bobb

Hi Guys,

I know we talked about casting codes for master cylinders a short while ago, but now I'm having trouble with the date codes. I searched on here and did an internet search at the Chevelle and Camaro sites, but the info I want doesn't appear to be in any of those places. I understand the casting codes, the stamping in the crescent in front of the MC, and the 3 digit Julian cast into the bottom. What I don't know is how to tell what YEAR it was cast.

For example, the following codes are from Sam's (72xw30) master cylinder. On the underside it reads:

5470409 - 1 1/8 * D1 @118@ where the "*" is the pizza symbol and the "@" are the cast screw heads.

Reading on this forum it said to ignore the D1 or any D code as that was the mold number for the casting. The "118" is the Julian. But what YEAR was this part made??

I just bought a nicely restored MC with codes that read:

5470409 1 1/8 *D31 @159@ that I was told was from a 71 Chevelle. I'm just not seeing how to get a YEAR of casting from these codes.

So as we say in Maryland.....HEEEEEELP!

thanks,
bob

BlackGold

Simple: on cast parts using the 1- to 3-digit date code, there is no designation for the year. That's true for block, heads, exhaust manifolds, rear-end housing, A/C bracket, etc. etc. and yes, master cylinder.

bobb

Hi Brian,

Well that sure makes it simple!!!! But why would the foundry bother with a Julian if they didn't code the year? Isn't the point of date coding to be able to track flaws or defects to lots or time periods?

As for blocks.......you may in fact be right that there's no year casting code, but I've found Mr. Trick's decoding scheme to be spot on so far for the 455 blocks I've looked at. That being the single digit located near the distributor hole next to the Julian to correlate to year as indicated in the VIN-derivative on the pad by under the #1 cylinder. Only place I haven't seen it work is on the other non-455 Olds blocks.

Thanks for the info on the master cylinder year coding.......now I can stop going nuts and just get back to being simply abnormal.

regards,
bob

stevengerard

I just checked mine as it has been sitting on a shelf for years, same part number

5470409 1 1/8 *D31 @314@ but as you can see the date is much later in the year which matches up to my November build.

Is this the correct part number for a Cutlass or 442 orW30 or all a-bodies from that era? The assembly manual doesn't say what the number is just an "assembly" number

BlackGold

From what I can tell, 5470409 is the correct casting number for a Moraine master cylinder for our 1970s. What I don't know is how many applications that casting was used for. Only power brakes? Power and manual? Only A-body? All series? Remember, the casting number belongs to the raw casting, before it is machined and before it is assembled.

Look for a stamped 2-letter code on the top-front of the casting. For my '70 442 with Power Disc Brakes it reads "EB" which is correct.

60193W30

Fellas...
I have a similar master cylinder w/ similar questions...

Numbers read 5470409 1 1/8 *D42 @8@

Where is this stamp going to be... "EB"

My unit does not have a half moon machined pad...

Manual Disc front brakes

Build date of car is 11C Lansing car

70Post

There won't be an "EB" stamping on the MC you have. The "EB" stamping was put on the half-moon machined spot.

The MC must have been a GM part sold over-the-parts-counter as a replacement.

60193W30

Thanks Patton...

So the power disc and the manual disc cars used the same MC?

70Post

I'm fairly sure they are the same part whether manual or power disc....I'm checking the Service Manual and Assembly Manual and will report back.


EDIT: Here's a pic from the '70 Olds Service Manual...note the data does NOT differentiate b/n power and manual brakes. So, "EB" would be correct for either one on the Abody.

60193W30

I appreciate the help...
Im looking to rebuild it if its factory correct...

Factory W car w/ docs...

No EB stamp though from what I can see

70Post

See my post/pic above. If you want to recreate the true "original" setup then you'll want a MC w/bleeders and the machined pad. Go look in the "Parts For Sale" section and you'll see an ad by RocketDevo for a "BE" original master. That one is for a '71 but it has the machined pad and bleeders.

You can find cores occasionally on this site or RocketDevo may have a rebuilt/resleeved unit ready to go.

EDIT/ADD: Here's a link to RocketDevo's "BE" master cylinder ad:

https://classicoldsmobile.com/forums...-cylinder.html

60193W30

Thanks for the info Patton!

70Post

Do you have a clear/closeup pic of the MC LID on the setup you have??
(ie - a pic with a clear view of the lettering stamped into it).

joe_padavano

The parts book (Jan 1972 printing) shows 1" bore for manual disc and 1.125" bore for power disc.

60193W30

These might not be the best pics... What are you looking for and I can try to clean that area a lil more...

70Post

Trying to get a shot of the actual lettering stamped into the MC lid.....there's lettering/wording/numbers stamped into the larger dome and on either side of the smaller dome (down on the flat areas above and below the smaller dome).

When I click on your pics and expand them it does appear to have some lettering/wording stamped into both the front dome and around the small dome-adjacent flat areas BUT it doesn't appear to be the "correct" lettering. Also....I believe the correct lid would also have a third "raised ridge" at 3:00 at the base of the small dome. That's obviously not present so I think it's a later style lid.

Is the car you're dealing with a 1970 model?

With Joe's info you should do some more checking on what is correct....don't know if the EB-stamped MC's came both ways (1" and 1-1/8" bore).

I checked 3 disc MC's here - ALL are cast with "409" casting number and "1-1/8" bore size. One is a "EB", the other is a "BE" and the third is not stamped. Original MC's on my two Oldsmobiles were replaced long ago with aftermarket/parts store stuff and I sourced these three more recently from parts sellers.

joesw31

This is a case of where the parts book is incorrect for the 1970 Manual disc brake car. The "EB" master cylinder was the same regardless if it was manual disc brakes or power disc brakes (bore 1 1/8).

60193W30

Looks like standard stuff...

"Use only DOT 5 fluid from a sealed container"

"Warning clean filler cap before removing"

Was going to get it rebuilt if it was real......

70Post

I believe the correct cover (at least for original "EB" and "BE" masters) will say "SERVICE WITH DELCO PARTS" on the larger front dome, "USE SAE J1073" above and to the L of the smaller rear dome and "DELCO BRAKE FLUID" to the lower left of the smaller dome.

Does the MC you show have bleeders above the two steel line connections?

You need:

>Bleeders above line connection spots

>Machined half moon spot on the nose/front with the letter stamping

>Correct style lid

I'd try to find another candidate as that one is lacking all or some of the above features. Pay particular attention to the "half moon" machined area and any stamping....that flat area is commonly rusted and pitted with the stamped-in letter codes being rusted away or only partially visible. Not the easiest things to find with a clean machined spot and nice letters.

60193W30

Thanks for the help PG!!! I appreciate it!