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**jocko** · 03-29-2013, 10:09 PM

sumter, got your pm, here's what I "think" I think

I'm not sure you need to swap the pedal itself, perhaps just the pushrod - but when you look at the 70, compare the pedals and if the same, I'd keep the 72 one in the 72 and re-use it. Here's what I'd look for/try to do:

Off the 70:
- grab the pushrod from the pedal to the back of the booster (and perhaps the pedal, just in case)
- grab the booster and its brackets that attach it to the firewall (and the vac line and check valve AND manifold vac fitting)
- grab the pushrod that comes out the front of the booster (it should be pretty short, just a nub stickin out).
- grab the mounting nuts and washers, etc.

From your 72:
- retain your prop valve and lines (to & from, hopefully the ones between prop valve and mc will fit)

THEN, check to see if the booster pushrod fits perfectly into the back of your master cylinder's piston hole (i.e. if you have a shallow hole in the back of your master cylinder to mate to the short nub intermediate pushrod coming out of the booster), then you can re-use the existing 72 master cylinder.

IF it doesn't mate up (i.e. short intermediate pushrod and deep hole in the master cylinder piston - or, vice versa for some reason), then, from the auto parts store:
- buy a new 72 disk/drum (implied in a 72) POWER brake master cylinder (look at it when you pick it up to make sure it is the correct depth master cylinder piston hole - the difference is very obvious to see when you see it).

Personally, I'd grab the mc from the store anyway, but if it was working, and it is from the 72, then it is already a disk/drum mc and should work in conjunction with the 72 prop valve you're already using - and then you're just adding a booster into the setup. If you're really not wanting to roll the dice on old parts, I'd buy a 72 booster and mc COMBO - that way you know they will mate up correctly and this little worry disappears. But, I understand you are wanting to save a few bucks and use the 70 stuff as much as possible. But, if it has been sitting for a long time and you're not sure if it works - I'd just nab the hard parts and buy new hydraulic stuff. But over to you on that. Completely understand wanting to save $ and the 70 booster and 72 mc may be just fine.

If you run into mounting problems, keep in mind CaptainFab makes a great booster bracket. Recommend pm him if interested and he can explain how to hook it up, etc.

Hope that helps.

03-29-2013, 10:09 PM	#19
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,994	Re: power brake ? sumter, got your pm, here's what I "think" I think I'm not sure you need to swap the pedal itself, perhaps just the pushrod - but when you look at the 70, compare the pedals and if the same, I'd keep the 72 one in the 72 and re-use it. Here's what I'd look for/try to do: Off the 70: - grab the pushrod from the pedal to the back of the booster (and perhaps the pedal, just in case) - grab the booster and its brackets that attach it to the firewall (and the vac line and check valve AND manifold vac fitting) - grab the pushrod that comes out the front of the booster (it should be pretty short, just a nub stickin out). - grab the mounting nuts and washers, etc. From your 72: - retain your prop valve and lines (to & from, hopefully the ones between prop valve and mc will fit) THEN, check to see if the booster pushrod fits perfectly into the back of your master cylinder's piston hole (i.e. if you have a shallow hole in the back of your master cylinder to mate to the short nub intermediate pushrod coming out of the booster), then you can re-use the existing 72 master cylinder. IF it doesn't mate up (i.e. short intermediate pushrod and deep hole in the master cylinder piston - or, vice versa for some reason), then, from the auto parts store: - buy a new 72 disk/drum (implied in a 72) POWER brake master cylinder (look at it when you pick it up to make sure it is the correct depth master cylinder piston hole - the difference is very obvious to see when you see it). Personally, I'd grab the mc from the store anyway, but if it was working, and it is from the 72, then it is already a disk/drum mc and should work in conjunction with the 72 prop valve you're already using - and then you're just adding a booster into the setup. If you're really not wanting to roll the dice on old parts, I'd buy a 72 booster and mc COMBO - that way you know they will mate up correctly and this little worry disappears. But, I understand you are wanting to save a few bucks and use the 70 stuff as much as possible. But, if it has been sitting for a long time and you're not sure if it works - I'd just nab the hard parts and buy new hydraulic stuff. But over to you on that. Completely understand wanting to save $ and the 70 booster and 72 mc may be just fine. If you run into mounting problems, keep in mind CaptainFab makes a great booster bracket. Recommend pm him if interested and he can explain how to hook it up, etc. Hope that helps.