Conversion Of A 300 F's Drums to Disc Brakes 

by Dan Reitz


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This article was copied from the 300 Club's website with permission from the club and the author.  There are many informative, technical articles on their site and we recommend that you visit them for additional information.


Also, read how Dan modified his 15" wheel rims to 14" rims to accommodate his new brakes.


       I set out to develop a method for mounting disc brakes on my 300F.  I wanted to keep the stock spindles because I had heard of others who attempted it and they lost turning radius. After fabricating many wooden mock-ups of brackets for mounting different types of calipers in various locations, I settled on the following method. It is rather simple. For purposes of this presentation, the explanations will be brief. I will submit a more detailed article to the club magazine.

NOTE: This information is strictly for the readers enjoyment. There has not been any engineering analysis nor testing done. Although the disc brakes now on my car are far superior to the drum brakes it came with, I do not recommend that anyone copy what is shown below. For this reason, I will not provide dimensions, only a story of what I did.


How I Did It

Here is a picture of the 4 pieces which each adapter bracket is made of.              
         This wooden mock-up shows what the adapter looks like after welding .


Here the adapter bracket is mounted on the spindle. Note that I had to grind off some of the surface near the outer perimeter to clear a part of the rotor. If I had been able to obtain thinner material, this would not have been necessary.


The rear side of the spindle with the bracket mounted.


Here is how the caliper bracket looks mounted on the adapter bracket. 



A complete assembly. The rotors and calipers are from '69-'72 C bodies. The bearing sizes and distances apart are identical to the drum set-up.



And here are some pictures of the new setup installed on the car.

Here's a picture of the left side disc setup, installed, next to the mockup .


Another view from the outside. Since the original spindle and steering arm are used, there's no need to take the car to alignment.



And a view of the backside - nice and clean. 


And a last view of the back side with the wheel turned full left. Note the clearance between the caliper and the frame.

I did not replace the single master cylinder with a dual master cylinder nor do I have a proportioning valve. I simply removed the check valve in the master. The brakes work just fine. My '66 300 convertible came with disc brakes and a single master cylinder, and no proportioning valve, and they worked just fine. However, I am considering modifying a dual master to replace the single.

This page was last updated November 17, 2003.  Send us your feedback, and come join the Imperial Mailing List - Online Car Club