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Discussion Starter #1 (Edited)
On my 66 mustang, I did a CSRP power disc brake conversion.

I'm ready to road test my new motor and trans (331 stroker and 4r70w trans) install. But I've got a concern.

When I installed the csrp disc brake conversion, I power bleed the system (and I prebled the master cylinder) The pedal felt odd. Sometimes okay, a bit spongy but never "stiff".

When I first started the car, the pedal went to the floor, but you could pump it up. I figured I needed to bleed the system. Had a buddy come over and bled. It got better, but not great. Never stiff/solid. I thought maybe i had the bias too far when I bled it. So I backed off the proportioning valve to see if the bias was set wrong and rebled.

I have the car on Jack stands, so I wanted to give the brakes a test before setting it down. When I put the car in reverse, with the brake pedal applied the rear tires will spin. I can pump it up and try to press harder, but can't get them to stop spinning. Obviously, this isn't desirable for an auto trans so shifting from reverse to park while the wheels are spinning isnt good for the tranny.

I thought, maybe I don't have them adjusted properly, so I tried spinning the adjusters out a few. Im turning and turning and not really getting much difference in the pad bite. (Mind you, I'm a disc brake guy and have always dreaded drum brakes with an unrealistic fear)

Tried again, wheels will still spin when in gear and brakes applied. (But with the car off I could physically feel the pedal difference after adjusting the out). I tried turning the bias to rear even more knowing its not fully counter clockwise per csrp instructions. That didnt help.

So, I thought I might need to rebleed the rears, so I did that. Again, still the wheels would spin while in gear on Jack stands. I had the tires off at this point, and when I tried to use the brakes this time, the drum shot off the passenger side bouncing off the ground.

Can come one give this knucklehead some advice? What am I doing wrong here? What am i missing? I can't test drive without brake confidence. Am I just not adjusted out enough? I can slide the passenger drum on, but it takes a wiggle to get it off. Same on drivers.

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You might try adjusting the rears out farther. Lots of threads on the rear drum brake adjustments after front disc conversions. I know when I had this problem, adjusting out until I could barely turn the drum and adjusted back down till the drag loosened up a little seemed to fix my issue.

Once you have the drag on the drums right. Then fine tune brake bias front to rear with prop valve adjustments.

Although rear adjustment may help some with the pedal travel, a spongy pedal usually means air in the system.
 

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Discussion Starter #4
Did you try taking the drums off and adjusting till the drums won’t go on? Then back off a few clicks, slide the drum on and then adjust for drag.


Mark
No, but I will right now.
 

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To correctly adjust any 1960's-1970's Ford Drum Brake (FRONT or REAR DRUMS), You have to bring the car on a side street or a parking lot and keep putting the car in reverse and hitting the brakes while driving in reverse. Do this about 15 to 20 times or as necessary. This brings out the Automatic Self Adjusters (Star Wheels) and the Brakes will automatically adjust themselves and the brakes will start to bite and the pedal will get harder. This all happens provided that all the Brake cylinders have been correctly bled along with Bench Bleeding the master cylinder...... What...?!??!?????.... Noone ever told you???.....lol... That's how the system works.

:eek:)

Tony K.
 

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Initially, The Drums should be able to turn with only the slightest drag.
 

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I have always adjusted drum brakes with the wheel on, and tighten till I couldn't turn the wheel any more, then loosen the adjuster till turned easily. If I remember, usually about 10 clicks or so.
 

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Discussion Starter #8
Did you try taking the drums off and adjusting till the drums won’t go on? Then back off a few clicks, slide the drum on and then adjust for drag.


Mark
Did this, and rebled.
Helped, but not stopping still. Slow creep at this point. Pedal is nice snd stiff when not running. As soon as the vac booster is introduced, the pedal drops a bit.

It does actually hit a wall now, but the drums will still rotate when in gear.
 

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On my 66 mustang, I did a CSRP power disc brake conversion.

I'm ready to road test my new motor and trans (331 stroker and 4r70w trans) install. But I've got a concern.

When I installed the csrp disc brake conversion, I power bleed the system (and I prebled the master cylinder) The pedal felt odd. Sometimes okay, a bit spongy but never "stiff".

When I first started the car, the pedal went to the floor, but you could pump it up. I figured I needed to bleed the system. Had a buddy come over and bled. It got better, but not great. Never stiff/solid. I thought maybe i had the bias too far when I bled it. So I backed off the proportioning valve to see if the bias was set wrong and rebled.

