Author Topic: Converting from power front discs to manual discs  (Read 687 times)

Offline Strawdawg

  • Resident
  • *****
  • Posts: 2209
    • Vortex Buicks
Converting from power front discs to manual discs
« on: November 26, 2009 - 08:03:20 PM »
Okay, I want to get rid of the power assist front discs on my '73 and go to standard/non power brakes.

I know I need the pedal rod for non power brakes, but, what else do I need?  Do I need to swap the pedal as well?  What m/c is preferred?  Is a m/c mounting adapter required?

I have seen a write up someplace on this conversion someplace, I think, but, I cannot find it.  I need to redo my brakes and I don't have enuf vacuum to make a booster to work correctly, anyway.

I appreciate the help,

Steve




Offline Changin Gears

  • Sr. Member
  • ****
  • Posts: 1011
Re: Converting from power front discs to manual discs
« Reply #1 on: November 26, 2009 - 08:21:44 PM »
You might also want to get the steel brake lines that connect to the master cylinder, or just bend yours.  I would just use the master cylinder you currently have.  The pedal you have now is fine.


The goal never changes - Stop the 60' timer with your back tires

Offline Chryco Psycho

  • Administrator
  • C-C.com Guru
  • *****
  • Posts: 36620
  • 70 Challenger R/T SE 70 tube Chassis Cuda now sold
Re: Converting from power front discs to manual discs
« Reply #2 on: November 26, 2009 - 08:33:12 PM »
you will need the firewall re-inforcement plate as well ,make sure your master has the groove int he rear piston to retain the pushrod with the rubber O ring

Challenger - You`ll wish You Hadn`t

Offline Strawdawg

  • Resident
  • *****
  • Posts: 2209
    • Vortex Buicks
Re: Converting from power front discs to manual discs
« Reply #3 on: November 26, 2009 - 09:09:18 PM »
Thanks,

The car has sat a lot in the past few years, and I am pretty sure the M/C is pitted and not very trustworthy...if at all so I am going to replace it rather than hoping that a rebuild will suffice.  Any preferred diameter in this case?  (ETA:  Looks like the book says 1.00" was the factory diameter for non-power assist.)

Also, is the reinforcement plate still available or is that something that I need to look for used?  I don't recall seeing it on the Mancini list but I was not looking for one specifically at the time.  Will go have another look.  (ETA:  I see adapters for switching from 4 bolt to 2 bolt M/C's)
« Last Edit: November 26, 2009 - 09:50:43 PM by Strawdawg »

Offline Chryco Psycho

  • Administrator
  • C-C.com Guru
  • *****
  • Posts: 36620
  • 70 Challenger R/T SE 70 tube Chassis Cuda now sold
Re: Converting from power front discs to manual discs
« Reply #4 on: November 27, 2009 - 12:13:49 PM »
I have not seen the re-inforcement plate available new , I have used the 74 dart manual disc brake master in the past

Challenger - You`ll wish You Hadn`t

Offline Katfish

  • Resident
  • *****
  • Posts: 3733
  • 70 Challenger
Re: Converting from power front discs to manual discs
« Reply #5 on: November 27, 2009 - 12:52:13 PM »
I put a MC from a 74 Dart as CP suggested, works good for me.

Here's some info I copied from Dr Diff if you're converting to the newer 2 bolt MC (you'll need an adapter also)

OEM 2-bolt aluminum master cylinders with plastic reservoir:

'95 Lebaron 7/8" bore**

'89 Dakota 15/16" bore**

'85 Diplomat (F-body) 1 1/32" bore*

'85 D-150 1 1/8" bore*

**Back of piston must be bored to accept manual brake push rod and retainer.

* Back of piston will accept manual brake push rod and retainer.

Rule of thumb:

1. Master cylinder piston size is relative to caliper piston size. Large caliper pistons require large MC piston.

2. All things equal, smaller bore master = higher line pressure and longer, softer pedal stroke.

Offline Strawdawg

  • Resident
  • *****
  • Posts: 2209
    • Vortex Buicks
Re: Converting from power front discs to manual discs
« Reply #6 on: November 27, 2009 - 01:19:04 PM »
Thanks, guys....I will keep my eye out for one...or modify/make one...I appreciate the information