4 Wheel Manual Drum to Front Power Disc Conversion Questions

[65Polara500]

I know there is a ton of information out there on this but I was hoping to get some help specific to my car. It is a 1965 Dodge Polara with the single pot of death 4 wheel manual drum. I bought the Leed brake kit FC2003-8405 which converts to power front disc. I have already installed rotors, calipers, etc. The wheel stuff is done. My problem is with the brake booster. The rods that connected the booster to the pedal were too long. I did call Leed and they sent me a smaller rod but it is still to long. When you press the pedal to the floor there is a bolt with a cotter pin that catches the side of the booster mounting bracket and sometimes gets stuck (first photo). I have not finished the install so I don't know if the pedal will actually travel all the way to the floor when completed but I don't want to do all the work of bleeding etc. and find out it does with the hazard of the brakes hanging up and not releasing. I would like to get the factory booster and master cylinder but do not know what to get. There are so many options with single diaphragm, dual diaphragm, etc. I have also read that I would need a power brake pedal assembly because it is different than the manual brake pedal assembly. Not sure if that is true. I do know that I should not use the power drum brake booster. Also a lot of the boosters have 4 bolts that mount it to the fire wall but my car has two bolts on the top coming out (second photo). Any help is greatly appreciated. Thanks

 

[MONC440]

Yes the power brake pedal assembly is different than the manual brake. The manual system pedal is longer and gives you more leverage. Maybe switch to the power pedal assembly and see if that helps.

 

[Davea Lux]

This application would of had 4 bolts to hold the master cylinder in place. Most were studs welded to the pedal brackets which sometimes got twisted off or if bolts, someone installed only two of them. The correct disc brake booster is a Bendix dual diaphragm unit and it will take a power brake pedal. This booster was used in '66-'67 and if hard to find as discs were rare for those two years. The manual brake pedal is different to acquire more leverage for the manual brakes. After market disc brake conversions have a host of problems with fitment. Most of the boosters supplied are of ChiCom origin and are poor overall quality. The '68-'70 Bendix booster will also work but you might need to modify the travel rod a fit the different firewall configuration.

Dave

 

[CBODY67]

As to your "single pot of death" comment, I lived through that as that was all there was prior to 1967 model year. Except on some early 1960s Cadillacs, which had a dual master cyl, but side-by-side rather than in series configuration. Those old master cylinders DO work just fine, as long as they work. The dual-reservoir master cyls, losing one section of them, stop longer n distance, but still stop, which is their saving grace. BTAIM

The factory booster pre-1969 was the dual-diaphram booster. Slightly smaller in overall diameter, but longer than the single diaphram booster. It all has to do with the area of the diaphram(s) and amount of boost needed. Disc brakes needing higher line pressures than drum brakes.

As mentioned, the manual brake pedal assy has a different fulcrum point than the power brake pedal assy. The manual brake needs more of a lever-mutiplier effect than the power brake pedal assy needs, due to the power boost/assist to get the same brake line pressure.

Not having investigated a power conversion kit, from anybody, as all of my cars have power brakes, I AM surprised that Leeds did not offer some kind of adapter to change the fulcrum point of the manual pedal assy to better match that of the power brake pedal assy! OR include an aftermarket/street rod style pedal assy with the needed fulcrum point as a part of the package. Which further indicates what you might have purchased was much more "universal-fit" than not, as to the cowl-moiunted items.

On some GM cars, the brake pedal assy is universal. With one hole/mounting for the brake pedal rod for manual brakes and another one, lower on the pedal assy, for power brakes.

UNLIKE many other brands, Chrysler usually did not change things within a body platform. Which means the pedal assys are probably the same from 1965 to 1968 model years of C-body cars. 1969 was different from the earlier ones, I strongly suspect, as the Fuselage cars had their cowl real estate re-arranged a bit to allow for a larger diameter booster than the earlier cars allowed, which meant the dual-diaphram booster was needed.

I suspect your issues can be solved with a power brake pedal assy from a salvage yard. THEN all you might need would be the OEM brake master cyl push rod, adjusted per factory specs, for your vehicle and its aftermarket booster.

Best of luck. Please keep us updated on your progress.
CBODY67

 

[65Polara500]

I have found a power brake pedal assembly on Ebay but it also has the two mounting bolts on the top. All the Bendix boosters I have seen have four bolts to mount through the fire wall.

 

[CBODY67]

Ae you aware of the Mopar-oriented salvage yard in Georgia?

 

[Davea Lux]

If you look closely at the second photo, there are 4 mount holes, try probing the lower ones with a screwdriver.

Dave

 

[65Polara500]

Ae you aware of the Mopar-oriented salvage yard in Georgia?

I am not aware of this salvage yard.

 

[65Polara500]

If you look closely at the second photo, there are 4 mount holes, try probing the lower ones with a screwdriver.

Dave

Yes there are 4 holes. My problem is the pedals I found have two bolts that take the top two holes so only the bottom two holes are open. The boosters have 4 bolts so they need four empty holes to mount.

 

[Davea Lux]

Yes there are 4 holes. My problem is the pedals I found have two bolts that take the top two holes so only the bottom two holes are open. The boosters have 4 bolts so they need four empty holes to mount.

In that case, you can probably drill out the pedal assembly.

Dave

 

[Milo]

below link the gold colored part is what is for added power brakes