I have the car on Jack stands, so I wanted to give the brakes a test before setting it down. When I put the car in reverse, with the brake pedal applied the rear tires will spin. I can pump it up and try to press harder, but can't get them to stop spinning. Obviously, this isn't desirable for an auto trans so shifting from reverse to park while the wheels are spinning isnt good for the tranny.

I thought, maybe I don't have them adjusted properly, so I tried spinning the adjusters out a few. Im turning and turning and not really getting much difference in the pad bite. (Mind you, I'm a disc brake guy and have always dreaded drum brakes with an unrealistic fear)

Tried again, wheels will still spin when in gear and brakes applied. (But with the car off I could physically feel the pedal difference after adjusting the out). I tried turning the bias to rear even more knowing its not fully counter clockwise per csrp instructions. That didnt help.

So, I thought I might need to rebleed the rears, so I did that. Again, still the wheels would spin while in gear on Jack stands. I had the tires off at this point, and when I tried to use the brakes this time, the drum shot off the passenger side bouncing off the ground.

Can come one give this knucklehead some advice? What am I doing wrong here? What am i missing? I can't test drive without brake confidence. Am I just not adjusted out enough? I can slide the passenger drum on, but it takes a wiggle to get it off. Same on drivers.
I will largely avoid the temptation to say that you should stick with only working on disc brakes...... and try to assist.

As others have said, you need to focus on the rear brakes. If you wanted to remove the rear drums, would they merely slide right off?
If so, they are not properly adjusted. Adjust until slight drag all the way around as you turn. Drag should be felt evenly, all the way around.
After this, any further issues with rear braking would see you focusing on the type of friction material in those shoes and whether your
system is bled completely. (I'm specifically wondering now also if there is a residual valve present in the rear circuit..... that would be a
good thing to verify)

ex-Global West GM
1991-1995
 
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Discussion Starter #10
To correctly adjust any 1960's-1970's Ford Drum Brake (FRONT or REAR DRUMS), You have to bring the car on a side street or a parking lot and keep putting the car in reverse and hitting the brakes while driving in reverse. Do this about 15 to 20 times or as necessary. This brings out the Automatic Self Adjusters (Star Wheels) and the Brakes will automatically adjust themselves and the brakes will start to bite and the pedal will get harder. This all happens provided that all the Brake cylinders have been correctly bled along with Bench Bleeding the master cylinder...... What...?!??!?????.... Noone ever told you???.....lol... That's how the system works.

:eek:)

Tony K.
Yeah, I know about the self adjusters and the reverse thing. I figured i could get them to atleast stop the wheels when on jackstands without this though.
 

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Discussion Starter #11
I will largely avoid the temptation to say that you should stick with only working on disc brakes...... and try to assist.

As others have said, you need to focus on the rear brakes. If you wanted to remove the rear drums, would they merely slide right off?
If so, they are not properly adjusted. Adjust until slight drag all the way around as you turn. Drag should be felt evenly, all the way around.
After this, any further issues with rear braking would see you focusing on the type of friction material in those shoes and whether your
system is bled completely. (I'm specifically wondering now also if there is a residual valve present in the rear circuit..... that would be a
good thing to verify)

ex-Global West GM
1991-1995
Lol, no id rather have 4 wheel disc but that's another topic that I'll start elsewhere.

Just rolled around everywhere and I'm not seeing any additional residual valving unless its built into the T on the axle.

I'll say this. They did stop before when I first got the car.

Would the emergency brake have anything to do with the stopping power? The 4r70w swap has created an emergency brake looseness that i havent fully figure out just yet.
 

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Lol, no id rather have 4 wheel disc but that's another topic that I'll start elsewhere.

Just rolled around everywhere and I'm not seeing any additional residual valving unless its built into the T on the axle.

I'll say this. They did stop before when I first got the car.

Would the emergency brake have anything to do with the stopping power? The 4r70w swap has created an emergency brake looseness that i havent fully figure out just yet.
Hoping you have a residual valve at the master cylinder's port for the rear circuit..... It's going to be tough to have an ideal setup without that on a drum setup.
If the rear shoes are in close proximity to the drums like they should be, friction material of the rear shoes and pressure at the rear. That's what you need to
ascertain at this point.
If you had pressure gauges, you'd be threading them into wheel cylinder bleeders at around this point in time.....

On the Mustang drum system the parking brake could be physically disconnected and it won't effect what you're looking at.

ex-Global West GM
1991-1995
 
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Discussion Starter #13
Hoping you have a residual valve at the master cylinder's port for the rear circuit..... It's going to be tough to have an ideal setup without that on a drum setup.
If the rear shoes are in close proximity to the drums like they should be, friction material of the rear shoes and pressure at the rear. That's what you need to
ascertain at this point.
If you had pressure gauges, you'd be threading them into wheel cylinder bleeders at around this point in time.....

