brake pedal needs pumping

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diymirage

diymirage

HP@idle > hondaHP@redline
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hey guys

car is a 71 duster, originally a /6 car with manual drums
last week in installed a 8 3/4 rear end with 10 inch drums
I installed new cylinder and hard lines in the rear and let everything else alone
we topped off the brake fluid and bled the lines until a steady squirt came out each time I opened the bleeder (first the passenger rear, then the driver side)

the pedal felt good after I bled it

when I started driving the car I noticed the first time I hit the brakes the pedal goes to the floor, then I pump it once or twice more and it becomes hard

it seems like when the pedal gets hard it specifically want to lock up the passenger side rear

did I just do a poor job bleeding it or is there something else I should look at?
 
I would adjust all four brakes (if drum in front) and re-bleed all four wheels starting from farthest away from the master and ending on the closest. Its possible your master went bad. Had one go bad after a bleed session once.
 
I agree on the adjustment as that can make the pedal go to the floor AND make a drum brake lock up.
If the shoes are too far away from the drum it uses all the fluid to get it out to the drum on the first push of the pedal.
And loose adjusted shoes can (cam in) to the drum and lock up that wheel.
 
thanks for the replies guys, I will check for leaky lines
I backed the adjusters all the way off when I redid the brakes, they should re-adjust soon no?

one thing I was wondering aswell, I'm not sure what size drums I have in the front, they could be 9s, would that be an issue, with the larger brakes out back?


oh, and when I drive it, I do need to pump the brake pedal EACH time
 
Adjustment on drum brakes can substantially affect the pedal height, but, it will not make it go to the floor. That's a hydraulic issue. You have a leaking wheel cylinder somewhere I bet.

Remember, "NEW" does not mean "GOOD".
 
diymirage said:
thanks for the replies guys, I will check for leaky lines
I backed the adjusters all the way off when I redid the brakes, they should re-adjust soon no?

one thing I was wondering aswell, I'm not sure what size drums I have in the front, they could be 9s, would that be an issue, with the larger brakes out back?
Click to expand...
I do it this way:
Before putting the drum on for the final time I adjust the adjuster out until the shoes are expanded just enough to slightly drag when I rotate the drum. It may take a couple tries to get a nice feel and to center up the drum. I find it FAR easier to operate the adjuster from the outside compared to working through the little slots in the backing plates. You can hear the scraping noise as the drum is rotated. That sets the shoes pretty close to the ID of the drum. Then I will drive the car in reverse and apply the brakes several times. Backing up and applying the brakes is what makes the self adjusters work. Also the arc of the new shoes may not exactly match the inside diameter of the drum but they will wear in. Unless you find a place that will grind the shoes to the exact radius of the drums.

Pumping the brakes with an open bleeder probably causes the MC piston to stroke further than a normal braking application. That "may" cause the MC to start leaking.

With everything installed, apply and hold the brake pedal down. It should be rock hard and stay solid forever. If it s-l-o-w-l-y heads to the floor, you have a hydraulic leak. MC, brake line, wheel cylinder, disc caliper, etc. Sometimes it just takes another 1/4 turn on a brake line nut to stop a leak.
 
I went underneath and looked, did not find any blatant leaks
what I did find was that I could turn the bleeder on the driver side rear another 1/4 inch

I went ahead and tightened that, see what that does :)
 
Automatic adjusters are for keeping the brakes adjusted, so it could take awhile even if the self adjusters are working right. (If) :D
I like to adjust them manually and then let the auto's keep it that way.
 
RustyRatRod said:
Adjustment on drum brakes can substantially affect the pedal height, but, it will not make it go to the floor. That's a hydraulic issue. You have a leaking wheel cylinder somewhere I bet.

Remember, "NEW" does not mean "GOOD".
Click to expand...

