new member needs brake help

[keepin the 75 alive]

I have heard that the master cylinder itself has a chck valve right where the brake lines tie in. this is so the fluid dosent escape and it holds a certain amount of pressure on the lines so the ( drum brake pads ) dont move to far away from the drum itself. Supposed to get better feel out of the brakes. Now, Ive also heard that when a disc conversion is done to the front , that that valve needs to be pulled out of the MC. so that the fluid pressure is released from the front calipers. Is this so ???? Man I dont know, as I just did my front disc conversion and am trying to find out if this is so or not. ANYONE that knows please help thanks.

Also Im new to posting so I realized that this thread is from 09, sorry bout that. Also realized that it had two pages and that the problem was solved, again my appologies. Im still wondering about the pressure valve though if anyone could pm me id be grateful.

 

[jamie]

i am having the exact same problem. did a yj booster with the original master and the front brakes are doing the whole lock up thing. im so frustrated

 

[keepin the 75 alive]

I found out the answer and here is the dope, You have to remove the risidual pressure valve from the master cylinder. Only the one for the front brakes. Not the back if they are still drum. As i interpreted the instructions. find out which chamber in your M/C feeds the front brake. Then unhook the front brake line from the M/C and insert a screw that can grip the little valve in there and pull it out.

Then you need the 2 lb risidual pressure valve replaced inline .I got mine at jegs shipped it was 22 bucks they have the jegs model a few bucks cheaper I used the wilwood one.

wilwood PN 260-1874 just type in the numbers on the jegs site and it will magically pop up.

So this is the reason as I got it. Drum brakes need to have the shoes retract from the drum but not alot. hence the 10 lb of back pressure. with a disc brake that is so much it will not let the pistons retract properly. But without any back pressure at all the pedal gets that douple pump spongieness that feels much like the old pintos gremlins and vegas.

not cool. so the fix. inline 2lb valve.

this is not associated with nor does it replace the proportioning valve. here after referred to as the PV cause its hard for me to spell a word like that.

Anyway hope this helps. good luck. remember , my front brakes are disc. not drum.

 

[jamie]

i went and bought a rebuilt master cylinder for a jeep with disk fronts, as it was the same price as the summit piece when you factor in shipping. plus i think i had a small leak from the back of the master after i took it off. ill let you know how it goes

 

[keepin the 75 alive]

wow, man where are you finding a mastercylinder for 22 bucks ? mine cost 100 bucks, and if I had my head screwed on straight I would have done the same.

 

[jamie]

i got my master cylinder from cap. it is for an 87 yj. the fittings are on the wrong side, but they are the same thread. i will let you know how it turns out