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  #1  
Old May 2nd, 2007, 06:58 PM
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Default Hey, Lets talk BRAKES some more!!!!

Okey Dokey, Really dumb qwerstion 2031. Can I take the '72 Corvette M/C, put a booster from a FSJ behind it, lengthen the rod to accomodate the plunging inside and have power brakes? Yes, No, Maybe????
If not, what would I have to do to get power brakes? Remember now, everything I know about brakes I could fit into a thimble.hahaha
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Old May 2nd, 2007, 08:12 PM
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Here's an old post from Barrman. It doesn't touch on the power brake question, but you'll still probably need to get a few more thimbles to put this added info into anyway:

(posted 3/10/05) Many people want to get rid of the stock single line master cylinder. Either for better braking or to replace a worn out stock one. Many have done this already. This post is not about arguing what might fit or power or non power. This is a swap that I have done to my truck using the following parts. The part numbers are NAPA and the prices are what I paid for them last week.

1976 Corvette non power disc/disc master cylinder: #10-1371 $23.99
30" 3/16" brake line: #813-1205 $2.49
3/16" line plug: #131 x 3 $.29
3/16" line butt connector splice: #302 X 2 $1.99

I also got a reducer to go from the new master cylinder to the 1/4" stock line at the master cylinder, and a reducer to go from the new master cylinder to the new 3/16" line. I wasn't billed for them and do not see any part numbers on the parts. Use your new master cylinder and the line you have to buy to figure out the right ones.

The swap involved pulling the stock master cylinder off. Bolting the Corvette one on using the stock mount and pedal push rod. (I think adding 1/2 to 1 inch to the stock rod would make the pedal have instant pressure from its rest height. Instead of the 2-3 inch travel I get now. I will add power brakes later and see no need to mess with it twice.) I used the reducer and connected the stock brake line to the port closest to the firewall on the new master cylinder.

I then disconnected the line going to the rear brakes from the distribution block that includes the brake light pressure switch. I put the plug in the block. Put the splice on the line and connect the new 30" line to it. Slightly bend it so it goes toward the master cylinder. I now had a new line sticking about 10 inches above the master cylinder. I put a loop in it the diameter of my fist and it came out right at the master cylinder. I connected it and the reducer to the master cylinder. That is it.

I did pull the lines off of the master to "bench bleed" it on the truck using the pedal. I just hooked the lines back up and had firm brakes right away. I vacuum bled the right rear wheel cylinder to get the air the 30" line contained out of the system. I can now here the brake shoe springs working when I hit the brakes with the engine off. Not so before.

The 1976 Corvette had the option of a non power brake system with disc front and rear. That means the master cylinder had to push a lot of fluid to stop the car. They have the biggest pistons of the same size front and rear without any proportioning valve that can be found nationwide. That makes them a perfect swap into our drum front and rear trucks. Spicergear figured this out years ago and the rest of us are just using his research for our benifit. Thanks Tom.
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Old May 3rd, 2007, 08:47 AM
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Tracy, the FSJ master bolts directly to the firewall. A unit from a 70 or so 3/4 ton is what I asked for. I just wanted a vehicle that had four drums to get the part from so I explained that to the counter guy. You could do the same with a power brake set up. (Mine was non power) that should be available as a complete unit pushrod and all. The vette MC is a cool mod but if somethings available that requires NO fabbing up at all, I say use it. Also, I think the part was less than 30 bucks for the non power MC, brake lines, and fittings.
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Old May 3rd, 2007, 10:06 AM
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I was going to start a thread kind of about this, but it fits good here.

I have had the above mentioned Corvette MC in the truck for more than two years now. I will have to look, but I think 5K miles or so is how far the truck and I have gone in that time. A lot of that milage was pulling a trailer. I even flat towed a M35 with the M715. The stock drums work great. High pedal effort is required though.

Remember, one of the criteria used to select the '76 Corvette MC was the biggest bore size available. Bigger bore means more resistance to your foot as you push the pedal. I never messed with my push rod length because I have planned all along to add a Hydroboost set up. Well, just Sunday night I got a Hydrobooster (Thanks Chris). I haven't installed it yet, but when I do I will get rid of all slack in the linkage so when I think about moving my right big toe, the brakes will be engaged. That is in the future.

Right now I have about 2" of travel before the brakes get any fluid moved. Lots of hard pushing is required to stop when it does start moving. I drove another members truck Tuesday that had the smaller Wagner FSJ master cylinder on it. The rod was slack free. I thought the truck had power brakes it stopped so easy until the owner looked at me like I was drunk when I mentioned it.

The point is this. The Corvette mc in my opinion is the most heavy duty, more fluid pushing one you can get for less than $100 at just about any auto parts store in the country. I had less than $40 invested in the entire swap and experienced no problems. But, the pedal effort is high.

A smaller FSJ type mc will probably work just as good and less pedal effort. Once you install one, you might find a booster isn't really needed.

Just my thoughts.
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  #5  
Old May 3rd, 2007, 04:02 PM
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Outstanding responses, thank you all very much. I've printed all this and will use it for reference.
I just got my new brake lines from Classic today and my M/C will arrive tomorrow. This weekend will be Brakes to the third power!!!!
If I get stuck I may have a new batch of dumb questions....
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Old May 3rd, 2007, 04:24 PM
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Well, I put in the FSJ M/C, and the truck doesn't stop any better than with the old M/C. As members here told me it doesn't mean it will stop better, just that the duel M/C is safer. I think a booster is the way to go. .02
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Old May 3rd, 2007, 05:25 PM
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I've had my Corvette MC in for about a year I guess. I also have stainless steel lines AND braided stainless steel flex lines. I got all the lines from Classic Tube.

Now the odd part. I did NOT modify the stock push rod and I experiance NO pedal delay. And while it is not power brakes ... I don't find the pedal effort excessive for manual. I've read a number of these post about pedal effort and push rod delay w/ the Corvette MC and find my situation at odds. I routinely drive my truck 55-60MPH and can friggin lock them up if I'm not to EASY on the pedal.

Perhaps the difference is in the adjustment of the pads or wear of same, coupled with ZERO brake line swell for stainless braided lines. I'm pretty anal about brake pad adjustment .. when I hit the brakes they grab!!!
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Old May 3rd, 2007, 10:28 PM
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While doing MY searching, <g>, I noticed that NAPA shows the FSJ master cylinder (disc/drum version) as having TWO different bore sizes.

Also, as I noted on my website (www.bigscaryjeep.com , go to M715 Disc Brakes) the DUAL diaphragm booster has a longer pushrod travel than the single booster. When I swapped to the dual diaphragm booster, everything worked great.
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Old May 4th, 2007, 04:39 AM
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i still have the single hose MC but somewhere along the line this vacuum booster was added. it makes some serious stoppage power
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Old May 4th, 2007, 04:55 AM
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I was going to put a brake booster on my truck but it hits the air cleaner. I know one thing, there is NO WAY with the FSJ M/C, D/D, I'm going to lock up the brakes! And it's just as hard to push as the single M/C. I have a good pedal, it's just hard to stop.
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