Hi Guys,

What exactly does the correct master cylinder look like for a 1970 W30 with manual front discs? From the 442.com FAQ it says it should be a 1" bore with dual bales. Looking at the 1970 Olds Chassis Service Manual it only shows illustrations of single bale units. Looking online the replacements with 1" piston and 2 bales come with and without bleeder screws about the brake lines that go into the master cylinder. And some top caps have 2 identical round domes and some have oblong domes of different sizes.

Based on what I'm reading I'm thinking the MC on my car now is most likely not the original one (it is a single bale unit with the different size oblong domes with bleeders on the side of the unit) and I'd like to get the correct one when I replace it in the near future. Thanks for any help you can provide.

regards,
bob

 

I have the exact same question.......nobody with the answer???

 

Hi 1970W30Post,

Seems info is a bit scarce on this one. From what I've found and seen it appears I have the correct original master cylinder still in my 70W. I'll attach a pic of it, along with a pic of the same master cylinder in an all original 70W I took pics of last year. So it seems the correct master cylinder for our cars (non-power discs W's) is a Single Bale, twin chamber (different sizes), with bleeder screws on the side. What's a bit weird is that I have the same brake setup on my 72 W30....that car is all original and it uses a DUAL BALE, twin chamber (SAME SIZE), with bleeder screws on the side. Why Olds would change.....I have no idea.

That's about all I can offer so far on this subject.

Ok, seems I'm having trouble uploading pics. The pic of what I think is correct for your 70 and mine did load. It's the pic of the original 70 I photographed last year.

Take care,
bob

later,
bob

 

Joe,

I've read that there is a code on the master cylinder, but I've never been able to find one....on either of my cars. When you say the "front pad" where exactly are you talking about? I also never looked UNDER the master for a Julian....thanks for that.

thanks,
bob

 

Awesome. Thanks Joe. I'll check tomorrow!

regards,
bob

 

Ok....for anyone interested in this post.....here's what I found. The master is stamped "EB" in that crescent moon area in the front, just under the hole for the bale. But it's incredibly faint and if Joe didn't give me the hint of "EB" I'd still be trying to figure it out. But it's there.....must have been a whimp doing the stamping on that shift. On the bottom of the master cylinder, facing the engine is a bunch of cast in numbers, codes, etc. I think the casting number is there along with the Julian date code. I took a bunch of pics (cause my head doesn't fit between the valve cover and the master cylinder) but can't really make out the numbers. I need a camera with a better macro feature. I'll keep trying and let you know what I find.

So for now it appears the correct master cylinder for a 70W with manual disc brakes is code EB, with a single bale, two different sized chambers, and bleeder screws. My W was made in March of 70, so I'm not saying things didn't change during the year.....just that in the March timeframe what I described is the correct master cylinder.

later,
bob

 

awesome info!!

 

According to the 1972 GMPD book, the correct master cylinder is the Moraine with two bails (not bales, please! ) and bright metal cover. The single bail black painted cover (as stated in the parts book) Bendix was not used in 67-72 F85s. However, I have a 67 3807 made in Lansing with manual drums that has an apparently original Bendix master cylinder with bright cover.

 

I'll have to check my old master I changed on my 71. Maybe they used the same one. Thanks for the info.

 

Where did you come up with the codes for the master? Is it in the GMPD book? On the underside I got a 5470409 1 1/8 *D24 and a BE stamped on the half moon spot. I know they call this hijacking but were kinda on the same page.
Thanks for any help.

 

Hi Guys,

Well....I wrote a long diatribe describing what I found out about master cylinders....then I submitted it and it never appeared. Oh well.....I'm not in the mood to do all that typing again.

The gist of what I found was that the MC codes are in the Chassis Service manual, as joesw31 pointed out, in Section 5 page 10 (thats 5-10 in the manual). But the manual only lists codes for the Delco Moraine MC, not the Bendix units. The 70 Cutlass Assembly manual only shows the Bendix MC as correct for manual disc brakes on W30 and W31, but that drawing is dated May 1969.

Also, the Chassis Service manual shows illustrations of both the Bendix and Delco Moraine, but neither looks like it does in real life. The Delco Moraine has the single bail (sorry about the "bale" spelling....I have horses and my mind is stuck on "bale") that runs from front to back with a cap with two different sized chambers. In the pic it has the long bail but the cap has two identical round domes, not the different sized non-circular ones that are correct. The Bendix illustration has two same sized circular domes on the cover (correct) but has a single long single bail, not the correct two bails that go side to side as opposed to front to back.

So it appears both the Bendix and the Delco Moraine may have been used in 70 W cars. I've never seen a Bendix MC in an original 70 W car, but if you have one I'd love to see a pic. I was thinking maybe the Delco Moraine took the place of the Bendix sometime during the 70 model year, but my 72 W30, which is original, has the dual bail Bendix MC....so it was still around in 72. So I'm at a loss in terms of when they used the Delco Moraine and when they used the Bendix. What did the 69 W cars use???

