Just put 4 new calipers, pads, brake lines, hoses and master cylinder on a manual brake C-3 this afternoon. You know the kind of job that should take 2 hours but takes 5 plus. Bled the brakes and am getting decent pedal. On road test the car seems like it does not want to stop soon enough (ie you can stand on the brakes and stopping distance is not adequate). The reason for the service was the pedal was bottoming out so rather than just do master cylinder I did the full monty. Any Ideas? Is this just a case of inadequate bleeding? I am certain the calipers were installed correctly. I also was careful not to get brake fluid on the pads. There seems to be no leakage at any of the lines and am getting good pedal as I mentioned.
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Re: C-3 Brake question
Chances are real good you don't have all the air out. I would jack the rear end as high as possible and leave it that way over night. Air will travel to the back. Bleed it the next day. Do the front the same way. It may take a while to get all the air out. There is a lot of info in the archives on the subject. People will also recommend power flushing. If it flushed easily enough, I would not suspect the rubber hoses. Good luck, Terry -
Remember the old saying
if it ain't broke...
All you probably needed was the master cylinder. Of course, many have experienced a low pedal with a '68 with power brakes for some reason that didn't affect brake performance.
Odds are, you don't have all the air out like Terry said. If you have a pressure bleeding system that attaches to the master cylinder and forces fluid through, many claim good luck with those.
I've always had good luck with the slow and true gravity bleeding. Crack a bleeder, and let it flow.
Using the vacuum systems that attach to the bleeder screws can pull air past the piston seals and add more air to the fluid than you started with.Comment
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Re: C-3 Brake question
Charles-----
Brake bleeding on a 65-82 Corvette, and especially early C3 models, can be a real bear. It's one of the jobs that I dread most on a Corvette. However, if you have a solid pedal and no excessive pedal travel at this point, then you may already have a good bleed.
One other thing that can cause the symptoms that you describe is that your pads may not be sufficiently "worn in". It takes a little while for the pads to wear in to the rotors and this is especially true for certain pad compounds.In Appreciation of John HinckleyComment
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semi-metallic pads
Semi-metallic pads have a higher pedal effort. This is usually not noticeable with power brakes, but is obvious with manual brakes. The original C3 brakes were organic type.Comment
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Re: C-3 Brake question
Thanks for the replies. Talk about instant gratification! The only component I haven't replaced at this point is the proportioning valve as this problem is not consistant with that. I am leaning toward air and rebleeding the entire system which I may have rushed. I will try lowering the rear in the next few days and post back. This is also mentioned on a few tech sites. I guess my next question is how important is bleeding order? The grunt work is done now, you know with parts, tools, solvents all over. If you have ever tried to remove frozen 30 year old brake lines with the space provided by corvette engineeering then you know what I mean. You can't rush it and a can of PB Blaster only seemed to help a little. Luckily I didn't have to salvage much of the old lines as the kit supplied fresh ones, just made sure the main hose blocks weren't damaged in the process. The web sites and tech features out there made the job seem alot easier in theory. Mike, I hear you about "if it ain't broke..." When I was road testing it The thought crossed my mind that I could have saved an afternoon if I had just done that. However by doing the work myself I got all new delco moraine o-ring style calipers and hardware for about $150 or so more then my Chevy dealer would have charged me for the MC alone. Of course the all important chance to bond with the Vette came at no additional cost.Comment
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Re: C-3 Brake question
Charles------
I don't know what year C3 you are talking about. However, the only C3s that had a proportioning valve were 1968 with J-56 and all 1978-82. The 68 proportioning valve was adjustable. The 78-82 valve was non-adjustable and was part of the brake fluid distribution block and pressure differential sensing switch. This arrangement is called a combination valve.
All other C3s used a simple brake fluid distribution block and pressure differential sensing switch. The switch detects pressure imbalance by deflection of an inner piston. Usually, these switches give no problems and are VERY unlikely the cause of the problem that you're experiencing.In Appreciation of John HinckleyComment
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