C2 67 MASTER CYLINDER

[Jimmy B.]

I would like to put this to rest once and for all. 1) What casting should a 67 master cylinder be with the J50 vacuum power brakes option? 2) What stamping should it also have? Is it DC, PG or something else? 3) Are the master cylinders stamped/cast with a date code? 4) Lastly is the internal bore the same or is it larger with a power brake set-up.
Thanks in advance.
Jimmy Blakely

[Joe L.]

Re: C2 67 MASTER CYLINDER

Jimmy-----

The following applies to 1967 Corvettes ONLY; SOME of the information is different for later years:

1) 1967 master cylinder with manual brakes or J-50 power brakes used a master cylinder with casting #5455509. 1967 Corvettes with J-56 power brakes used master cylinder casting #5460346;

2) The '509' casting master cylinder was stamped "DC"; the '346' master cylinder was stamped "PG";

3) I don't think that 1967 master cylinders were date coded but it's possible that some were. If so, it is a small stamping on the forward brake line fitting machined surface. If present, it's a Julian date code, the first digit representing the last digit of the year and the last three digits representing the consecutive day of the year. There is no meaningful date coding cast on the master cylinder;

4) The "DC" coded master cylinder used with manual brakes and J-50 power brakes was a 1" diameter bore; the "PG" coded master cylinder used with J-56 power brakes was a 1-1/8" diameter bore.

To remind, the above information is accurate for 1967 Corvettes ONLY. Some of it may be the same as later models and some is NOT the same as later models.

[Jimmy B.]

Re: C2 67 MASTER CYLINDER

Thanks Joe. This is exactly what I needed to dispel all the inaccurate information I was accumulating.
Jimmy Blakely

[Timothy B.]

For the experts -Re: C2 67 MASTER CYLINDER

This might be a good thread to address something that I have been wondering: What is the effect when you install the manual brake (1") bore MC on a power brake car??? I would suspect that you would have overly grabby brakes? I have discovered that when you go to a parts store and ask about master cylinders for these cars, they ask if the car is manual or power brakes. I have discovered however, that regardless of how you answer that question, that sometimes you get a MC with a 1 1/8" bore and sometimes 1" bore. I wonder how many manual brake cars are out there with MC really sized for power brake cars?? The large bore would require more force to generate the same pressure, so that might explain why sometimes folks complain of high manual brake effort and some others say it is fine??? Just wondering what the experts think...

[Mark #28455]

Re: For the experts -Re: C2 67 MASTER CYLINDER

To go one further, the manual brake big block cars require a fair amount of effort by today's standards. If you swap over to semi-metallic pads you'll really learn the meaning of high pedal effort!
I would only recommend the semi-metallic pads on a power brake car.

[John H.]

Re: For the experts -Re: C2 67 MASTER CYLINDER

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Manual and J50 power brake 67's use the EXACT same master cylinder - power brakes make no difference (5455509/DC cylinder). Parts stores are a poor reference for old Corvette parts; the kids at the computer with orange hair and 14 body piercings don't understand us

[Craig S.]

Re: For the experts -Re: C2 67 MASTER CYLINDER

Tim - as Joe notes, both maunual and J50 power brakes used the 509 DC cylinder, they both have 1" bore. The 1.1825" PG he references is the J56 optional power brake setup, seems like is was used mostly with the L88 engine if I recall. Craig