plates, and the old plates reinstalled add $60 to each caliper. New guide plates - add the cost of the plate.
I do have a few of these caliper rebuild kits in stock at $49.50 each. I have four of the 44mm rebuild kits and three of the 36mm rebuild kits in stock. Note that price is for what you see here: 1 piston with seal rebuild kit from Brembo.
You can see how, if you need 4 new pistons, a caliper rebuild can get pretty expensive pretty quickly.
Last edited by Carl Fausett; 01-10-2019 at 11:40 AM.
01-08-2019, 09:24 PM
