Can you tell a repop from an original 67 master cylinder?

[Chris E.]

The title says it all. How close is the repop to the original?

[Tom M.]

Re: Can you tell a repop from an original 67 master cylinder?

Chris,

The only difference I have noted when I had them side by side was in the size of the DC stamp.

[Chris E.]

Re: Can you tell a repop from an original 67 master cylinder?

Any other comments?

If I put a repop on my car, it doesn't sound like it will get a deduction?

[Joe L.]

Re: Can you tell a repop from an original 67 master cylinder?

Chris,

The only difference I have noted when I had them side by side was in the size of the DC stamp.

Tom-----


One other possible difference is the material the master cylinders are cast from. Originals were cast from malleable/ductile iron. I don't know what the reproductions are cast from. I made inquiry to the primary supplier of these master cylinders and my inquiry was ignored. That may mean they don't know (not a good thing) or they know they are not manufactured from the original material and don't want that information to "get out" (an even worse thing).

So, why is the material important?

1) If they are manufactured from gray iron (as I suspect), this material is not nearly as strong as malleable/ductile iron. Is gray iron adequately strong for the master cylinder application? I strongly suspect that it is, but it's not as strong as the original material;

2) I have noted over the years that sand castings manufactured from malleable/ductile iron seem to have a slightly smoother surface texture than those manufactured from gray iron. In fact, this is the primary reason I suspect the master cylinder reproductions are manufactured from gray iron------to my eye, they seem to have a SLIGHTLY rougher surface texture than original master cylinders.

Would I use one of the reproductions? Yes.

[Jim O.]

Re: Can you tell a repop from an original 67 master cylinder?

I don't know why you want to replace your master cylinder. If it is corroded and severely pitted in the piston bore you can repair it with a bronze sleeve. I had this process done and it works great with no more concerns with corrosion. Hope this helps.

[Chris E.]

Re: Can you tell a repop from an original 67 master cylinder?

The master cylinder that I took off the car was wrong for 67 (no bleeders).

[Joe L.]

Re: Can you tell a repop from an original 67 master cylinder?

The master cylinder that I took off the car was wrong for 67 (no bleeders).

Chris-----


Assuming the master cylinder has the correct casting number (i.e. 5455509), you can easily add non-functional bleeder valves and make the master cylinder configurationally correct. No observer, including judges, will ever know that the bleeders are non-functional. You don't otherwise need the bleeders as bench bleeding does not require them and bench bleeding is what you need to do. I believe this is why the bleeders were eliminated from these master cylinders in the early 70's.

To install non-functional bleeders obtain 2 configurationally correct bleeder valves. Mill down the threaded end until it's only about 3/16" long. Then, drill and tap the master cylinder boss, dead center on the boss. Install and tighten the bleeders. Done. No one will be the wiser.

[Joe R.]

Re: Can you tell a repop from an original 67 master cylinder?

The title says it all. How close is the repop to the original?

Hi Chris:

The reproduction casting is very close to the original. I *think* I can tell the difference from an original, but I don't think I would deduct for it during judging.

The difference that I have seen in comparing known 1967 originals to the reproduction is in the recessed area circled in the attached photo. The originals I have seen have a wide, almost oval shape to the recessed area, while the reproductions have a narrower, round shape.

Just because I've seen SOME originals with this difference from the reproduction doesn't mean that ALL originals are the same. I know that the vendor who makes the reproductions worked pretty hard to match what they thought was the original design. So, until I have more data, I'm willing to give them the benefit of the doubt that perhaps some originals had the narrower recess.

I'd be interested in comments/photos from others who have original or reproduction units.

BTW, the font used on reproduction cap does differ somewhat from teh original, and I think the difference might justify a 1 point deduction.

[Kenneth B.]

Re: Can you tell a repop from an original 67 master cylinder?

Tom-----


One other possible difference is the material the master cylinders are cast from. Originals were cast from malleable/ductile iron. I don't know what the reproductions are cast from. I made inquiry to the primary supplier of these master cylinders and my inquiry was ignored. That may mean they don't know (not a good thing) or they know they are not manufactured from the original material and don't want that information to "get out" (an even worse thing).

So, why is the material important?

1) If they are manufactured from gray iron (as I suspect), this material is not nearly as strong as malleable/ductile iron. Is gray iron adequately strong for the master cylinder application? I strongly suspect that it is, but it's not as strong as the original material;

2) I have noted over the years that sand castings manufactured from malleable/ductile iron seem to have a slightly smoother surface texture than those manufactured from gray iron. In fact, this is the primary reason I suspect the master cylinder reproductions are manufactured from gray iron------to my eye, they seem to have a SLIGHTLY rougher surface texture than original master cylinders.

Would I use one of the reproductions? Yes.

I built patterns for a lot of the master cylinders from 1963 on. They were for Delco Moraine. They were cast in Coldwater Mi. at Midwest Foundry which was a gray Iron foundry. I don't recall any master cylinders made with anything but gray iron. no reason. Calipers heads blocks were all gray iron. In fact ductile iron as it was fairly new alloy & had to be licensed by a British co. was not used on cars till later & only because they were trying to save weight. Malleable iron/ductile was only used because of its tensile strength for flexing ability not strength. Rear ends were made of malleable iron because they needed to flex a bit at Albion Mallable in Albion Mi. for Dana/GM in the day
KEN

[Kenneth B.]

Re: Can you tell a repop from an original 67 master cylinder?

Also the finish has only to do with the sand & how much the casting was cleaned in the wheelabrater befor shipping not the alloy.
KEN

[Jack C.]

Re: Can you tell a repop from an original 67 master cylinder?

I see here that no one is talking about the m/c cover itself. Can someone chime in (Grant Wong).

[Gerard F.]

Re: Can you tell a repop from an original 67 master cylinder?

Chris,

I put a 67 CSSI master cylinder on my 67 when their new repro just came out (in 2006).

Judged twice and I don't think I lost more than 1 or two points.

At the 2006 judging, I told the then Team Leader that it was the new repro after it had been judged. We had a 67 with it's true original (same DC) M/C sitting right next to mine. So we had a little exercise going back and forth between the two cars comparing the two. Be darned if we could tell the difference visually.

The actual difference was in the material for the bales and bleeders being SS. There are also some slight differences in the size and spacing of the lettering on the cap, which a few judges would pick up on (like Joe R in this thread )

[Gerard F.]

Re: Can you tell a repop from an original 67 master cylinder?

Sorry Chris, it was CSSB for my M/C supplier.

Take a look at this thread form 2006:

https://www.forums.ncrs.org/showthre...inder&uid=4953

After it was compared with an original in the field at an April 2006 Regional, it received a no deduct.

[Joe R.]

Re: Can you tell a repop from an original 67 master cylinder?

I see here that no one is talking about the m/c cover itself. Can someone chime in (Grant Wong).

Hi Jack:

I mentioned the cap fonts in an earlier email, but a photo helps to clarify the differences. Since the TDB won't let me upload the same photo twice, see the photo in my earlier post in the thread at:

https://www.forums.ncrs.org/showthre...60881&uid=2785

In particular, compare the "W" and the "D" characters.

[Jack C.]

Re: Can you tell a repop from an original 67 master cylinder?

Thanks, my 68 has the same cap as the 67.