Brake Master Cylinder 46010-E4602 - Up to 9/1971

[Terrapin Z]

4 minutes ago, Captain Obvious said:

No, no. No apologies necessary!

When you posted up a pic of that master cylinder, my immediate thought was "Weird... Why would someone switch the plastic reservoirs from F to R?" Well the answer is "They didn't. It's a new style master that has the "F" closer to the firewall. Duh."  Couldn't see the forest through the trees!

Oh. and the hardware arrived over the weekend. Looks great. I'm sure there will be something in there I can use for my starter. And the level of patina is perfect! Thanks again @Terrapin Z

I like to think I know about the differences in the years on the S30's but like you said sometimes you don't see the forest for the trees. I didn't note the later M/C either. 

[Captain Obvious]

And while I'm posting pics.... Anyone have any info about the markings of "F" and "R"?

I have high confidence that the master cylinder I have here is the original one that came from the factory mid-1970. Note that the "F" and "R" circuit markings are STAMPED into the cylinder body, NOT cast in. In fact, if you look close, you can see that there was some sort of grinding that took place before the "F" and "R" were stamped. Like they ground off the original marks and restamped the master with the front and rear as documented on the early cars.

Here's what I'm talking about... If you look closely, you can see the grinding marks and the stamped "F" and "R":

[Captain Obvious]

And for comparison, here's the one bought on ebay by @inline6. Note that the "F" and "R" markings are cast into the cylinder body as opposed to mine which are stamped. Now, there's no telling where in the chronology this ebay body came off the assembly line, but it was clearly at some time after they decided where "F" and "R" should really be:

I'm thinking that Datsun changed their minds very early on? And then there was a revision to the casting to cast the "correct" locations into the body without having to grind and stamp? 

[Captain Obvious]

Anyone with an early car have any input into the stamped vs. cast-in "F" and "R" markings? I have strong evidence that this master cylinder was on the car when it left the factory in mid-1970. Or has everyone else had their master cylinder replaced somewhere along the way?

 

 

[CanTechZ]

Here is my collection of early M/C's. 

This is the one that was on my 7/70, HLS30-06521 until 2014. It was engraved, I believe it was the original, as I have owned it since 1978, and didn't need to replace it until 2014.

 

Here is the one that I purchased from a local Nissan dealer in 2014 to replace the original. Currently removed due to my ongoing restoration.

 

Lastly, here is one I pulled off a 12/70 parts car about 35 years ago. It has the "cast in" F & R markings. No idea if it was actually the original, but I suspect it likely was.

 

Edited April 23 by CanTechZ

[bluez]

On 4/16/2024 at 10:13 AM, Captain Obvious said:

I'm working on an early master cylinder now. @inline6 How did yours turn out?

I had to resort to drastic measures to get the rear circuit piston out... Anyone got a half dead early master cylinder around they would offer up as parts? I could use one of these:

Also, the valve seats for the output check valves... Mine are stuck in there. How did you get these out?:

 

And just to make searching easier, here are a couple master cylinder related links:
https://www.classiczcars.com/forums/topic/68100-master-cylinder-anomaly/
https://www.classiczcars.com/forums/topic/66276-brakes-dragging/
https://www.classiczcars.com/forums/topic/66168-brake-master-cylinder-identification/
https://www.classiczcars.com/forums/topic/21826-brake-master-cylinder-240z/

 

 

13 minutes ago, CanTechZ said:

Here is my collection of early M/C's. 

This is the one that was on my 7/70, HLS30-06521 until 2014. It was engraved, I believe it was the original, as I have owned it since 1978, and didn't need to replace it until 2014.

 

Here is the one that I purchased from a local Nissan dealer in 2014 to replace the original. Currently removed due to my ongoing restoration.

 

Lastly, here is on I pulled off a 12/70 parts car about 35 years ago. It has the "cast in" F & R markings. No idea if it was actually the original but I suspect it likely was.

 

That’s pretty amazing a dealer after 44 yrs still had a new m/c. My 12/70 has the same casting.

Note there a few places that will bore and re-sleeve cylinders.

[CanTechZ]

13 minutes ago, bluez said:

 

That’s pretty amazing a dealer after 44 yrs still had a new m/c. My 12/70 has the same casting.

Note there a few places that will bore and re-sleeve cylinders.

On your 12/70 are the F & R markings engraved in, or cast?

I definitely got lucky, the parts guy ordered it in from Japan, took about 4 weeks. I think it was one of the last ones available. They went NLA shortly after. If I remember correctly I only paid a little over $200 and it came complete with new reservoirs, caps and rubber bleeder screw covers. Was a no brainer.

Edited April 23 by CanTechZ

[Captain Obvious]

1 hour ago, CanTechZ said:

This is the one that was on my 7/70, HLS30-06521 until 2014. It was engraved, I believe it was the original, as I have owned it since 1978, and didn't need to replace it until 2014.

Awesome, thanks. So it seems the F&R markings were stamped into the masters early on, and then sometime between 7/70 and 12/70 they changed the mold to cast the F&R markings directly into the body.

Makes me wonder what was on those early castings before Datsun ground it off. I'm thinking that the circuit locations were stamped with the original "R" being towards the radiator and the original "F" was towards the firewall. Then for some reason (safety or testing of some sort?) they decided at the last minute to change it. Would have been an interesting decision making process. Would have loved to be there to hear part of that.

[bluez]

1 hour ago, CanTechZ said:

On your 12/70 are the F & R markings engraved in, or cast?

I definitely got lucky, the parts guy ordered it in from Japan, took about 4 weeks. I think it was one of the last ones available. They went NLA shortly after. If I remember correctly I only paid a little over $200 and it came complete with new reservoirs, caps and rubber bleeder screw covers. Was a no brainer.

It’s cast.

[Captain Obvious]

Thanks bluez. So it definitely looks like between 7/70 and 12/70 they changed the markings from stamped-in to cast-in.

Haha!! Another detail to look for on the early cars for authenticity. Stock class judges be aware!

"It's got an early style M/C." 
"Yeah, but it's not an early early style."

 

[CanTechZ]

There are two part numbers for the "early" brake M/C, sadly no implementation (from) date is shown in the Nissan parts book for E4602. Thanks CO for posting about this interesting bit of Zed trivia.

46010-E4601 Early, Early?

46010-E4602 Early?

[Captain Obvious]

21 hours ago, CanTechZ said:

46010-E4601 Early, Early?

46010-E4602 Early?

That could certainly be the case. I don't know how Datsun handled their part number replacement scheme, but where I came from, we would have probably used a different P/N if we changed the mold. Especially if the production floor processing was different between the two.

So picture this... On the production floor, the early early one required the output port markings to be ground off and re-stamped. Then they changed the casting and the requirement for that processing became unnecessary. You would need a way to document that and communicate it to the shop floor.

A new part number and accompanying new work order paperwork would be a good way to handle that.