Again, if anyone has a pic of a 70 W car with the dual bail Bendix please post.

Ok, my fingers hurt. You guys have a great night!!

later,
bob

 

Bob,
I have not found any original 1970 W30 and W31's with manual disc brakes that have the rounded two bail style master. All the ones I have found are the 5470409 1 1/8 with the "EB" code same as the power brake application. I realize that I cannot prove any of these cars left the factory that way, as I am not the original owner of any of the cars I have researched, but the ones I believe are original, have been date coded correct. Your point about the May 1969 drawing may explain why the assembly manual does not appear correct when the 1970 model went into production but was for 1969. Manual disk brakes became available on 1969 W30's late in the model year and used the dual bail style. (By March for sure).

 

Tom....thanks...that's good info. In the past I wasn't really looking at the master cylinder when I looked under the hood of cars. I]'m going to go look thru my photo "archives" and see what I can find.

thanks again,
bob

 

According to the parts book, the single bail is the Bendix.

Also:

70 F85 disk brakes, first type, assys # 0884 or 1344 on the power cylinder housing tab, 5470664; 70 F85 disk brakes, second type, asssys. 1804., Moraine code BE, 5471802.

 

Ok, you guys had me thinking of what my 70w30 had as a master cylinder. The car is an automatic that came with manual brakes. The master cylinder is in a box in my garage as I was going to send out to get rebuilt while my car is getting done. I will pull it out later and take pictures and will post them. I believe it to be the original master, but who knows??????? We will find out!

Cheers,

Sam

 

Here is pictures of the one of my 70 W30 with a build date of June 1970.
Is this the correct one? Thanks
Cheers,
Sam.

 

Hi Guys,

Run2.....me thinks your parts book is hosed (as Joe said). The master cylinder on my 70 W is the same as Sam's pictures. Same code, same cover, same casting number. The Delco Moraine is definitely a single bail and the Bendix is a two bail, despite what the parts book says. Makes you wonder what other things are wrong in all these manuals and parts books we rely on so heavily. (

I checked the pics I took of my MC the other day and the casting number is in fact 5470409. Mine's pitted worse than Sams so I'm having a hard time reading the Julian, but I'll get some better pics tomorrow. My best guess at it right now is 361, meaning late December 69, and my car was made on March 12, 1970.

Another thing that's a bit interesting is when I was looking and wire brushing my MC it looked like there was a layer of paint in the pits. I thought these MCs were installed bare, meaing not painted or plated. If you look at Sam's pics...especially the one showing the casting numbers and Julian you can see what looks like black paint. All the resto articles I've seen on other GM cars always says the MC body was "natural" or "bare steel". I guess on our Oldsmobiles at least.....they were painted black from Delco. What do you guys think???

regards,
bob

 

What colour should the top cover be?
Thanks in advance,

Sam

 

Cadmium plated (yellow) that oxidizes over time to look like galvanized silver.

regards,
bob

 

I think some early '70 cars got the dual bale setup.

You should also consider having it sleeved with brass or stainless. Lots of places out there that offer the service.

Most platers will redo the cap with a yellow (ie gold) zinc finish. Don't sandblast the cap or you'll end up with a real dull finish if you have it replated. Probably best to just give the cap to the plater "as is" and explain that you'd like a nice bright finish on it. If heavily pitted with rust then consider a repro cap or a better used one as the rust pits will remain after the plating process.

 

I've seen on other GM cars always says the MC body was "natural" or "bare steel". I guess on our Oldsmobiles at least.....they were painted black from Delco. What do you guys think???

regards,
bob[/quote]


Bob,
It is common to find restored cars with natural or cast painted MC bodies. Originals were black just like Sam's.

 

Tom,

With regard to original master cylinders being painted black......I believe you're right. I looked on Ebay for NOS master cylinders and the vast majority of them were painted black. Why everyone restores them to a "cast iron" finish is a bit strange. Seems that type of detail would have been picked up by restorers from the get-go. Interesting.

later,
bob

 

But the factory didn't install NOS parts. NOS parts were sold over the parts counter. I can't tell you whether or not the master cylinders installed on the assembly line were painted or not. But I do know that I've seen lots of NOS parts which look nothing like the original parts they were intended to replace.

 

Brian,

That's a great point....thanks for catching that! So since mine and Sam's original master cylinders have remnants of black paint I guess the best we can say is SOME master cylinders installed on the assembly line were painted black. We just can't make a blanket statement and say they all were.

And just to clarify what I said about the NOS master cylinders being painted......they were painted black EXCEPT in areas where they were machined. Those areas were unpainted or natural.

Have a good one,
bob

 

Brian,
Good point about the differnce between NOS and original to the car. Hood hinges come to mind as being different. (ie in 1970 Cutlass / 442, originals were gray phosphate, and NOS are typically painted black.) On master cyclinders, I have not seen enough NOS to know if they are all painted black like the originals or not.