2nevets Posted December 10, 2019 Share Posted December 10, 2019 Stuck here-my dilemma when I hook up all the brake lines to the junction box-no brake pedal-when I disconnect the rears-I get a perfect pedal-All I did at first was adjust the external brakes with the large nuts on the backing plates and then wham all goes south-there is no air in the lines trust me-so I replaced-master-all wheel cylinders- hoses -steel lines-junction block-I cant get a damn pedal unless I bypass the rears.shoes are fine-from what I have read its all in the adjustments because it appears others with the same era car have had the same issue.makes no sense-I can adjust so the drum wont turn and still no pedal Any old timers out there? many thanks Link to comment Share on other sites More sharing options...
trini Posted December 10, 2019 Share Posted December 10, 2019 Use the same analogy used in trying to find a stubborn electrical short by isolating the different circuits. Make a plug/cap to block the back line at the junction block and bleed the front. If the front turns out good then there is a problem with the rear section . could be a blocked line some where especially in old hoses. Disconnect lines and blow with air, assuming , as you said, the cylinders are replaced with new ones. A lot has to do with patience. remove a bleeder screw and plug the hole with you finger. Get an assistant to pump the pedal and see if the fluid is coming through. Also check the distribution block. Another "fault " could be the adjusting cam (big nut, eccentric) could go over the high point and drop back right down to zero. I am not saying that is the cause but it is a possibility worth looking into. The correct way to adjust the linings is to adjust the eccentrics using a screw driver with the big nuts loose until the wheel is locked and then back off to a slight drag then lock down the big nut. THOSE BRAKES LINING ARE INTERNAL , NOT EXTERNAL. Link to comment Share on other sites More sharing options...
JACK M Posted December 10, 2019 Share Posted December 10, 2019 Make sure that the piston depth is the same from your old wheel cyls. to the new ones. If the pistons are deeper the little rod that goes in there wont push the piston far enough to get a pedal. I have seen this on old Mopars. Link to comment Share on other sites More sharing options...
2nevets Posted December 10, 2019 Author Share Posted December 10, 2019 (edited) 16 hours ago, trini said: Use the same analogy used in trying to find a stubborn electrical short by isolating the different circuits. Make a plug/cap to block the back line at the junction block and bleed the front. If the front turns out good then there is a problem with the rear section . could be a blocked line some where especially in old hoses. Disconnect lines and blow with air, assuming , as you said, the cylinders are replaced with new ones. A lot has to do with patience. remove a bleeder screw and plug the hole with you finger. Get an assistant to pump the pedal and see if the fluid is coming through. Also check the distribution block. Another "fault " could be the adjusting cam (big nut, eccentric) could go over the high point and drop back right down to zero. I am not saying that is the cause but it is a possibility worth looking into. The correct way to adjust the linings is to adjust the eccentrics using a screw driver with the big nuts loose until the wheel is locked and then back off to a slight drag then lock down the big nut. THOSE BRAKES LINING ARE INTERNAL , NOT EXTERNAL. All new brake goodies-I already isolated the rears and the brakes work perfect-once I hookup the rears all goes south-what do you mean internal not external? Edited December 11, 2019 by 2nevets (see edit history) Link to comment Share on other sites More sharing options...
keiser31 Posted December 10, 2019 Share Posted December 10, 2019 1 minute ago, 2nevets said: All new brakes goodies-I already isolated the rears and the brakes work perfect-once I hookup the rears all goes south-what do you mean internal not external? Internal are inside the drum and pushing toward the outside as your do. External wrap around the drum on the outside and push inward as in the older 1920s stuff. Link to comment Share on other sites More sharing options...
2nevets Posted December 11, 2019 Author Share Posted December 11, 2019 (edited) Im thinking master cylinder maybe? I pulled the drums and had my son pump the brakes and only one side of the shoe would expand-and that was driver and passenger side-I even clamped the wheel cylinders so the cups would not expand still nothing-now I would think that if the internals of the wheel cylinder could not move I would have a pedal-however when I isolate the front from the rear I have a rock hard pedal-could it be I have a defective chinese piece of &^$^&&^ master? I bled the lines so I know its not that Edited December 11, 2019 by 2nevets (see edit history) Link to comment Share on other sites More sharing options...
keiser31 Posted December 11, 2019 Share Posted December 11, 2019 (edited) Did you bench bleed the master cylinder first? Sometimes, that is a must. Edited December 11, 2019 by keiser31 (see edit history) Link to comment Share on other sites More sharing options...
