Hard to see the details in your pics, but I can help some.

First thing, there should be two holes in the brake pedal itself....the original hole the brake rod from the power boosted set-up was hooked to, and a second hole about 1-1/2 inches higher up the pedal toward the pivot point. This second higher hole is the manual brake hole, it gives the proper pedal leverage ratio for manual brakes (about 7 to 1 ratio) and puts the rod straight on line to the master cylinder.

Second thing is about the master cylinder itself.....it HAS to be a true manual brake master cylinder, it can't be a repositioned power brake master. The difference is in the master cylinder piston itself, the manual piston has about a 1" deep hole for the brake rod to fit into, while a power master piston just has a small dimple cup. The rod has to fit up inside the piston to prevent vibration or a quick pedal stab and return from allowing any slack and allowing the brake rod to fall away from the piston - instantly you'd have ZERO brakes. Bad situation !!

As far as I know, nearly all GM brake pedals have both holes, sometimes there is a sheetmetal bracket that contacts the brake light switch plunger bolted into the second hole that you will have to reposition.....but your '76 year is getting just new enough I'm not 100% certain that second hole will be there already....you may have to pull the pedal and drill one yourself.

 

A post from way back

Posted by ERICNOVA back in 2014
"One thing that has to be right...the brake rod into the master cylinder has to be perfectly straight (or very nearly so) in line with the master cylinder piston bore...too much angle and it can cause sticking."

That's what I was worried about. I didn't know if an angle could be tolerated in the master cylinder pushrod. I THOUGHT I checked and didn't see any more holes in the pedal. This hole should be ABOVE the one that it is currently in, correct? I'll look closer tomorrow. That would make the piston travel straight from the brake pedal into the master cylinder. In the pic I posted, I have the adjustable pushrod mocked in place, and it seems to push the piston into the master cylinder nicely, although at a ~30 degree angle. Of course, the master is not connected to any fluid/hoses yet.

The master I have has a ~1" lip on it where the pushrod rests in it. I hope this is the correct one?

 

Second hole in the pedal will be above the original, that is correct.
I kind of expect it to be there, the '76 Nova I built from a 6cylinder car had manual front disc brakes from the factory, and GM was good about not having to have multiple versions of the same part for minor differences in application like this(unlike FORD, LOL).

If the back of the aluminum piston in the master has a 1" deep hole, you've got that part correct.

I've converted a '69 Chevelle, '72 Nova, '85 S-10, '81 El Camino, and '84 Monte Carlo SS to manual brakes, all of those had the second correct hole for manual brakes already in the pedal. The S-10 and the ElCo/Monte had the brake light contact bracket bolted into the upper hole, which then had to be flipped over/reversed and remounted in the lower hole once the brake rod was hooked to the upper hole.

One other thing about the pedal hole...when you convert to manual and leave the rod hooked to the original power brake hole, it makes the pedal feel real stiff, just like a power set up after the engine stalls,.....that's the second reason to move the rod up, to get the lever ratio to a better mechanical advantage and feedback/feel.

 

Okay I'll definately look into that second hole. MaYbe I'll use my fingers to feel about 1 to 2"s up from the current location, and see if I feel anything. It would be a total bummer to have to take the whole brake pedal down and drill really mess something up lol.

So the rod just lays in the master cylinder hole, and just rests on the notch on the pedal?
.... Wait, as I'm typing this out, I'm realizing that it isn't even a 'hole' on the brake pedal, but a built in round notch that protrudes out to the side of the pedal, and the hole of the adjustable pushrod slips onto it. Am I to somehow remove that notch and place it higher?? Ill try to repost the pic that shows the notch on the pedal

 

In your third pic in your first post, there is a bolt head visible on the side of the pedal, with a flat bracket being held down by the bolt....is the pushrod hooked to the other end of this bolt/stud on the other side of the pedal??

 

Thanks for sticking with me through this EricNova, I will take a look at it this evening, snap a couple more pics, and post them here

 

convoluted twists

I bent my arms in ways that I didn't know they could bend in order to get a clear picture so we can see clearly whats going on with the brake pedal arm.

It appears the the stud is not on the other side of that bolt head. Looks to b a part of the brake light apparatus? And I also don't see anything at all north of the protruding stud that the OEM connected to. :drunk:

 

Well, looks like a first for me. first time I've seen a RWD GM pedal with a stud like that, and no upper manual brake hole.

You may want to contact a Nova restoration specialty parts vendor like J&W Nova Parts, see if they can give you some insight. SS396.com, Classic Industries, Year One, etc.

All the GM pedals I've dealt with had both holes drilled, and the brake rod was fitted with a clevis on the inner end, it straddled the brake pedal and then a pin with a retaining clip was placed through one side of the clevis, through the pedal arm, through the other side of the clevis and the clip then installed to retain it.

