I am in the process of dissambling and cleaning my calipers in a car recently purchased. It had been sitting for many years and I had noticed some break fluid on one rear wheel. After disassembly, I found that all the seals and parts looked brand new and the calipers had been sleeved.There was what appeared to be grease on the pistons and seals and a fine gritty sandlike substance in the grease and on the pistons. I intend to clean them up and reinstall . My questions are - I was told that the sand is often left over from the blasting/resleeving process if the calipers are not thoroughly cleaned. Is this true? What kind of grease or lubricant , if any should I put on the parts/seals when I reinstall them? Is it possible that the function of the grease is to trap fine particles so they don/t score the piston/sleeve?
-
-
Re: 1966 brake calipers
Howard------
It's possible that th material you found in the calipers is "left-over" from the caliper machining process. There are some very low quality rebuilds out there in the "aftermarket". In fact, some of these "bargain basement" rebuilds use decorative stainless for the sleeves instead of high quality, 304 or 316 stainless. All of the major Corvette rebuilders use high quality sleeves and have their quality control to the point where no machining/cleaning debris is going to persist in the calipers. However, the major Corvette suppliers are NOT the only ones that re-manufacture these calipers. Clean your caliper halves FULLY with denatured alcohol or SPECIALLY FORMULATED AND LABELLED brake cleaner solvent. Don't use ANYTHING else.
While the seals and parts may APPEAR brand new, that does not mean that they are ok for continued use. The seals and other parts often appear "like new" even after they are "long gone". So, you can't judge by casual inspection.
NEVER, EVER re-use the piston seals. They MUST be replaced at every disassembly. Theoretically, you could re-use the piston BOOTS. However, I would not. The interference fit of the steel shell of the boot in the caliper half casting groove is lost after disassembly. The boots might fit "ok" on re-installation, but I wouldn't accept that as meaning that it's the way it ought to be.
Examine the pistons carefully. Pay particular attention to the sealing ring surface. This is the part of the pistons which forms its greatest diameter. You will note that the pistons are anodized ("gold"). If ANY of the gold anodize on the edge of the piston sealing ring is wron away, the piston is not suitable for re-use. At least, it's not suitable for re-use if you want the brake job to last for a good while. You may need to use a magnifying glass to inspect the piston area that I'm referring to.
As far as assembly lube goes, you can use brake fluid but you must use the same type of fluid that you are going to use in the system. Glycol fluid if you are going to use conventional DOT-3 or DOT-4 fluid and silicone fluid if you are going to use DOT-5 silicone fluid. You can also obtain specially formulated brake assembly lubes but you must use a type which is compatible with the brake fluid you plan to use. Most folks just use brake fluid.
When assembling the pistons into the caliper halves, you MUST ensure that the lip seal is not damaged, even slightly, when the pistons are inserted into the bores. Special ring compressor tools are available for this and these are the best way to install the pistons.
By the way, your 1966 originally used 1st design calipers with pyroceram insulators on the piston faces and piston guides on the rear of the pistons. I take it that yours have either been converted to 2nd design or exchange 2nd design calipers have been previously installed on the car. What are the first 3 digits of the casting number found on EACH of the caliper HALVES (there are EIGHT caliper halves per car)?In Appreciation of John Hinckley -
Re: 1966 brake calipers
You might consider an O-ring conversion.....
...HNComment
-
Re: 1966 brake calipers
I once had some brake calipers sleeved by an operation in South Florida called "Florida Caliper" and they actually inserted the stainless sleeve and then sandblasted the sleeve. Needless to say they didnt work so well and I had to replace the calipers.
FL Caliper also stole another set of calipers that I sent back because they didn't fix em right either. I hope you don't have any of their work.
BrandonComment
Comment