gramercyjam Posted June 18, 2004 Share Posted June 18, 2004 Recent thread on classiczcars.com about the reaction disk. I just cut up a booster and it looks like a little nickle sized rubber disk about 1/8" thick. My MC is bolted directly to the firewall, no booster anymore ... Take the booster off and shake it around until the disk falls back into place .... Quote Link to comment Share on other sites More sharing options...
jgkurz Posted June 18, 2004 Author Share Posted June 18, 2004 gramercyjam, Thanks for the post. jmortenson also suggested the disc as as a potential problem. The link at classiczcars was extremely helpful. The person who started the thread seems to be having the exact problem as I am. Unfortunatley, it looks like I will have to somehow get the "reaction disk" back into place. I guess I'll try this last "Hail Mary" to keep the 15/16 MC. http://www.classiczcars.com/forums/showthread.php?threadid=12572&perpage=15&pagenumber=1 I'll keep you all posted with my progress. Quote Link to comment Share on other sites More sharing options...
jgkurz Posted June 19, 2004 Author Share Posted June 19, 2004 I can't believe it, my brakes are finally fixed. The problem was the "reaction disc". I pulled my booster last night and yup, no disc. I finally got it to drop out then I glued it back into place. I put it all together this morning and the brakes are better than ever now!!! The 15/16 MC does require a bit more effort, but WOW do the brakes work well. I'm using KVR pads all the way around and am happy so far. The car stops straight and is very predictable. The adjusting rod behind the booster did not need to be changed. I left it the same length as with the 7/8 MC. What's puzzles me is why the reaction disc made such a difference. Earlier in my troubleshooting I adjusted the rod out far enough to compensate for the missing disc (not know it was missing) and still my brake were poor. Oh well, I'm done trying to figure out Z car brakes for a while. I think I'll go for a drive...... The only thing left to do is to get my Wilwood proportioning valve tuned properly. I can't thank everyone enough for their support and advice. Regards, Quote Link to comment Share on other sites More sharing options...
srgunz Posted June 19, 2004 Share Posted June 19, 2004 John, When you take off the clip and washer onfront of booster, pull rod all the way out. Take a flashlight and look in bottom of cannister. You should see the black disc there. We just used a long needlenose pliers to retrieve mine as I recall. A dab of brake caliper grease works good to keep disc stuck back onto rod until it is seated back in place. Having done this once, I maybe could do the whole operation with booster on car. I know it is a pain to remove and reinstall. Quote Link to comment Share on other sites More sharing options...
jgkurz Posted June 20, 2004 Author Share Posted June 20, 2004 Hi Steve (srgunz), I think our posts crossed in cyberspace. I ended up taking the booster out to fix the reaction disc. The brakes work great now! Take a look at my post above yours. Thanks for your suggestion. Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted June 21, 2004 Share Posted June 21, 2004 I can't believe it, my brakes are finally fixed. The problem was the "reaction disc". Very cool!! Glad to hear you fixed it. Sorry you had to go through it but I know I learned something from it. To be honest I had never even heard of a reaction disk!! Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 21, 2004 Share Posted June 21, 2004 Speaking of reaction "disks" or "discs" does anyone actually know when either of those is appropriate? It's disc brakes, buy flying disk. That's about as far as I can take it. Congrats on fixing it though. Nice to end the frustration... Quote Link to comment Share on other sites More sharing options...
TOMAHAWKZ Posted July 23, 2004 Share Posted July 23, 2004 TOMAHAWKZ - So I could just replace the rear drum 10 lb. spring with a front disk 2 lb spring and install disk brakes on the rear, right? That way I'm not having to change out the entire MC for one that pushes about 12% more oil?[/quoteNOT REALLY AND HERES WHY. REPLACING THE SPRING WOULD SOLVE THE PROBLEM OF DRAGING THE REAR DISKS BUT THE FLUID VOLUME REQUIRED FOR DISK BRAKES IS ALOT MORE THEN WHAT IS IN DRUM BRAKE CYLINDERS. I WOULD BE WILLING TO GUESS THAT YOU WOULD NOT BE ABLE TO DISPLACE ENOUGH FLUID WITH A DRUM TYPE M/C AND THUS NOT BUILD ENOUGH PRESSURE TO FULLY APPLY THE REAR DISKS..IF YOU LOOK AT A DISK/DRUM M/C YOU WILL NOTICE THE RESERVOIRS ARE USUALLY DIFFERENT SIZES, I BELIEVE THE AMOUNT OF DISPLACEMENT WITHIN THE M/C IS ALSO DIFFERENT FROM FRONT DISK TO REAR DRUM. NOW WITH EVERYTHING I JUST SAID THERE JUST MAY BE ENOUGH DISPLACMENT I GUESS YOU COULD JUST TRY AND PUT PRESSURE GUAGES ON THE CALIPERS AND SEE IF THEY BUILD UP THE PROPER AMOUNT OF PRESSURE TO APPLY THE BRAKES PROPERLY!! WOULD SAVE THE COST OF A NEW M/C AND WE COULD ALL BENIFIT FROM THIS EXTRA PIECE KNOWLEDGE... Quote Link to comment Share on other sites More sharing options...
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