Another Rear Drum Dragging Thread

[stain]

After taking mine apart for the 3rd time today I am stumped also. I thought the hold down pins were too long causing the shoes to get cock-eyed but after fixing that the right drum gets to 300 degrees vs the left drum at @130 after 6 miles of normal driving.
New shoes, hardware, new rear hose, turned the factory drums myself.
At this point I am question the arc of the shoes. I checked against my original and they seemed to be a match but I am grasping at straws now.

 

[Pauly's67Polara]

@300cruiser

Has you checked the length of the brake rod going into the master cylinder? If it's too long, it will hold the brakes on slightly. Easiest way to check is to back off the nuts on the MC until it's a little loose and see if the brakes release. There may be a spec shown in the FSM as how far it needs to stick out, but we can figure that out if need be.

@Pauly's67Polara You really need to start your own thread about this. It's too confusing as both have different problems. Perhaps we can get @tallhair to split these up so both of you guys can be helped.

Hi John,
The brake rods on these new masters are not adjustable from what my buddy (a Mopar guy, car mechanic by trade and 3 A body owner), who has been helping me told me. We did separate the master from the wall twice and still happening.

Also, yes, if they can split them, that would be good. I am not good at all with sites like this. Actually, the is the only one I belong to and have ever used. I also actually couldn't find where to start a new thread to be honest and at the same time I know that admins don't want similar new threads, but I see your point that this is getting to be a separate issue. I don't even know how to ask to have that done. Again, I'm very not good at this, sorry John. Thanks for the help buddy!

 

[Pauly's67Polara]

After taking mine apart for the 3rd time today I am stumped also. I thought the hold down pins were too long causing the shoes to get cock-eyed but after fixing that the right drum gets to 300 degrees vs the left drum at @130 after 6 miles of normal driving.
New shoes, hardware, new rear hose, turned the factory drums myself.
At this point I am question the arc of the shoes. I checked against my original and they seemed to be a match but I am grasping at straws now.

Hey Stain...yup, sounds like my deal! My drums turned purple...even melted the coating on the shoe frame...lol! But the head scratcher for me on yours is that you have the factory drums. So in your case, if you can, when they are hot, lift the rear up try to turn the rear wheel. If it is hard to turn or stuck, loosen the bleeder to see if pressure is released (keep a rag on it as if can shoot everywhere)...and if the wheel is freed after doing that, its hydraulic. Just scroll up and see all of those culperates for that are posted all over this thread. If it's still stuck, it's mechanical or structural. Mine is structural/mechanical, because after cracking the bleeded, it is still stuck!

Luigi164 posted above that the new shoes he bought were getting hung up followed by the heat, even though it said they were his shoe size. He bought Wagner's and it solved his problem as they were 0,5mm less wide. I'm assuming he has 11x2.5" brakes, because Wagner doesn't sell 11x2, which is what I have. check the width vs your originals too.

 

[Pauly's67Polara]

do you have a better picture of the shoes against your windowed drum? in the pictures above the arc of the shoes doesn't look right.

I'll try to take some more shots next week. I would have to jack it up and pull the wheel again, and I don't think I'll have time, because I'm getting ready to travel for business tomorrow. When I get back buddy!

 

[Pauly's67Polara]

Yes and yes. The reason why is because drums are getting harder to find as well as other parts. PST along time ago ran a sale and I jumped on it as the price was right. No fade or anything, I do notice that below 50 mph that they grab tons better then drums. I feel it's been my best upgrade to the vehicle by far. Good Luck

Thank you Stubs...if all fails, I may just have to go that route. It's sounding better everytime I talk to ya...lol! Thank you very much!!

 

[Pauly's67Polara]

What about the master cylinder?
If the plunger doesn’t return properly, it’s going to have residual pressure and cause the same thing as you are experiencing

Yes bud...I told John too...The brake rods on these new masters are not adjustable from what my buddy (a Mopar guy, car mechanic by trade and 3 A body owner), who has been helping me told me. We did the test of separating the master from the wall twice and still happening.

 

[Davea Lux]

Yes bud...I told John too...The brake rods on these new masters are not adjustable from what my buddy (a Mopar guy, car mechanic by trade and 3 A body owner), who has been helping me told me. We did the test of separating the master from the wall twice and still happening.

Unless you bought a booster/master cylinder combo, the travel rod will have to be adjustable as that is the only way to compensate for different sized rebuilder master cylinder pistons. When you get to it, remove the master cylinder and look at the rod sticking out of the booster (travel rod) It should have an adjusting nut on the end where it fits into the master cylinder.

Dave

 

[Pauly's67Polara]

do you have a better picture of the shoes against your windowed drum? in the pictures above the arc of the shoes doesn't look right.

Unless you bought a booster/master cylinder combo, the travel rod will have to be adjustable as that is the only way to compensate for different sized rebuilder master cylinder pistons. When you get to it, remove the master cylinder and look at the rod sticking out of the booster (travel rod) It should have an adjusting nut on the end where it fits into the master cylinder.

Dave

Ok Dave...after I get back from my trip, I will check...It's a Dorman: Dorman Products - M71258

 

[Big_John]

Hi John,
The brake rods on these new masters are not adjustable from what my buddy (a Mopar guy, car mechanic by trade and 3 A body owner), who has been helping me told me. We did separate the master from the wall twice and still happening.

Also, yes, if they can split them, that would be good. I am not good at all with sites like this. Actually, the is the only one I belong to and have ever used. I also actually couldn't find where to start a new thread to be honest and at the same time I know that admins don't want similar new threads, but I see your point that this is getting to be a separate issue. I don't even know how to ask to have that done. Again, I'm very not good at this, sorry John. Thanks for the help buddy!