On the Mustang drum system the parking brake could be physically disconnected and it won't effect what you're looking at.

ex-Global West GM
1991-1995
Master cylinders rear port comes off the proportioning valve. Not sure if there's a residual valve in there.

I'd be pretty shocked if Dennis at CSRP/discbrakeswap.com didn't have this kit configured correctly. I highly doubt thats the case, unless something is wrong with the proportioning valve/master cyl/booster
 

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"I'll say this. They did stop before when I first got the car"
If this means that the rear brakes did stop, I think the answer to the issue is to focus on what has been changed.
You've got a power booster that's been added and (I assume) a new master cylinder? As I mentioned before, I
wonder if there's a residual valve in that rear brake port?

ex-Global West GM
1991-1995
 

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On my 66 mustang, I did a CSRP power disc brake conversion.
Good choice. His stuff is based on the OEM K/H brakes.
I'm ready to road test my new motor and trans (331 stroker and 4r70w trans) install. But I've got a concern.
The road test is always a little like that, no matter how much experience.
When I installed the CSRP disc brake conversion, I power bleed the system (and I prebled the master cylinder) The pedal felt odd. Sometimes okay, a bit spongy but never "stiff".
Adjustment will remove that. And perhaps more bleeding.
When I first started the car, the pedal went to the floor, but you could pump it up. I figured I needed to bleed the system. Had a buddy come over and bled. It got better, but not great. Never stiff/solid. I thought maybe i had the bias too far when I bled it. So I backed off the proportioning valve to see if the bias was set wrong and rebled.
Proportioning valve has nothing to do with that.
I have the car on Jack stands, so I wanted to give the brakes a test before setting it down. When I put the car in reverse, with the brake pedal applied the rear tires will spin. I can pump it up and try to press harder, but can't get them to stop spinning. Obviously, this isn't desirable for an auto trans so shifting from reverse to park while the wheels are spinning isnt good for the tranny.
You got that right. Always stop first.
I thought, maybe I don't have them adjusted properly, so I tried spinning the adjusters out a few. Im turning and turning and not really getting much difference in the pad bite. (Mind you, I'm a disc brake guy and have always dreaded drum brakes with an unrealistic fear)
Unrealistic is right. Approximately a spazillion cars had only drum brakes. For fun I drive a 5000 pound Army truck with manual drum brakes.
Tried again, wheels will still spin when in gear and brakes applied. (But with the car off I could physically feel the pedal difference after adjusting the out). I tried turning the bias to rear even more knowing its not fully counter clockwise per csrp instructions. That didn't help.
Stop screwing with the proportioning valve. It won't change pedal feel. More later.
So, I thought I might need to rebleed the rears, so I did that. Again, still the wheels would spin while in gear on Jack stands. I had the tires off at this point, and when I tried to use the brakes this time, the drum shot off the passenger side bouncing off the ground.
That's because you don't have the Tinnerman nuts that Ford provided on the rear for just that problem. You can replace them, though. I still have my originals. $4 for a set of 6 from AMK.
757383

Can come one give this knucklehead some advice? What am I doing wrong here? What am i missing? I can't test drive without brake confidence. Am I just not adjusted out enough? I can slide the passenger drum on, but it takes a wiggle to get it off. Same on drivers.

Drum Brake Adjustment 101
My Grandad taught me this.
Spin the wheel, tightening the adjuster until you can barely turn the wheel. Loosen one notch at a time until the wheel turns, with some drag. Repeat on the other side. Now you have preloaded the brakes, and removed all the free play in the parts. Before self adjusters were common, this had to be done at every oil change.


Proportioning Valve Adjustment 101
Find a smooth gravel road or long driveway. Drive at about 25 mph, gradually increasing pedal pressure until the front or rear brakes lock. If the rear brakes lock first, decrease rear brake pressure until the front locks first. If the fronts already lock first, increase rear brake pressure until the rears lock first, them back off until the front locks slightly before the rears. This is the ideal setting. You want the fronts to lock first for safety, but the rears should do as much as possible. Naturally, if the rears lock first, the car will swap ends every time you slam on the brakes, and you will die. Or at least, your car will die. This is true for four-wheel disc, too.
 