Hey rusty, he said he left the adjusters backed ALL the way off if I understand correctly. Definitely have a super low pedal if that's the case! You need to check for leaks, and properly adjust your rear shoes..........
 
replicaracer43 said:
Hey rusty, he said he left the adjusters backed ALL the way off if I understand correctly. Definitely have a super low pedal if that's the case! You need to check for leaks, and properly adjust your rear shoes..........
Click to expand...

yes, if I had backed them off any further, they would be in the trunk

ill pull the drums and adjust the brakes out to be snug, see what that does for me



thanks guys
 
diymirage said:
yes, if I had backed them off any further, they would be in the trunk

ill pull the drums and adjust the brakes out to be snug, see what that does for me



thanks guys
Click to expand...

That is why I mentioned adjusting them manually first, and then let the auto adjust take it from there.
I suspected it was using all the fluid one press of the pedal had just to get the shoes out to the drums.

Another thing about that is if you leave that much travel in the wheel cylinders they can very eaisily suck air in around the cups and need bleeding again just from movement.
 
Besides the pedal-issue, you can't just increase the size of the rear brakes and expect everything is still fine.

A brakesystem always needs to have a small bias to the front brakes. Meaning that the fronts should lock up first just before the rear ones do, in case of panic braking.
 
I'll 3rd the drive in reverse in an empty parking lot and jam the brakes on many times so the self-adjusters do their thing. I usually adjust the shoes a bit loose so no risk of dragging and over-heating. I can feel the play reduce each time I jam them. After about 3 times the travel greatly reduces. After driving a few weeks the shoes wear to better match the drum, so even less travel.
 
So why on earth would you leave the adjusters back all the way off?
 
diymirage said:
yes, if I had backed them off any further, they would be in the trunk

ill pull the drums and adjust the brakes out to be snug, see what that does for me



thanks guys
Click to expand...

Yes the brake shoes need adjusted back out after the job is done or you will have a pedal on the floor as you have.
 
diymirage said:
thanks for the replies guys, I will check for leaky lines
I backed the adjusters all the way off when I redid the brakes, they should re-adjust soon no?
Click to expand...

Lol, yeah, you need to adjust them up manually. Jack the rear up so you can spin the wheel, adjust just until you hear/feel slight contact.

Also when bleeding, I don't like the pedal to go hard against the floor. I use a small half inch thick piece of plywood under the pedal to keep it off the floor, as the wife is usually operating the pedal.


You did bleed, in this order, right rear, left rear, right front, left front, yes??
 
Bad Sport said:
Lol, yeah, you need to adjust them up manually. Jack the rear up so you can spin the wheel, adjust just until you hear/feel slight contact. (Then step on the pedal and adjust till contact again) and keep doing it little at a time until you step on the pedal and still have a slight contact after.
Stepping on the pedal centers the shoes and gives more you can adjust out.

Also when bleeding, I don't like the pedal to go hard against the floor. I use a small half inch thick piece of plywood under the pedal to keep it off the floor, as the wife is usually operating the pedal.


You did bleed, in this order, left rear, right rear, right front, left front, yes??
Click to expand...

You'll get it.
 
Thanks for aLloyd the help guys

I dI'd bleed the brakes in the proper order, but I haven't gotten to the fronts yet

The reason I adjusted the adjusters all the way out was because I didn't think it would negatively affect things, and allow me to get the drums on easier
 
diymirage said:
The reason I adjusted the adjusters all the way out was because I didn't think it would negatively affect things, and allow me to get the drums on easier
Click to expand...

That's fine, but after the drums are on then you must adjust them up.
 
this might sound silly, but I never knew that
I installed the adjusters, so I figured it would self adjust soon enough
 
with the forum being down this morning I had some time this morning to adjust the brakes (along with some other things)
I ran the adjusters out far enough to make it tight getting the drums back on

now, within about 1/3 of regular pedal travel I can lock up the brakes bad enough to squeak the tires and make it clear I haven't properly aligned the front end yet
 
If you follow post 19 now that they are back on the car you will have an even better pedal.
 
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