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Power Drum to Disc Brake Swap Question

Mr. PNW

Well-Known Member
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Location
WA State
After many years of dealing with health issues, I’m finally starting to look at working on my Coronet again. The car is a driver and I want to get it road worthy (safe) this summer and then do winter projects on sections of the car so it’s not down during the summer months (being a vert in WA state).

There are two main areas to start with, brakes and radiator. Brakes is number one.
My car is a “H code” 383/4bbl/auto with factory power 11” drums on all four. I have a complete set of 74 A-body disc brakes from upper arms down to spindles. I’ve read numerous article from Mopar Action, Mopar Muscle etc but those are from at least 8 years ago, probably more.

So what is the most popular brake swap, with parts list/numbers, being done today?

Are we still doing the A-body spindles with Cordoba rotors, calipers/brackets combo? What about my power booster, is it compatible, do I just need to add a proportioning valve on the rear line? If so I’ll probably send it to Booster Dewie for a restore.

Thanks for any and all comments and advice.

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After many years of dealing with health issues, I’m finally starting to look at working on my Coronet again. The car is a driver and I want to get it road worthy (safe) this summer and then do winter projects on sections of the car so it’s not down during the summer months (being a vert in WA state).

There are two main areas to start with, brakes and radiator. Brakes is number one.
My car is a “G code” 383/4bbl/auto with factory power 11” drums on all four. I have a complete set of 74 A-body disc brakes from upper arms down to spindles. I’ve read numerous article from Mopar Action, Mopar Muscle etc but those are from at least 8 years ago, probably more.

So what is the most popular brake swap, with parts list/numbers, being done today?

Are we still doing the A-body spindles with Cordoba rotors, calipers/brackets combo? What about my power booster, is it compatible, do I just need to add a proportioning valve on the rear line? If so I’ll probably send it to Booster Dewie for a restore.

Thanks for any and all comments and advice.

View attachment 1101720 View attachment 1101721 View attachment 1101722
I would recommend the 73-76 A body spindles with the 11 3/4 Cordoba rotors like you were saying. Since the A body spindles have dried up alot of people are using the slightly taller 73 and up FMJ spindles instead and seem to have good luck with them. I believe Dr Diff has reproduction A body type spindles if you can't find any. Some additional info on calipers, I believe the 75 and older A body calipers had smaller 2.60" bores and in 76 they went to the larger 2.75" bore caliper that bigger bodied cars used.
 
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Send a email to Dr Diff. Plug in play conversion kit.
 
I would recommend the 73-76 A body spindles with the 11 3/4 Cordoba rotors like you were saying. Since the A body spindles have dried up alot of people are using the slightly taller 73 and up FMJ spindles instead and seem to have good luck with them. I believe Dr Diff has reproduction A body type spindles if you can't find any. Some additional info on calipers, I believe the 75 and older A body calipers had smaller 2.60" bores and in 76 they went to the larger 2.75" bore caliper that bigger bodied cars used.

I found the article on the a-body spindles. I already have a complete set of upper arms to spindles from a 74 Dart.
http://arengineering.com/tech/mopar-musclecar-brake-upgrade/
 
I already have the knuckles, shields, and hardware from a 74 Dart.

The disc-o-tech article recommends the PIN type bracket and calipers.
https://www.moparaction.com/2016/03/16/disc-main/
https://www.allpar.com/threads/brake-upgrade-parts-list.237037/
Caliper Adapters for '76-'78 B-body (Chrysler pn 3880557) Pin-Type (not slider)

It simply says..."the “slider” type calipers, which we don’t like as well as the K-H pin type (they require more maintenance)"
They say if all you can find is the slider style get those. I see the slider brackets are reproduced now (Dr. Diff).

So what's the general thought today on these two style of calipers? If the PIN style is preferred, is anyone making the PIN style bracket?

--------------------------------------------------------------------------------------
NAPA and O'Reilly both carries the PIN style calipers for the 70-72 B-Body.
https://www.napaonline.com/en/p/ACA...+-+Front&impressionRank=1&keywordInput=brakes
https://www.napaonline.com/en/p/ACA...+-+Front&impressionRank=4&keywordInput=brakes
https://www.oreillyauto.com/detail/...omotive-car-1972-dodge-coronet?q=brakes&pos=8
https://www.oreillyauto.com/detail/...omotive-car-1972-dodge-coronet?q=brakes&pos=9
And they both have the 11.75 rotors.
https://www.napaonline.com/en/p/NBO...+-+Front&impressionRank=1&keywordInput=brakes
https://www.oreillyauto.com/detail/...otive-car-1979-chrysler-cordoba?q=rotor&pos=0
 
The pin caliper brackets most of the time are $300+ for the large rotors. I'd buy a kit.
 
