63 Master Cylinder Cap

[Harry Sadlock]

I have a 63 Master Cylinder Cap. The Cap has on it 'Use Delco Brake Fluid'. It does not have on it ' Fill to 1/4 Below Rim'

I need some help to determine if this is the real deal or not.

Thanks

Harry

[John D.]

Re: 63 Master Cylinder Cap

Harry, At the Auburn Regional Jimmy Greg and Duane were bored on Sat since they weren't judging and they were going around and looking at all the 63 master cylinder caps and comparing them. Yours might be from a steel Chevy. Here's another one Harry. There are two different heights of lettering on these caps. My master cylinder was the original one that came with the car. But the cap was a NOS one that came on a 1" bore master cylinder from a steel car. It had a tad smaller lettering that the real deal. That's what I was told anyhow. But when I came home I found my original pitted one and another really good original one and all my examples including the one on the car had the small size lettering. Maybe some of the 63 show cars had a repro car (no you say) that had bigger lettering. Or maybe there are two heights of lettering. Nit pickin for sure but that's the fun stuff. John

[Harry Sadlock]

Re: 63 Master Cylinder Cap

John, this one has the small lettering, not sure if thats a problem. But the absence of 'fill to 1/4 beloe rim' bothers me.

Harry

[mike cobine]

Re: 63 Master Cylinder Cap

I just looked at mine, and what I noticed is the "Fill to ..." is stamped much lighter than the rest. So much that you can barely see the "rim" with the corrosion. Maybe your cap, if you don't know the history, has been buffed and polished to get rid of the rust enough that the light lettering is not visible.

That area has too much light and I can't really tell anything about your picture.

[Harry Sadlock]

Re: 63 Master Cylinder Cap

Mike, I had it under my glass that I tie flies with and there is nothing there, 'fill 1/4....' Looks to be in great shape, normal scratches, but no sign of severe rust.

I guess the question is, did a 63 Vette have a MC cap without the 'fill 1/4...' on it. The JG says it's there. But the 63/64 is ????

I'm not up late tonight just to hang out, just waiting to leave for the airport to pick up my son who is coming in from Charlotte to NH. Seems there was a mechanical problem and they had to turn around. Oh well, sxxx happens.

Harry

[John D.]

Re: 63 Master Cylinder Cap

Harry, I am told that the repro does in fact have all the correct info on the cap. Your may be an original that has been poorly stamped. These caps are somewhat of a pain when you are trying to make stuff look pretty. They always seem to be pitted because of the elements. It would be interesting if some of the 63 owners would send in some good imput though. Surprised you didn't get more imput. Just measured two 63 mc caps. Both have 5/32: letters,etc. Next size up in my collection of stamps is 3/16". Doesn't look like there is enough room on the lip of the cap for such large letters. Maybe so but the letters would be clear out to the very edge. Hey RJ. Write in and help out please. Measure your Z06 and check out the size. There's one Harry. You don't suppose the Z06 had another style or height letters on the cap since it came from a taxi to you??? Heard those tankers had some taxi cab parts on them. And as I mentioned before the steel Chevy 63 or 64 had the same MC cap. If you want your stock 63 without power brakes to have super good brakes put the 1" master cylinder on it and boy do they stop good. Did it long time ago on a driver 63 with metallic brakes. Didn't stop for crap with 7/8" but with the 1" it was like another car. Very similiar in appearance also. No good go judging though. John P.S. Harry-could it be another Corvair part???

[Joe M.]

Re: 63 Master Cylinder Cap

My cap has the "1/4 fill" and "small" letters about 5/32. Deeply imprinted.

[Verne Frantz]

Re: 63 Master Cylinder Cap

With the same foot pedal pressure, the 7/8" bore master should apply more lbs/sqin to the fluid than a 1" bore. The same applied pressure is condensed over a smaller area. A silly analogy would be: IF a 100lb woman backed up and stepped on your foot, would you rather that she was wearing sandles or spike heels??

