C-3 Brake Master Cylinder

[Steven B.]

I have a 1968 Corvette with Power Brakes, 327 300HP, and I was wondering how to tell if it has the appropriate NCRS Spec Master Cylinder?
Thanks,
Steve

[Joe L.]

Re: C-3 Brake Master Cylinder

Steve-----

If correct, it should have a casting number on the right side of "5480356". Also, on the very forward portion of the master cylinder there should be a semi-circle-shaped machined area with the stamping "PG".

The above represents the identifying features of the original which will be judged in NCRS/NCCB events. If you want to check the master cylinder for it's actual originality to the car, you can inspect the machined surface surrounding the forward brake line fitting. This will contain a julian date code. I don't think that this is judged, though. The characters are very small and you will have to look very closely to see them.

[Joe L.]

Correction

I made a typographical error on the master cylinder casting number; it should be "5480346" and NOT "5480356".

[Jack H.]

Re: C-3 Brake Master Cylinder

Joe Lucia did as well as anyone at giving you specifics on the master cylinder. However, the body/casting is simply one piece of the component. There are bails to hold the lid, the lid itself and identifying tag to consider along with finish issues.

Your lid should have two discrete domes with NO interconnecting pressure relief passage. One dome should be embossed "Service With Delco Parts" while the other should read "Use Delco Brake Fluid Only". Later caps (and current reproduction caps) are embossed "Use Delco SAE J1703 Brake Fluid" here while other later caps have been seen embossed "Service With SAE J1703 Brake Fluid".

Reproduction bails to hold the cap are typically SS vs. simple carbon steel and a broadcast code sticker was wrapped around the rear bail for factory configuration identification ('TG' in red letters on white background for power brake and 'YA' for manual brakes).

Last, the main body casting was painted BEFORE final machining, so the side bosses where the brake lines connect will be natural. And, in this era, you should have bleeder screws above the brake line connections that were dropped in later years.

By the way, this detail is nicely given in the '68-69 Technical Information Manual and Judging Guide.... This is a handy book to have in your classic car support library that's available from NCRS (STORE--this site).

[Steven B.]

Re: C-3 Brake Master Cylinder

Jacj & Joe,

A BIG THANKS as usual!!!

[Jon S.]

Re: C-3 Brake Master Cylinder

Joe - You indicated that the date code should be a julian code. Is this a standard julian date, starting with 1 for 1/1/69 (in my case, I'm trying to identify a master cylinder for a '69) and counting forward numerically? The reason I ask is that I may have located a correct master cylinder, but it's a long way away. The owner says what is stamped where the date code should be is '1D0'. I am trying to figure out how to decipher this, but the judging manual does not say what format the date code should be in (it also does not mention whether it is or is not judged).

Thanks,
Jon Strachan
NCRS 10673

[Joe L.]

Re: C-3 Brake Master Cylinder

John-----

The master cylinder julian date code that I'm familiar with uses a 4 digit series. The first 3 digits represents the consecutive day of the year (e.g. January 31 would be "031". The final digit is the last digit of the year of manufacture (e.g. for 1969 it would be "9"). So, for this system, a master cylinder manufactured on January 31, 1969 would have the date code "0319".

The coding on the master cylinder that you have located is not a julian date code system. However, other systems may have been used at other times. The "1D0" might represent April 1, 1970, assuming that a change in the date coding system occured after 1969. I sort of doubt it, though. Delco and Delco-Moraine used the julian date coding system for many years.

As far as I know, these date codes are not judged.

[Joe L.]

Correction

In the julian date coding system that I refered to the last digit of the year comes FIRST in the 4 digit series NOT last. So, a master cylinder manufactured on Jamuary 31, 1969 would have the code "9031"

[Jon S.]

Re: Correction

Thanks for the info Joe. That's just what I was looking for.

Jon

[Terry M.]

C-3 Brake Master Cylinder date code *TL*

Joe is quite correct that other systems have been used. That is the reason the TIM&JG becomes vague on the exact style of the date. We simply do not know all the codes which were used. Some, like the one you mention, are open to conjecture as to their meaning. There is the added element of the stamping often being difficult to see. I believe most judges will judge a code they can see and understand.