Drum Brake Wheel Cylinder replacement (1 Viewer)

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I have a rear brake cylinder leaking and decided to go ahead and replace all 4 along with springs and new pads. Got everything from SOR & had the drums turned. I poked around and found lots of threads on the master cylinder but nothing comprehensive on replacing the wheel cylinders, bleeding, etc. Can someone point me in the right direction? Thanks.
 

3_puppies

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IIRCC, they may be front and back wheel cylinders, do they have different part #'s?
what year rig?
on later year rigs, the front does most of the braking,
do you have good insurance on the wife?
 
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IIRCC, they may be front and back wheel cylinders, do they have different part #'s?
what year rig?
on later year rigs, the front does most of the braking,
do you have good insurance on the wife?
Ha! Yes, very good insurance.

It’s a 72 but I did power steering and Axel swap so it’s got disc’s in the front, drums in the rear.
 
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@JRod24

@Coolerman to the rescue:


If you ever need electrical connectors or proper color-coded wire, he's the man!
Ok so I got everything back together & bled. However, I noticed when I was bleeding the brake pedal was not going down as far as it did before. It’s as if it’s hitting a wall. Took it out for a quick test drive and it “stops” but the brakes are very weak. Even applying a ton of force doesn’t increase the braking power. Do I need to tweak the pedal or master cylinder? Could I have not bled everything correctly? Thanks for the help.
 

BeerM3

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Is the front axle swap new or something that's been installed and working fine prior to servicing the rear drums? Did you cover your bases with the right master, residual valve, booster adjustment, etc? An all-drum MC will be putting about 10psi to the front and back, instead of having a residual valve for the front circuit to meter the pressure down closer to 3psi or thereabouts.
 
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Is the front axle swap new or something that's been installed and working fine prior to servicing the rear drums? Did you cover your bases with the right master, residual valve, booster adjustment, etc? An all-drum MC will be putting about 10psi to the front and back, instead of having a residual valve for the front circuit to meter the pressure down closer to 3psi or thereabouts.
The axle swap was done previously and has been working fine for years but was done in a shop, so I’m not familiar with the details on what they did. When replacing the wheel cylinders and bleeding all I did with the master was to refill It according to coolerman’s instructions. Is there more to do with the pedal and master cylinder once the wheel cylinders are back in place perhaps?
 

EStein

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I wouldn’t dare try to offer advice because when I did mine a few weeks ago it was the first time I’d ever seen a drum brake. I will say all my issues were related to not getting them bled properly. @Coolerman articles were invaluable. Also check out his other write ups if you haven’t already. I wonder if your rears are adjusted to tight and your front isn’t doing as much braking as it should? Again I am totally an amateur.


 

BeerM3

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Others on here that know far more than I do can tell you a lot from a picture of your MC setup and brake lines. More importantly they can probably tell you if something looks dangerously wrong (doubtful since it was working prior but you'd be suprised). If you pumped or emptied one of the reservoirs completely you may need to take it off and bench bleed the MC before starting again. Rule of thumb is to start bleeding at the longest brake line run and work counterclockwise. On my '76 that would be driver's rear, passenger rear, passenger front, driver front.

And for what it's worth I'm assuming you've seen in other threads recommendations to snug up the rear drums fairly tight before starting the bleeding and then back them off 2-5 clicks (depending on who you ask) after you've got a good solid pedal? That was a mistake I learned the hard way.
 
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Others on here that know far more than I do can tell you a lot from a picture of your MC setup and brake lines. More importantly they can probably tell you if something looks dangerously wrong (doubtful since it was working prior but you'd be suprised). If you pumped or emptied one of the reservoirs completely you may need to take it off and bench bleed the MC before starting again. Rule of thumb is to start bleeding at the longest brake line run and work counterclockwise. On my '76 that would be driver's rear, passenger rear, passenger front, driver front.

And for what it's worth I'm assuming you've seen in other threads recommendations to snug up the rear drums fairly tight before starting the bleeding and then back them off 2-5 clicks (depending on who you ask) after you've got a good solid pedal? That was a mistake I learned the hard way.
Ok so this is interesting. I did not bleed the front brakes. I just assumed that because they operate from a separate reservoir and because they are disc (makes no sense now that I think about it) that I just needed to bleed the brakes I was working on. The fluid in the front reservoir on the master never moved and is full. Should I bleed the fronts too?
 

EStein

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Ok so this is interesting. I did not bleed the front brakes. I just assumed that because they operate from a separate reservoir and because they are disc (makes no sense now that I think about it) that I just needed to bleed the brakes I was working on. The fluid in the front reservoir on the master never moved and is full. Should I bleed the fronts too?

I would assume as you did that they don’t need it but it wouldn’t hurt to do them again. I second that previous post to snug up your rear pads before trying to bleed. I agonized over mine for days because I couldn’t get them bled properly. Snugged up the rear drums and a huge bubble came out within a couple pedal pushes. Fixed them good! Just make sure to get them backed off properly. My rear still locks up prior to the front so I need to back them off some more. I just haven’t gotten to it yet.
 
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I would assume as you did that they don’t need it but it wouldn’t hurt to do them again. I second that previous post to snug up your rear pads before trying to bleed. I agonized over mine for days because I couldn’t get them bled properly. Snugged up the rear drums and a huge bubble came out within a couple pedal pushes. Fixed them good! Just make sure to get them backed off properly. My rear still locks up prior to the front so I need to back them off some more. I just haven’t gotten to it yet.
What did the pedal feel like before you had them bled properly? My pedal travels about half the distance that it used to and it’s like it hits a wall and wont go down any further no matter how much pressure I put on it. My mechanic neighbor said that sounds like a booster issue. Did you experience anything similar?
 

EStein

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Hmm. Mine was opposite. First push would go to the floor. Two or three pumps to get it solid. Seems like if your booster was good before then your issue is most likely in the rear drums? Are they possibly too tight still? If you brake hard will they lock up?
 
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Hmm. Mine was opposite. First push would go to the floor. Two or three pumps to get it solid. Seems like if your booster was good before then your issue is most likely in the rear drums? Are they possibly too tight still? If you brake hard will they lock up?
That’s what’s so weird about this- the pedal travel is reduced but the brakes are super weak. They wont even come close to locking up. I tried a couple of times to slam it and it would barely come to a slow stop. I’ll try adjusting the pads again but I feel like the problem is in the MC, booster or pushrod, none of which I touched when working on the wheel cylinders.
 

EStein

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That’s what’s so weird about this- the pedal travel is reduced but the brakes are super weak. They wont even come close to locking up. I tried a couple of times to slam it and it would barely come to a slow stop. I’ll try adjusting the pads again but I feel like the problem is in the MC, booster or pushrod, none of which I touched when working on the wheel cylinders.

Again I don’t have any experience with this but could you take off the drums and have someone work the pedal just to make sure everything is working inside like it’s supposed to? Could something be binding or a cylinder stuck? I’m just throwing stuff out there.
 

iptman

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Again I don’t have any experience with this but could you take off the drums and have someone work the pedal just to make sure everything is working inside like it’s supposed to? Could something be binding or a cylinder stuck? I’m just throwing stuff out there.


Not a good idea. If you do this you may push the pistons right out of the cylinders.

OP, you do know you have to adjust each of the cylinders by turning that toothed wheel through the slot on the backing plate?
 

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