Topic: Brake issue need help

[68 S Code]

Didn't know which heading to put this under so I figured Miscl should work. I am concerned with the braking in the car after getting it running this past weekend. It seems to me that there is just too much pedal travel. The brakes were hand bled a few weeks ago. When we were getting the front end alignment done before we fired up the motor my mechanic friend noticed that the front pads were installed too low in the caliper. He fixed the pad placement then power bled the system and then did it again by hand.

The pedal was almost going down to the floor as I pulled into the driveway off the trailer. There is no air in the hydraulic system or leaks. My mechanic friend said that it may be caliper related in that the piston receeds too far back in the bore and then cant get out far enough to apply the pressure. The master cylinder could be bad (but no leaks)? The Power booster not getting enough vacumme (he said it would make them feel non power assist but shouldn't effect the brake pedal travel). The calipers are SS but have been sitting around for a few decades waiting for the car. They don't leak so I figure they should be good. Any ideas what the culprit might be for the poor braking? I'm hoping the response is not "The Mechanic" who is me.

[ruppstang]

The rod from the booster to the master cylinder has some adjustment you might try that. A solution may be found in the service manual. Marty

[68 S Code]

Thanks Marty I will look into the service manual. Hate to think I need to take the master cylinder off at this point. i was thinking about it last night and wondering is the master cylinder cap could cause this? I am using a vented one. I know when i bled the system I saw the rubber bellow expand down on the rear section as fluid emptied out.

[TLea]

Rubber bellow should drop as fluid exits. Are you saying pedal starts high then goes down or is always down? How did he adjust the pad height in your caliper, they only fit one way? Calipers are self adjusting by nature and piston return travel is the same regardless.

[68 S Code]

Tim, the pedal seemed high and had some stiffness to it when my son and I bled the system at  home. I then took the car to my mechanic friend for an alignment and to start it up. Since it was a 100 mile round trip I corresponded the drop=off at friends shop the day I took my older son to college. It seems that when they got it up on the alignment machine they noticed that the pads were sitting to low in the caliper so they took off the calipers and raised the pads. I am going by the explaination here as I wasnt present. They then went and power bled the system and again hand bled it. Said there was no air in the system. This friend owns two repair facilities, owns a number of high end old mopars and repairs many viper club members competition coupes and racing vipers. i trust his work and ethics. So I thought maybe installed the pads incorrectly. He also said i needed to adjust the rear brake star adjuster which was correct as I hadnt done that yet.

So when I unloaded the car off the trailer my son said "drive it up the driveway" (he was excited to hear it finally run and he wouldn't have to push it the 200 yards). Thats when i noticed that the pedal sank towards the floor as I held the brakes. Now I was basically ideling (high idle) up the street and the driveway with my foot on the brake. But felt I didn't have much pedal travel to go as I was trying to go slow. Thats my biggest fear with these old cars. They can go like a bat out h.. but the stopping is questionable compared to modern cars. The pedal travel as I have it is unacceptable for driving right now. Dont know what to attack next. Hate to think of replacing the master cylinder because of the potential mess. But it did sit around for 25 years and doesnt leak. Same for the calipers. They were brand new 25 years ago but they did sit on the car installed without a running car. They also dont leak. Rear cylinders are a similar issue. Old but not leaking. The rod that Marty mentioned did get installed but I never adjusted its length, figuring it was the factory setting.  I thought that maybe I didn't crimp the booster hose on tight enough to the steel line. I didn't do the short fuel line too tight and it leaked when Bill tried starting the car but he recrimped it. He said if there was a leak at that vacume hose the power assist wouldn't work so that doesn't seem to be the issue. I need to get this resolved before final tuning so we can dial in the carb under driving conditions.

[midlife]

Rear brakes definitely need to be adjusted.  If they are really way out, you can get the pedal feel that you are feeling. 

[TLea]

Still dont understand raising the pads. They only fit one way and there is no adjustment. Anyway if you had pedal and are losing it, it has to be hydraulic.

[68 S Code]

Tim you mention hydraulic related as the problem. Is there any component that can leak internally in the system thus not loose any fluid externally. What I mean is it leaks past a seal into a chamber it isn't supposed to get in and then comes out when you release pressure.? The only two that I can think of would be the calipers or master.

Midlife I will adjust the rears first.

Marty or Tim mentioned the rod which sits in the booster. If it is adjustable how do you set it to be correct length. What is that length?

Rodger Rode is great with PS systems. Is there someone out there who knows brakes? Maybe I need the caliprs or master cylinder to be looked at internally.

[ruppstang]

There is a check valve in the master cylinder that when it gos bad lets the pedal keep dropping till you let off and push again.(nothing will leak) I had one go out in the rocky mountains was a long trip home pumping the brake. Marty

[TLea]

The adjustment procedure for the pushrod is in the Ford service manual. Assuming you have no leaks, I wouls suspect MC

[68 S Code]

Marty and Tim I think your both right about the MC. It's been sitting a long time and there was some surface rust in the bowls so I can imagine internally as well. Time to look for a new Bendix unit. More disassembly required. I guess if I wasn't so close to having her drivable I would just look at it as something to do but now it's just another obstacle. I'll look at the shop manual for the rod adjustment.

[68 S Code]

Did a little checking locally at the bigger auto parts box stores and all the master cylinders are brands I never heard of. No bendix, Wagner or raybestos. Checked NPD and they say theirs is "correct style" whatever that means. So what would you guys recommend? Rebuilt or new is also a question. If rebuilt and sitting on shelf for years how long will it last?

[mustangted]

raise the pads in the calipers?

[TLea]

I go to the local auto parts store (helps if you know someone there) and ask to look through their rebuilts. Some cores are way off (truck?) but usually you can find a correct core.

[68 S Code]

Tim the correct core has Bendix cast into it on the bottom and a raised nipple with a hex head cap? Regarding the cap should it be imprinted with raised lettering or just flat on the two angled faces? I know its not supposed to be vented.