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70 B body drum brakes bleeding #134174
10/09/08 08:56 AM
10/09/08 08:56 AM
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Maryland, USA,
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satgtx Offline OP
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I had to change out my Master cylinder, then the right front wheel cylinder stuck and i changed out both of them and new shoes. i now have no pedal. I have bleed the fronts twice, bleed the master again and bleed the rear with little difference, What could be my problem? I cant seem to get a pedal at all.

Re: 70 B body drum brakes bleeding [Re: satgtx] #134175
10/09/08 09:04 AM
10/09/08 09:04 AM
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Ohio
LS-300 Offline
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Ohio
Did you "bench bleed" the master cylinder prior to install? If so check connections and possible other leaks.


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Re: 70 B body drum brakes bleeding [Re: LS-300] #134176
10/09/08 09:22 AM
10/09/08 09:22 AM
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Maryland, USA,
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satgtx Offline OP
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yes i bench bleed the master and had good pedal until the wheel cylinder froze. now it will not pump up. the drum did get hot. i turned both drums as well and installed new wheel seal. I will try again tonight, maybe tighten all brake adjusters a little more and see what happens.

Re: 70 B body drum brakes bleeding [Re: satgtx] #134177
10/09/08 07:44 PM
10/09/08 07:44 PM
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Lincoln Nebraska
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RapidRobert Offline
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I would bleed the MC again then RR,LR,RF,LF. Be carefull not to have the wheel cyl screws too far open so that air gets pulled back in as you are bleeding. If still problematic buy a brass plug & cap one of the MC ports & isolate which half is the problem. EDIT drums should have the shoes expanded until they are locked solid then backed off until they are free then tightened back up until you reach a point where as you spin the wheel at one point in the circumference you hear a SLIGHT "tick" of contact at that one point that you can HEAR but not FEEL it slowing it down.

Last edited by RapidRobert; 10/09/08 07:52 PM.

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Re: 70 B body drum brakes bleeding [Re: RapidRobert] #134178
10/09/08 08:49 PM
10/09/08 08:49 PM
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Illinois
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Oldcar_Mechanic Offline
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If all else fails. Gravity bleed them. Remove the top from the Master cylinder and fill it. Open the furthest bleeder from the Master which will be the right rear. Watch the fluid level in the Master and before it gets to the bottom and sucks air, refill the cylinder. Close the bleeder on the right rear and move to the next wheel cylinder. When you have done all 4, you should have a pretty good pedal.

I've used this method many times with good results, especially when you do not have a helper.

Hope this helps
Ron

Re: 70 B body drum brakes bleeding [Re: Oldcar_Mechanic] #134179
10/10/08 08:29 AM
10/10/08 08:29 AM
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Maryland, USA,
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satgtx Offline OP
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is there a chance that a could have damaged the new master cylinder when the wheel cylinder/drum got hot and in turn HOT brake fluid got back to the master cylinder rubber bushings and distorted them? I will try everything once again this weekend, i was to tired to mess with it last night. Thanks all.

Re: 70 B body drum brakes bleeding [Re: RapidRobert] #134180
10/10/08 01:39 PM
10/10/08 01:39 PM
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Santa Cruz, California
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Lefty Offline
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Quote:

I would bleed the MC again then RR,LR,RF,LF. Be carefull not to have the wheel cyl screws too far open so that air gets pulled back in as you are bleeding. If still problematic buy a brass plug & cap one of the MC ports & isolate which half is the problem. EDIT drums should have the shoes expanded until they are locked solid then backed off until they are free then tightened back up until you reach a point where as you spin the wheel at one point in the circumference you hear a SLIGHT "tick" of contact at that one point that you can HEAR but not FEEL it slowing it down.






Also - make sure the gap between the brake pedal push rod and the MC piston is OK when the brake pedal is at rest. SB 1/16" to 1/8"

Re: 70 B body drum brakes bleeding [Re: Lefty] #134181
10/15/08 09:24 AM
10/15/08 09:24 AM
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Maryland, USA,
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satgtx Offline OP
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i plugged off the front brake resivoir(rear of MC)and i have full petal with 0 leakage. So the problem is up front with either the wheel cylinders or the brake hoses i am thinking. I will try and work on it tonight. I will clamp off the front brake lines to see if the pedal is still good first. Could the brake hoses be collapsing? the pedal goes to the floor when i bleed the front brakes but slowly comes back up after sitting for a few minutes.







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