1962-1979 Nova Brake Booster Rod Fork

Just like this image : https://www.bing.com/images/search?...rake+pedal+assembly+image&simid=607988240979135784&selectedIndex=153&ajaxhist=0

Might just need to get a different pedal itself, from a similar year or from a range of years.

 

Rather than take the whole pedal assy out have a look at the pedal pivot point, sometimes the pedal has pin going through the assy just held in with a circlip. If so you can just drop the pedal out to drill another hole higher up. If this is possible what i would do is drop pedal out, press out the pivot pin, refit the pedal back up without retainer, carefully mark the pedal where you want the new hole with the push rod level, remove the pedal, drill to accept the pivot pin, may have to tack it in with a weld, refit pedal and reconnect M/C.

 

No Easy Option?

Wow. NOT what I was trying to hear. So I have some out-of-the-norm brake pedal? This is an all original car, came with a 305 v8 2bbl, 38k on the motor. I guess I'll take a closer look behind the dash to check for the pivot point and see if it has a removable pin or something.

So, the way I have it now, won't work? At a ~30 degree angle roughly? I have it mocked in there, but the master is new and empty, so I don't know how the feel will be.

I'll look at some websites also to see if they have the kind of pedal that I need too. So replacing the pedal would be a lot of work? Or is it just hard to reach ?

 

Pedal just swings on a pin, through nylon bushings in the pedal itself. Pin is held in by an kind of funky clip, you have to lift the face of the clip up 1/16" or so and then slide the whole clip over 1/4""off the groove on the end of the pin.

If you Google it you'll see what I mean. You can see the clip in Picture 7 at this link: 1969-1973 Clutch Pedals - Nova Research Project
Another view of the clip: 1962-1979 Nova Brake Booster Rod Clip
With a clutch pedal, the pin is welded to the end of the pedal, but with an automatic is it a separate individual pin

Like you've guessed, just getting your hand up in there and working is a chore, but it can be done. If you've got bucket seats I recommend just removing the drivers seat so you can comfortably lay on your back rather than contort yourself laying in through the door opening, it will make it a bunch easier.

That 30° rod angle is going to make for a very stiff pedal feel, and it will quickly wear the seals at the rear of the master cylinder piston leading to a leak and outright failure.
I certainly wouldn't try to run it like that myself, I'd pull it and move the stud like Brading laid out before I'd run with what you've got right now.

Stuff got a little funky in the mid -1970's, looks like you've got one of those differing situations.

 

Like ericnova72 says it's a pain in the butt to do, but it's better to set it correct now than end up flying down the road one day with no brakes.

 

The diff between the PB and manual points on the pedal will increase your pedal effort (~25%) enough so you'll hate driving it.

Russ

 

How do work that out. It is actually the opposite if you move the pin up you decrease the pedal effort in exchange for more pedal travel. Explained here.


How To Measure Brake Pedal Ratio

 

Well Russ that first post is now cleared up no problem. On your second post I totally agree with you, plus what has already been said that leaving the push rod in the PB position will lead to early M?C failure.

 

The pin is riveted into the pedal. If you grind it off on the back side, you can drive it out with a punch. Drill a new hole where you want it, and insert the pin. You will have to have it welded on the back side to hold it in place.

 

Or forget about reusing that stock pin, , just drill the correct hole and switch to the clevis and slip fit pin that GM used on almost everything else.

I posted a link to it in an earlier post

Also looks like the clevis would get you closer to dead straight alignment left to right, or is that just picture distortion?

 

Whoops, guess I didn't post the clevis link previously....:embarrass

1962-1979 Nova Brake Booster Rod Fork

Same clevis is used on manual brakes too.

 

2 choices

I bought these two adjustable brake pushrods, figuring one would work and I'll just send the other one back. Of course, I was hoping the $40 model would work:
https://www.summitracing.com/parts/sdk-a21161

But now, if I go to the clevis route, it looks like I'll be using the other device, the $60 model:
https://www.summitracing.com/parts/ssb-a1726

SO, it's looking like I can get under there, unbolt the brake pedal using a wrench on one side and some vicegrips on the other? Take the pedal off and drill a hole big enough for the clevis to go through and try to hook it up that way. If so, no press or welding would be needed correct?

EricNova I was looking at what you were saying about the pushrod pedal possibly being offset. I'm not sure, remember the way that I have it now is pretty much how the factory had it, right? Off to the side? With the clevis and pin method, the rod will be DIRECTLY behind the pedal as opposed to off to the side hooked to the nub. But I would assume GM would have the nub directly lined up with the master cylinder's plunger, making the brake pedal itself offset?

