Lets Talk Residual Valves!

[BFS57]

Hello;
Got my Vicky back from Kens the other day. They did quite a bit of work chasing leaks and straightening some things out. One of which was the brake system seemed to never have enough "pedal" to stop quick if desired.
Everything seemed quite good until I passed the point of no return and that is when I realized that the brakes were dragging just enough to make me notice it. I immediately called Ken to see if he knew anything about this. He seemed to remember that my brake lights were on and wouldn't go out (pressure brake switch). I barely made it home! Ken told me that he thought it might be my residual valves "sticking" I hadn't had any problems before?
I'm thinking that the contact rod inside the booster was over adjusted and needs to be re adjusted. My temp. cure is to make a pair of spacers out of washers and slip them in between the master and booster. The plumbing is quite rigid there and I can't remove the master without taking the brake lines off, something I already paid them to do, just so I can drive it back to them, to fix!
Does any body know anything about "sticking" residual valves or what may be causing this problem other than the booster rod length?
Ken advised me to crack the bleeder on the front caliper to relieve the pressure. I did and the hot fluid went all over the place. Both front and back brakes were hot!!!

Bruce

[kb426]

I've never had one stick. My thought is if it was stuck, it would be like the parking brake that you used to see on forklifts that held pressure until the valve was released. Disc brakes are supposed to be 2 lb. and drums are 10 lb. Is there a chance that there is the wrong one installed? Was the master cylinder overfilled so there was no place for fluid to return?

[GPster]

Is this a disc/drum brake system? Could the lines be reversed on the master cylinder or the brake safety switch block (or whatever it's called) so that the drum brake residual pressure is on the disc side of the system? This is as good as I think or type on Sunday morning. GPster

[wayne petty]

if the booster pushrod length is too long.. it won't let the piston all the way back to the snap ring and will not expose the fill ports that let the pressure out when you take your foot off the brakes..

does the brake pedal return fully.. so there is no application of the booster..
no carpet or rubber floor seal holding it to prevent the free return the last amount..  


if you have residual pressure at the calipers...    pump the pedal some more...     do you have residual pressure at the master cylinder lines when you crack them...   then the master is not releasing the pressure..

i have not seen your car..  but i have used clutch return springs on some brake pedals as the only return is sometimes the master cylinder internal spring.. and thats just not enough to return the pedal to the stop..

i don't live and breath brakes..  i do know that the grooves for the piston seals in some caliper bores are sometimes shaped like this.. .   pad side..\_| caliper side..  this allows the piston seal to rock over slightly when the piston is extended to apply the brakes.. this pulls the piston back slightly to reduce drag...   some of the versions of this had a lot of taper and required fast take up master cylinders .. they have since reduced the angle of the outer side to reduce the amount of pull back..

[BFS57]

Hello;
Yes, went through this while driving. I reached down and pulled the brake pedal and it was all the way to the top.
I was able to slide my big body under the car, loosten the nuts on the master and insert two thin washers between the booster and master, this will tell the tale!
One thing I do know about power brakes is that a tiny bit of adjustment seems to go a very long way! I had this kind of problems on my 57 when I installed the power brakes, started driving and ended up having to park it because it didn't want to go anymore, at least I was able to get my Vicky home!
I  also noticed that the trans and engine leaks had not been fully fixed! Gotta take it back anyway!
I have owned this car for seven years and am sure that the residual valves (Wildwood) are properly plumed, I just wanted more pedal!
I saw once that CPP has a tool to "properly" measure the distance between the booster and master. Is this distance guessed at or is there proper measuring tools to check this distance?

Bruce

[GPster]

Have you changed the wheel/tire combination recently on this car? I know that Jeep ( I've got a newer one too) had some problem with front discs warping.They were replacing front discs because they said the new design wasn't made with the right quality metal for the job.In a couple of years the design seemed to work better but it still wasn't right. Then finally the problem seemed to be fixed. They went from 15" to 17" wheels. GPster

[papastoyss]

This same thing happened to me at a rod run about 150 miles from home.I opened a front bleeder & that turned the brakes loose. I bought a new residual valve from a vendor there & replaced it at one of the club members home shop. About 3 wks later the new one stuck also, I removed it ,redid the metal line &no more problem. The older Wilwood valves had a spring &plunger arrangement, the ones I had trouble with  had a simple rubber valve. I reasoned that the silicone brake fluid somehow reacted with & caused the rubber valve to swell & stick.(Your results may vary)

[BFS57]

Hello;
I have had this car for 7 years and have logged about 5000 miles on it but I didn't have any brake problems until after my last repairs were done so I am thinking that the booster rod adjustment is the culprit! Anyway, When I drive it next with the washers between the master and booster, that will tell the tale!!!

Bruce

[BFS57]

Hello;
I just love it when I'm right!!! Drover the Vicky to work, no problems with the brakes after I installed 2 washer spacers between the booster and master!!!!!

Bruce