Brakes Guru needed!!

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chrissock

chrissock

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This is going to get confusing so stay with me. I have a 71 Dart Swinger with a /6 and a 7 1/4 rear. Drum Brakes all around. I'm upgrading the complete drive train and swapping in an 8 3/4 Sure grip. I bought the rear second hand. It was installed in a Barracuda so I thought it was an a body rear. I was wrong. Upon further inspection it appears to be a B body rear. It came with 11" rear drums already installed on the axle. I am rebuilding it all now and I want to redo the brakes.

Now my issues. The drums measure 3" wide. The shoes measure 2.5 inches wide. I have tried searching for a way to tell if they are 2.5 or 3" brakes but I am more confused after reading for a bit. I found both listings on the Napa site just need to confirm which i need.

Second, I need new parking brake cables. Do i order them for an a body or for the car the rear was out of? Will the ones in the car work?

lastly, I am upgrading the front breaks to a Willwood disc setup. I assume I need an adjustable proportioning valve to make all this work correct?

Any help would be greatly appreciated!!
 
chrissock said:
This is going to get confusing so stay with me. I have a 71 Dart Swinger with a /6 and a 7 1/4 rear. Drum Brakes all around. I'm upgrading the complete drive train and swapping in an 8 3/4 Sure grip. I bought the rear second hand. It was installed in a Barracuda so I thought it was an a body rear. I was wrong. Upon further inspection it appears to be a B body rear. It came with 11" rear drums already installed on the axle. I am rebuilding it all now and I want to redo the brakes.

Now my issues. The drums measure 3" wide. The shoes measure 2.5 inches wide. I have tried searching for a way to tell if they are 2.5 or 3" brakes but I am more confused after reading for a bit. I found both listings on the Napa site just need to confirm which i need.

Second, I need new parking brake cables. Do i order them for an a body or for the car the rear was out of? Will the ones in the car work?

lastly, I am upgrading the front breaks to a Willwood disc setup. I assume I need an adjustable proportioning valve to make all this work correct?

Any help would be greatly appreciated!!
Click to expand...

Brakes 1.JPG


Brakes 2.JPG
 
chrissock said:
Second, I need new parking brake cables. Do i order them for an a body or for the car the rear was out of? Will the ones in the car work?

!
Click to expand...

The ones in the car will work or order new for the A Body
 
Toss the Chinese menu rear drum ****, and get some complete f/m body rear assemblies off a car at the salvage yard. with large bolt pattern axles that have the proper offset built in, you have everything you need AND you know where it's from. Parking cables hook up and it's Bolt on.

Do the big disc conversion on the front with late A spindles (I will neither confirm nor deny suitability of the fmj spindles) and you're big bolt pattern all around with the best wheel choices, and most common parts.

In my opinion.
 
Excellent choice on the Wilwood set up switched my duster over to it 3 years ago WELL worth the money spent,over anything the factory made thats for sure..much more stopping power then any factory ****, took 35 pounds off the front end and they look awsume..
 
First of all, A body cables will work. Second of all, you'd be better off IMO to get a F/J/M rear assembly for bbp axles. That's what we did with the duster. Just my 2 cents
 
jos51700 said:
Toss the Chinese menu rear drum ****, and get some complete f/m body rear assemblies off a car at the salvage yard. with large bolt pattern axles that have the proper offset built in, you have everything you need AND you know where it's from. Parking cables hook up and it's Bolt on.

Do the big disc conversion on the front with late A spindles (I will neither confirm nor deny suitability of the fmj spindles) and you're big bolt pattern all around with the best wheel choices, and most common parts.

In my opinion.
Click to expand...

I really feel like the rear 11" setup is all B body stuff just need to confirm 2.5 or 3" setup. After digging around in some pictures I am fairly confident its a 2.5 set up. So that is easy. The rear is a BBP rear so I don't need to change anything just a quick rebuild.

Are you saying to change the front spindles and then do a Willwood kit for a later A body?
 
BigBlockMopar28 said:
First of all, A body cables will work. Second of all, you'd be better off IMO to get a F/J/M rear assembly for bbp axles. That's what we did with the duster. Just my 2 cents
Click to expand...

The rear already is going to convert me to a BBP in the rear. Then the front will be converted when I do the Willwood kit.
 
chrissock said:
I really feel like the rear 11" setup is all B body stuff just need to confirm 2.5 or 3" setup. After digging around in some pictures I am fairly confident its a 2.5 set up. So that is easy. The rear is a BBP rear so I don't need to change anything just a quick rebuild.

Are you saying to change the front spindles and then do a Willwood kit for a later A body?
Click to expand...

I can't comment on the Wilwood setup. I'm completely unfamiliar with it.

Your rear axle is the reason I make a parts list for all my custom stuff. There's no telling what's really in there once I kick off this mudrock and leave my garbage to some unfortunate schlub.
 
If you use the later (73-76) A-body disc spindles, you can use 73-76 factory disc brake parts instead of a conversion kit. That will give you the large bolt pattern on the front wheels and might save a few bucks.
 