 

I bought these two adjustable brake pushrods, figuring one would work and I'll just send the other one back. Of course, I was hoping the $40 model would work:
https://www.summitracing.com/parts/sdk-a21161

But now, if I go to the clevis route, it looks like I'll be using the other device, the $60 model:
https://www.summitracing.com/parts/ssb-a1726

SO, it's looking like I can get under there, unbolt the brake pedal using a wrench on one side and some vicegrips on the other? Take the pedal off and drill a hole big enough for the clevis to go through and try to hook it up that way. If so, no press or welding would be needed correct?

EricNova I was looking at what you were saying about the pushrod pedal possibly being offset. I'm not sure, remember the way that I have it now is pretty much how the factory had it, right? Off to the side? With the clevis and pin method, the rod will be DIRECTLY behind the pedal as opposed to off to the side hooked to the nub. But I would assume GM would have the nub directly lined up with the master cylinder's plunger, making the brake pedal itself offset?

On the first question, with the clevis and pin, you are correct thet no welding will be needed.
Second question I can't really answer, as I've never seen that riveted pin pedal in a GM before, it strikes me as being just like how
Ford does theirs....I know many of their boosters and brake master cylinders have that style of end made on the rod, a loop to fit over a pin. My experience has never seen that on a GM.

I'd want the rod as straight a shot as possible...could be with a power booster it ran at a sight angle off the pedal sideways, the booster would be a lot more forgiving of that than the rear of the brake master cylinder will.

Could be yours is different than what most of us have encountered and were expecting due to which assembly plant it came from.... I know differences have been known to happen that way either by design or due to a supply line delay or interruption causing a short term substitution. Actually having production stoppage on the assembly line was a no-no, so other measures get taken....you see this a lot with engine stampings or casting numbers not matching what most forums, web sites and reference material "says" it should be..

Know where yours was built??

 

looking at your first group of pictures again, I can see now that your pedal has a sideways joggle bend up closer to the pivot, looks like it is to offset it so the riveted pin actually ends up on centerline side to side....I typically see a straight pedal in that location which would match up to using a clevis.

Any chance of a local wrecking yard having any other 68-up RWD GM cars....I know most pedals are the same, I've put '74 Pontiac Ventura(NOVA) automatic pedal in a '69 Chevelle that was swapped from 4-speed to automatic and the pedal fit right in place....put a '78-79 Camaro pedal in a '69 Firebird too.

 

Yeah, leave it up to MY nova to be the oddball. And not in the rare, worth $$$ type of way. In the frustrating, I don't know why yours don't work like the rest of ours way :smash:

At least I have a plan of action, something that, thus far, I can feel comfortable attempting. Maybe I should have left the power brakes altogether and searched for a smaller power booster where the tall valve covers would clear.

Anyway, I went out and snapped a pic of the VIN. Can you tell me any info?

 

Okay, found a local yard near me that catalogues having a 1970 impala. I may go look at in the morning. What is the EASIEST way to take the brake assembly down? Possible size wrench or what I may run into?

 

'70 Impala will just be pins with that funky over-the -end 1/4" slide clip. 3/8" or so pin at the clevis and 3/4-7/8" pin at the pedal pivot.

Dropping the steering column at the under dash stirrup will probably make getting to the brake easier. Will be 5/8", 11/16" or possibly the old 19/32", that is the only place I've ever found that rarely seen old school size.

On the Nova, there will usually be a sticker on the door frame, by the bearclaw latch that tells where it was made.

 

W stands for

Willow Run, MI... In my own back yard, so-to-speak. I'm going to try to take my pedal off before I go out to look at the Impala. I'm thinking that I may just drill a hole higher up in my pedal and use the pushrod kit that I have and build a fitting clevis connection for it. I understand that it may be off to the side by .25" or so, but maybe that won't make 'much' of a difference? Sure beats going to the salvage yard in tomorrow's 38 degree weather and clamoring under an Impala's dash.

Also, to my understanding, Power boosted brake pedal app's did not use a return spring? Will I need to fabricate/install one of those, too? ain:

 

I've never seen a return spring on a pedal.....master cylinder has a piston return spring in it that pushes it all back when released.

 

Just to lighten the mood and give you a little lift....when building a hot ride, "if it was easy, everyone would do it" :thumbup:

 

brake pedal off

Okay, so it took a while, but I have the brake pedal off now. Looks like I am going to drill a hole 1.5" higher than where the original power brake pin is, and use a clevis and pin type device. I've never drilled through half inch steel. I have the DeWalt charging, any tips from the pros on how to make this easy as possible? I'll probably have to go buy some drill bits. Anything specific?

 

I’ve got a step drill bit.
Great for larger holes.

Like this.
https://www.homedepot.ca/en/home/p....:pla-305539978020&gclid=EAIaIQobChMI6aGlsO3I2QIVBmt-Ch0fkwJcEAQYASABEgLeyPD_BwE