70 Challenger front drum to disc conversion

[miketyler]

Happy Holidays all -

I want to convert the drum brakes on my 70 Challenger to discs as economically as possible. Would really like to put the large OEM 11.75" diameter discs on. Has anyone gone down this path and found a good place to source all the various OEM parts? I know I can buy new rotors and calipers pretty cheap form local parts houses. The conversion is described in detail on the Disc-o-tech page on the Allpar website. https://www.allpar.com/d3/history/mopar/brakes/disc-main.html

Any help or comments on this particular conversion?

[70vert]

I guess that would make sense if you are showing your car and need to keep everything OEM. But swapping from drum to disc is already making it non numbers matching so I'd go with a quality 4-wheel conversion and get way better braking. Just my opinion.

[miketyler]

I guess that would make sense if you are showing your car and need to keep everything OEM. But swapping from drum to disc is already making it non numbers matching so I'd go with a quality 4-wheel conversion and get way better braking. Just my opinion.

Hey 70vert

The car isn't particularly special. Its is a 318 convertible and I don't believe it to be a numbers car. This OEM upgrade seems like a good solution but there is some cost in time and shipping on the various parts. Still I think this is a far cheaper solution if you compare to 3rd party big discs. Entry-level 12" kits are very expensive. I do plan to upgrade the rear to discs as well later.   

[tparker]

I converted mine. I didn't do a lot of research and just picked one from year one, I think. I figured it would be ok. The kit was OK but there were a few issues. Some directions were OK but I had a few questions. After going to the website I found the manufacturer didn't really support Mopars. They had all sorts of great info for other makes and models and almost nothing on Mopars. Even finding my product on their web page was difficult. The other issue was the components were nothing like the original equipment. I am not a stickler for exact details, but it wasn't even close. The whole booster, master cylinder and proportioning valves were way different.

I got a decent price so I am not too upset but if I was to do it again I would find someone who caters to mopars, has good documentation online, and parts that are consistent with mopar ones.

[miketyler]

I converted mine. I didn't do a lot of research and just picked one from year one, I think. I figured it would be ok. The kit was OK but there were a few issues. Some directions were OK but I had a few questions. After going to the website I found the manufacturer didn't really support Mopars. They had all sorts of great info for other makes and models and almost nothing on Mopars. Even finding my product on their web page was difficult. The other issue was the components were nothing like the original equipment. I am not a stickler for exact details, but it wasn't even close. The whole booster, master cylinder and proportioning valves were way different.

I got a decent price so I am not too upset but if I was to do it again I would find someone who caters to mopars, has good documentation online, and parts that are consistent with mopar ones.

Hi TParker- I have the same concerns. Some of those 11" conversion kits on eBay look good at $400-$500 but I'm unsure on just how it will fit and how it will hold up over time. OEM was pretty good quality stuff and made here in the USA. Although the description sounds like a Frankensten setup it appears to be well thought out. Admittedly there is a benefit in buying all new parts and getting it all from one place and I may ultimatley end up doing the same thing 

[Katfish]

Did the 11.75 disco tech swap many years ago, junkyards are dried up so that's not an option.
Dr Diff is your best bet

https://www.doctordiff.com/front-disc-brake-kit-for-11.75-on-disc-knuckles.html

[HP2]

Scrap yard parts are getting tougher to find in some areas, ot so much in other.  Discs off any FJ or M body will also work, but will be the smaller 10.8 discs, which still isn't a bad set up.

Dr Diff does have new 11.75 caliper adapters along with everything else you would need for a conversion. I'd go with him ahead of a random ebay seller.

[Skid Row]

  I installed these this week  on my 73 Challenger using M body spindles with 11.75 caliper brackets. Rotors are $200
from Jegs.

[miketyler]

Although probably minor, the F/M/J solution could possibly skew the geometry and cause other issues but  I'm not totally opposed to that.  Agree on the random eBay sellers too unless I could get all the parts from one person that had good feedback. I like drDiff stuff. I put his rear disc kit on my 72 Cuda several years ago and worked out great. I just noticed that DrDiff is out of stock on the Stage 2 11.75" kits. Adding it all up I'd probably be pushing $750 delivered to my door going that route so still looking at my options.   

[mopar jack]

I have done 2 conversions on E bodies following the disco tech article. I like using parts that might be available in the future such as bearings, calipers, pads, and rotors. Most of these parts can be found or ordered locally. You can buy a complete kit from Dr.Diff for $600 or just the spindles and caliper brackets for around $250. Then you can source the rotors, calipers and pads from rock auto or local parts store for $150.

[miketyler]

I have done 2 conversions on E bodies following the disco tech article. I like using parts that might be available in the future such as bearings, calipers, pads, and rotors. Most of these parts can be found or ordered locally. You can buy a complete kit from Dr.Diff for $600 or just the spindles and caliper brackets for around $250. Then you can source the rotors, calipers and pads from rock auto or local parts store for $150.

Thanks for the info Mopar Jack! So can you ballpark me on what would be my all-in cost for parts? Also, where is the best source for the spindles and caliper brackets-only kit? DrDiff or? 

[mopar jack]

Thanks for the info Mopar Jack! So can you ballpark me on what would be my all-in cost for parts? Also, where is the best source for the spindles and caliper brackets-only kit? DrDiff or? 
[/quote]

Dr. Diff is the only one I know but there may be others. My first E body I sourced from a salvage yard years ago. The list I quoted is around $400 and you will need bearings, a seal, fluids, brake lines and I would replace the lower ball joint. Sorry no cost break down. One advantage with the Dr.Diff kit is the fasteners that are included.

[bc3j]

I've done it with 11.75" rotors with all stock parts similar to Dr Diff. Kept it manual brakes, safety switch as was used on disc brake cars after January 1, 1970 with metering valve, factory 11 x2.5" drums, 15/16" aluminum master from Dr. Diff. No problems on installation. I get 1200 psi to the front discs and can lock all four wheels. It was done 8 years ago and I probably have about $700-$800 into it. Original kit was from CPP for around $385, then upgraded to 11.75" rotors. Parts sourced from Dr. Diff and RockAuto. Only problem was aftermarket calipers from RA that leaked at the bleeders screws and needed to be replaced, twice. Other than poor quality calipers, the installation was easy.

[HP2]

Although probably minor, the F/M/J solution could possibly skew the geometry and cause other issues but  I'm not totally opposed to that.  Agree on the random eBay sellers too unless I could get all the parts from one person that had good feedback. I like drDiff stuff. I put his rear disc kit on my 72 Cuda several years ago and worked out great. I just noticed that DrDiff is out of stock on the Stage 2 11.75" kits. Adding it all up I'd probably be pushing $750 delivered to my door going that route so still looking at my options.   

Yes, those spindles do alter geometry. BigBlockDart.com did an extensive analysis of this back in the earl '00s when the debate was fiercely raging on the interwebs. They aren't harmful at all and it makes available several million more candidates for parts.  Detailed read is here: https://www.bigblockdart.com/techpages/spindles.shtml

Knowing this info and the range of vehicles they come from, it is entirely possible there may be a local yard to source the spindles and adapters from, which is the most difficult and potentially expensive part of the swap.