More brake issues

[car62]

so,finally built my own escort caliper brackets for use on mustang 7.5 rearend,got everything all hooked up,pump the brakes to bleed them and everything is good,10 seconds later when you press the brake pedal it goes straight to the floor, changed 3 master cylinders,2 were brand new from 2 different parts stores,changed the distribution block or proportioning valve(whatever its called)still same results. Tried hand bleeding,gravity bleeding,vacuum pump bleeding,and an air powered gravity bleeder,all with the same results. Then tried bleeding with the calipers off and hanging up high,then down low,even kept the bleeder valves the highest point for the air to escape...i know many have converted to this setup,so i ask,WHAT IS THE TRICK????

[mtbailey]

so,finally built my own escort caliper brackets for use on mustang 7.5 rearend,got everything all hooked up,pump the brakes to bleed them and everything is good,10 seconds later when you press the brake pedal it goes straight to the floor, changed 3 master cylinders,2 were brand new from 2 different parts stores,changed the distribution block or proportioning valve(whatever its called)still same results. Tried hand bleeding,gravity bleeding,vacuum pump bleeding,and an air powered gravity bleeder,all with the same results. Then tried bleeding with the calipers off and hanging up high,then down low,even kept the bleeder valves the highest point for the air to escape...i know many have converted to this setup,so i ask,WHAT IS THE TRICK????

Do you have a residual pressure valve for the rear brake circuit? going from drum to disc you would need to add one I think. It holds a few pounds in the line and only allows the pads to release the clamping force but keeps the pads in slight contact. also is your master cylinder good for front and rear disc brakes? or is it the original set up for disc/drum? One more thing, if there was air in the master cylinder it is very important to bench bleed it before connecting up the rest of the circuit. a search of the web will give you the procedure. Hope that helps.

[car62]

i have bench bled both new masters,the other master was a known working master from another car(also the 1st master we put on),there is no residual valve that i know of,unless it is built in to the stock distribution block/proportion valve,and finally,the master is for a front disc/rear drum setup,however fluid capacity is not an issue,the issue is getting the rear calipers to fill up with more fluid and less air,i have a feeling the problem is the factory distribution block/proportion valve is not allowing enough fluid to travel to the rear calipers since it was designed for small wheel cylinders.

I am considering eliminating the block and running directly off the master and using a wilwood proportioning valve on the rear brakes(driver adjustable),HOWEVER, i am not sure if 1 master cylinder will work both the front and rear together(stock type factory master)...so i am kind of stuck,i cant exactly go with aftermarket pedal and masters(rules).

[mtbailey]

Hear is what you need http://www.summitracing.com/parts/wi...3278/overview/ I have had the same issue with rear disc brake conversions. Also a good Idea you have to get rid of the block and ad a driver controlled proportioning valve to be able to tune your brakes. I repeat though that you need the residual pressure valve. Also you will need one on the front brakes as well after you remove the block. Good luck and please post the results.

[car62]

do i use the 2psi for both front and rear?

[crcltrakr]

Just gut the block and add a valve alongside the seat, the M/C is high enough to keep a minimal back pressure in the line.

[car62]

ok,so i have talked to 3 places including wilwood that said because my master cylinder is considerably higher than the calipers,that i do not need the residual valves for a disc brake application...so with that ruled out...when making brake lines do you want to use a single flare tool, or double flare tool?

[crcltrakr]

Always double flare for brake lines!