Also, the '64 Passenger cars used a bail-top master cylinder. Steel cars only used the "screw-top" in '62&'63. I have a rather large collection of originals buried away which I can check and report findings on stampings and font size. I know I have all 3 versions.

Verne

[Jack H.]

There are four variations...

I see them ALL the time on scrap yard cars (Corvette wasn't the only vehicle to use this master cylinder cover). One has the legend extention (Fill To 1/4" Below Rim) and it comes in BOTH large and small font. The version lack the legend extention and also comes in BOTH large and small font.

The current '63-64 JG book defines the version with the extention as being 'correct' for '63 Corvette and is SILENT on the size of the font used to emboss. When I see the versions without the emboss extention, they're ususally installed on 1962 passenger cars, BUT, I HAVE seen several without the emboss extention on early build 1963 cars. Our JG books don't acknowledge the possibility of early '63 Corvettes having the 'short' version of the emboss...

[John D.]

Re: 63 Master Cylinder Cap

Verne, Your logic on the master cylinder sounds good. But in reality the one inch mc's do give better braking. Did it on two 63's and noticed a big difference. There is a master cylinder from 63 and or maybe a 64 steel Chevy without the bail that is almost identical to the Corvette. In fact I have one here. I remember Armand Filer of Thousand Oaks, CA writing an article about them many years ago in "The Restorer". If you want I can find my NOS one and get the casting number from it. I do agree that most of the steel Chevy's used the bail type cap but not all of them. I remember that it was an Impala or a 409 or something other than the typical sedan. Maybe someone can help out here. Thanks, John

[John D.]

Re: There are four variations...

Jack, Should have read your post before I wrote mine. That's some good info you have there on the MC's. Now if can figure out what size font our '63's are supposed to have it would help. On the other hand maybe they did have two sizes echoing what you said. A lot of DB answers are echos and I don't want this one to be. On the other hand I personally don't care if the font is large or small. Just want a cover on my car that is not all eaten up. My car is early March. Has the small font. So then maybe Harry's cap is very early 63 then. Since you seem to know more than most about this part it would be nice for you to write a nice little article on them. Happy Thanksgiving, John

[Mike McKown]

Re: 63 Master Cylinder Cap

'62-'63 Corvair and Chevy II with metallic brake linings used a master cylinder with a thumb screw top that was very, very similar, if not the same as '63 Corvette including the 7/8 cast on the cylinder. If not equipped with metallic brakes, they used a very similar looking thumb screw cap with 1" bore.

As far as cylinder bore size, I'd have to agree with Verne. The smaller bore applies more pressure. It's difficult to get a car with metallic brakes to stop well unless they are at least warm. The smaller bore of the 7/8 cylinder vs. the 1" provides the extra boost required on cold metallic brake equipped Corvair, Chevy II and Chevelle. I don't know about full size. The smaller bore will also require a longer pedal stroke to apply pressure because the smaller cylinder doesn't displace as much fluid as the larger one but it does supply more pressure.

I did have the occasion to replace the small cylinder on my '63 Corvette with a 1". Same thing with my '65 Nova SS w/metallic brakes. I now have a higher pedal on both but the pedal force is much greater for the same deceleration rate with the larger cylinder installed.

As a matter of fact, I've often wondered if many of the C-2 owners that want to convert to power brakes haven't already had their original 7/8" master cylinder replaced with a 1" causing the higher effort.

[John D.]

Re: 63 Master Cylinder Cap

Mike, So once again our cars have Corvair parts on them. Course the same stuff was used throughout chevy production. Between you and Jack Humphrey,etc. we have learned a lot of insite on the master cylinders for our toys. I bet some of the cars mentioned also used the same master cylinder as the Z06??? Know that Checker cab did or some Chev cabs. Maybe some of the regular passenger cars did also. Interesting thing we all learned is that the MC cap sure made it rounds on a variety of models. No wonder so many variations in the font, size of font, and info. Thanks, John

[Verne Frantz]

[Verne Frantz]

The '62 Pass. Metallic brake master *NM*