After many years of dealing with health issues, I’m finally starting to look at working on my Coronet again. The car is a driver and I want to get it road worthy (safe) this summer and then do winter projects on sections of the car so it’s not down during the summer months (being a vert in WA state).

There are two main areas to start with, brakes and radiator. Brakes is number one.
My car is a “G code” 383/4bbl/auto with factory power 11” drums on all four. I have a complete set of 74 A-body disc brakes from upper arms down to spindles. I’ve read numerous article from Mopar Action, Mopar Muscle etc but those are from at least 8 years ago, probably more.

So what is the most popular brake swap, with parts list/numbers, being done today?

Are we still doing the A-body spindles with Cordoba rotors, calipers/brackets combo? What about my power booster, is it compatible, do I just need to add a proportioning valve on the rear line? If so I’ll probably send it to Booster Dewie for a restore.

Thanks for any and all comments and advice.

View attachment 1101720 View attachment 1101721 View attachment 1101722
That is a very nice looking car. Know you enjoy it and what you are doing will make it that much nicer to drive. Good luck on the brakes. Also all the other up grades you are doing.
 
What about my power booster, is it compatible, do I just need to add a proportioning valve on the rear line? If so I’ll probably send it to Booster Dewie for a restore.
The drum booster will not provide enough boost for the discs. You will need to upgrade to a dual diaphragm booster.
 
The drum booster will not provide enough boost for the discs. You will need to upgrade to a dual diaphragm booster.

Thanks, so we are talking about the same booster that came with disc brakes in 68 or something newer? Is the current drum master cylinder OK or is that different part too? My drum master is NOS.
 
Thanks, so we are talking about the same booster that came with disc brakes in 68 or something newer? Is the current drum master cylinder OK or is that different part too? My drum master is NOS.
Drum brake boosters are single diaphragm with not enough boost. Drum master cylinders do not have a large enough bowl for the disc brakes so yes, they are different. Don't waste your money getting your drum brake booster rebuilt like I did. My 68 Charger had power drum brakes and I sent the booster out for rebuild when I upgraded to front discs. After learning the single diaphragm wouldn't stop the car properly I ended up getting a dual diaphragm unit from Pirate Jack. The OEM boosters are getting hard to find but still out there. Disc brakes in B bodies were pretty rare in 68. I would call Cass at Dr Differential with questions on which master you need. He may have a booster for you also. 406 883 4772
If you end up getting a new dual diaphragm booster from Pirate Jack or most any other, be aware they are all made in China and the boot that goes through the firewall is larger than the original and will require a little enlarging with a dremmel tool or file. Everything under the dash will bolt up with no problem.
 
Ok....so why is it that a manual disc brake system (no power assist) works well and another doesn't? Bought a 74 D100 back in 76 with 40k miles on it and was surprised to see disc brakes on the front but it stopped just fine with a manual set up. Pulled a 5000 lb trailer with it once and yeah, it didn't like it but it stopped that sucker 'ok' with of course, more pedal effort. The truck had a harder time getting it rolling than stopping it!
 
NEEDED
#6 Caliper adapters two p/n 3880557, 1976-78 B-body pin-type calipers for 11.75 Cordoba rotors.
F45F53B0-F3A5-4774-A6BD-A5B007A3193F.png
 
Member @chignikred is in my neck of the woods and might have a pair but his inbox is full and I can’t leave a message, so hopefully he gets this.
 
Dr Diff all the way!

I agree having a vert here in WA can be interesting, I have thought about getting something convertible for a while but just never have, I am down near Olympia.
 
I work in
Dr Diff all the way!

I agree having a vert here in WA can be interesting, I have thought about getting something convertible for a while but just never have, I am down near Olympia.

I’ve been emailing Dr. Diff after he was first mentioned in the thread. I’ll be getting one of the boosters, mast cyl and the updated proportioning value to replace my drum versions.
If I can’t find the brackets I will go with his slider ones.
 
If this is something you are hot on, call Cass (Dr Diff), I have found that this is the best way to get information with him as he can be a little slow in responding to emails.

I see you wrote "I work in"... not sure what they means,
 
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