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Discussion Starter #1
I converted my a 67 Camaro to 4 wheel 12" disk brakes from a 98 LS1 Camaro (dual pistons in front), I Used stock lines with metric adapters into the caliper lines; a 79 TA 4-wheel disk master cylinder and a Jegs adjustable proportioning/distribution valve. I had the system professionally bled so there is no air. I have the matched short Master Cyl plunger and short Master Cyl puck set up (Power Brakes).. the brakes don't gradually grab, but seem to grab all at once near the bottom of the pedal stroke. Not impressive as they should be. They're very stale. I adjusted the valve to all the way closed and mostly open and don't feel a huge difference moving the car around the driveway. One thought is that the lines from the MC to the Porp Valve are 5/16".. I'm wondering if 3/8" would make a huge difference??

Anyone got any suggestions on trying to figure out why, so I can improve braking to what it should be??
 

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The LS1 brakes need a master cylinder no larger than a 1" bore, like from a 70's era Corvette. What is the bore diameter of the 79 TA?
Are you sure all the air is out of the lines? Was the master cylinder bench bled?
 

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Discussion Starter #4
Yes, system bled with machine and MC bench bled.. TA MC has 1-1/8 bore. I thought bigger was better for volume??
 

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Bigger gives you more volume but smaller gives you more power. The LS1 Camaros had master cylinders with a 1" bore and piston, you need to duplicate that with your car. These guys sell conversion kits using Corvette parts and their M/C has the 1" bore. http://www.touring-classics.com/accessories.htm
Are you running the vacuum assisted brake booster?
 

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Do you know if the Vette MC has the shallow hole for plunger rod or deeper hole?
I just got the 4 wheel disc M/c from Matts, it off a 69 Vette I was told, has the stock 69 PB plunger depth, not sure what you call deep or shallow, it was 1 3/4" deep .

Just did a rear drum to disc conversion.
 

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Discussion Starter #9
The rod hole depth on mine is real shallow. Maybe 3/4" or so. The deep one is 1.750" deep. I do have both rods available, so I can use what I can find. I may try the 1" bore vette M/C since I've been seeing it mentioned and have researched it further. Is the power brake MC 1-1/8 and manual 1"? I've been seeing this mentioned in a couple of articles..

What does the 69 one measure?
 

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The 69 factory power disc/drum used a 1 1/8 bore MC. The 1969 single piston calipers had huge pistons. Even though your LS1 brakes have 2 pistons (fronts) the total area of the two is still less than the area of the single piston 69 caliper. The smaller bore MC is needed to create enough line pressure to operate your smallish piston calipers. With your current setup you should have very little pedal travel, and not enough line pressure to operate the brakes effectively. If you have a fair amount of pedal travel I'd suspect air in the system.
 

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Discussion Starter #14
and yes, I have quite a bit of travel in the brakes..maybe since the system is new, there's hidden air in the prop valve or still in the MC
 

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I just re-read your orginal post, you said you have a proportioning valve with 4 wheel discs? I was told that I did not need one with my set up from RightStuff.
So far , I have no issues other than keeping the correct tension on my rear E-brake cable to keep the rear brakes adjusted. Set up if basically a 79-80 TA system.
 

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Discussion Starter #17
We thought of the e-brake thing, but it pertains to pre 98 as I was told. These have the drum ebrakes. I believe there needs to be a way to balance the brakes to 65% front and 35% rear, or what ever it's suppose to be. I have the Jegs or SSBC adjustable prop/dist valve without any factory valve anywhere else.
 

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Discussion Starter #18
Embarrassing lesson learned: Make sure the long rod is in when the MC calls for one. The short rod doesn't work so well in a deep hole MC..Also, the MC was not bled as well as it should have been... After fixing both of these items, I have good brakes now!
 
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