2nevets Posted December 11, 2019 Author Share Posted December 11, 2019 4 minutes ago, keiser31 said: Did you bench bleed the master cylinder first? Sometimes, that is a must. absolutely 1 Link to comment Share on other sites More sharing options...
19tom40 Posted December 11, 2019 Share Posted December 11, 2019 If you have a stock type single master cylinder and you block off the rear brakes to get a good pedal, then the master must be good. Check for a blockage in the line going to the rear brake 4 hours ago, 2nevets said: Im thinking master cylinder maybe? I pulled the drums and had my son pump the brakes and only one side of the shoe would expand-and that was driver and passenger side-I even clamped the wheel cylinders so the cups would not expand still nothing-now I would think that if the internals of the wheel cylinder could not move I would have a pedal-however when I isolate the front from the rear I have a rock hard pedal-could it be I have a defective chinese piece of &^$^&&^ master? I bled the lines so I know its not that If only the front shoe or the rear shoe moves, then the pistons or the rods are not correct for the wheel cylinder, as Jack M posted. If they are not the correct size, the master cylinder rod will reach the end of its travel before the shoes can expand. Link to comment Share on other sites More sharing options...
2nevets Posted December 11, 2019 Author Share Posted December 11, 2019 (edited) the shoe goes directly into the cylinders-there are no pins-all new lines to the rear-plenty of fluid when I bleed the rears- Edited December 11, 2019 by 2nevets (see edit history) Link to comment Share on other sites More sharing options...
keiser31 Posted December 11, 2019 Share Posted December 11, 2019 Did you see my last answer on the H.A.M.B.? Link to comment Share on other sites More sharing options...
trini Posted December 11, 2019 Share Posted December 11, 2019 With the drum ON loosen the big nut on the eccentric bolt and turn right up until the wheel locks up. IF IT DOES NOT THEN IT NEEDS SHOE RELINED. relining those shoes on old drums , shoes should be arched for best results. If the shoes are not moving when pedal is pressed ,but lots of fluid coming out of the bleeder then obviously the wheel cylinders are duds. Link to comment Share on other sites More sharing options...
2nevets Posted December 11, 2019 Author Share Posted December 11, 2019 my guess is wheel cylinders-I disconnect the line to the cylinders pedal is up top-I connect them pedal sinks these are new cylinders-thoughts? Link to comment Share on other sites More sharing options...
19tom40 Posted December 11, 2019 Share Posted December 11, 2019 Your guess is the same as mine and Jack M's. The shoes are not contacting the pistons, so you were sold cylinders that are not correct for your car. Link to comment Share on other sites More sharing options...
trini Posted December 12, 2019 Share Posted December 12, 2019 Obviously the rear cylinders are not working. Pistons may be stuck. THIS IS WHAT I WOULD DO. remove one cylinder, remove the piston and rubbers ,cleanup and reinstall the pistons and rubber. hold it in a vize and use shop air to see if pistons are moving. Pistons could be seized: rubbers could be swollen. Alumunium cylinders are famous for corrosion and seizing. If you are sure the cylinders are correct have them lined with stainless steel. Link to comment Share on other sites More sharing options...
dalef62 Posted December 12, 2019 Share Posted December 12, 2019 If when you connect the back brakes up and you loose pedal pressure then the wheel cylinders are moving if there is no air in the lines. If the wheel cylinders are froze up you would still have pressure at the pedal, just like when you take the rears out of the system. I would guess that either the wheel cylinders are not contacting the finger on the shoe, or the shoes are not contacting the drums. Is this a single bowl cylinder? Link to comment Share on other sites More sharing options...
JACK M Posted December 12, 2019 Share Posted December 12, 2019 OK, so take the rear drums off, Take the shoes off, get a c-clap or similar and cover the pistons so that they cant pop out of the cylinders. You might even cobble spacers of some kind so you are sure the pistons have a solid stop. You will have to do both sides at the same time. If this makes sense then you should be able to figure gist of what I am trying to explain. Link to comment Share on other sites More sharing options...
2nevets Posted December 12, 2019 Author Share Posted December 12, 2019 That's exactly what I did and It held 1 hour ago, JACK M said: OK, so take the rear drums off, Take the shoes off, get a c-clap or similar and cover the pistons so that they cant pop out of the cylinders. You might even cobble spacers of some kind so you are sure the pistons have a solid stop. You will have to do both sides at the same time. If this makes sense then you should be able to figure gist of what I am trying to explain. held the pressure Link to comment Share on other sites More sharing options...
trini Posted December 12, 2019 Share Posted December 12, 2019 dalef62 you are on the ball. You said it like I did but with fewer words. Probable the shoes missed the slotted pins in the cylinder. Sum ting wong in there. Link to comment Share on other sites More sharing options...
