65-82 caliper question....

[Greg L.]

I'm trying to figure out what the best plan of attack is for the calipers on my 69. The bores are all pitted and I knew that before hand because I put kits in them 18 years ago and they were pitted then. Anyways I'm pretty sure that they are original but the pads with the date codes are too badly rusted to make out any dates so I can't prove they are original. If I can't prove they are original then I'm not too keen on paying to have them re-sleeved so I was thinking of getting an exchange or outright set that is allready sleeved. My main concern though is that I end up with "original" and correct calipers. My casting numbers are 5473795/5473796 for the front and 5473806/5473807 for the rear. Do these appear to be correct and what years were these castings used on? Are there different variations of calipers with these same casting numbers or would I be safe to just make sure that the replacement calipers have these casting numbers? As always any advice on this is appreciated.

[Joe L.]

Re: 65-82 caliper question....

greg-----

These caliper castings are not original to the car. These castings were used in PRODUCTION from about 1973. The original calipers used for 1969 all had casting numbers that began with "545".

[Greg L.]

Re: 65-82 caliper question....

Thanks Joe, I'm actually quite suprised that they are all non original to the car seeing as the bores were quite pitted 18 or so years ago when I first had them apart...I just assumed they were original. Too bad that whoever replaced them didn't go with the sleeved type instead of just "good used".

Would you happen to know if there are any noticeable differences in the"545" and the "547" castings as well as the current Delco Moraine casting or is it pretty much just the casting numbers that are different? Thanks again Joe.

[Joe L.]

Re: 65-82 caliper question....

greg-----

I would say that at sometime in the car's life, the original calipers were replaced with GM SERVICE caliper halves. By that time, the "547" caliper halves were being sold as the SERVICE caliper halves for all 65+ applications. This occurred in the mid-1970's, so the replacement likley occured after that time.

It may be that when the calipers were replaced, stainless steel sleeved calipers were not "invented yet" or, at least, were not widely known. If the job was done at a Chevrolet dealership, they would have replaced the caliper halves, as required, with new GM caliper halves. In this case, it looks like all the caliper halves needed to be replaced, which is just about what I would expect. Replacing caliper halves at rebuild time was once the only way to deal with the always VERY common caliper bore corrosion problem on 65+ Corvettes until stainless steel calipers were invented and became generally known in the brake business. However, the replacement calipers quickly corroded just like the original calipers. So, by 18 years ago when you got into them, you found them badly deteriorated.

I can tell you one thing: the "547" caliper castings were NEVER originally installed on a 1969 Corvette. I am 100% certain of that. So, while I can't say, for sure, how they got on the car, I know they didn't get on the car at St. Louis.

The "546" and "545" caliper castings are made from ductile or malleable iron; the "547" are cast from gray iron. So, the surface finish is a bit different. The earlier castings are usually noticeably smoother than the "547". Also, the earlier castings have a deeper well between the piston bores (on the inside, so it's not visible with the calipers installed on the car) than the "547" which have a much shallower well (more material was needed in this area to strengthen the castings since gray iron was used).