Hot Rods I need a brake pedal ~ UPDATE

What is your pedal ratio now??

 

What's the bore size of the master cylinder Danny ?
If you posted it I don't remember.
Larry

 

If the master is 1 inch and you drop it to 7/8 inch you will have a lot more pressure at the expense of about 3 inches of pedal travel. Just have to make sure it will still bottom the master in case of emergency. Smaller diameter calipers and wheel cylinders will do the same, only more time and money. Check pressure with each change, did I mention check pressure?

 

Yeah,I 'm thinking the master cylinder is next.

It's a Pete & Jake pedal.

Larry,I honestly don't know,I hope I can figure it out when I pull it out.

I will have to pull the master cylinder and try to figure what size it is. HRP

 

For what it's worth my buddy with the orange 27 RPU has discs on the front and an 8" Maverick rear with drums.
His system works really well with a manual master cylinder from a 1974 Pinto which has a 15/16" bore size.

If yours is 1" then I'm betting a 15/16" masters cylinder would be better.

 

Just pull the boot back from where the pushrod goes in and measure the bore size with your caliper if you can get at it.
Or maybe ask the builder.

 

Thanks Larry. HRP

 

This is the modified brake pedal I removed,it appears to have been shortened at least 5".



This is the Pete & Jake's replacement. HRP

 

Danny, that's what I figured happened, I posted in your other thread.
The pedal will be into the steering column.

If the pedal pivot can't move rearward the foot pad MUST be at the end of the 12" pedal.
If the foot pad needs to be located where it is, the pivot MUST move rearward.

Redesign time

 

I used the hot wrench to heat up the arm that comes through the floor and it is now located to the left of the column,I didn't cut the pedal at all,there is some improvement but I'm still going to look at the master cylinder and figure out what size the bore is,from what I was told it's a corvette and I would think it is at least a inch to a inch and a quarter.

I also had to do a little more floor cutting than I wanted to do and I have to make a new patch to seal the floor around the pedal.HRP

 

I literally just went through this very same issue. Here's what I ended up doing.
Because of the way I built my frame, the crossmember was smack dab in the way of the brake MC mount that I had bought. Additionally the straight part of the brake pedal (same pedal as you have) was hitting my floor substructure. If I moved the whole assembly forward, the curved part of the pedal was in the column. What to do.
I ended up notching out a rather large C section to clear the substructure in the floor. Then, because the "throw" of the pedal would not provide me with the correct geometry to give me leverage, I extended the curved portion of the pedal arm by about 5" using the same arc. Works great.
I also had to make a new MC mount and machine a longer plunger to go under the crossmember.
Not sure if my pic helps. If you need a close up just holler.


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Forgot to mention the most import part. The piece pedal arm under the pivot, that connects to the MC plunger rod, had to be pie cut and made to that I still got the actual travel I needed when pedal was depressed.
I'll draw a pic and attach it here shortly.

 

How far over did you bend it.
Pedal ratio is figured in side view.
So if you put a Z type bend in it, that shortened up the ratio again

 

Nope. Everything remained the same. Essentially just moved the location of the actual pedal and MC plunger hole AROUND the main pivot. Ratio completely unaffected.


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He's at a conundrum now , smaller master or smaller caliper and wheel cylinders to raise pressure.

 

Master cylinder will be the lesser of the evils and the easiest thing to change. HRP

 

In my case I just reversed the bend,from right to left so the pedal is still the exact same length. HRP

 

What master cylinder did you use? HRP

 

You may have to do a combo of a bunch of things . You know, get the dozen one egg at a time.

How far above the floor board is the foot pedal pad?

 

I'll take a photo later,the battery in the camera is dead.

On a side no I drove my old beater sedan last night and darn near slung my wife through the windshield,that car has great brakes. HRP

 

Honestly I have no idea. It has no obvious markings. My guess is a cheaply 1" bore unit probably from Speedway store or the like. It was in a box of parts I bought.
I had it on my 28 Tudor which has disc/disc set up.


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I think I'm going to try a Mustang master cylinder,something like a late 60's. HRP

 

You'd be further ahead if you knew what you had now as far as bore size so you could make an informed guess what direction to go and how far. The exact Application doesn't make much difference

 

From the limited amount of room for measuring it looks like 1 1/8" but I'm going to have to remove it to make sure. HRP

 

If that is 1 1/8th" , get one for a manual disk drum mid 70's Maverick 15/16th" bore, if it's 1" I'd go for ( the memory is working now ) 79 or 80, 81 Fairmont and Garnada 7/8" bore manual disk drum. If you drop too far you will run out of pedal, ( on the floor ) before the master bottoms. ( safety ).

 

Danny, sounds kinda like you're revamping quite a lot of the brake system. I suggest while you're doing this you put a dual master cylinder on it and repl;umb as necessary. My roadster is using a '72 Must. master cylinder. IIRC, it's a 1" bore. I'm using Buick drums and Lincoln bendix type brakes on the front and some 10" fords from an unknown model on rear. Early 9" rear with small axle bearings and whatever brakes it had when I got it as a rolling chassis.

 

Dave, .the car does have a dual master. HRP

 

Thank you,all good information. HRP

 

That's when the small bore caliper and wheel cylinders come in to get the pedal back up.

Still don't know how far the pedal pad can travel. If it's less than 5" it will probably need a booster