A while ago I had an ingenious idea to get an underfloor booster/master setup in my '53 F100. After installation and a TON of bleeding its been nothing but a headache... The unit is a knock off brand from Ebay, which is my first screw up, and I've ran all new lines; which I have blown out and made sure were debris free. I am using Wilwood residual check valves; 2psi in front and 10psi in rear, and a Wilwood proportioning valve in the rear. it has a '70 Monte Carlo clip in it as well and this is the first time I've had a problem. Issues are as follows: First off, apparently the brake fluid doesn't think it is a good idea to stay in the lines and is overflowing out the cap. could this be a symptom of a cheap m/c? Second, the calipers are not fully releasing and are dragging. I'm not sure if this is relevant but my truck also has air suspension. Some please help me before i put it back on the firewall and forget this whole mess!
I know stock braking systems don't use residual pressure valves with disc bakes, only with drum brakes. Why is there a rpv up front?
I think theres so many post with brake issues guys are tired of responding to them.Tman made a comment a while back about brakes that stuck with me.They need to be fully engineered with compatable componets instead of some thrown together mess that never has a chance to work.
how much are the calipers dragging? to the point where u cant turn the rotor by hand or you can just hear them dragging while the wheel turns?
I put a 70 Monte in my 55 f100......your are going to be extremely pleased with the performance and ride if it was installed properly...i.e. 10 degree anti dive, etc on the upper A arm rod/support, etc. I used the stock 70 monte poportioning valve I am sure...but I had it fire wall mounted with the brake booster... On my 51 ford car with monte clip, I also used the 84 monte proportion valve...no brake problem... both of these had disc front and drum rears. Did you check the rod length between MC and booster....brake pedal should have about 1/4 inch play before engaging. Good luck...
Need to know how everything is connected together.....a proportioning valve shouldn't just be on the rear. It should be plumbed to split the lines between front and rear. The problem with the brake fluid draining back to the master shouldn't happen if all the air is out of the system and it's not sucking air in anywhere. Posted using the Full Custom H.A.M.B. App!
do you have a return spring on the pedal? is the mc pushrod too long, needs a small gap to the mc so it can retract all the way...
Dragging calipers will eventually heat up the fluid, which will expand and push fluid back towards the MC, and if it expands enough, out the cap. With the exception of the dragging calipers and leaking, do the brakes work OK? Soft or firm pedal? When does the fluid leak out, when the car sits for a while or immediately after a drive?
not backwards , more like the disc on on the drums and vice versa, but they do have to be installed for flow otherwise you would hit a hard pedal right off the bat .
1) get rid of the residual valves till you fix the problem. female/female fittings are available. 2) Check the pedal to push rod gap. No gap can cause what you are seeing. 1/8" is what I use. You should be able to feel a little play when wiggling the brake pedal. 3) If that don't fix it, time for a new MC.
So last night I got rid of the residual valves, double checking first that I had the correct valve going in the correct direction, then took off all the front lines and blew them all out. I also checked the pin depth. The brake pedal has always been absolutely terrible and it hasn't stopped anywhere near as good as it did when the master/booster was on the firewall.
Are you pressure bleeding or are you vacuuming it at each wheel? Not a great idea to keep introducing air into the system by blowing out the lines unless you're sure there is crap in them. Bleeding with the master below the calipers can be tough, be sure to either pull the fluid from the wheel or pressure bleed the master. Sounds like everyting else is correct.
I pulled off the lines and blew them out just to make sure that there really wasn't anything in the lines. and I've been pressure bleeding them 'cause I don't have a vacuum bleeder. is it a better idea to vacuum bleed versus pressure bleeding when the master is below the calipers?
and the million dollar question: should I even be running a residual pressure valve up front or is it unnecessary?
So on Friday I replaced the master cylinder and VIOLA! Now I'm fighting an issue of a rock hard pedal that doesn't return. I haven't looked into it since Friday but does anyone have any suggestions?
I'm not exactly sure. When I bought the other one the description was pretty vague. The brand new one is an AC Delco product off a '74 Corvette with power brakes. The only physical difference is that the old one has ports on both sides.
As long as your hookups were correct, then I would look at the booster. Maybe a bad check valve for the booster?
I shall do... I have always wondered why a bad booster/check valve yields a rock hard pedal? Does vacuum sneak past the valve or diaphragm and that's what your fighting?