Guest Posted December 12, 2019 Share Posted December 12, 2019 Reading your troubles makes me so happy I have mechanically operated brakes. I do wish you good luck in solving your conundrum. Link to comment Share on other sites More sharing options...
hchris Posted December 13, 2019 Share Posted December 13, 2019 Have you centralised the shoes ? Chrysler/Dodge/Plymouth brakes require that you get the shoes concentric in the drum before anything else, it's complicated if you don't have the right tool, plenty written up about it. Link to comment Share on other sites More sharing options...
trini Posted December 13, 2019 Share Posted December 13, 2019 hchris , you are on the ball.I worked on old vehicles where I had to send the shoes to be fitted with oversize linings which then had to be arched to fit the drums. Brakes do not work by magic but by mechanical and hydraulic means. Very easy to diagnose. and repair. It is # 1 safety issue.NO COMPROMISE. Link to comment Share on other sites More sharing options...
JACK M Posted December 13, 2019 Share Posted December 13, 2019 19 hours ago, 2nevets said: That's exactly what I did and It held held the pressure Pretty much sums it up to a problem with the shoes. Link to comment Share on other sites More sharing options...
2nevets Posted December 13, 2019 Author Share Posted December 13, 2019 6 hours ago, JACK M said: Pretty much sums it up to a problem with the shoes. I need to pay attention to what I write It didnt hold sorry New cylinders going on tomorrow Link to comment Share on other sites More sharing options...
m-mman Posted December 14, 2019 Share Posted December 14, 2019 You describe a sudden problem. If there is no leaking fluid to be seen, (it has to drip out somewhere) then the hydraulics should be good. My thought - Check your lock nut. I'm Not an expert on Desotos but a similar thing happened to my friend with a 51 Kaiser. He adjusted the brakes (previously low pedal) drove it around the block, had a good pedal for a few stops then the pedal almost goes to the floor. The cam type adjustment for the shoes that is accessible on the backing plate is held in place with a lock nut. He loosened the locknut, adjusted the wheel for a slight drag and tightened the locknut BUT NOT ENOUGH. As he drove it, the cam lost the adjustment and no pedal. He jacked it up again, readjusted for slight drag and then tightened the heck out of the locknut. no more problem. Link to comment Share on other sites More sharing options...
c49er Posted December 14, 2019 Share Posted December 14, 2019 19 hours ago, hchris said: Have you centralised the shoes ? Chrysler/Dodge/Plymouth brakes require that you get the shoes concentric in the drum before anything else, it's complicated if you don't have the right tool, plenty written up about it. If needed and always is on a quality brake job reline and new hydraulics.. Reline the shoes using lining material...... .180"thickness up to .030" oversize drums....... .200" for up to .060" over size drums ( too thick of lining on .030" and under drums and you won't get the drum on! The shoes have to fit even to the drum or the shoes twist....low pedal! Arc each set (2) of shoes to fit match each drum...find someone to do it... a big truck shop or brake rebuilder. Do this step! Move the shoes up/down to center them in the drum using the lower anchor bolts ....and them adjust them outward to lightly rub the drums for the last adjustment ( 1-1/16" hex bolt) in the middle of the backing plate. one for each shoe. READ your factory shop manual !!! Pictures showing arcing of MoPar shoes and doing a major adjustments with the ammco 1750 and the miller factory tool set.... pictures showing shoes that the linings don't match the drum at all. Also the tools to do the job quickly and correctly. But not available. Others can chime in on other cheater ways to get the shoes to fit the drums enough for wear in. Link to comment Share on other sites More sharing options...
hchris Posted December 14, 2019 Share Posted December 14, 2019 Plenty of home made cheap and effetive centralising tools out there, do a search. Link to comment Share on other sites More sharing options...
keiser31 Posted December 14, 2019 Share Posted December 14, 2019 (edited) 8 hours ago, hchris said: Plenty of home made cheap and effetive centralising tools out there, do a search. Here is an idea.... Edited December 14, 2019 by keiser31 (see edit history) Link to comment Share on other sites More sharing options...
2nevets Posted December 14, 2019 Author Share Posted December 14, 2019 Put the new cylinders on and all is good I cant believe I would have defective cylinders 2 1 1 Link to comment Share on other sites More sharing options...
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