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Hang two gauges on the rear wheel cylinders. That'll be a smoking gun I assure you.

ex-Global West GM
1991-1995
 
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Discussion Starter #17
"I'll say this. They did stop before when I first got the car"
If this means that the rear brakes did stop, I think the answer to the issue is to focus on what has been changed.
You've got a power booster that's been added and (I assume) a new master cylinder? As I mentioned before, I
wonder if there's a residual valve in that rear brake port?

ex-Global West GM
1991-1995
Yes, new master cylinder, proportioning valve, and booster. Came as a kit. Took it for a quick ride. It stops, not great, and definitely not stopping hard. But I don't have the proportioning valve set yet.
 

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Discussion Starter #18
On my 66 mustang, I did a CSRP power disc brake conversion.
Good choice. His stuff is based on the OEM K/H brakes.
I'm ready to road test my new motor and trans (331 stroker and 4r70w trans) install. But I've got a concern.
The road test is always a little like that, no matter how much experience.
When I installed the CSRP disc brake conversion, I power bleed the system (and I prebled the master cylinder) The pedal felt odd. Sometimes okay, a bit spongy but never "stiff".
Adjustment will remove that. And perhaps more bleeding.
When I first started the car, the pedal went to the floor, but you could pump it up. I figured I needed to bleed the system. Had a buddy come over and bled. It got better, but not great. Never stiff/solid. I thought maybe i had the bias too far when I bled it. So I backed off the proportioning valve to see if the bias was set wrong and rebled.
Proportioning valve has nothing to do with that.
I have the car on Jack stands, so I wanted to give the brakes a test before setting it down. When I put the car in reverse, with the brake pedal applied the rear tires will spin. I can pump it up and try to press harder, but can't get them to stop spinning. Obviously, this isn't desirable for an auto trans so shifting from reverse to park while the wheels are spinning isnt good for the tranny.
You got that right. Always stop first.
I thought, maybe I don't have them adjusted properly, so I tried spinning the adjusters out a few. Im turning and turning and not really getting much difference in the pad bite. (Mind you, I'm a disc brake guy and have always dreaded drum brakes with an unrealistic fear)
Unrealistic is right. Approximately a spazillion cars had only drum brakes. For fun I drive a 5000 pound Army truck with manual drum brakes.
Tried again, wheels will still spin when in gear and brakes applied. (But with the car off I could physically feel the pedal difference after adjusting the out). I tried turning the bias to rear even more knowing its not fully counter clockwise per csrp instructions. That didn't help.
Stop screwing with the proportioning valve. It won't change pedal feel. More later.
So, I thought I might need to rebleed the rears, so I did that. Again, still the wheels would spin while in gear on Jack stands. I had the tires off at this point, and when I tried to use the brakes this time, the drum shot off the passenger side bouncing off the ground.
That's because you don't have the Tinnerman nuts that Ford provided on the rear for just that problem. You can replace them, though. I still have my originals. $4 for a set of 6 from AMK.
View attachment 757383

Can come one give this knucklehead some advice? What am I doing wrong here? What am i missing? I can't test drive without brake confidence. Am I just not adjusted out enough? I can slide the passenger drum on, but it takes a wiggle to get it off. Same on drivers.

Drum Brake Adjustment 101
My Grandad taught me this.
Spin the wheel, tightening the adjuster until you can barely turn the wheel. Loosen one notch at a time until the wheel turns, with some drag. Repeat on the other side. Now you have preloaded the brakes, and removed all the free play in the parts. Before self adjusters were common, this had to be done at every oil change.


Proportioning Valve Adjustment 101
Find a smooth gravel road or long driveway. Drive at about 25 mph, gradually increasing pedal pressure until the front or rear brakes lock. If the rear brakes lock first, decrease rear brake pressure until the front locks first. If the fronts already lock first, increase rear brake pressure until the rears lock first, them back off until the front locks slightly before the rears. This is the ideal setting. You want the fronts to lock first for safety, but the rears should do as much as possible. Naturally, if the rears lock first, the car will swap ends every time you slam on the brakes, and you will die. Or at least, your car will die. This is true for four-wheel disc, too.
My man, thanks!!!
I definitely had no dive on this run.
 

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Discussion Starter #19
Hang two gauges on the rear wheel cylinders. That'll be a smoking gun I assure you.

ex-Global West GM
1991-1995
I dont know that I've ever seen a brake wheel cylinder pressure gauge.
 

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Discussion Starter #20
I'm wondering if it would just be best to go ahead and put new wheel cylinders and pads on the rear?

I can buy new cylinders for less than the brake pressure gauge.

I've got a call into Dennis at CSRP about the residual valve possibility.
 
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