Revfan

I am really comming down the homestretch now.

Fired up the car today, and she ran great... though it was up on stands. I was really excited as I have done a lot in the last 6 months:

I replaced engine & Dash harness, Starter, Ballast Resistor, Voltage Regulator, Switched to H1/H4 headlamps and added relays, LED dash lights, replaced Alternator (with a dated 67 replacement) rebuilt wipers, steering box, and headlamp motors.

So all that is left is to put my steering column (which I rebuilt) back in and bleed the brakes.

Which leads me to my newest problem.

The brake pedal seemed kind of clunky after I got everything back in. I bought a replacement Master Cylinder that was listed as good to go for the Original 5455509.

The one that was previously on my car worked, but was nasty looking so I got a new one, a 5469309.

My question is, the replacement MC had a "rod" in the push rod hole, while the one that was on the car previously didn't. The rod in the hole makes it a very tight fit and puts a constant load on the master cylinder, so that it seems to be continually "on" and interfering with the brake light switch and bracket.

Because the previous MC was not stock, and I have found a few other non stock later corvette items on the car, I was curious how the set up was supposed to be. The AIM isn't much help here.

Here are some pics to give you an idea of what I am dealing with.


Here is the new one... with the black rod in place.

Here is the new one, without the rod inplace, which makes it appear like the one removed from the car. I don't know the MC # on that one off hand, but I believe it was for a 70s Corvette.


Any ideas on how to go forward on this?

Thanks

Vet65te

I've never seen a master cylinder that had an 'insert' like that before.
Since it's obviously an extra piece, have you tried to pry it out of the piston? When probably adjusted, you should have a small amount (~1/8 to 1/4") of free play from the pedal pushrod and the piston.
Mike T.

JohnZ

'67 was the only year where manual and power brakes used EXACTLY the same master cylinder (casting #5455509, stamped "DC" on the front pad); due to that, the "DC" master cylinder had a "deep" hole in the rear piston like manual master cylinders do, and the power booster had a "long" rod to the master cylinder instead of the usual "short" rod.

Your replacement master cylinder should have a "deep" hole in the rear piston, just like the 509, and will use the same clevis and pushrod from the pedal arm to the master cylinder.

Revfan

So to be clear, the second pic is the same master cylinder as pic one, but with that spacer rod removed... thus creating a "deep" hole.

Just leave that rod out and proceed as normal?

There doesn't seem to be a lot of info on this... as most sites lump all the MC for 67-76ish together, then differentiate power and non power.

tbarb

That is correct, leave the small rod out and proceed with the rod and clevis that's in the car now.