I need brake help quick please

[SteveSS]

Ever since I bought the 1969 Charger SE the brakes have been weak. It feels like the power brakes have no power assist. I can barely stop it when it's going 10 mph. Faster is a little easier but not much. I had the brakes rebuilt at every wheel. Now we put a new power brake booster on. It was a bear. No difference. We jacked it up and every wheel is stopping if you turn it by hand. Tested the master cyl and it has a thin stream when depressed. What next? We are running out of options and the mechanic friend is on the clock.

 

[Mike67]

Bleed, bleed, bleed, bleed..
You didn't say, is it a soft peddle, go to the floor?

 

[Yatzee]

Ever since I bought the 1969 Charger SE the brakes have been weak. It feels like the power brakes have no power assist. I can barely stop it when it's going 10 mph. Faster is a little easier but not much. I had the brakes rebuilt at every wheel. Now we put a new power brake booster on. It was a bear. No difference. We jacked it up and every wheel is stopping if you turn it by hand. Tested the master cyl and it has a thin stream when depressed. What next? We are running out of options and the mechanic friend is on the clock.

You didn't say what brake combination you had as this makes a difference in the pressure applied to the wheel cylinders weather they be drum or disk. First check you amount of vacuum and although others may argue the point, the minimum is 18Hg. On a drum system,
a master of 7/8 bore is preferred, on disk systems 15/16. If you are suffering "pedal drop" on application look to you master and booster. Even new ones are found to be faulty. You will find a booster test procedure online, just Google it. Air in the system is the enemy so a minimum of three bleeds using a clear plastic hose submerged in a glass container will reveal the most minute bubbles. You can place a light behind the jar for easier detection. Keep the lower end of the hose submerged in fluid in the jar. Last but not least, the clearance between the tip of the booster pin and the pocket of the master has to be correct. You can find that spec online or by contacting the manufacturer of the booster. Good luck!

 

[SteveSS]

Okay I'm back inside now since it's dark. We blew the little oil line that runs the aux oil pressure pump and it coated the driver's carpet with oil. Got a new gauge installed so that's fixed.

The car is a 1969 Charger SE 383. It has power brakes but they are all drums. The brake pedal has always just gone halfway down and stopped, from there you have to stand on it, I mean lots of foot pressure. Never spongy. My friend mechanic redid all the brakes and lines (not the long ones) new parts everywhere else.

I was convinced it was the power booster because it felt like power brakes do when the car is not running. Spent money on a new check valve and new booster. My son installed the booster then the pedal didn't move at all. Today we took off the master cylinder and pushed the thingy it in with a screwdriver. It squirted from the front reservoir first then the rear reservoir at the same time. A pretty tiny stream I thought. Put it all back together then it went back to it's old ways of having a hard pedal halfway down. Thanks for the help I'll try to measure vacuum and the ID of the MC.

 

[Big Bad Dad]

After I re-did the drum brakes on my 64 Fury, it has never seemed to stop as well as before. I think the newer brake shoes with little or no asbestos don't have the same stopping or friction power.....

 

[PurpleBeeper]

OK, don't freak out. If I had ANY question about the master cylinder, I'd replace it (cheap) and bench bleed it before installing. Also, if you "pedal bleed" the brakes, do you get a big, solid squirt of fluid out of all the wheel cylinders? If some have "weak squirts" (like the rears gush & the fronts dribble), then you "might" have a bad proportioning and/or hold off valve. Also, bleed the rear brakes holding the little pin out on the proportioning valve.

 

[Dennis H]

Are they 11"? This kit provides great performance.

www.musclecarbrakes.com.

 

[1967coronet]

You can narrow down the problem by going to your Napa ect and getting 2 plugs for your master cyl. Isolate each system front and back by a plug in that port on the cyl.

If you have no change after testing each end put both plugs in the cyl and check it.

