Guest tom sixbey Posted August 20, 2003 Share Posted August 20, 2003 OK. Never again will i rebuild stock brake calipers - its a waste of F#@%ing time. It would appear that my calipers warped while baking in the oven for the VHT coating i used on them (like i had feared beforehand!), and now the pistons will not fit back into the bores. On top of that the new quad seals didnt fit correctly into the grooves. DAMMIT - i had everything PERFECT!! - i spent a week carefully cleaning and recondition the parts to perfection and about 60 dollars on the rebuild kits and coatings only for them to be reduced to cores.. What a let down. Now i gotta take them to AIP tomorrow to exchange them on some new ones (which will cost me about 400 freaking dollars!)... Why do mundane tasks ALWAYS turn into impossibly rediculous wastes of time and money?!? Quote Link to comment Share on other sites More sharing options...
Tim240z Posted August 21, 2003 Share Posted August 21, 2003 Tom, that seems quite incredible! Were they working A-OK before you stripped them? Maybe you can try the other paint suggested in your other post next time, stuff that doesn't require baking? Are these stock 240 calipers? I have a set that came off my V8 project. They have been sitting for a couple of years, but they are yours if you want. Tim Quote Link to comment Share on other sites More sharing options...
Guest tom sixbey Posted August 21, 2003 Share Posted August 21, 2003 Hey Tim, they were the stock calipers on my '79 280zx, and they were working great before i took them off the car. It was supposed to be nothing more than a simple rebuild (new seals, cleaning and rehoning the pistons) - nothing i havent done a million times, except this time i thought i'd coat them for protection (being that they're cast iron). The baking screwed them up - i did everything else correctly.. I just didnt think that 550 degrees would screw up a caliper. It only screwed up one caliper - the pistons will fit back into the others, but the aftermarket (Beck Arnley) quad seals are WAY too loose in the calipers, so i'm just going to throw them away. I'm too pissed off now to give them any more chances. Thanks for offering me those other calipers - i really appreciate it, but i'm gonna go ahead and get a fresh set and forget about all of this... Quote Link to comment Share on other sites More sharing options...
Tim240z Posted August 21, 2003 Share Posted August 21, 2003 Tom, Did you put them in a cold oven, then turn it on, or did you preheat the oven? Tim Quote Link to comment Share on other sites More sharing options...
Guest tom sixbey Posted August 21, 2003 Share Posted August 21, 2003 i put them in a cold oven and let them heat up slowly with the oven as it pre-heated... i heat cycled them very gently - letting them cool for 30 minutes between each increase in temperature.. - starting at 250, then 400, them 550. It just doesnt make any sense. - they get a lot hotter than than on the car dont they? When i put that piston in, it went in normally and the hung all of a sudden. I was only putting it by hand - and it went in at least 1/2 way, so i know it went in straight. when i tried to pull it back out by hand it wouldnt budge. i finally got it to move some, but when it cam out, the piston was scratched to hell - which doesnt make sense because there were no rough edges anywhere, and the bore was lean enough to eat off of. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted August 21, 2003 Share Posted August 21, 2003 You definitely did things right! I can only assume that that caliper had 'issues' prior to the bake. Tim Quote Link to comment Share on other sites More sharing options...
Guest tom sixbey Posted August 21, 2003 Share Posted August 21, 2003 i guess so.. but its still frustrating to put so much effort into something and get screwed on a technicality, but i guess thats the nature of auto restoration... Quote Link to comment Share on other sites More sharing options...
blueovalz Posted August 21, 2003 Share Posted August 21, 2003 These little NAPA brake hones may save the day here. I've used them before and they will work. They come in sizes from about 1" bores on up to about a 3" bore. It will probably be the cheapest part you've bought for the brakes so far. Quote Link to comment Share on other sites More sharing options...
j260z Posted August 21, 2003 Share Posted August 21, 2003 did you separate the two halves of the caliper? i did and then read in my haynes manual that you are not supposed to!! to me if there are bolts on it i assume that it can be taken apart and put together again!! this may be one of the reasons why. in order to get my back together again i had to talk to one of the mechanics at nissan and he had to take out one of his books on deciphering the bolt grading stamps in order to get me the torque settings. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted August 21, 2003 Share Posted August 21, 2003 Tom is using the ZX calipers which are one piece castings. Quote Link to comment Share on other sites More sharing options...
johnc Posted August 21, 2003 Share Posted August 21, 2003 Brake calipers normally go through heat cycles while bolted to the car. 550F is a pretty high caliper temperature and is something I've seen only after a hard session on the track. You'll see temps over 1,000F at the rotor and the pad but temps drop quickly once you get into the caliper itself. That 550F caliper temp would boil most brake fluids (except Motul, Castrol SRF, etc.) Quote Link to comment Share on other sites More sharing options...
Guest tom sixbey Posted August 21, 2003 Share Posted August 21, 2003 thanks for the responses guys - besides the piston sticking in the caliper, the quad seal grooves are chipped up from rust, and the new quad seals didnt want to seat properly - i could tell i was in trouble the minute i put them in - WAAAAYY too much play in the groove... I was hoping that they would "just work" , but apparently that was not on the agenda... Quote Link to comment Share on other sites More sharing options...
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