Brake conversion 73 duster

-
max hurlbut

max hurlbut

Member
Joined
Apr 9, 2020
Messages
7
Reaction score
2
Location
Uk
Hello. Looking to get some input
Complete newby to old assemblies, but quite mechanically minded.

So anyway. Can someone please confirm? The spindle bolts to the steering gear, ball joint etc.
Over the spindle goes the 2 tapered wheel bearings?
Then the rotor itself sits over the bearings and gets bolted into place through the middle?

If that's the case, could I then find a rotor that fits my drum spindle, fabricate a backing plate and caliper holder and essentially MAKE a brake conversion kit rather than buying one.

How do I test a good fit rotor to the spindle, and would the caliper bracket be made out of hardened steel, or would mild / stainless be enough?

Would greatly Appreciate any help or ideas
 
I thought 73 was the year the all started coming with disk brakes.
 
'73-6 6cyl. A-bodies could still have drum brakes. I wouldn't try messing around piecing a disc brake setup together. Safety being the main issue, but, the shear hassle trying to get everything to play well together is another reason. Get either a stock disc brake setup (my personal choice) or a kit from a known vendor. At least you currently have the large ball joint upper control arms, so, that won't be needed to be sourced.
 
cudamark said:
'73-6 6cyl. A-bodies could still have drum brakes. I wouldn't try messing around piecing a disc brake setup together. Safety being the main issue, but, the shear hassle trying to get everything to play well together is another reason. Get either a stock disc brake setup (my personal choice) or a kit from a known vendor. At least you currently have the large ball joint upper control arms, so, that won't be needed to be sourced.
Click to expand...
I forgot about slant cars. Heres all the stuff you'll need.
https://www.doctordiff.com/brakes/front/
 
73-76 A bodies with 318's could also have drums on all 4 corners, and small bolt pattern.
 
I dont know if the later model front drum was still swegged to a hub at the lug studs or If they were hub and drum in 1 casting. Piece milling a disc brake assembly is exactly what Scarebird does. They once used chevy celebrity parts but I think they now use toyota parts.
 
Demonic said:
73-76 A bodies with 318's could also have drums on all 4 corners, and small bolt pattern.
Click to expand...

Disk brakes were standard on all 318's starting in '73. They were even standard for a /6 if you ordered a sure grip. Right in the dealer manual. Hamtramck-historical has the Dealership data books posted, these are links and excerpts from the Dodge book but it's the same in the Plymouth book as well. For all the '73 up cars. In mid-'76 all of them went BBP disks due to federal safety laws.

https://www.hamtramck-historical.com/images/dealerships/DealershipDataBook/1973/73_Dart0014.jpg
Screen Shot 2020-06-25 at 4.19.26 PM.png



https://www.hamtramck-historical.com/images/dealerships/DealershipDataBook/1973/73_Dart0019.jpg
Screen Shot 2020-06-25 at 4.18.19 PM.png


cudamark said:
Never seen a factory V8 without disc brakes.
Click to expand...

At least on a '73+ car it would have needed to have been a special order, if it was available at all. It's Ma Mopar so I'm not sure I'd say "never". But drag race guys used to swap out the disks for drums, especially early on. They thought the rolling resistance from the pad knock back on the disks would slow them down.
 
max hurlbut said:
Hello. Looking to get some input
Complete newby to old assemblies, but quite mechanically minded.

So anyway. Can someone please confirm? The spindle bolts to the steering gear, ball joint etc.
Over the spindle goes the 2 tapered wheel bearings?
Then the rotor itself sits over the bearings and gets bolted into place through the middle?

If that's the case, could I then find a rotor that fits my drum spindle, fabricate a backing plate and caliper holder and essentially MAKE a brake conversion kit rather than buying one.

How do I test a good fit rotor to the spindle, and would the caliper bracket be made out of hardened steel, or would mild / stainless be enough?

Would greatly Appreciate any help or ideas
Click to expand...

Yes your idea will work just fine. I made disc brake conversion kits for many years using the drum brake knuckles. The drum brake knuckles on a '73 A body use the same bearings as the disc brake cars so a 11.75 rotor will slide right on there. Then you just build a bracket to hold a caliper. I used Viper calipers when I was building my kits. I'll attach a picture. Of course, it would be less work to just buy a kit from Doctor Diff. He sells the same thing that I used to make but he has refined it a bit.
AR011_bkt.jpg
 
Here is the Doctor Diff kit. It fits the late model drum knuckles (big bearing spindles) and uses a Viper caliper with a Dodge 1/2 ton pickup rotor. It is a nice setup that is a little unique. You'll definitely get some attention at the car shows with the Viper calipers. I ran this setup on my car for a while before I stepped up to bigger wheels and bigger rotors.

Viper Caliper Mounting Brackets for Mopar DRUM Knuckles
 
The kit I designed used an 11.75 cop car rotor, Doctor Diff uses a 1/2 ton rotor with a bearing spacer to make up the difference. His design is a little better since the pickup rotor is 1.25 wide. The Viper caliper needs a 1.250 thick rotor and it is nice to have the extra beef in the rotor. My kit used pad spacers to take up the extra distance but I think running a 1.250 rotor is the better way to go. Good luck and have fun. Either build your own kit or buy the one from Doctor Diff. I've been building my own brake kits for more than 20 years. When I first started building brake kits nobody had big brakes on a Mopar.
AR011.jpg
 
AndyF said:
The kit I designed used an 11.75 cop car rotor, Doctor Diff uses a 1/2 ton rotor with a bearing spacer to make up the difference. His design is a little better since the pickup rotor is 1.25 wide. The Viper caliper needs a 1.250 thick rotor and it is nice to have the extra beef in the rotor. My kit used pad spacers to take up the extra distance but I think running a 1.250 rotor is the better way to go. Good luck and have fun. Either build your own kit or buy the one from Doctor Diff. I've been building my own brake kits for more than 20 years. When I first started building brake kits nobody had big brakes on a Mopar.
View attachment 1715551389
Click to expand...


Thankyou! That's exactly what I was looking for
 
You must log in or register to reply here.
-

Back
Top