Disk Brake Problems

Shawn

Just Hanging Out
Location
Holly Day
Man, I'm stumped...
The Commando has 4 wheel disk brakes. I just swapped out the old drum/drum master cylinder for a new disk/disk master off of a a 69 vette. Everything was working well.. well I think. When the swap was done I could push the peddle down about 2 inches hardly any travel in the peddle. I was able to lock up the rears going forward and the fronts gonig backwards. Well today, I was comming home down little cottonwood canyon, so I was using the brakes, and shortly after exiting the canyon the brakes started to engage... :ugh: I had to shift from 4th to 3rd, and then from 3rd to 2nd just to keep moving :eek: Well I pushed it all the way home and when I pulled into the garage all four wheels were smokin.. :eek: and the peddle wont even go in at all...

So I take off for awhile and when I return I try them again and they go all the way to the floor..... :ugh: wtf......... :confused:

So I bench bleed the master again, try and bleed the rears and they won't bleed...There is no gravity bleeding, and they wont pressure bleed. I know that the master moves fluid because when I bench bleed it, it moves. I swap the front line to the rear and the rear to the front and I'm able to bleed the rear brakes.

It kind of sound like the master might be bad. God, why did I buy this one from Ebay. It was "new in the box"..

Anyone ever experience this before?
 

Shawn

Just Hanging Out
Location
Holly Day
rckcrlr said:
Do you still have the stock porportioning block/valve/distribution block?
Checkvalve?
As far as I can tell there never was one. The lines go from the master all the way to the calipers with nothing in between.
 

OCNORB

Well-Known Member
Supporting Member
Location
Alpine
Does your set-up have a vacuum booster??

When I did my dad's YJ D60 rear disks it would engage the brakes after driving a little while. I had to adjust the pushrod between the pedal and the cylinder 6-7 times before it was right. (1/2 ton rotors and caddilac calipers)
 

Shawn

Just Hanging Out
Location
Holly Day
OCNORB said:
Does your set-up have a vacuum booster??

When I did my dad's YJ D60 rear disks it would engage the brakes after driving a little while. I had to adjust the pushrod between the pedal and the cylinder 6-7 times before it was right. (1/2 ton rotors and caddilac calipers)
No booster. The rod between the peddle and the master was home made... Think I made it to long?
 

OCNORB

Well-Known Member
Supporting Member
Location
Alpine
Shawn said:
No booster. The rod between the peddle and the master was home made... Think I made it to long?

I'm not sure, but it could be. How hard would it be to make it adjustable?

Is it possible that while coming down the canyon you had pumped the brakes up harder than ever before, and the adustment changed so that the ports in the MC no longer lined up. Was the pedal hard when they started engaging?
 

Shawn

Just Hanging Out
Location
Holly Day
OCNORB said:
I'm not sure, but it could be. How hard would it be to make it adjustable?

Is it possible that while coming down the canyon you had pumped the brakes up harder than ever before, and the adustment changed so that the ports in the MC no longer lined up. Was the pedal hard when they started engaging?
After doing some mass reading on POR it looks like my push rod is to long. I will add some washers in between the fire wall and master until I figure out how much to cut off. Unless,,, I just change it all out for hydo boost ;)
 
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