'66 L79 crank pulley; faking "Parkolac"

[Gary B.]

I have the original crank pulley for my '66 L79, which is GM part #3858533. The newest edition of the '66 TIM&JG says the pulley should be "black phosphate and coated with 'Parkolac' or equivalent." Unfortunately, I restored the pulley about 4 years ago and I based my restoration on then current, 4th edition of the '66 TIM&JG which said the pulley could be either phosphate or semi-gloss black. I opted for the semi-gloss black. So, my question is, what is "Parkolac" and can something be applied or easily done to my painted pulley that will make it look like it's coated with Parkolac?

Gary

[David L.]

Re: '66 L79 crank pulley; faking "Parkolac"

Gary,

I have a pair of NOS 3755820 pulleys and they both have a charcoal gray non-smooth finish. I guess this is what is called "black phosphate". Isn't the process to get this finish somehow involve electrolysis or something like that.
I currently have a NOS 3858533 pulley and it is painted semi-gloss black but I believe that it was made in the 1980's.

Dave

[Gary B.]

Re: '66 L79 crank pulley; faking "Parkolac"

Dave,

I also have a 3858533 pulley that I bought from GM a few years ago (the part is still available from GM under that part number) and it is definitely painted semi-gloss black. So, the "recent" service part is not phosphate. I've read in the archives that most people think the change to semi-gloss black paint happened in the '70s or '80s.

Gary

[Mark G.]

Re: '66 L79 crank pulley; faking "Parkolac"

Gary -

This may help. https://www.forums.ncrs.org/showthre...78597&uid=3078

B. F. Goodrich had/has an alternate rubber resin coating. It still must pass the gasoline and salt spray tests.

[Gary B.]

Re: '66 L79 crank pulley; faking "Parkolac"

Mark,

I saw your May 2010 posting previously, but I wasn't certain if it applied to the crank pulley. In the '66 TIM&JG, the water pump pulley and crank pulley descriptions are different.

The crank pulley section talks about the " "Parkolac 30" or equivalent".

The water pump pulley section doesn't mention Parkolac. Instead it says "All [water pump] pulleys are either gray to black phosphate or an optional phosphate and a black rubber resin based spray coating." I assume the rubber resin spray coating being referred to there is the B.F. Goodrich #A-1256-B.

It would make sense to me the the optional B.F. Goodrich spray coating would apply to both the water pump pulley and the crank pulley. In the JG, the wording isn't consistent between the two pulleys.

Gary

[Gary B.]

BF Goodrich A-1256-B

Mark,

Unfortunately, a Google search for BF Goodrich A-1256-B produces no clear hits.

Gary

[Mark G.]

Re: '66 L79 crank pulley; faking "Parkolac"




I think the phosphate would clean and texture the steel so the Parkolac (black rubber resin) would have something to be into. Finishes needed to look good until the car sold and service parts would not rust on the self. This link is pretty good.

http://www.akd-tools.gr/xmsAssets/File/TDS/TEROSON/ubs_spray.pdf

Mark

[Gary B.]

Parkolac & BF Goodrich rubber resin

http://www.akd-tools.gr/xmsAssets/File/TDS/TEROSON/ubs_spray.pdf

Mark

Mark,

I'm not certain how similar the Teroson coating is to the BF Goodrich. The coating thickness spec on the Teroson is 400 to 500 micrometers, which is 0.016" to 0.020", which is 40 to 50 thicker than the 0.0004" thickness of the BF Goodrich spec. I wonder if the Teroson wouldn't make the part feel too much like it's rubber coated. I'd like to see an example part coated with the Teroson before I'd have my two pulley done with that.

Gary

[Ronald L.]

Re: '66 L79 crank pulley; faking "Parkolac"

Mark,

Were these notes in the original edition of the drawing? Or, a change noted in the revision column?

Interesting history, I knew and dealt with Parker Chemical Co of Madison Hgts, Ford bought them in '83 and then later sold them to Henkel.

Henkel still has the Bonderite process we used for a lot of chassis parts back in the 70's. I shot them an inquiry, let's see where it goes...

[Terry M.]

Re: '66 L79 crank pulley; faking "Parkolac"

Mark,

Were these notes in the original edition of the drawing? Or, a change noted in the revision column?

Interesting history, I knew and dealt with Parker Chemical Co of Madison Hgts, Ford bought them in '83 and then later sold them to Henkel.

Henkel still has the Bonderite process we used for a lot of chassis parts back in the 70's. I shot them an inquiry, let's see where it goes...

Parker Chemical Co. also marketed "Parkerizing" which is a phosphating process (several chemical baths) commonally used in the 1960s and early 1970s to surface treat parts so the lubricant uased in metal forming would be more effective.

[Ronald L.]

Re: '66 L79 crank pulley; faking "Parkolac"

As Terry has indicated the phosphate coating is the first step that etches the surfact and puts a crystal layer down that paint and other materials can stick to.

Here is Henkel's answer this morning, pasted below, how do we say day late & a dollar short?

OK - next step is to understand what Parkolac was how it looked as a finished part and how the new replacement material is different.


The Parcolac line was obsoleted this year due to a raw material shortage. Our suggested replacement is the P3 Prevox SN-400C. I have attached the MSDS and techincal process bulletin below. Please let me know if you need anything else.

Thank you for your interest in Henkel products!

[Gary B.]

Re: '66 L79 crank pulley; faking "Parkolac"

The Parcolac line was obsoleted this year due to a raw material shortage. Our suggested replacement is the P3 Prevox SN-400C. I have attached the MSDS and techincal process bulletin below. Please let me know if you need anything else.

Thank you for your interest in Henkel products!

Do you think this alternative has the same friction properties for use on a pulley as the BF Goodrich rubber resin or the Parkolac? I assume the standard oil treatment post-Phosphating would not be appropriate for a part that works with a belt via friction. A vendor might only be thinking of the rust or salt spray protection equivalent and not the functional requirements of the pulley.

Gary

[Ronald L.]

Re: '66 L79 crank pulley; faking "Parkolac"

Gary, I asked the question mid day, I would expect they'd get back to me later inthe afternoon.

[Gary B.]

Re: '66 L79 crank pulley; faking "Parkolac"

Gary, I asked the question mid day, I would expect they'd get back to me later inthe afternoon.

Ronald,

Also, the tech sheet or MSDS for the P3 Prevox SN400C describes it as a brown liquid. Depending on the hue of brown it gives to the part, the color could be a judging issue.

Gary

[Ronald L.]

Re: '66 L79 crank pulley; faking "Parkolac"

Gary,

No answer yet, but before we decide that the alternate coatings circle 3 and circle 4 are appropriate for 1966, we need to know the date they were added to the print.