 

[Mike67]

Another test you can do is to disconnect the lines at the mc, bend 2 lines and rub them back into the reservoir. Make sure it is full and work your pedal.
This is bench bleeding the mc while on the car, like beeper said but without removing it. Fluid should come out as long as the pedal is traveling downward. Do this until no bubbles appear from the tiny ports at the bottom of the mc.
Note any difference in pedal feel, should be a lot softer, if that is the case you probably have a bad/dirty/stuck prop valve.
Another thought could be that your adjustment on the pushed is wrong.
Good luck!

 

[moparmarks]

Did you try another master cylinder?

 

[69Bee]

New brake shoes on all four corners can/will have crappy stopping ability until they break in. Shoes use to have to be arced on a shoe grinder to match the drum. I did all four corners on a 69, and it sailed right thru the intersection on the test drive. You can test the brake booster by putting your foot on the brake pedal with the motor off. Start the engine, and the brake pedal should drop about an inch as the booster is sucked down by engine vacuum. As far as the other stuff, listen to these guys about bleeding and adjusting the linkage.

 

[lewtot184]

After I re-did the drum brakes on my 64 Fury, it has never seemed to stop as well as before. I think the newer brake shoes with little or no asbestos don't have the same stopping or friction power.....

lining material is a major factor. the organic stuff doesn't work good cold but will stop hot. I've been going thru this issue for years. finally gave up.

 

[afx man]

Did you adjust your shoes up? I know they have self adjusters.. I think that getting a good baseline by having your shoes manually and equally adjusted is critical. It has solved a lot of problems for me!!

 

[ws23jrt]

After reading all of this over a few times what makes me scratch my head is you have a "hard pedal half way down".
If you have -some- braking as the pedal moves down to where it gets hard and no further braking from that point It seems like a clue about the pedal to booster linkage as a place to eliminate next. Unless you have already done that. --Does the pedal just stop at the hard spot? With maybe some flexing but no further braking?

When I was first test driving my 69 coronet after assembly I had an opposite problem. I had some braking without touching the pedal and found the booster to be too close to the linkage connection. (It hit the firewall just barely).
In my case I had left out four spacers (1/8"thick washers) for the booster mount to the bracket. (This is a Hemi only deal cause the offset bracket was not engineered properly). I had to look closely at the blow-up picture in the FSM to identify my issue.

 

[SteveSS]

It has no braking until the pedal is halfway down then braking engages but you have to stand on it. It's impossible to lock the wheels up no matter how hard or quick you push on the pedal. Just like power brakes feel like when the engine is not running. Braking doesn't feel any different with the engine on or off. Someone once mentioned vacuum pressure being a problem at our altitude.7,500 feet above sea level. I don't know how to check vacuum pressure but I'm sure I can google it. I never had a problem with PB on any other car, although the '71 Challenger has manual brakes with discs upfront and it stops on a dime.

 

[lewtot184]

It has no braking until the pedal is halfway down then braking engages but you have to stand on it. It's impossible to lock the wheels up no matter how hard or quick you push on the pedal. Just like power brakes feel like when the engine is not running. Braking doesn't feel any different with the engine on or off. Someone once mentioned vacuum pressure being a problem at our altitude.7,500 feet above sea level. I don't know how to check vacuum pressure but I'm sure I can google it. I never had a problem with PB on any other car, although the '71 Challenger has manual brakes with discs upfront and it stops on a dime.

look for a small vacuum port at the booster check valve.

 

[ws23jrt]

It has no braking until the pedal is halfway down then braking engages but you have to stand on it. It's impossible to lock the wheels up no matter how hard or quick you push on the pedal. Just like power brakes feel like when the engine is not running. Braking doesn't feel any different with the engine on or off. Someone once mentioned vacuum pressure being a problem at our altitude.7,500 feet above sea level. I don't know how to check vacuum pressure but I'm sure I can google it. I never had a problem with PB on any other car, although the '71 Challenger has manual brakes with discs upfront and it stops on a dime.

Hmm--It's like your booster is just plain not boosting. Of course, it is powered by vacuum. If it gets the vacuum but does not perform??? It must be broke.
As for your elevation being the issue?? That makes no practical sense.