So you know, I was addressing 300cruiser's problem (which seems hydraulic) and not your's (which looks mechanical). Your problem looks to me to be the worn braking plates catching the shoes and not letting them retract. It sounds like you are on the right track to fix that by building those areas back up and grinding them flat.

But, since you mention it, yes, the push rod is adjustable. Download a factory service manual here: MyMopar - Mopar Forums & Information - MyMopar Tools/Reference

Go to page 5-23 and you'll see the measurement.

I also found a video about the subject that may help @300cruiser He also mentions the residual valve possibly (rarely) giving similar issues.



and the rest of his video on diagnosing hydraulics if anyone is interested.

 

[stubs300]

Thank you Stubs...if all fails, I may just have to go that route. It's sounding better everytime I talk to ya...lol! Thank you very much!!

Happy to help in any way I can!

 

[1970cat]

I'll try to take some more shots next week. I would have to jack it up and pull the wheel again, and I don't think I'll have time, because I'm getting ready to travel for business tomorrow. When I get back buddy!

no need to go out of your way. i was just curious. from the pictures it looks like the shoes are touching at the bottom and top but not the center. does the car have self adjusters?

 

[tallhair]

@300cruiser

Has you checked the length of the brake rod going into the master cylinder? If it's too long, it will hold the brakes on slightly. Easiest way to check is to back off the nuts on the MC until it's a little loose and see if the brakes release. There may be a spec shown in the FSM as how far it needs to stick out, but we can figure that out if need be.

@Pauly's67Polara You really need to start your own thread about this. It's too confusing as both have different problems. Perhaps we can get @tallhair to split these up so both of you guys can be helped.

Will do when I get on the laptop

 

[rkrochen]

no need to go out of your way. i was just curious. from the pictures it looks like the shoes are touching at the bottom and top but not the center. does the car have self adjusters?

If memory serves me correctly didn’t people grind the shoes to fit. There was a special machine to arc them to be true which prevented this from happening. Maybe with the quality of shoes we see now that is something that should be done again. I seem to remember a mobile brake and clutch shop that would come to your shop to machine the drums and fit the shoes. That’s a long time ago though.

 

[stain]

I am thinking about going the PST rear brake conversion kit at this point. Anything to make this stop better is a plus anyway.

 

[68PK21 440.6bbl]

If memory serves me correctly didn’t people grind the shoes to fit. There was a special machine to arc them to be true which prevented this from happening. Maybe with the quality of shoes we see now that is something that should be done again. I seem to remember a mobile brake and clutch shop that would come to your shop to machine the drums and fit the shoes. That’s a long time ago though.

Correct! there is/used to be a machine that would sand the friction material, goes back to the 20's/30's if memory serves. I remember watching that show "The Guild"? where they were seriously hung up on a set of linings that were binding on some pre-war antique, so much so that they were contacting the supplier to get the 'Correct' shoes. Of course this was the final leg of some restoration that was years past it's due date so to say (aren't they all?).

None of them restoration experts in the shop had a clue about this old shoe sanding machine.
I kept thinking FFS get out a belt sander and with the right touch your good to go and it's out the door!

(edit) quick search to please the pic-whores!

The abrasive: sanding vs grinding (not really a grinder IMO)

 

[68PK21 440.6bbl]

Next topic "Star' vs 'Curled' brake rivets.

 

[mr. fix it]

Next topic "Star' vs 'Curled' brake rivets.

NO!!!!!!!

 

[Big_John]

Correct! there is/used to be a machine that would sand the friction material, goes back to the 20's/30's if memory serves. I remember watching that show "The Guild"? where they were seriously hung up on a set of linings that were binding on some pre-war antique, so much so that they were contacting the supplier to get the 'Correct' shoes. Of course this was the final leg of some restoration that was years past it's due date so to say (aren't they all?).

None of them restoration experts in the shop had a clue about this old shoe sanding machine.
I kept thinking FFS get out a belt sander and with the right touch your good to go and it's out the door!

(edit) quick search to please the pic-whores!

View attachment 298884

View attachment 298885

The abrasive: sanding vs grinding (not really a grinder IMO)

View attachment 298886

I have only ever seen a couple of those in all my years. I'll bet that they started getting tossed when a couple things happened... First, most cars are using disc brakes and I'll say that a lot of young mechanics don't know anything about drum brakes. Second, it became more cost effective to replace brake drums... No oversize drums, no shoe grinding needed.

But third... Just gotta think about a machine over in the corner that ground asbestos shoes and sprayed a fine dust into the room. Not what I would want around.

I was just in a NAPA store the other day. I asked my buddy that works there if he could check the size of a questionable brake drum I had... He told me that none of the NAPA stores turned drums or rotors any more. He couldn't even tell me a place that did it on a regular basis.

 

[Davea Lux]

I have only ever seen a couple of those in all my years. I'll bet that they started getting tossed when a couple things happened... First, most cars are using disc brakes and I'll say that a lot of young mechanics don't know anything about drum brakes. Second, it became more cost effective to replace brake drums... No oversize drums, no shoe grinding needed.

But third... Just gotta think about a machine over in the corner that ground asbestos shoes and sprayed a fine dust into the room. Not what I would want around.

I was just in a NAPA store the other day. I asked my buddy that works there if he could check the size of a questionable brake drum I had... He told me that none of the NAPA stores turned drums or rotors any more. He couldn't even tell me a place that did it on a regular basis.

O'Reilys still did it the last time I checked. At $25 a drum it is not really worth fooling with.

Dave

 

[Big_John]

O'Reilys still did it the last time I checked. At $25 a drum it is not really worth fooling with.

Dave

They just opened an O'Reilly's here about a month ago. First one in the area and I haven't been in there yet. I'll have to check.