1970 Power Brake Conversion

[MoparHonda]

This has probably already been discussed...

I want to convert my 1970 GTX from manual drums to power disk using all original 1970 parts.

1) DO I need to change anything under the dashboard to add the power brake booster? Are there any changes to the linkage under the dash? Any change to the pedal assembly?

2) Is it possible to install the 1970 power booster and master cylinder and use that with the drum brakes? I'd like to do everything under the hood and them do the wheels several months later.

 

[Rishi]

In 1970, the master cylinder is the same for both power and manual drum brakes. But it's a different M/C for disc brakes, visually different. The push rods are different between manual and power brakes. Referring to the dealer parts book will be a big help in answering some of these questions. Many have successfully made this conversion using OEM parts and in ways that are difficult to distinguish from originally equipped.

Your discarded manual drum brake parts can be sold, as they are still in demand. I'm looking for rebuildable front wheel cylinders.

 

[MWbirdLOVER70]

Don’t forget the firewall plate is different

 

[MoparHonda]

Thank you, Rishi and MWBird. I know the backing plate is different, I have a power brake backing plate on order.

I have the parts book, it's kinda confusing. I was hoping someone who has done this could tell me what (if anything) is different under the dash and what to do if it is different.

 

[MWbirdLOVER70]

Thank you, Rishi and MWBird. I know the backing plate is different, I have a power brake backing plate on order.

I have the parts book, it's kinda confusing. I was hoping someone who has done this could tell me what (if anything) is different under the dash and what to do if it is different.

Boy it’s been awhile but I’m sure a search will yield faster results than my babbling lol

 

[MWbirdLOVER70]

Thank you, Rishi and MWBird. I know the backing plate is different, I have a power brake backing plate on order.

I have the parts book, it's kinda confusing. I was hoping someone who has done this could tell me what (if anything) is different under the dash and what to do if it is different.

Tell me what’s confusing and I’ll try to help if I can but others will chime I’m sure here out.

 

[Rishi]

1) DO I need to change anything under the dashboard to add the power brake booster? Are there any changes to the linkage under the dash? Any change to the pedal assembly?

Sorry I missed answering this direct question. No, under the dash, electrically, there is no change. But if you count the rod/lever between the brake pedal arm and the object on the other side of the firewall, the pushrod or lever is different between the two. AKAIK, the only thing that changes is this pushrod/lever. Everything else is the same, on the interior side of the firewall.

 

[PurpleBeeper]

This has probably already been discussed...

I want to convert my 1970 GTX from manual drums to power disk using all original 1970 parts.

1) DO I need to change anything under the dashboard to add the power brake booster? Are there any changes to the linkage under the dash? Any change to the pedal assembly?

2) Is it possible to install the 1970 power booster and master cylinder and use that with the drum brakes? I'd like to do everything under the hood and them do the wheels several months later.

IF you use a pirate jack’s (?) brake booster, you’ll need to enlarge the firewall hole by about 1/8”

 

[Sixpactogo]

If you purchase the booster, backing plate and knuckle, The knuckle assembly gets mounted on your brake existing brake pedal. that is all that needs to go under your dash. You can then do your disc swap when ever you want. Circled in the pic is the part you need to install under the dash. You need to purchase the dual diaphragm booster though.

 

[Rishi]

I like the idea of upgrading in stages. That's pretty slick.

 

[MoparHonda]

Thank you, Rishi and SixPackToGo, I believe you have answered my question. I'll probably start on this in January. I have another car I need to work on in the meanwhile.