JB

Been looking at MCs, thinking about getting a correct numbers part. I've seen original Chevy 5460346 MCs with the correct dates both with and without bleeder screws. Anybody know what the Vette had? The pic in the AIM seems to show without, and Bizzoco's 1969 Stingray Guidebook doesn't say, though he's got a pic of a replacement MC that has 'em.

JB


[Modified by JB, 4:25 PM 2/20/2004]

GDaina

Yes, can't bleed the MC without bleeders...duals had bleeder screws, single, no.

rponfick

Just looked at my early 69 and it has bleeders. The part no. on it is 5455509. Hope this helps.

JB

Thanks, guys. The 5460346 casting was for power brakes, the 5455509 for non-power, so rponfick, I'm guessing you've got to stand on the pedal to get good whoa going. :D

So since I keep running across 5460346 castings without bleeders, what car was that for, and why'd GM make both? Or is it possible that early '69s had no bleeders (both the non-bleeder castings I looked at were early--one had a 318 date, which is January 31, 1968--or is that in the '68 build year?).

JB


[Modified by JB, 5:33 PM 2/20/2004]

Paul Borowski

Bleeders were on ORIGINAL master cylinders '68-'73, regardless whether the car had power or manual brakes. My '74 with it's original master cylinder(PB 346 unit), car built 9-11-73 has the "boss" or circular area for bleeders, but were not "tapped" for a bleeder. The date of my MC is "4003"(1974, 003rd day). Also, as far as I can remember, they were'nt dated until '70. '68 & '69 I believe did'nt have dates. The ones without bleeders, but had the circular pads where they would've been I'm sure were '74-'82. GM Service Replacement units MAY HAVE had these features also(no bleeders, blank circular pads). Another MC out there, which looks very close to a GM unit is those "Wagner" ones. These say "Made in USA" on the left side of them. Not sure about the "circular pads" on these units.

rponfick

JB, you are correct. My 69 in non-power brakes. I can't read the casting date on the master cylinder (and it looks like it has one), but my car assembly date was Dec. 68.

JB

Paul, you made me have to go back and look at my Bizzoco, and I think I may have it figured out. The date on the one casting I remember the exact code on was 318. Bizzoco says that casting dates on '69 MC's were days first (1 through 365) followed by the year. EXCEPT that some of the examples he found were the other way around, year followed by the day. I'm thinking the casting I was looking at was cast on the 18th day of 1973, not the 31st day of 1968, which would explain the fact that it had no bleeders but did have the pads. Or, on second thought, it wouldn't, would it. That would still be the '73 model year, not the '74.

Oy, my head hurts!

JB

Paul Borowski

JB, I'm just going from memory and what I've seen. Seems as this date thing can be "some" may have it, some not. I've also seen where the last digit of the year was FIRST, then three characters for the "day of year". Then I've seen "day of year" FIRST, then last digit is the "last digit of the year". Seems it went both ways :confused: I believe I'm pretty sure on the bleeders though. :crazy: Also my 003rd day of '73 master cylinder has no bleeders, but the pads. There was probably a time frame here where LATE '73s did not have bleeders OR earlier than my '74(VIN # 01950)did possibly have bleeders. Could have even been a time frame where the "bleeders/no bleeder" MCs could have been mixed too :confused:

wacked

The # on mt M/C is 29969 and it has no bleeders.
I dont know if its original or not.

LemansBlue68

You can bleed the M/C if it does not have the bleeder screws if you disconnect the brake lines and install some special plastic fittings (available at most auto parts stores) in the bosses for the brake lines. The fittings have clear tubing attached and you can bend these over into the brake fluid resevoir with the cap removed. By pumping the brakes, the fluid (and any entrapped air) circulates through until the all of the air is purged.

It is most convenient to do this on the work bench before installing the M/C in the car by using a screw driver or blunt punch to cycle the piston in and out.

It can be nearly impossible to get all the air out of the braking system without doing a "bench bleed" of a new M/C.

The M/C bleeder screws were no doubt deleted in the early '70's as a cost savings.