5468309 MASTER CYLINDER

[bc69]

Are there different applications or versions of the 309. The stamping on front side and reference in boosters/cylinder section on CRG seems to suggest that there is.
I have aftermarket on my 69 and plan to install new w/new booster at same time.

[william]

As stated 309 masters that were positioned near-level did not have bleeders; those mounted at an angle [Camaro] did.

The 309 had other GM applications and other codes stamped on the pad. Only 'US' is correct for a '69 Camaro. Early '69 346 masters were also stamped 'US'.

Plenty of 309s out there so careful what you buy.

[bc69]

So any 309 w/bleeders will work with any disc/drum, disc/disk situation? There are a number of 309's without 'US'  stamp, not correct (visually), but will work?

[william]

I have no idea who could answer that.

Quoting from the January 1970 Delco service manual "With all of the variables to be found in master cylinders, which look alike externally, it is important that the complete assemblies be properly identified. For this purpose a two-letter metal stamp will be found on the end of each master cylinder."

From a quick glance at the manual, piston length and check valves are among the variables.

[bc69]

Thanks for input William. Will keep on digging into this and check a few other forums history. Maybe receive some more input from here.
My application is disc/drum on sb 69ss, so it's common enough.

[montgomg]

My recently purchased 69 Z28 has a 309 master cylinder but it is stamped EA on the machined pad. Seems to operate okay but I am looking for the correct US stamped master cylinder.

[tom]

Don't know about master cylinders, but I do know that rebuilders of alternators will use any functional core to build what they have a market for. So if the difference between a US and a EA 309 master cylinder is all internal, the EA core could have been rebuilt, and sold for the US application, just not restamped as such.

[L78 steve]

The people to ask about this would be the guys at White Post Resto's.