Author Topic: Help with rear disc brakes!!  (Read 17823 times)

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Offline mattblack84

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Help with rear disc brakes!!
« on: September 14, 2011, 12:18:22 PM »
my 79 trans am has been sitting for a while and i finally got it back from the body guy and am going through the car slowly what are my best approaches for repairing the rear brakes there is no leaks but there def not grabbing and i was thinking new pads and rotors but isn't there somthing with the calipers on these i'm looking at the service manual and am a little confused any help would be greatly appriciated!!

Offline Tin Indians Rule

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Re: Help with rear disc brakes!!
« Reply #1 on: September 14, 2011, 12:59:56 PM »
I'm going to hold off responding and see if Evan jumps in here. I know he just went through the wringer with his so I'll see if he or others pony up advice first.
What's she wearing now? Come on!
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Offline mattblack84

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Re: Help with rear disc brakes!!
« Reply #2 on: September 14, 2011, 01:14:30 PM »
well let me know so I can get my baby fixed!!!

Offline eroc022

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Re: Help with rear disc brakes!!
« Reply #3 on: September 14, 2011, 01:42:17 PM »
yup, these are a headache.... they have to be so accurately set with the emergency brake in order to get a good pedal feel...  I think Renovations has the link or pdf file that describes how to do it the best... its in the service manual as well... basically you will have to get the emergency brake as close as possible to engaging then you can bleed the brakes normally, to get the emergency brake set right you have to take off the inside lever and manually adjust the depth that the inside pad sits... by turning the shaft clockwise or counterclockwise the pad will move in and out... get it to where it touches the pad, and then just barely back it off of it so you have no drag.... then reinstall the lever, and bleed the brakes as normal... new pads and rotors are always a good idea too.....
Eroc
Fixing the car that Restore A Muscle Car jacked up....

Offline jjr

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Re: Help with rear disc brakes!!
« Reply #4 on: September 14, 2011, 01:52:01 PM »

 From what I've seen and experienced the rear calipers are kinda
suspectable to corrosion from "not" using the parking brake every
time.

 Most folks buy rebuilt units rather than to do them themselves.

 You have to follow the very detailed instructions on setting them
up correctly, something I have to review each time I do a set.

 The rear discs work both by fluid and by mechanical means and so
setup is special.

 You'll need a few tools, a special one to be able to get the piston
at the proper depth, do you know which one I mean?

 Then there is a trick to the bleeding, if you aren't careful you
may create a difference in system pressures and trip the proportioning
valve to lock out one or the other system (front/back). Often the
old friend in the car pumping the pedal procedure does this.

 How where you planning on bleeding the system?

 Joe

 
1979 10th Aniv 400/4spd
1980 Black SE 301NA
1980 Indy Turbo Pace 301T
1981 Turbo 301T
1981 Black SE 301T
1981 Daytona Pace 301T
www.301garage.com

Offline eroc022

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Re: Help with rear disc brakes!!
« Reply #5 on: September 14, 2011, 05:44:18 PM »
Joe, I reverse bled my system by feeding the fluid in through the caliper into the master cylinder... no air is in the system, but yet I still have a horrible pedal feel... whats the trick for the rest of it? its about to just go to the shop...
Eroc
Fixing the car that Restore A Muscle Car jacked up....

Offline jjr

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Re: Help with rear disc brakes!!
« Reply #6 on: September 14, 2011, 09:15:31 PM »

 While I love and have used the reverse method, it's not 100% either.

 The thing that works is a obscure tool that holds the end of the pin
on the prop valve in place keeping the shuttle from moving. On the
aftermarket valves, a temp replacement for the differential switch
has a solid tip that prevents the shuttle from moving.

 Have you seen this?

 Joe
1979 10th Aniv 400/4spd
1980 Black SE 301NA
1980 Indy Turbo Pace 301T
1981 Turbo 301T
1981 Black SE 301T
1981 Daytona Pace 301T
www.301garage.com

Offline eroc022

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Re: Help with rear disc brakes!!
« Reply #7 on: September 15, 2011, 02:07:15 AM »
my disc brake valve doesnt have a pin on the end..... solid brass but I do know what you are speaking of....
Eroc
Fixing the car that Restore A Muscle Car jacked up....

Offline kc79ta

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Re: Help with rear disc brakes!!
« Reply #8 on: September 15, 2011, 05:28:29 AM »
Joe, I reverse bled my system by feeding the fluid in through the caliper into the master cylinder... no air is in the system, but yet I still have a horrible pedal feel... whats the trick for the rest of it? its about to just go to the shop...

Eroc, That might be your problem. Unless you pulled the MC back off and bench bled it after. I no pro on brakes, but I remember hearing that reverse bleeding a system with a tipped back MC can trap air in it that can only be bled out with it level on a bench. Just a thought before you spend some $$$ at the shop.
« Last Edit: September 15, 2011, 05:32:41 AM by kc79ta »
Keith

Offline jjr

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Re: Help with rear disc brakes!!
« Reply #9 on: September 15, 2011, 09:31:08 AM »

 The brass one... then:



 Joe
1979 10th Aniv 400/4spd
1980 Black SE 301NA
1980 Indy Turbo Pace 301T
1981 Turbo 301T
1981 Black SE 301T
1981 Daytona Pace 301T
www.301garage.com

Offline eroc022

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Re: Help with rear disc brakes!!
« Reply #10 on: September 15, 2011, 10:58:47 AM »
aha well I found out I have a leak somewhere too. front brake resivoir is much much lower now than when I did this... I think its all coming off and hydroboost is going on.....
Eroc
Fixing the car that Restore A Muscle Car jacked up....

Offline mattblack84

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Re: Help with rear disc brakes!!
« Reply #11 on: October 13, 2011, 02:55:49 PM »
well i found out today it is my rear calipers no adjusting, the screw moves a little i'm thinking i might be able to fre them up been spraying pb blaster and working the ebrake.

Offline mattblack84

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Re: Help with rear disc brakes!!
« Reply #12 on: July 28, 2012, 11:51:37 AM »
Well got the e-brake to move every thing there ok, but the levers in the calipers themselves don't want to move much should i rebuild or try and free them up?

Offline eroc022

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Help with rear disc brakes!!
« Reply #13 on: July 28, 2012, 04:19:48 PM »
They shouldn't move much except for to clamp down on the rotor..... Very tight tolerance with them
Eroc
Fixing the car that Restore A Muscle Car jacked up....

Offline mattblack84

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Re: Help with rear disc brakes!!
« Reply #14 on: July 29, 2012, 11:45:31 AM »
ok but how do u get the piston to come out so i can put it against the rotor?