When you say installed in a barracuda was the car actual driving or was it just sitting under it? A b-body rear end is wider than an a-body, so unless someone has narrowed it your going to have to do that...
 
You need to measure that rear. If it's a B body rear, even if it fits, you will probably have trouble finding the right offset wheels.
 
You don't have to change the spindles with the Wilwoods (another reason to switch to them)and they come with the hub drilled and threaded for small or big bolt pattern,unlike the factory crap!!
 
Nothing wrong with the 11" drums, I run 11x2.5" drums on my Duster and my Challenger, and have a set installed on my '71 Dart GT as well. If you measure the offset on the backing plates that will tell you if you have a 11x2.5" or 11x3" backing plates, the BBP axle offset was the same so the backing plate offset is different for the different width 11" drums.

To measure the backing plate offset you want to set the backing plate flat on a bench. You'll need to hang the bottom 1/3 of the backing plate off the edge of the bench so that the mounts for the e-brake cables don't keep the backing plate from sitting flat. It isn't much, but they do change the measurement. Then, measure from the bench to the top of the backing plate through the center hole (for the axle) in the backing plate.

If you get ~1.75", you have 11x2.5" plates. If you get ~1.5", you have 11x2" plates. Those I know for sure, as I've measured them. I don't have a set of 11x3" backing plates, but the math would say you'd get ~2" measuring them as I described above.

Like this
img_2848-jpg-1714942228-jpg.1715019208


If you have a B body rear make sure you measure the perches center to center, if it's 43" they were moved to the A-body width, if you get 44" they're still B-body width. People have been known to do shade-tree crap like slotting the holes in the perches, or just using the perches to pull the springs out without doing anything. Both will result in less than great results, the only way to do it right is to remove and weld on a new set of perches at the right perch spacing.

You'll also want to figure out which B body rear axle you have, there are a bunch of different widths, and some will work a lot better than others, especially on a Swinger. You'll need more backspacing on your rear wheels to make any of them work, but some of them would probably require custom rims. Barracuda's are a little wider in the wheel wells, so, a wider rear axle isn't as much of an issue as it can be on a Swinger. There's a sticky with all the rear axle measurements here http://www.forabodiesonly.com/mopar/threads/an-accurate-8-3-4-rear-axle-width-list.365494/. For a Swinger your best bet would be a 65-67 B rear. A 68-70 would work, but only with high offset wheels and you won't find those in 15's unless you go custom.

For the front brakes you don't need the SBP since your rear axle is already BBP, and if you had 9" drums you want to get rid of those weaker spindles/lower ball joints anyway.
 
72bluNblu said:
Nothing wrong with the 11" drums, I run 11x2.5" drums on my Duster and my Challenger, and have a set installed on my '71 Dart GT as well. If you measure the offset on the backing plates that will tell you if you have a 11x2.5" or 11x3" backing plates, the BBP axle offset was the same so the backing plate offset is different for the different width 11" drums.

To measure the backing plate offset you want to set the backing plate flat on a bench. You'll need to hang the bottom 1/3 of the backing plate off the edge of the bench so that the mounts for the e-brake cables don't keep the backing plate from sitting flat. It isn't much, but they do change the measurement. Then, measure from the bench to the top of the backing plate through the center hole (for the axle) in the backing plate.

If you get ~1.75", you have 11x2.5" plates. If you get ~1.5", you have 11x2" plates. Those I know for sure, as I've measured them. I don't have a set of 11x3" backing plates, but the math would say you'd get ~2" measuring them as I described above.

Like this
img_2848-jpg-1714942228-jpg.jpg


If you have a B body rear make sure you measure the perches center to center, if it's 43" they were moved to the A-body width, if you get 44" they're still B-body width. People have been known to do shade-tree crap like slotting the holes in the perches, or just using the perches to pull the springs out without doing anything. Both will result in less than great results, the only way to do it right is to remove and weld on a new set of perches at the right perch spacing.

You'll also want to figure out which B body rear axle you have, there are a bunch of different widths, and some will work a lot better than others, especially on a Swinger. You'll need more backspacing on your rear wheels to make any of them work, but some of them would probably require custom rims. Barracuda's are a little wider in the wheel wells, so, a wider rear axle isn't as much of an issue as it can be on a Swinger. There's a sticky with all the rear axle measurements here An accurate 8 3/4" rear axle width list. For a Swinger your best bet would be a 65-67 B rear. A 68-70 would work, but only with high offset wheels and you won't find those in 15's unless you go custom.

For the front brakes you don't need the SBP since your rear axle is already BBP, and if you had 9" drums you want to get rid of those weaker spindles/lower ball joints anyway.
Click to expand...

This is exactly what I was looking for!! Thank you! The rear spring perches were indeed slotted! I cut them off and moved the new ones in to 42 to account for the dr diff offset shackles. I have a set of high offset 15 inch wheels from a pickup that I am currently running with spacers. This rear is perfect without the spacers. I plan to do the willwood set up on front. Figuring I need an adjustable proportion Valve to make that all work correctly. Thanks again for a great response!!

IMG_3403.JPG


IMG_3408.JPG
 
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