I just finished converting the 62 to 4 wheel disc brakes. I used a kit from ECI, and ECI's mastercylinder made specifically for the early Vettes. I used silicon brake fluid.

I ran the lines as ECI recommended, without a prop valve (according to ECI, not needed with the MC I ordered).

Front - from the front port of the MC to the frame junction. From the junction, a line was ran to each caliper.

Rear - from the back port of the MC to the the rear frame junction. From the fram junction to the rear housing junction via rubber hose. From the rear housing junction to each rear caliper.

I get a good stream of fluid from each bleeder screw, but have no pedal pressure, until the third pump, but the pedal still goes to the floor.

1. Is it possible to still have air in the lines, even though there is a good stream of brake fluid coming out of each bleeder screw? Shuld the MC cap be on while I'm bleeding the brakes?

Note: The MC was bled on the car instead of bench bled. Should I remove it and bench bleed it?

2. Would I be better off trying to bleed the brakes with a speed bleeder or a vacuum pump? Are there any tricks to using either?

3. The MC and brake pedal rod came as a kit. I think the rod is adjustable. If it needs adjusted, is it more likely too long or too short given the soft pedal to the floor condition?

4. Other things I should look for?

Thanks for taking the time to read. Any suggestions would be appreciated.

Progess pics: http://www.picturetrail.com/gallery/view?p=999&gid=7883567&uid=649897

Bummer!....when you got ready to install did you bench bleed the master cylinder? I have done 2 converions now and w/one I did a bench bleed and the other I did it once installed in the car....the one I bench bled cleared the air from the lines immediately and was fine...the second one where I bled the master through the lines took an extraordinarily long time to clear the air....I think it took me 4 or 5 tries to get it all out....also...did you start bleeding from the point furthest from the master? (ie.....rt rear, lt. rear, rt. front then lt. front)? usually that is the process to eliminate it.....spongy pedal is usually because of air......good luck gettin er done....

surfing greg,

Thanks for the reply. The MC was bled on the car. I started bleeding left rear first, because the rear frame junction and rear housing junction are both on the passenger side... so, I figured the driver side rear had the longest brake line.

I just picked-up some speed bleeders, so I'm going to give it another try. Wes

Wes,

I can't comment on the M/C you're using, but it seems like it's probably just a bleeding/air issue since you get a hard pedal on the third pump. One thing that has always served me well is to gravity bleed - just leave the furthest bleeder open until it starts dribbling, then do the same for the other corners. I have never had to bench bleed anything doing it this way, but you're probably already past this point anyway. I'm sure the speed bleeders will help if there's still some air. Also, I usually bleed with the caps off as long as the wind isn't trying to blow junk under the hood - just make sure the fluid level doesn't drop too low.

Is the silicon stuff the DOT4 or DOT3? I don't think it would matter in this case, just curious.

I've also heard (from grumpy mechanics) that a lot of the 4-wheel disc stuff is hard to get working properly. Best of luck!!

Ryan

Ryan, the fluid I'm using is DOT 5. I just noticed after reading your post that the MC lid said to use DOT3...

Using the speed bleeders on the rear, I've put a pint of fluid through, and the pedal shows no improvement. Having my wife pump the front brakes 3 times and hold, either of the front calipers will shoot a stream of fluid 5 feet high using standard bleeders.

If I were to try to gravity bleed, would I start with the longest line, or the furthest from the MC? The right rear is further, but the left rear has a longer fluid path.

Thanks again. Wes

PS I sent you a PM about your job search

If I were to try to gravity bleed, would I start with the longest line, or the furthest from the MC? The right rear is further, but the left rear has a longer fluid path.

Thanks again. Wes

Wes, it probably doesn't matter which one you start with, but try the longer fluid path first. It probably won't help though since it seems like you've bled the lines just fine. It might be that you have a bad master or some sort of imbalance - do they suggest some type of adjustable prop valve (like a Wilwood piece?) for this application? What if you try switching the lines on the master? I don't know if that's a good idea but you never know. Thanks for the PM - I'm headed out the door, but I'll get back to you on that one later.

Good luck!
Ryan

Check the lining clearence at the rear calipers.
If they are parking brake activated, failure to adjust the pads outward to meet the rotors may result in this problem. Adjust the pistons outward by ratcheting the lever on the back of the calipers.

ECI told me that a prop valve wasn't needed if I wanted to run 4WDB with their master.

I just individually loosened the bleeds and let them drip. Starting at the rear, I got a slow steady drip from each side. I did not see any bubbles come out while I was doing it.

The front calipers dripped much quicker. The pedal stil feels the same. as before, soft and to the floor.

Would there be any benefit to trying a vacuum pump? If it might help, I could buy one and try it. If there's not likely to be any benefit, I won't. BTW, can a pump be used with silicon fluid?

BTW the MC, which is specifically marketed by ECI for the early Vette swaps, hit my hood. If I want to keep the disc brakes, I'll need to notch the hood about 1/4 - 3/8" the length of the MC.... which is less material than I had to remove from ECI's vehicle-specific bolt-on rear caliper brackets.

Additional suggestions or thoughts would be appreciated.

Thanks again,

Wes

Check the lining clearence at the rear calipers.
If they are parking brake activated, failure to adjust the pads outward to meet the rotors may result in this problem. Adjust the pistons outward by ratcheting the lever on the back of the calipers.

Chevry, I wasn't aware of this. I will give it a shot tomorrow. Thank you for the tip.

Im doing the same rear conversion and am having the same problem. I dont think the 1" bore vette master WE are trying just doesnt have enough volume for the large 2.406 piston rear calipers.
Im using the Steeltech brackets on my Nova but our calipers are the same displacement

A 1" bore master sounds small for those rears, assuming you are running larger displacement front calipers.

I installed the 1 1/8 bore master from a 68 vette "POWER BRAKES" and my pedal is just right.