Unpainted, machined areas on 65/66 brake calipers; A questionable area

[Joe L.]

Re: Unpainted, machined areas on 65/66 brake calipers; A questionable area

You are right. We made tooling for Danville when I worked for another pattern shop.. Dont know if Defiance OHIO GM foundry also cast them. When i started my own shop in 1976 we made them for Coldwater foundry & they were dipped in black paint.

Kenneth------


As you may be aware, there are two co-located GM foundries in Defiance, OH. One is a gray iron foundry that does (or, did) mainly engine blocks and cylinder heads. In fact, it was this foundry that cast big block cylinder blocks and heads after the Tonawanda foundry closed MANY years ago. I believe this foundry has now been converted to aluminum sand castings for things like cylinder blocks and heads.

The other foundry in Defiance is (or was) a nodular iron foundry. It cast mostly other engine components like flywheels, crankshafts, etc. But, I'm pretty sure it also made other types of nodular iron castings. It's very possible that it was the source of the 1965-66 Corvette brake calipers.

[Kenneth B.]

Re: Unpainted, machined areas on 65/66 brake calipers; A questionable area

The foundry ID you call a hour glass is the Midwest foundry. M over W.

[Mark F.]

Re: Unpainted, machined areas on 65/66 brake calipers; A questionable area

The foundry ID you call a hour glass is the Midwest foundry. M over W.

thank you, Ken...

and if you want a 1985 vintage souvenir of that plant, type into Google:

"Vintage Midwest Foundry Paperweight Marmon Group Coldwater Michigan Cast Iron"

and you should go to an eBay listing with this image:

Midwest Foundry Marmon logo paperweight_001.jpg

[Joe L.]

Re: Unpainted, machined areas on 65/66 brake calipers; A questionable area

The foundry ID you call a hour glass is the Midwest foundry. M over W.

[Kenneth B.]

Re: Unpainted, machined areas on 65/66 brake calipers; A questionable area

I have a Midwest piggy bank that we made the patterns for.

[Gary B.]

Re: Unpainted, machined areas on 65/66 brake calipers; A questionable area

Does anyone have an idea how long after the caliper halves were machined before they were assembled with seals and pistons? I suspect not long since the freshly machined surfaces would start to quickly rust from humidity.

Gary

[Mark F.]

Re: Unpainted, machined areas on 65/66 brake calipers; A questionable area

Does anyone have an idea how long after the caliper halves were machined before they were assembled with seals and pistons? I suspect not long since the freshly machined surfaces would start to quickly rust from humidity. Gary

Hi Gary,

Machining of castings and downline assembly of whatever those castings were for that I have seen (mostly engine plants) occur in a continuous sequence.

In other words, the raw castings go into multiple enclosed tooling booth stations that are DRENCHED with cutting fluids. Those fluids were just transitioning to heavily-amended water-based "oil-like-emulsions" in some operations I saw, but many were still straight oil-based.

Regardless of what cutting fluids were used, the fully machined part had to be cleaned (vapor degreased; dipped; sprayed; whatever) before flowing into the assembly line for whatever part was involved.

I don't recall seeing lots of storage areas for fully machined and cleaned parts waiting for follow-up assembly; casting blanks waiting for machining was a different story.

So, short of line shut-downs - or break-downs, TFP for most castings that required follow-on assembly operations were fairly continuous. I never saw caliper assembly lines, but I'll bet their line speeds (and others I did see) precluded significant corrosion as far as I can remember.

[David B.]

Re: Unpainted, machined areas on 65/66 brake calipers; A questionable area

A lot of OPINIONS on this thread.. If I had to choose any I would stick with G.M. Engineering drawing specs. (that is why they are created). The particular prints referenced are Delco Moraine 5452270 thru 5452274, Pearlitic Malleable iron G.M. 85-M drawn 4-9-65 and updated thru 8-2-71 (Joe's research appears right on). 5452271-2 are machine drawings with very specific specs and contain no reference to dipping in paint prior to machining, only specifies D.M.-6034.

[Mark F.]

Re: Unpainted, machined areas on 65/66 brake calipers; A questionable area

A lot of OPINIONS on this thread.. If I had to choose any I would stick with G.M. Engineering drawing specs. (that is why they are created)...

Totally agree (stick w/ original specs).
But how many of us have access to any of them ?
If we do, I'd love to know where that is.

[Gary B.]

Re: Unpainted, machined areas on 65/66 brake calipers; A questionable area

Speaking of opinion, in my opinion, the photos that Jack posted and the descriptions by Ken are convincing evidence and far from just their opinions.

Now maybe the DM-6034 coating called out in the engineering specs winds up looking like a dead ringer for black paint. We may never knew. In which case black paint on the non-machined calipers areas is apt to remain the accepted finish for judging.

Gary

[Rocco S.]

Re: Unpainted, machined areas on 65/66 brake calipers; A questionable area

I realize this is an older thread but wanted to share some information sent to me by a good friend and Corvette owner. He found the attached Delco Moraine Engineering Production Parts List on a Camaro site. It relates to Master Cylinders but calls out "DM-6034" as "Paint-Black". The release date of this document was 11-26-1966.
So it would seem that the 1966 Corvette Brake Calipers would have had the same DM-6034 coating (black paint). Hope this helps answer the question.
Delco Moraine Master Cylinder.jpg

[Gary B.]

[Jack M.]

Re: Unpainted, machined areas on 65/66 brake calipers; A questionable area

I realize this is an older thread but wanted to share some information sent to me by a good friend and Corvette owner. He found the attached Delco Moraine Engineering Production Parts List on a Camaro site. It relates to Master Cylinders but calls out "DM-6034" as "Paint-Black". The release date of this document was 11-26-1966.
So it would seem that the 1966 Corvette Brake Calipers would have had the same DM-6034 coating (black paint). Hope this helps answer the question.
[ATTACH=CONFIG]122837[/ATTACH]

Excellent job, Rocco... pretty much as we suspected, and appears to add detail to David's caliper print notation.
Additionally, it seemz to match what Ken witnessed at the foundry, as well as period correct assembly line images.