66 PB master cylinder opinions needed

[Brian K.]

I'm looking for opinions if this 66 power brake master cylinder is an original or is one of the new repops. Thanks sincerely Brian

[Brian K.]

Re: 66 PB master cylinder opinions needed

A couple more pics. Thanks for looking.

[Michael G.]

Re: 66 PB master cylinder opinions needed

Brian,

I'll toss in my BG. Based solely on the mild pitting around the filler cap area I'm thinking the cylinder is the real deal.

[Joe L.]

Re: 66 PB master cylinder opinions needed

Brian------


I'd say it's an original GM piece, although not necessarily one that was originally installed on a car (i.e. possibly a SERVICE part).

By the way, even the reproductions that have the Delco-Moraine markings cost $850.

[Michael G.]

Re: 66 PB master cylinder opinions needed

Brian------

although not necessarily one that was originally installed on a car (i.e. possibly a SERVICE part).

What's your thought there Joe?

[Joe L.]

Re: 66 PB master cylinder opinions needed

What's your thought there Joe?

Michael------


In many cases, there's no real way to tell a part that was originally installed on a car from one that was sold in SERVICE. These master cylinders have no meaningful dates on them, so there's no way to even discern when it was manufactured. There are no configuration differences between PRODUCTION and SERVICE master cylinders of this part number.

[Brian K.]

Re: 66 PB master cylinder opinions needed

Thanks Michael and Joe.

[Bill M.]

Re: 66 PB master cylinder opinions needed

I'm looking for opinions if this 66 power brake master cylinder is an original or is one of the new repops. Thanks sincerely Brian

Based on another post it sounds like the repops are dated with a stamping. The originals are dated with a cast-in Julian date. If you can find out what the Julian date is cast into the repops that would probably tell the tale. This cylinder looks to be 005?

[Robert T.]

Re: 66 PB master cylinder opinions needed

I obviously haven't seen everyone ever made, but I looked at a lot when I was searching for mine. All the ones I looked at had a very pronounced "seam" down the middle of the casting. Pictures attached. Maybe the rebuilder ground them off. Maybe, but even the areas under the cap are perfectly aligned. Looks like a new mold to me. Just my 2 cents.

bt

[Dick W.]

Re: 66 PB master cylinder opinions needed

There are three master cylinders, the one made by Moraine, a now deceased vendor, and the ones presently reproing them today. There is a very minute difference in the OEM and the first repro's (one could look at them all day and never see the difference unless he knew what he was looking at. The current repro's that either CCSB or Lonestar has (don't know which one is actually having them made) I would expect to be spot on.

[Dan A.]

Re: 66 PB master cylinder opinions needed

There are three master cylinders, the one made by Moraine, a now deceased vendor There is a very minute difference in the OEM and the first repro's (one could look at them all day and never see the difference unless he knew what he was looking at.

I'm thinkin the person was not too far from Columbus Ohio with a first name beginning with a B. The part may not have had a casting date and some times the filler caps don't fit very well. N'est pas?

[Dick W.]

Re: 66 PB master cylinder opinions needed

I'm thinkin the person was not too far from Columbus Ohio with a first name beginning with a B. The part may not have had a casting date and some times the filler caps don't fit very well. N'est pas?

[Jeff S.]

Re: 66 PB master cylinder opinions needed

Brian

In addition to the mold parting line seam mentioned by Bob Taylor's response, the original m/cyl has eccentric & varying wall thickness on the filler cap bosses. See photos of my original (Jul '66 car) below. I'd say your photos are not of an original part.

Jeff

[Brian K.]

Re: 66 PB master cylinder opinions needed

Thanks for the catch Jeff, since I have this M/C in hand I just checked it and it does have varying thickness on the cap machined area. Caliper readings on the front fill area varies between 0.142 to 0.185 the rear is 0.170 to 0.201 . Again I want to thank you as I would like confirm its original, so far I'm leaning too its correct, Pros- the pitting under the caps on the machined surface and the brass inlets don't look new. Cons- the mold parting line looks to nice but when looking on the inside looks more miss matched and pronounced. This could be one of those old repops Dick metioned or OEM replacement or a cleaned up original, but I'm pretty sure now its not a new repop by Corvette Stainless Steel Brakes. Any other comments are more than welcome

Brian

In addition to the mold parting line seam mentioned by Bob Taylor's response, the original m/cyl has eccentric & varying wall thickness on the filler cap bosses. See photos of my original (Jul '66 car) below. I'd say your photos are not of an original part.

Jeff

[Brian K.]

Re: 66 PB master cylinder opinions needed

Dick would you happen to know what the differences are between the Moraine and the deceased vendor? Thanks for any info Sincerely Brian

There are three master cylinders, the one made by Moraine, a now deceased vendor, and the ones presently reproing them today. There is a very minute difference in the OEM and the first repro's (one could look at them all day and never see the difference unless he knew what he was looking at. The current repro's that either CCSB or Lonestar has (don't know which one is actually having them made) I would expect to be spot on.