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More disc brake conversion ?'s

3K views 26 replies 9 participants last post by  1973_Nova_SS 
#1 ·
I got everything installed, bench bled the MC and bled the system. Took forever to get fluid to the rear...After I bled the front...the driver's side pads seem real tight. (I had to take one of the shims off the back of the pad on that side originaly to get the caliper on the rotor). That allowed the driver's side to turn more freely than the passenger side after the shim was removed, but now after bleeding the system, it is tight again...can not turn the rotor by hand. I can turn it if I put the wheel on, but there is a lot of resistance. The passenger side still turns freely. Is this normal? Do I just need to drive it a bit to break the pads in? Just don't know if there is something I should check while the wheels are still off and it is up on the jack stands....
 
#3 · (Edited)
Yeah...I hate bleeding brakes. The speed bleeders helped. I ended up using my vacuum guage set up to do the rear. It took forever to get fluid back there! I used it on the front as well, and when I was doing the passenger side I almost ran the resevior out of fluid. Just as it was about to go dry I was able to dump more fluid in...close one. I am getting no air bubbles from the front or the rear...so hopefully I won't have to bench bleed the MC again. I still need to hook up the vacuum line to the booster and see how the pedal acts with the car running. Right now the pedal feels alot fuller than it did with the drum brake set up...I would say the pedal depresses about 1/4 to 1/2 way to the floor.
 
#16 ·
Disc brakes drag, they will have some drag, I would be concerned about the one that spins freely, never had disc brakes spin freely. On my four wheel disc car I can turn the hubs with two hands. Say if I grab two opposing wheel studs with my thumbs and other fingers I can rotate the hub around but its not like I can grab one wheel stud with one hand and spin it around. Just trying to give an idea of what kind of drag Im talking about.

I say take it for a drive and bed the pads. If you know everything is bolted up tight, dont forget the RED locktite then you arent gonna loose brakes, its safe. Drive it then check the rotation of the wheels when up on the jack stands, both wheels should have equal drag on them.

And whats more concerning is the pedal going half way to the floor. I dont know if this is common for un-assisted brakes. I have about an inch of pedal movement then its TIGHT. On my boosted system that is.. And when the engine is on I get about another inch of travel and the brakes are locked up and the pedal wont move any further. JR
 
#17 · (Edited)
I may have misspoke...it wasn't spining "freely", I was able to turn it pretty much the way you said, with two hands after. Now both sides are turning with the same amount of resistance.

It is power brakes...I found out why the pedal is going in so far...there was still alot of air in the lines after I tried bleeding again tonight. But, I stripped out the threads of my rear wheel cylinder on the driver's side...so I will get to do some more work tomorrow:mad:
 
#18 ·
I believe you are suppose to bleed the rears then the front. I remember when bleeding the rears there was some gunk that got stuck in it after 20+ years of sitting in one space for a while.

BTW do you have any kinks in the line?
 
#19 ·
I don't have any kinks in the lines that I can see...I did bleed the rear first before moving to the front, but I was doing it by myself and thought I had all the air out, but there was still quite a bit when I went back and tried re-bleeding the back again....could that have messed anything up? Done something to the prop valve or MC?
 
#20 ·
No, that shouldn't have had anything to do with your bleeding problems.

I said it once, and I'll say it again... BLEEDING BRAKES SUCKS! :mad:

Your problems are more than likely from your speed bleeders. Most of the time they do not work as advertised and suck air back into the system. The only brake bleeding methods I have been sucessful with are vacuum bleeding (Mightyvac, or venturi bleeders) or the tried and true two man method. On brand new systems (new MC or new lines) the two man bleeding method is the way to go.
 
#21 · (Edited)
In all of your bleeding attempts, have you made sure you havn't tripped the proportioning valve? Once tripped, you are done until you reset it. You can check it by putting an ohmmeter on the switch in the proportioning valve. If it is showing zero or near zero resistance, you've tripped it.

If all else fails, get a power bleeder. It costs about $100 with the adapter, but you will be done in 15 minutes.

Another thing I ran in to on my CPP brake kit was the rear calipers where poorly machined. The hoses wouldn't seal until I cleaned up the calipers with a dremel.
 
#22 ·
I haven't checked it, but I am guessing it is tripped if I had that much air in the rear lines...how do I reset it?

I ran into another issue late Friday night...stripped the threads out on the rear wheel cylinder with one of the speed bleeders. So I decided to take a break from the car for a few days...just getting too frustrated and loosing patience too quickly.
 
#23 ·
I bought an old medical vacuum unit for 20 bucks. It looks really old, saw the same one on a MASH show once. Basically a motor, vane pump and two glass jars. One to recieve and one on the exhaust.

I just make sure my fluid reservoir is full, hook up the vacuum line and crack the bleeder. I let it suck while I go to the front and fill the reservoir as needed. Ill burn though two large containers of fluid, (its cheap) for the entire system. Pedal is rock hard engine off. Engine on I have about an inch and a half of pedal and the brakes are locked.

In an attempt to solve a screw up of mine (had the front calipers swapped wrong side) I made a pressure bleeder that used a spare MC cap and I applied about 8 psi of air to it. Strap clamps helped to hold the cap on. Now with the MC pressurized I just go to the wheel I want to bleed and crack the bleeder, major pressure blowing everything out, gunk, air and fluid. Its a pain though cause you have to de-pressurize and remove the cap to re-fill the reservoir. I like my vacuum pump the best. JR
 
#26 ·
Bench bleeding the master cylinder again and replacing the front bleeder screws(leaked around the threads) with speed bleeders solved my problems. I just need a pedal pusher for the rears.
 
#27 ·
this is my first posy but i go to a tech school and am in the auto program. When your bleeding your brakes start from the furthest point of the MC, so mine was right rear, left rear rigth front left front. You can vac bleed or pump and dump them if the pedal is spoungy. thats what were tougth to do in lab but if you can get some one to help it makes a difference. I had to do this a few times on my nova becasue both of my rear wheel cylinders were shot.
 
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